@article {20_TAP_EDUARDO_PABLO_BOWTIE_UNITARIO, title = {Bow-Tie-Shaped Radiating Element for Single and Dual Circular Polarization}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {68}, number = {2}, year = {2020}, month = {Feb}, pages = {754-764}, keywords = {Antennas, Aperture antennas, bow-tie rotator, orthogonal polarizations}, issn = {1558-2221}, doi = {10.1109/TAP.2019.2943357}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares and J A Ruiz-Cruz} } @article {20_EDUARDO_MONOPULSE_DIFUSSION, title = {Diffusion-bonded W-band monopulse array antenna for space debris radar}, journal = {AEU - International Journal of Electronics and Communications}, volume = {116}, year = {2020}, pages = {153061}, abstract = {In this letter, the design and fabrication of a W-band high-gain monopulse array antenna are presented. The antenna is conceived as a proof of concept for a space debris detection project to develop an on-board radar for a satellite system. The antenna array consists of 16 by 16 circularly polarized radiating cavities fed by a corporate waveguide network with an amplitude taper. An underlying monopulse beamforming network is implemented in waveguide technology as well, providing monopulse capability in both main radiating planes. By means of diffusion bonding, the antenna has been fabricated in a single piece, despite its intricate, multilayer topology. Moreover, the experimental performance shows high agreement with simulations, which is remarkable due to the high sensitivity to manufacturing tolerances at this frequency. Over a 10\% bandwidth is experimentally achieved for efficiency over a 75\%, axial ratio under 3~dB and impedance matching under -10~dB.}, keywords = {millimeter wave technology, Planar arrays, radar antennas}, issn = {1434-8411}, doi = {https://doi.org/10.1016/j.aeue.2019.153061}, url = {http://www.sciencedirect.com/science/article/pii/S1434841119320436}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @article {20_EDU_PABLO_ARRAY_GUIA_CUADRADA, title = {Dual Circularly Polarized Array Antenna based on Corporate Feeding Network in Square Waveguide Technology}, journal = {IEEE Transactions on Antennas and Propagation}, year = {2020}, pages = {1-1}, keywords = {Antenna arrays, omnidirectional antennas, Slot antennas}, issn = {1558-2221}, doi = {10.1109/TAP.2020.3019355}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares and J A Ruiz-Cruz} } @conference {20_EUCAP2020_ARRAY_DUAL_BOWTIE_EDUARDO, title = {Dual Circularly Polarized Waveguide Array Antenna Formed by Full-Metallic Bow-tie Radiating Cavities}, booktitle = {2020 14th European Conference on Antennas and Propagation (EuCAP)}, year = {2020}, month = {March}, pages = {1-5}, abstract = {A full-metallic dual circularly polarized antenna based on an array of bow-tie shaped radiating elements is presented in this contribution. The radiating element, formed by a bow-tie shaped cavity, can generate dual circular polarization. It is fed by a square waveguide path that supports the two degenerate modes TE10 and TE01. The excitation of the TE10 mode in the input port generates left-hand circular polarization while the TE01 mode generates right-hand circular polarization. Furthermore, a dual circularly polarized array antenna formed by bow-tie radiating elements has been designed. The two degenerate modes TE10 and TE01 are supported by a four-way feeding network implemented in square waveguide technology. Both the single radiating element and the dual circularly polarized array have been fabricated by CNC milling techniques. A pure circular polarization performance, high gain or high efficiency have been obtained, experimentally validating the dual circularly polarized bow-tie element in an array configuration.}, keywords = {antenna diversity, Aperture antennas, Dual-polarized antennas, waveguide arrays}, doi = {10.23919/EuCAP48036.2020.9135228}, author = {E Garcia-Marin and P Sanchez-Olivares and J L Masa-Campos and J A Ruiz-Cruz and J Herranz-Alpanseque} } @article {20_ANTENA_ARRAY_DUAL_SLOT_BOMBARDERO_KUMAR, title = {Dual-linearly polarized travelling-wave array antenna based on triple plus slots fed by square waveguide}, journal = {AEU - International Journal of Electronics and Communications}, volume = {119}, year = {2020}, pages = {153176}, abstract = {A dual-linearly polarized travelling-wave array antenna design at Ku-band composed by a novel single element named as triple plus slot is presented. It is formed by a plus slot with an additional pair of short auxiliary slots. The generation of the dual polarization is based on the two degenerated modes TE10 and TE01 supported by a square waveguide following a series feeding topology. Following the operation principle of the conventional plus slot, the transversal slot is only excited by the TE10 mode to generate vertical polarization while the longitudinal slot is only excited by the TE01 mode to generate horizontal polarization. The auxiliary slots provide new degrees of freedom to the antenna design process that allow to accomplish some strict requirements and overcome some design issues. Thus, the proposed triple plus slot has been experimentally validated in a dual-linearly polarized travelling-wave array configuration. The antenna has been fabricated and measured, providing some features such as high efficiency (>80\%), high gain (>13~dB) with a 1~dB-gain bandwidth higher than 10\%, grating lobe mitigation, high isolation between orthogonal polarizations (>25~dB) as well as a fractional impedance bandwidth (S11~<~-14~dB) higher than 11.7\% (from 16 to 18~GHz).}, keywords = {Antenna arrays, Dual-polarized antennas, Slot antennas}, issn = {1434-8411}, doi = {https://doi.org/10.1016/j.aeue.2020.153176}, url = {http://www.sciencedirect.com/science/article/pii/S1434841119332042}, author = {P Sanchez-Olivares and J L Masa-Campos and E Garcia-Marin and D Barrio-Tejedor and P Kumar} } @article {20_TAP_PABLO_ESCALONA_SLOT_CONFORMAL_CIRCULAR_WAVEGUIDE, title = {High-Gain Conical-Beam Traveling-Wave Array Antenna Based on a Slotted Circular Waveguide at $Ku$ -Band}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {68}, number = {8}, year = {2020}, month = {Aug}, pages = {6435-6440}, abstract = {A high-gain conical-beam traveling-wave array antenna based on a slotted circular waveguide is designed at the higher part of Ku-band. A single radiating element is formed by a ring of eight equally spaced slots fed by a circular waveguide. The excitation of the nonfundamental TM01 mode provides a uniform feeding distribution to each slot, generating an omnidirectional radiation performance. Thus, an array antenna formed by 48 rings of slots is proposed following the design rules of traveling-wave arrays. Every ring is properly designed to achieve a uniform power distribution and consequently maximum directivity for the array antenna performance. The distance between elements is also adjusted to obtain the better input matching response and mitigate the grating lobe appearance, generating a high-gain conical-beam radiation performance suitable for satellite and fifth-generation communications. The proposed antenna design has been manufactured in plastic material by using a 3-D printing process and plated by a spray metallization process. A -10 dB impedance bandwidth higher than 23\%, high-gain values around 13.5 dB, or total efficiency higher than 98\% has been achieved for the whole frequency band.}, keywords = {Antenna arrays, antenna radiation patterns, circular waveguides, Couplings, Dipole antennas, omnidirectional antennas, Slot antennas}, issn = {1558-2221}, doi = {10.1109/TAP.2020.2970031}, author = {P Sanchez-Olivares and J L Masa-Campos and E Garcia-Marin and D Escalona-Moreno} } @conference {20_EUCAP2020_LENTE_BOULDER_EDUARDO, title = {Ka-band Multi-beam Planar Lens Antenna for 5G Applications}, booktitle = {2020 14th European Conference on Antennas and Propagation (EuCAP)}, year = {2020}, month = {March}, pages = {1-5}, abstract = {A low-cost solution for multi-beam antenna systems is explored for 5G applications in the 26-GHz band. A 4-port stacked-patch microstrip antenna is used as feeder of a perforated flat lens. Each feeder is placed in a different position with respect to the lens, yielding four high-directivity independent beams. The beams cover an angular range from broadside to a 30-degree steering with a gain over 18 dB. The antenna has been implemented by low-cost processes, employing Printed Circuit Board fabrication for the feeder and 3D printing for the lens.}, keywords = {5G mobile communication, Beam steering, Microstrip antennas}, doi = {10.23919/EuCAP48036.2020.9135364}, author = {E Garcia-Marin and D S Filipovic and J L Masa-Campos and P Sanchez-Olivares} } @article {20_LENTE_PARCHES_BOULDER_EDUARDO, title = {Low-cost lens antenna for 5G multi-beam communication}, journal = {Microwave and Optical Technology Letters}, volume = {n/a}, number = {n/a}, year = {2020}, abstract = {Abstract A planar dielectric lens has been designed for low-cost multi-beam antennas in the 26-GHz band of 5G communications. The lens feeder is a stacked-patch microstrip antenna with four input ports, thus permitting four independent high-directivity radiation beams. Maximum steering of 25{\textdegree} can be attained, which a simulated gain over 18 dB for all scanning angles. The antenna has been implemented with low-cost manufacturing techniques. The feeder is fabricated as a printed circuit board, while the lens is realized as a perforated 3D-printed dielectric piece. Experimental results confirm the multi-beam capability of the lens system, suggesting that the spillover efficiency can be improved in further works.}, keywords = {5G mobile communication, Beam steering, Microstrip antennas}, doi = {10.1002/mop.32486}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.32486}, author = {E Garcia-Marin and D S Filipovic and J L Masa-Campos and P Sanchez-Olivares} } @article {20_IEEE ACCESS_LUCAS POLO_ARRAY DESFASADORES TORNILLOS, title = {Mechanically Reconfigurable Linear Phased Array Antenna Based on Single-Block Waveguide Reflective Phase Shifters With Tuning Screws}, journal = {IEEE Access}, volume = {8}, year = {2020}, pages = {113487-113497}, abstract = {This work presents the design and prototyping of a reconfigurable phased array in Ku band (16 to 18 GHz) implemented in waveguide technology. The design is based on the use of a novel seamless waveguide module integrating four reconfigurable phase shifters to adjust the relative phase shift between the unitary elements of a linear array, which are illuminated uniformly by a corporate waveguide feeding network. The phase shifters are implemented by a 90{\textdegree} hybrid coupler in waveguide technology where two of its ports are loaded with a tunable reactive load, implemented in this proof of concept with a tuning screw. The four phase shifters have been manufactured in a single part using direct metal laser sintering, avoiding the losses related to bad electric contacts and misalignments associated to multipart devices. This also simplifies the assembly of the full phased array, leading to a modular approach with three parts whose design can be addressed separately. The experimental results for the complete array antenna show great performance and demonstrate that the main-lobe of the radiation pattern can be effectively scanned continuously between the angles -25{\textdegree} and 25{\textdegree}, with a high efficiency in the whole design band thanks to the proposed waveguide implementation.}, keywords = {antenna radiation patterns, Beam steering, Couplers, Fasteners, linear antenna arrays, phase shifters, Phased arrays}, issn = {2169-3536}, doi = {10.1109/ACCESS.2020.3003193}, author = {L Polo-Lopez and J L Masa-Campos and A T Muriel-Barrado and P Sanchez-Olivares and E Garcia-Marin and J C{\'o}rcoles and J A Ruiz-Cruz} } @article {Haro-Baez2020, title = {A new 4 x 4 rectangular waveguide short-slot coupler in 3d printed technology at ku-band}, journal = {Electronics (Switzerland)}, volume = {9}, number = {4}, year = {2020}, note = {cited By 0}, doi = {10.3390/electronics9040610}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084128425\&doi=10.3390\%2felectronics9040610\&partnerID=40\&md5=ea2d24ab6f28e22c3ef1c4566c8ba61f}, author = {Haro-Baez, R.V. and Ruiz-Cruz, J.A. and J C{\'o}rcoles and Montejo-Garai, J.R. and Rebollar, J.M.} } @article {Mor{\'a}n-L{\'o}pez2019944, title = {Analytical expressions of the Q-factor for the complete resonant mode spectrum of the equilateral triangular waveguide cavity}, journal = {Electronics Letters}, volume = {55}, number = {17}, year = {2019}, note = {cited By 0}, pages = {944-947}, doi = {10.1049/el.2019.1420}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070995669\&doi=10.1049\%2fel.2019.1420\&partnerID=40\&md5=19090b75e53bc347286c215ec3e93256}, author = {Mor{\'a}n-L{\'o}pez, A. and Ruiz-Cruz, J.A. and J C{\'o}rcoles and Montejo-Garai, J.R. and Rebollar, J.M.} } @article {19_ANT_MAG_PABLO_PAULA_CONFORMADA_DIODOSPIN_3_5GHZ, title = {Circular Conformal Array Antenna With Omnidirectional and Beamsteering Capabilities for 5G Communications in the 3.5-GHz Range [Wireless Corner]}, journal = {IEEE Antennas and Propagation Magazine}, volume = {61}, number = {4}, year = {2019}, month = {Aug}, pages = {97-108}, keywords = {5G communications, 5G mobile communication, 5G terrestrial communications, Antenna arrays, antenna radiation patterns, array elements, array signal processing, Beam steering, circular conformal array antenna, Conformal antenna, Conformal antennas, conformal structure, double-stacked microstrip patches, eight-way tunable feeding network, frequency 3.5 GHz, Frequency measurement, microstrip, microstrip antenna arrays, octagonal holding structure, omnidirectional antennas, omnidirectional radiation, P-i-n diodes, Power dividers, single radiating elements, T-junction operation modes, TFN network, tunable T-junctions}, issn = {1558-4143}, doi = {10.1109/MAP.2019.2920049}, author = {P Sanchez-Olivares and P Sanchez-Dancausa and J L Masa-Campos and M Iglesias-Menendez-de-la-Vega and E Garcia-Marin} } @conference {19_URSI_PABLO_CONICAL_ARRAY_SLOTTED_ESCALONA, title = {Conical-beam travelling-wave array antenna based on slotted circular waveguide at Ku-band}, booktitle = {Simposium Nacional URSI 2019}, year = {2019}, month = {September}, abstract = {A high-gain conical-beam travelling-wave array antenna based on a slotted circular waveguide is designed at the higher part of Ku-band (16-18 GHz). The single radiating element is formed by a ring of equally spaced slots fed by a circular waveguide. The excitation of the TM01 mode provides a uniform feeding distribution to each slot, generating an omnidirectional radiation performance. Thus, an array antenna formed by 48 rings of slots is proposed following the conventional design rules of travelling-wave arrays. Every ring is optimized to achieve a uniform power distribution and consequently maximum directivity for the array antenna performance. The distance between elements is also adjusted to obtain the better input matching response and mitigate the grating lobe appearance, generating a high-gain conical-beam radiation performance suitable for satellite communications. The proposed design has been manufactured by using a 3D printing process. Input matching under -15 dB, high-gain values around 13.5 dB or total efficiency higher than 98\% have been achieved for the whole frequency band.}, author = {P Sanchez-Olivares and J L Masa-Campos and D Escalona-Moreno and E Garcia-Marin} } @conference {19_URSI_EDUARDO_MONOPULSO_DIF_BONDING, title = {Diffusion-bonded circularly polarized W-band monopulse array antenna}, booktitle = {Simposium Nacional URSI 2019}, year = {2019}, month = {September}, abstract = {A W-band circularly polarized antenna array with monopulse capability has been designed and fabricated by diffusion bonding of copper plates. The antenna is presented as a proof of concept for a space debris radar project. A waveguide monopulse beamforming network provides monopulse operation in the two main radiation planes. The feeding network is implemented in waveguide technology as well, with corporate topology and amplitude tapering to ensure adequate radiation patterns for the monopulse system. Circular polarization is straightforwardly achieved by hexagonal-shaped radiating cavities. Experimental results validate diffusion bonding for complex multilayer antenna fabrication at W-band, providing a bandwidth over 10\% for axial ratio under 3 dB, impedance matching under -10 dB and total efficiency over 75\%.}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {19_EUCAP_PABLO_ANTENA_BOMBARDERO, title = {Dual Polarized Travelling-Wave Array Antenna Formed by Printed Cross Slots}, booktitle = {2019 13th European Conference on Antennas and Propagation (EuCAP)}, year = {2019}, month = {March}, pages = {1-5}, keywords = {Antenna arrays, Antenna measurements, Arrayed waveguide gratings, Couplings, dual linear polarization, dual polarization, dual polarized array antenna, dual polarized travelling-wave array antenna, electromagnetic wave polarisation, linear antenna arrays, linear orthogonal polarizations, longitudinal slots, microstrip antenna arrays, mutual coupling effects, printed cross slots, rectangular waveguides, slot antenna arrays, Slot antennas, square waveguide feeding, transversal slots}, issn = {null}, url = {https://ieeexplore.ieee.org/document/8740194}, author = {P Sanchez-Olivares and J L Masa-Campos and P Kumar and E Garcia-Marin} } @article {Haro-B{\'a}ez2019, title = {Higher-Order Mode Electromagnetic Analysis of a Material Sample between Two Flanged Coaxial Probes for Broadband Modelling of Dielectric Measurement Setups}, journal = {Advances in Mathematical Physics}, volume = {2019}, year = {2019}, note = {cited By 2}, doi = {10.1155/2019/6404812}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060546268\&doi=10.1155\%2f2019\%2f6404812\&partnerID=40\&md5=99dfa79bacb0fc265d2b665e49630370}, author = {Haro-Baez, R.V. and J C{\'o}rcoles and Ruiz-Cruz, J.A. and Montejo-Garai, J.R. and Rebollar, J.M.} } @conference {19_IMWS_AMP_EDUARDO_INKJET_PATCH_MALAGA, title = {Ink-jet Implementation of Stacked-Patch Antenna for Wireless Applications}, booktitle = {2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP)}, year = {2019}, month = {July}, pages = {151-153}, keywords = {antenna bandwidth, Antenna measurements, Antennas, Bandwidth, conductive silver ink, dielectric materials, frequency 5.0 GHz, high-impact polystyrene substrate, Hip, ink jet printing, ink-jet implementation, ink-jet printing, Kapton film, Kapton layer, mechanical stability, microstrip, Microstrip antennas, microstrip lines, Patch antennas, silver, stacked-patch antenna, Substrates, Three-dimensional printing, wireless applications, Wireless LAN}, issn = {null}, doi = {10.1109/IMWS-AMP.2019.8880078}, author = {E Garcia-Marin and E M{\'a}rquez-Segura and P Sanchez-Olivares and J L Masa-Campos and J A Ruiz-Cruz and C Camacho-Pe{\~n}alosa} } @article {19_ANT_MAG_EDUARDO_5G_SIW, title = {Planar Array Topologies for 5G Communications in Ku Band [Wireless Corner]}, journal = {IEEE Antennas and Propagation Magazine}, volume = {61}, number = {2}, year = {2019}, month = {April}, pages = {112-133}, keywords = {5G communication environment, 5G communications, 5G mobile communication, antenna array, Antenna arrays, antenna feeds, antenna radiation patterns, dielectric losses, directivity performance, feeding network configurations, Ku band, microstrip, microstrip antenna arrays, Microstrip antennas, microstrip dielectric loss, planar antenna arrays, planar array topologies, radiating elements, SIW feeding network, SIW technologies, substrate integrated waveguide, substrate integrated waveguides, Substrates, two-level corporate feeding network}, issn = {1558-4143}, doi = {10.1109/MAP.2019.2895633}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @article {19_ANT_MAG_EDUARDO_5G_SIW, title = {Planar Array Topologies for 5G Communications in Ku Band [Wireless Corner]}, journal = {IEEE Antennas and Propagation Magazine}, volume = {61}, number = {2}, year = {2019}, month = {April}, pages = {112-133}, keywords = {5G communication environment, 5G communications, 5G mobile communication, antenna array, Antenna arrays, antenna feeds, antenna radiation patterns, dielectric losses, directivity performance, feeding network configurations, Ku band, microstrip, microstrip antenna arrays, Microstrip antennas, microstrip dielectric loss, planar antenna arrays, planar array topologies, radiating elements, SIW feeding network, SIW technologies, substrate integrated waveguide, substrate integrated waveguides, Substrates, two-level corporate feeding network}, issn = {1558-4143}, doi = {10.1109/MAP.2019.2895633}, author = {E. Garcia-Marin and J. L. Masa-Campos and P. Sanchez-Olivares} } @article {19_IJRFMCAE_LUCAS_DESFASADOR_PLANO_H_DMLS, title = {Reconfigurable H-plane waveguide phase shifters prototyping with additive manufacturing at K-band}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {29}, number = {12}, year = {2019}, pages = {e21980}, abstract = {Abstract This work presents the design and manufacturing of a K-band reconfigurable phase shifter completely implemented in waveguide technology for reduced insertion loss, good matching, and large phase shifting range. The device is based on the combination of a short slot coupler and two tunable reactive loads implemented as a section of short-circuited waveguide where an adjustable metallic post is inserted. Three prototypes of this design have been manufactured using different techniques (conventional computer numerical control machining, a low-cost fused filament fabrication technique and direct metal laser sintering) in order to assess its performance for different applications. The prototypes have been characterized experimentally and the achieved results are evaluated and compared. The proposed phase shifter, since it is fully developed in waveguide technology, eliminates the need of adding transitions to planar structures in order to integrate lumped components like pin diodes or varactors. Therefore, this device has a great potential in high-power beam steering phased arrays.}, keywords = {additive manufacturing, fused filament fabrication, phase shifter, reconfigurable, selective laser sintering, waveguide}, doi = {10.1002/mmce.21980}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/mmce.21980}, author = {L Polo-Lopez and J L Masa-Campos and J A Ruiz-Cruz} } @article {Polo-L{\'o}pez20192781, title = {On the Theoretical Maximum Directivity of a Radiating Aperture from Modal Field Expansions}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {67}, number = {4}, year = {2019}, note = {cited By 1}, pages = {2781-2786}, doi = {10.1109/TAP.2019.2896660}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064268357\&doi=10.1109\%2fTAP.2019.2896660\&partnerID=40\&md5=aaf2b48c5f18f5b72e611774c27cbfea}, author = {Polo-Lopez, L. and J C{\'o}rcoles and Ruiz-Cruz, J.A. and Montejo-Garai, J.R. and Rebollar, J.M.} } @article {19_MOTL_BRANDE_ARRAY UWB, title = {UWB four elements antenna array}, journal = {Microwave and Optical Technology Letters}, volume = {61}, number = {5}, year = {2019}, pages = {1284-1294}, abstract = {Abstract In this work, a planar UWB four elements antenna array with and without notch filter is designed. The feeding system of the array is an UWB four branch multiple segment power divider/combiner. Each branch has a three segments impedance transformer. Measurements show that the array works well within the band 3.1 to 10.6 with S11 lower than -10 dB. It is shown that the maximum gain varies with the operating frequency having a value of 8 to 12.3 dB and that it is higher than the gain of the single element.}, keywords = {antenna array, notch filters, ultra-wideband antennas}, doi = {10.1002/mop.31664}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.31664}, author = {B T Ahmed and J L Masa-Campos and D Brande-Hern{\'a}ndez} } @conference {19_EUCAP_EDUARDO_MONOPULSO_DIFF_BONDING, title = {W-band Monopulse Antenna Array Manufactured by Diffusion Bonding}, booktitle = {2019 13th European Conference on Antennas and Propagation (EuCAP)}, year = {2019}, month = {March}, pages = {1-5}, keywords = {16 circularly polarized radiating cavities, antenna feeds, antenna radiation patterns, array signal processing, beamforming network, copper sheets, corporate waveguide feeding network, Diffusion bonding, diffusion bonding technology, electromagnetic wave polarisation, etching, etching proces, frequency 90.0 GHz to 98.0 GHz, impedance matching, input matching, millimeter wave technology., millimetre wave antenna arrays, monopulse capabilities, noise figure -10.0 dB, noise figure -15.0 dB, noise figure -20.0 dB, noise figure 2.0 dB, Planar arrays, principal radiation planes, radar antennas, simulated axial ratio, Taylor distribution, W-band monopulse array antenna}, issn = {null}, url = {https://ieeexplore.ieee.org/document/8739388}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @article {18_IJEC_BAZIL_MIMO, title = {(3.1{\textendash}20) GHz MIMO antennas}, journal = {AEU - International Journal of Electronics and Communications}, volume = {94}, year = {2018}, month = {september}, pages = {348-358}, abstract = {In this paper, a super-wideband (SWB) printed monopole antenna has been designed and manufactured. The measured frequency band in terms of reflection coefficient is from 3.1 to 20 GHz under a -10 dB criteria, thanks to the inclusion of a taper impedance adapter. This single antenna has been used to implement and analyze several MIMO antenna configurations, where the isolation between the compounding elements has been checked and optimized to improve the Envelope Correlation Coefficient. Two elements MIMO configurations (parallel ports or orthogonal diversity), as well as four element MIMO antennas with parallel ports are presented. Non continuous ground planes of the MIMO antenna elements with the inclusion of L shaped thin strips are proposed as valid structures to significantly improve the side by side mutual coupling from an initial peak value of 15 dB to better than 24 dB within the entire frequency band. In all the presented MIMO antenna structures, the measured values demonstrate good performance up to 20 GHz, both in reflection and isolation. Nevertheless, the influence of the mutual coupling effects has been checked as more significant in the lower part of the frequency band, especially in the 4 element MIMO configuration. The inclusion of the L shaped strips in the ground plane significantly mitigates this effect. Although the antennas have only been measured up to 20 GHz (upper frequency limit of the laboratory Vector Network Analyzer), simulations show satisfactory antennas{\textquoteright} performance up to 50 GHz.}, keywords = {MIMO antenna, Polarization diversity MIMO antenna, SWB antenna}, issn = {1434-8411}, doi = {https://doi.org/10.1016/j.aeue.2018.07.026}, url = {https://www.sciencedirect.com/science/article/pii/S1434841118310823}, author = {B T Ahmed and P Sanchez-Olivares and J L Masa-Campos and F Moreno-Vazquez} } @conference {18_URSI_PABLO_SANCHEZ, title = {Conformal Patch Array Antenna with Switchable Omnidirectional or Sectorial Coverage at 3.5 GHz}, booktitle = {Simposium Nacional URSI 2018}, year = {2018}, month = {September}, abstract = {A circularly conformal array antenna with beam steering capabilities as well as omnidirectional performance in S-band is presented. The single radiating elements are formed by double stacked microstrip patches placed on the planar faces of an octagonal supporting structure fabricated with a 3D printer. An eight-way tunable feeding network in microstrip technology is designed, manufactured and integrated into the conformal structure in order to excite the array elements. Novel tunable T-junctions based on PIN diodes are proposed to form the tunable feeding network. This novel T-junction allows a splitting configuration with uniform distribution to the two output ports, or a switching mode to deliver the signal to either output port. In all T-junction operation modes, a good input matching performance is achieved. The tunable feeding network is integrated into the conformal antenna and digitally controlled by a microcontroller Arduino UNO. A total of 29 states, grouped in 6 modes with a global matching bandwidth of 17.2\% can be selected. An omnidirectional radiation as well as beam steered directional patterns (covering 360 deg) can be electronically selected. The proposed antenna is able for future 5G terrestrial communications in the 3.5 GHz IMT range.}, author = {P Sanchez-Olivares and P P Sanchez-Dancausa and J L Masa-Campos and M Iglesias-Menendez-de-la-Vega and E Garcia-Marin} } @article {18_COMM_MAG_EDUARDO_DIFF_BONDING1, title = {Diffusion Bonding Manufacturing of High Gain W-Band Antennas for 5G Applications}, journal = {IEEE Communications Magazine}, volume = {56}, number = {7}, year = {2018}, month = {July}, pages = {21-27}, abstract = {The incoming 5G systems propose unprecedented communication capabilities that require a maximization of the channel and spectrum exploitation. Waveguide antenna arrays can play an important role in 5G environments due to their high performance in terms of efficiency and bandwidth. Moreover, higher frequencies appear necessary in order to achieve the requirements of channel capacity and spectrum bandwidth. At millimeter-wave frequencies, new challenges for the design and fabrication of the communication devices are encountered. The feasibility of traditional manufacturing techniques and conventional additive manufacturing processes severely decreases, since part tolerances, assembly, and alignment become critical for the antenna performance. In order to illustrate the possibilities of the diffusion bonding technique applied to waveguide antennas operating in the W-band of 5G systems, a circularly polarized cavity array has been successfully manufactured. This manufacturing process provides the advantages of both traditional and additive manufacturing. A 5.6 percent effective bandwidth at 90 GHz has been experimentally obtained with reflected power under 10 percent, axial ratio below 3 dB, and antenna efficiency over 50 percent.}, keywords = {5G mobile communication, Antenna arrays, Diffusion bonding, Three-dimensional printing}, issn = {0163-6804}, doi = {10.1109/MCOM.2018.1700986}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {18_EUCAP_PABLOSANCHEZ_Array_RPS_varactor, title = {Electronically reconfigurable microstrip array antenna with reflective phase shifters at Ku band}, booktitle = {12th European Conference on Antennas and Propagation (EuCAP 2018)}, year = {2018}, month = {April}, pages = {1-5}, keywords = {Patch antennas, phase shifters, Phased arrays}, doi = {10.1049/cp.2018.1134}, author = {E Garcia-Marin and P Sanchez-Olivares and J Herranz-Alpanseque and A J Martin-Trueba and J L Masa-Campos and J C{\'o}rcoles-Ortega} } @article {18_AWPL_EDUARDO-GARCIA_EVALUATION_ADD_MANUF, title = {Evaluation of Additive Manufacturing Techniques Applied to Ku-Band Multilayer Corporate Waveguide Antennas}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {17}, number = {11}, year = {2018}, month = {Nov}, pages = {2114-2118}, keywords = {additive manufacturing techniques, Antenna arrays, antenna feeds, antenna layers, antenna prototypes, Aperture antennas, axial ratio, conventional milling, corporate-fed waveguide array antenna, digital communication, direct broadcasting by satellite, direct metal laser sintering, DMLS antenna, electrical performance, end-user digital broadcast satellite communications, gain ratio, impedance matching, intricate multilayer structure, Ku-band multilayer corporate waveguide antennas, laser sintering, layered manufacturing, Metals, Milling, multilayer structure, multilayers, Planar arrays, prototypes, rapid prototyping (industrial), reference prototype, reliability, satellite antennas, single block fabrication, slot antenna arrays, stereolithography, Three-dimensional printing, waveguide antenna implementation}, issn = {1536-1225}, doi = {10.1109/LAWP.2018.2866631}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares and J A Ruiz-Cruz} } @conference {18_URSI_EDUARDO_GARCIA, title = {Fabricaci{\'o}n por Diffusion Bonding de Agrupaciones de Antenas en Gu{\'\i}a de Onda para Banda W}, booktitle = {Simposium Nacional URSI 2018}, year = {2018}, month = {September}, abstract = {Millimeter-wave radiating systems appear attractive for radiofrequency applications like radio-positioning or telecommunications. High-gain array antennas can be implemented in reduced-size devices in this part of the frequency spectrum. Waveguide implementations seem indispensable to mitigate the dissipation losses inherent to these frequencies. Nevertheless, the implementation of multilayer waveguide array antennas is a challenge. Electrical contact between the antenna layers must be guaranteed to prevent power leakage, which is ensured only in part with mechanical tightening. Additive manufactured antenna arrays provide electrical continuity, although dimensional accuracy diminishes and dissipation losses increase owing to surface roughness and reduced conductivity. In this context, diffusion bonding allows complex multilayer designs by joining accurately-etched metallic sheets without additional sticking or tightening material. A corporate-fed waveguide antenna array is presented in this paper to experimentally validate this manufacturing technique for W-band implementations.}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {8439652, title = {Implementation of Millimeter Wave Antenna Arrays by Diffusion Bonding}, booktitle = {2018 11th Global Symposium on Millimeter Waves (GSMM)}, year = {2018}, month = {May}, pages = {1-4}, keywords = {Antenna arrays, Diffusion bonding, Millimeter wave communication, Millimeter wave radar, millimeter wave technology, Planar arrays}, doi = {10.1109/GSMM.2018.8439652}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @article {18_TAP_PABLO-SANCHEZ_WG-SLOT-ARRAY-TUNING-SCREWS, title = {Mechanical Technique to Customize a Waveguide-Slot Radiating Performance}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {66}, year = {2018}, pages = {426-431}, abstract = {A mechanical technique to tune the radiating performance of a waveguide-fed slot is presented. Three metallic tuning screws are introduced through the bottom wall of the feeding waveguide. The field radiated by the slot is mechanically controlled with the insertion length of the tuning screws and a good input matching response is also maintained. One of the tuning screws modifies the slot coupling parameter as well as the phase of the transmitted signal, while the other pair of screws compensates the impedance mismatch introduced by the first one. A five-element traveling-wave (TW) linear array antenna has been designed and manufactured as a proof of concept to validate the performance of the tuning screws. Several improvements such as a main beam steering range of 17{\textdegree}, an enhancement of the antenna efficiency, the mitigation of the undesirable grating lobe appearance typical of TW air-waveguide-fed arrays, as well as the compensation of the mutual coupling effects or manufacturing tolerance errors could be experimentally achieved by using the proposed mechanism based on tuning screws.}, keywords = {linear arrays, Slot antennas, waveguide arrays}, issn = {0018-926X}, doi = {10.1109/TAP.2017.2772078}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8103014}, author = {P Sanchez-Olivares and J L Masa-Campos and J Hernandez-Ortega} } @article {18_AWPL_PABLO-SANCHEZ_CORPORATE-ARRAY-TUNING-SCREWS, title = {Mechanically Reconfigurable Linear Array Antenna Fed by a Tunable Corporate Waveguide Network With Tuning Screws}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {17}, number = {8}, year = {2018}, month = {Aug}, pages = {1430-1434}, abstract = {A mechanical technique to provide beam-steering capabilities to a linear array antenna is presented. The methodology is based on the insertion of metallic tuning screws into power dividers in rectangular waveguide technology. These tuning screws establish a short circuit between the top and bottom plates of the waveguide, and a phase change in the transmitted signal is then generated. Therefore, the phase difference between the output ports of a conventional waveguide divider can be controlled with these tuning screws. A corporate waveguide feeding network with several tuning screws has been designed. This tunable waveguide network is used to feed an aperture stacked patch array, forming the final mechanically reconfigurable linear array. Seven different phase configurations have been synthetized by using the tuning screws, which provide a noncontinuous angular scanning. In particular, a main beam steering from -26{\textdegree} to +26{\textdegree} with 13 discrete radiation patterns has been obtained. The use of waveguide technology makes the proposed reconfigurable antenna suitable for low-loss and high-power applications. Total efficiency values higher than 90\% have been achieved for every configuration.}, keywords = {Aperture-coupled antennas, Beam steering, Electromagnetic waveguides, Fasteners, linear antenna arrays, microwave antenna arrays, Tuning, waveguide arrays}, issn = {1536-1225}, doi = {10.1109/LAWP.2018.2848911}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8388289}, author = {P Sanchez-Olivares and J L Masa-Campos and A T Muriel-Barrado and R Villena-Medina and G M Fernandez-Romero} } @article {C{\'o}rcoles2018286, title = {Nested 2D finite-element function-spaces formulation for the mode-matching problem of arbitrary cross-section waveguide devices}, journal = {Applied Mathematical Modelling}, volume = {60}, year = {2018}, note = {cited By 2}, pages = {286-299}, doi = {10.1016/j.apm.2018.03.019}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056421811\&doi=10.1016\%2fj.apm.2018.03.019\&partnerID=40\&md5=a88135b98cd6718f6663527036afa3bd}, author = {J C{\'o}rcoles and Mor{\'a}n-L{\'o}pez, A. and Ruiz-Cruz, J.A.} } @article {Moran-Lopez2018623, title = {Robust Calculation of the Modes in Parabolic Cylinder Metallic Waveguides by Means of a Root-Finding Method for Bivariate Functions}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {66}, number = {2}, year = {2018}, note = {cited By 2}, pages = {623-632}, doi = {10.1109/TMTT.2017.2777969}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038868625\&doi=10.1109\%2fTMTT.2017.2777969\&partnerID=40\&md5=efc4e4344491c5f81ac77e8451e3cf35}, author = {Mor{\'a}n-L{\'o}pez, A. and J C{\'o}rcoles and Ruiz-Cruz, J.A. and Montejo-Garai, J.R. and Rebollar, J.M.} } @conference {17_EUCAP_EDUARDOGARCIA_4x4_stackedPatch_eucap, title = {W-band array antenna for radar detection of space debris}, booktitle = {12th European Conference on Antennas and Propagation (EuCAP 2018)}, year = {2018}, month = {April}, pages = {1-4}, keywords = {millimeter wave technology, Planar arrays, radar antennas}, doi = {10.1049/cp.2018.0737}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @article {17_IET_TFM-PAULA-SANCHEZ_CONF-ARRAY-SWITCHED, title = {Circularly conformal patch array antenna with omnidirectional or electronically switched directive beam}, journal = {IET Microwaves, Antennas and Propagation}, volume = {11}, year = {2017}, pages = {2253-2259}, abstract = {A circularly conformal array antenna of double stacked microstrip patches is presented in two radiation versions: omnidirectional and electronically switched directive beam. Every single element is disposed on an eight-faced regular prism structure built in 3D print technology. The omnidirectional pattern is achieved in the azimuth plane by using a microstrip uniform power divider to equally excite the circular antenna. The switched directive beam coverage is obtained by replacing the uniform power divider with an electronically switched power divider. Four switched beams of 90{\textdegree} angular separation are digitally configured. A fractional matching bandwidth of 17.2\% has been measured for both omnidirectional and switched beam prototypes. The conformal antenna was entirely manufactured by using both printed circuit board and 3D printing technologies. Therefore, a very compact, low cost and light weight antenna design has been implemented, suitable to many applications such as Worldwide Interoperability for Microwave Access, wireless local area network, unmanned aerial vehicles or direction finding.}, issn = {1751-8725}, doi = {10.1049/iet-map.2017.0195}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8221750}, author = {P Sanchez-Olivares and P P Sanchez-Dancausa and J L Masa-Campos} } @article {17_AWPL_PABLO-SANCHEZ_RADIALWG_ARRAY_OMNI, title = {Compact Omnidirectional Conformal Array Antenna in Waveguide Technology}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {16}, year = {2017}, pages = {1102-1105}, abstract = {A conformal array antenna has been designed in the waveguide technology in order to obtain an omnidirectional radiation pattern in the azimuth plane at the Ku-band. The antenna shape is a regular prism, where the single radiating elements, which consist of a rectangular waveguide ended on a cavity{\textendash}slot, are placed on the planar faces of the prism. The physical dimensions as well as the number of faces of the regular prism have been optimized following the conformal array formulation in order to achieve a minimum ripple omnidirectional pattern. An eight-faced regular prism with an apothem of 20.6 mm has been selected as the radiating structure. The single elements are fed by an eightway radial waveguide power divider symmetrically excited by a 50-Ω SMA input port. The use of waveguide technology to design the single elements and the feeding network makes the conformal array suitable for low losses and high-power applications. Several prototypes have been manufactured in order to experimentally validate the antenna performance. An omnidirectional pattern with a maximum ripple of 1.6 dB in the azimuth plane, 95.3\% efficiency, and 11.7\% input matching bandwidth has been measured..}, keywords = {Conformal antennas, omnidirectional antennas, slot arrays}, issn = {1536-1225}, doi = {10.1109/LAWP.2016.2622919}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7725535}, author = {P Sanchez-Olivares and R V Haro-Baez and P P Sanchez-Dancausa and J L Masa-Campos and J A Ruiz Cruz} } @conference {17_URSI_EDUARDO-GARCIA_diffusionbonding_antenna, title = {Diffusion-bonded Circularly Polarized Corporate-Fed Cavity Array for W-band}, booktitle = {Simposium Nacional URSI 2017}, year = {2017}, month = {September}, abstract = {A circularly polarized radiating cavity array has been designed at 94 GHz and manufactured by the innovative technique of diffusion bonding of thin metallic layers, introduced to the European research community for the first time. The array is composed of 16x16 radiating elements, fed by a two-level waveguide corporate feeding network with uniform distribution. A 5.5 \% bandwidth has been experimentally achieved with matching under -10 dB and axial ratio below 3 dB. At 90 GHz, 30.6 dBi gain and 0.4 dB axial ratio have been measured. The experimental results are considered successful and further improvements in the manufacturing process are expected to refine the performance of the antenna in future prototypes.}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {moran2017direct, title = {Direct computation of parabolic waveguide modes via a bivariate root-finding algorithm}, booktitle = {Numerical Electromagnetic and Multiphysics Modeling and Optimization for RF, Microwave, and Terahertz Applications (NEMO), 2017 IEEE MTT-S International Conference on}, year = {2017}, pages = {152{\textendash}154}, publisher = {IEEE}, organization = {IEEE}, author = {Mor{\'a}n-L{\'o}pez, Ana and J C{\'o}rcoles and Ruiz-Cruz, Jorge A and Montejo-Garai, Jos{\'e} R and Rebollar, Jes{\'u}s M} } @conference {Moran-Lopez20171192, title = {Dual-mode filters in equilateral triangular waveguides with wide spurious-free response}, booktitle = {IEEE MTT-S International Microwave Symposium Digest}, year = {2017}, note = {cited By 4}, pages = {1192-1195}, doi = {10.1109/MWSYM.2017.8058816}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032469925\&doi=10.1109\%2fMWSYM.2017.8058816\&partnerID=40\&md5=9a25dd6727f443bd4d44ecf5bed76d99}, author = {Mor{\'a}n-L{\'o}pez, A. and J C{\'o}rcoles and Ruiz-Cruz, J.A. and Montejo-Garai, J.R. and Rebollar, J.M.} } @conference {moran2017efficient, title = {Efficient computation and orthonormalization of multiple TEM numerical modes arising from FEM for microwave computer-aided-design}, booktitle = {Numerical Electromagnetic and Multiphysics Modeling and Optimization for RF, Microwave, and Terahertz Applications (NEMO), 2017 IEEE MTT-S International Conference on}, year = {2017}, pages = {197{\textendash}199}, publisher = {IEEE}, organization = {IEEE}, author = {Mor{\'a}n-L{\'o}pez, Ana and J C{\'o}rcoles and Ruiz-Cruz, Jorge A} } @article {17_MOTL_PFC_ALFONSO_MURIEL, title = {H-plane corporate waveguide-fed 4-aperture-stacked circular microstrip patch linear array for Ku band applications}, journal = {Microwave and Optical Technology Letters}, volume = {59}, number = {9}, year = {2017}, pages = {2216-2223}, abstract = {In this article, a linearly polarized 4-element linear array in Ku band is presented. The single element consists of a circular microstrip patch capacitively coupled to a printed slot-end WR-51 waveguide. A corporate waveguide feeding network at H-plane is designed, which is composed of bends, T and Y-junctions. An optimization process with septums and irises is performed to get the best possible matching coefficient. An antenna prototype has been manufactured and measured. A maximum gain of 12.6 dBi, up to 91.6\% radiation efficiency and 13\% bandwidth (16 to 18.3 GHz) has been experimentally achieved.}, issn = {1098-2760}, doi = {10.1002/mop.30711}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.30711/epdf}, author = {A T Muriel-Barrado and J L Masa-Campos and P Sanchez-Olivares} } @conference {17_EUCAP_EDUARDOGARCIA_4x4_stackedPatch_eucap, title = {Implementation of 4 {\texttimes} 4 stacked patch array with corporate feeding network for Ku-band applications}, booktitle = {Antennas and Propagation (EUCAP), 2017 11th European Conference on}, year = {2017}, month = {March}, pages = {1967-1971}, abstract = {In this work, the experimental implementation of a 4 x 4 stacked-patch array with linear polarization and a corporate feeding network for Ku-band is exposed. The feeding network is split into two levels, with an initial power distribution in Substrate Integrated Waveguide and a second distribution in microstrip technology. The experimental results show a matching coefficient better than -10 dB in a 15.9\% bandwidth. In addition, the measured gain attains 16.8 dBi, 0.8 dB below the simulated gain, while radiation efficiency is 66 \%. The structure is validated for higher-gain arrays, and hence designs of 8 x 8 and 16 x 16 radiating elements are also proposed and the simulated results presented. Therefore, antennas with several gain values are available in order to suit the different elements of the communication system, such as the end user and the base station.}, keywords = {antenna, array, corporate feeding, linear polarization, microstrip, replication., SIW, stacked patch}, doi = {10.23919/EuCAP.2017.7928530}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7928530}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @article {17_TAP_PABLO-SANCHEZ_RECONF_RADIALWG_ARRAY, title = {Mechanically Reconfigurable Conformal Array Antenna Fed by Radial Waveguide Divider With Tuning Screws}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {65}, year = {2017}, pages = {4886-4890}, abstract = {A conformal array antenna with a reconfigurable radiation pattern in the azimuth plane at Ku band is presented. An eight-faced prism has been set as 3-D antenna structure. The radiating element consists of a rectangular waveguide ended on a slotted cavity. A radial waveguide network (RWGN) fed by a symmetrically placed coaxial probe has been implemented to equally feed each radiating element obtaining an omnidirectional behavior in the azimuth plane. The insertion of several metallic tuning screws (TSs) provides a reconfiguration mechanism of the electric field distribution in the RWGN and modifies the conformal array antenna amplitude feeding. Eight different configurations generating directional radiation patterns can be tuned by means of the insertion of certain TSs. In addition, the symmetrical positioning of them allows performing a main beam scanning every 45{\textdegree} in the azimuth plane. Several prototypes have been manufactured and measured to experimentally validate the antenna performance. A total of 65 different radiation patterns have been experimentally obtained using the proposed TSs, which provides a simple, low-loss, and low-cost reconfigurability mechanism to the presented conformal array antenna.}, keywords = {Conformal antenna, Slot antennas, waveguide arrays}, issn = {0018-926X}, doi = {10.1109/TAP.2017.2723918}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7970137\&isnumber=8024125}, author = {P Sanchez-Olivares and J L Masa-Campos} } @conference {17_EUCAP_PABLOSANCHEZ_SingleSlot_TuningScrews_eucap, title = {Mechanically reconfigurable waveguide-slot single element using tuning screws}, booktitle = {Antennas and Propagation (EUCAP), 2017 11th European Conference on}, year = {2017}, month = {March}, pages = {1962-1966}, abstract = {A mechanically reconfigurable waveguide-slot single radiating element is presented. The tuning mechanism consists on three metallic screws introduced through the bottom wall of the feeding waveguide. The insertion length of the tuning screws and the distance to the slot are used to control the radiated signal as well as to maintain a good input matching response. Several prototypes with different slot lengths have been manufactured to experimentally validate the reconfigurable performance. The proposed triple tuning screw waveguide-slot radiator provides a low cost and simple mechanism to conform a reconfigurable array antenna.}, keywords = {reconfigurable antenna, Slot antennas, waveguide antennas.}, doi = {10.23919/EuCAP.2017.7928264}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7928264}, author = {P Sanchez-Olivares and J L Masa-Campos and J Hernandez-Ortega} } @article {murbach2017pregnant, title = {Pregnant women models analyzed for RF exposure and temperature increase in 3T RF shimmed birdcages}, journal = {Magnetic resonance in medicine}, volume = {77}, number = {5}, year = {2017}, pages = {2048{\textendash}2056}, author = {Murbach, Manuel and Neufeld, Esra and Samaras, Theodoros and J C{\'o}rcoles and Robb, Fraser J and Kainz, Wolfgang and Kuster, Niels} } @conference {17_URSI_PABLO-SANCHEZ_conformalarray_reconfig, title = {Reconfigurable Conformal Antenna in Radial Waveguide Technology}, booktitle = {Simposium Nacional URSI 2017}, year = {2017}, month = {September}, abstract = {This work proposes a compact conformal array antenna using radial waveguide technology. The conformal structure is approximated as a regular prism with planar faces to obtain a significant manufacturing cost reduction. It provides a mechanical technique to reconfigure the antenna radiation pattern in the azimuth plane, based on the insertion of several metallic screws into the radial feeding network. Depending on the inserted-screw configuration, the electric field distribution in the radial waveguide network is modified. Therefore, the feeding distribution of the single radiating elements is controlled. The radiation pattern can be mechanically reconfigured from omnidirectional to directional behavior, achieving a main beam scanning every 45 deg in the azimuth plane.}, author = {P Sanchez-Olivares and J L Masa-Campos and E Garcia-Marin} } @conference {17_NEMO_EDU_JUAN_CAD2_ANTENNA, title = {Slotted Waveguide Antenna Design by Segmented Simulation and Multi-Objective Genetic Algorithm}, booktitle = {IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization for RF, Microwave and Terahertz Applications (NEMO)}, year = {2017}, month = {May}, abstract = {A progressive-wave antenna automated design technique is presented in this work. By means of a simulation method based on spherical wave expansion and generalized scattering matrix, full-wave analysis of a slotted waveguide array can be efficiently performed. Since coupling effects are considered in the simulation, a final antenna design can be obtained without any further modification required on it. In order to achieve such design, a multi-objective optimization based on Nondominated Sorting Genetic Algorithm Version III (NSGA-III) state-of-theart genetic algorithm is carried out. At the working frequency of 17 GHz, final design provides a 16.6 dBi gain, Side-Lobe Levels lower than -18.3 dB and a 0.6\% power waste at the output port. A -15-dB matching bandwidth of an 8.8\% is obtained. The results have been validated with commercial-software simulations.}, author = {E Garcia-Marin and J C{\'o}rcoles and J Rubio and J L Masa-Campos and P Sanchez-Olivares} } @conference {16_EUCAP_EDUARDOGARCIA_patcharray4x4, title = {4 {\texttimes} 4 stacked patch array with siw and microstrip corporate feeding network for ku-band}, booktitle = {Antennas and Propagation (EUCAP), 2016 10th European Conference on}, year = {2016}, month = {April}, pages = {1-4}, abstract = {A 4 {\texttimes} 4 linearly-polarized stacked-patch array with a fully corporate feeding network for Ku-band is presented in its work. Antenna replication in larger arrays is straightforward with this corporate approach, which in addition prevents unintended main beam steering. The feeding structure is divided in two levels, where the first power distribution is made in Substrate Integrated Waveguide and the second in microstrip technology. This procedure takes advantage of the strengths of each technology, combining waveguide low losses with microstrip versatility. A 18.4-dBi gain is attained in simulation with matching better than -14 dB in the entire bandwidth.}, keywords = {antenna, array, corporate feeding, linear polarization, microstrip, replication, SIW, stacked patch}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {16_URSI_PABLO-SANCHEZ_conformalarray_omni, title = {Agrupaci{\'o}n Conformada con Alimentaci{\'o}n en Gu{\'\i}a de Onda Radial para Cobertura Omnidireccional en Banda Ku}, booktitle = {Simposium Nacional URSI 2016}, year = {2016}, month = {September}, abstract = {A conformal array antenna fed by a radial waveguide divider has been designed in order to obtain an omnidirectional performance at Ku band. The single radiating elements consist on a waveguide ended on a cavity-slot and they have been placed on the regular prism faces conforming the final antenna shape. The array dimensions as well as the number of faces have been optimized to generate a maximum ripple in the omnidirectional pattern, obtaining an eight-faced regular prism antenna with an apothem of 20.6 mm. The single radiating elements are fed by an equal power eight-way radial waveguide divider. The use of waveguide technology makes the structure suitable for high power applications. The conformal array have been manufactured in order to experimentally validate the antenna performance. An omnidirectional pattern with a maximum ripple of 1.6 dB in the azimuth plane, a total efficiency of 98.8\% and an input matching bandwidth of 11.7\% has been measured.}, author = {P Sanchez-Olivares and R V Haro-Baez and P P Sanchez-Dancausa and J L Masa-Campos and J A Ruiz Cruz} } @conference {16_URSI_EDUARDO-GARCIA_4by4patcharray, title = {Agrupaci{\'o}n plana de parches apilados con alimentaci{\'o}n corporativa en tecnolog{\'\i}a mixta SIW-microstrip para banda Ku}, booktitle = {Simposium Nacional URSI 2016}, year = {2016}, month = {September}, abstract = {A 4 x 4 linearly-polarized stacked-patch array with a fully corporate feeding network for Ku-band is presented in its work. Antenna replication in larger arrays is straightforward with this corporate approach, which in addition prevents unintended main beam steering. The feeding structure is divided in two levels, where the first power distribution is made in Substrate Integrated Waveguide and the second in microstrip technology. This procedure takes advantage of the strengths of each technology, combining waveguide low losses with microstrip versatility. A 18.6-dBi gain is attained in simulation with matching better than -14 dB in the entire bandwidth.}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {16_URSI_LUCAS-POLO_horn_PEW_PMW, title = {An{\'a}lisis de discontinuidades en gu{\'\i}a de onda con condiciones de contorno de pared magn{\'e}tica perfecta laterales y transversales}, booktitle = {Simposium Nacional URSI 2016}, year = {2016}, month = {September}, abstract = {This contribution presents the analysis of waveguide problems involving general boundary conditions of perfect magnetic wall. This type of boundary condition, when the waveguide device under analysis has physical symmetry, is used very commonly to speed up the computation time in general waveguide solvers by exploiting the symmetries of the excitation. This contribution is focused on extending its use in general problems having this type of boundary condition in the lateral and transverse walls, applying the mode-matching method. The formulation will be applied to classical waveguide devices surrounded by perfect magnetic walls, but also to simulate radiating problems. The simulation results will be compared with those obtained by other numerical techniques (based on different solvers) to test the validity of the presented formulation.}, author = {L Polo-Lopez and J A Ruiz-Cruz and J R Montejo-Garai and J M Rebollar-Machain} } @article {16_AWPL_JUAN-CORCOLES_CAD_SLOTTED_ANTENNA, title = {Computer Automated Design of an Irregular Slotted Waveguide Array for Ku-Band}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {15}, year = {2016}, pages = {1593-1597}, abstract = {A computer automated design methodology to synthesize a progressive wave array antenna is presented. The proposed method is based on the generalized-scattering matrix and spherical wave expansion analysis of the array. Mutual coupling effects between radiating elements are inherently considered in the design process. A linearly polarized 24-element irregular slotted array antenna at Ku-band is presented to describe the proposed computer automated design methodology. A prototype has been manufactured to experimentally validate the antenna performance. At the design frequency (17 GHz), 15.9 dB realized gain and 97\% efficiency (excluding aluminum losses) values are achieved. Although the array is designed at a single frequency, it shows an overall experimental 7\% usable bandwidth.}, keywords = {Array antenna, computer automated design, generalized scattering matrix, slot, spherical wave expansion}, issn = {1536-1225}, doi = {10.1109/LAWP.2016.2517928}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7381600}, author = {J C{\'o}rcoles and P Sanchez-Olivares and J Rubio and J L Masa-Campos and J. Zapata} } @conference {16_EUCAP_PABLOSANCHEZ_conformal_array_omni_eucap, title = {Conformal Array Antenna Fed by Radial-Waveguide Divider for Omnidirectional Coverage at Ku Band}, booktitle = {Antennas and Propagation (EUCAP), 2016 10th European Conference on}, year = {2016}, month = {April}, pages = {1-5}, abstract = {A conformal array antenna for omnidirectional coverage in the azimuth plane at Ku band is presented. An eightfaced prism structure has been used to obtain the omnidirectional radiation pattern following a maximum theoretical ripple criterion. The radiating element consists of a rectangular waveguide ended on a cavity-slot. An equal power eight-way radial-waveguide divider has been designed to feed each radiating element. The use of waveguide technology minimizes the propagation losses and makes the structure suitable for high power applications with omnidirectional coverage requirements. The achieved simulation results show a maximum realized gain of 2.4 dB, a maximum ripple of 1.5 dB for the omnidirectional pattern and a matching bandwidth of 16.2\% around 17 GHz.}, keywords = {antenna, conformal array, omnidirectional pattern., radial-waveguide}, author = {P Sanchez-Olivares and R V Haro-Baez and P P Sanchez-Dancausa and J L Masa-Campos and J A Ruiz Cruz} } @conference {16_URSI_RAUL-HARO_radial_divider, title = {Desarrollo de Redes Divisoras de Potencia con N-puertos}, booktitle = {Simposium Nacional URSI 2016}, year = {2016}, month = {September}, abstract = {Power division/combination is a very important function for achieving high-performance power amplification in microwave and millimeter-wave systems. This function allows the use of simpler individual amplifiers to provide microwave/millimeter wave high power signals. In this paper we address the development of divider/combiners in waveguide technology for large number of ports. Radial waveguide dividers will be studied, starting from the S-parameters representing the N-port waveguide junction, and ending with the full-wave simulations. Two different designs in this technology are studied, radial divider and conical radial divider. The experimental evaluation will come from a prototype at Ku-band, fabricated and tested in order to validate the design.}, author = {R V Haro-Baez and J L Masa-Campos and J A Ruiz Cruz and P Sanchez-Olivares and E V Carrera} } @conference {16_URSI_JESUS-RUBIO_dao_slotted_array, title = {Dise{\~n}o Automatizado por Ordenador de una Agrupaci{\'o}n de Ranuras con Alimentaci{\'o}n en Gu{\'\i}a de Onda}, booktitle = {Simposium Nacional URSI 2016}, year = {2016}, month = {September}, abstract = {A Computer Automated Design method based on the generalized-scattering matrix and spherical wave expansion analysis is used to configure a linearly polarized 24-element slotted array antenna at Ku band. The mutual coupling effects between slots have been considered in the proposed methodology. Therefore, it is possible to remove the typical compensation step in the design process. The computing costs of the whole antenna optimization process is significantly reduced using the proposed method compared to the commercial full-wave simulation tools. An antenna prototype has been manufactured in order to experimentally validate the antenna performance. A realized gain and efficiency values of 15.9 dB and 97\% have been measured at the design frequency (17 GHz), respectively.}, author = {J C{\'o}rcoles and P Sanchez-Olivares and J Rubio and J L Masa-Campos and J. Zapata} } @conference {16_URSI_ANA-MORAN_comblineS, title = {Dise{\~n}o de un filtro combline en banda S por subdivisi{\'o}n y optimizaci{\'o}n en etapas}, booktitle = {Simposium Nacional URSI 2016}, year = {2016}, month = {September}, abstract = {Microwave filter design can be done using different approaches. These types of filters are typically found in the frontend of high-frequency transceivers of very diverse systems such as radar, satellite TV or microwave links. This paper addresses the strategy of subdividing the design process of a combline filter into minor stages, each of which takes into account less degrees of freedom (i.e. parameters of design) than in a direct global design. This work evidences how optimization divided into simpler stages becomes an excellent approach to accomplish this task, making it possible to achieve the level of refinement that the physical design parameters require to reach the desired partial responses.}, author = {A Mor{\'a}n-L{\'o}pez and J A Ruiz-Cruz} } @article {16_AE_JL_PRADEEP_DUAL_UWB, title = {Dual Polarized Monopole Patch Antennas for UWB Applications with Elimination of WLAN Signals}, journal = {Advanced Electromagnetic}, volume = {5}, year = {2016}, pages = {46-52}, abstract = {This paper presents the design, fabrication and measurement of dual polarized microstrip patch antennas for ultra wideband (UWB) applications with notch at 5-6 GHz band. The proposed antenna rejects the wireless local area network (WLAN) signals and work properly in the entire remaining ultra-wideband. Two antennas are designed for two different frequency bands of ultra wideband and both antennas together produce the entire ultra wideband with notch at 5-6 GHz band. The antennas are fed by a 50 {\textohm} coaxial probe and the entire design is optimized using CST Microwave Studio. The bandwidth of 3.1-5 GHz is achieved by the optimized design of Antenna-1 and the bandwidth of 6 -10.6 GHz is achieved by the optimized design of Antenna-2. The bandwidth of the optimized combined antenna is 3.1-10.6 GHz with elimination of the 5-6 GHz band. Both antennas are simulated, developed and measured. The simulated and measured results are presented. The two designed dual polarized antennas i.e. Antenna-1 and Antenna-2 can be used for 3.1-5 GHz band and 6-10.6 GHz band dual polarized applications, respectively, and the combined antenna structure can be used for UWB dual polarized applications with elimination of 5-6 GHz band signals.}, keywords = {Antennas, UWB, WLAN}, issn = {2119-0275}, doi = {10.7716/aem.v5i1.305}, url = {http://www.aemjournal.org/index.php/AEM/article/view/305}, author = {P Kumar and J L Masa-Campos} } @article {moran2016electromagnetic, title = {Electromagnetic Scattering at the Waveguide Step between Equilateral Triangular Waveguides}, journal = {Advances in Mathematical Physics}, volume = {2016}, year = {2016}, publisher = {Hindawi Publishing Corporation}, author = {Mor{\'a}n-L{\'o}pez, Ana and J C{\'o}rcoles and Ruiz-Cruz, Jorge A and Montejo-Garai, Jos{\'e} R and Rebollar, Jes{\'u}s M} } @conference {moran2016generalized, title = {Generalized Scattering Matrix of the discontinuity between an equilateral triangular waveguide and a rectangular, circular or elliptical waveguide}, booktitle = {Microwave Conference (APMC), 2016 Asia-Pacific}, year = {2016}, pages = {1{\textendash}4}, publisher = {IEEE}, organization = {IEEE}, author = {Mor{\'a}n-L{\'o}pez, Ana and J C{\'o}rcoles and Ruiz-Cruz, Jorge A and Montejo-Garai, Jos{\'e} R and Rebollar, Jes{\'u}s M} } @article {16_2x2_patcharray_Eduardo_MOTL, title = {Linearly polarized small patch array fed by corporate SIW network}, journal = {Microwave and Optical Technology Letters}, volume = {58}, number = {3}, year = {2016}, month = {Mar.}, pages = {587 - 593}, abstract = {In this article, a linearly polarized 2 {\texttimes} 2 patch array uniformly fed by a corporate substrate integrated waveguide network for Ku band is presented. Undesired main beam steering is avoided by means of a fully corporate feeding network, although grating lobes may appear due to greater separation between radiating elements. Moreover, a reduced patch separation to avoid grating lobe appearance leads to an antenna matching coefficient degradation due to the proximity of antenna discontinuities. In consequence, a tradeoff approach has been developed, achieving a measured 4.1\% matching bandwidth and a measured gain of 13.27 dBi, which corresponds to an 86\% radiation efficiency. Good agreement between simulated and measured results is observed in all cases}, issn = {1098-2760}, doi = {10.1002/mop.29628}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.29628/epdf}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @article {16_PIERC_PAULA-SANCHEZ_TFG, title = {Omnidirectional Conformal Patch Antenna at S-Band with 3D Printed Technology}, journal = {Progress In Electromagnetics Research C}, volume = {64}, year = {2016}, pages = {43-50}, abstract = {A conformal patch array antenna with omnidirectional pattern in the azimuth plane at S-band is presented. A theoretical study of the generated ripple in the omnidirectional radiation pattern according to the number of faces that conform the array has been computed. A six-faced regular prism 3D structure has been chosen following a maximum 3 dB ripple criteria in the omnidirectional radiation pattern. A rectangular microstrip patch fed by a microstrip line has been designed as single radiating element. An equal power divider has been designed as feeding network in microstrip technology to feed each radiating element. Several prototypes have been manufactured and measured to validate the theoretical and simulated results. The entire conformal array has been assembled on a hexagonal regular prism manufactured in PolyLactic Acid (PLA) material using a 3D printer. In spite of the complexity of the proposed antenna structure, the used manufacturing processes, such as microstrip and 3D printing, allows to perform a low cost, low weight and compact final antenna. A higher radiated field ripple than the expected one is generated due to small deviations between experimental and theoretical critical parameters such as the feeding network performance or the 3 dB beam-width of the single element radiation pattern. A maximum ripple value of 4 dB has been experimentally obtained in the omnidirectional radiating pattern.}, issn = {1937-8718}, doi = {doi:10.2528/PIERC1602241}, url = {http://www.jpier.org/PIERC/pier.php?paper=16022410}, author = {P P Sanchez-Dancausa and J L Masa-Campos and P Sanchez-Olivares and E Garcia Marin} } @article {murbach2016virtual, title = {Virtual population-based assessment of the impact of 3 Tesla radiofrequency shimming and thermoregulation on safety and B1+ uniformity}, journal = {Magnetic resonance in medicine}, volume = {76}, number = {3}, year = {2016}, pages = {986{\textendash}997}, author = {Murbach, Manuel and Neufeld, Esra and Cabot, Eugenia and Zastrow, Earl and J C{\'o}rcoles and Kainz, Wolfgang and Kuster, Niels} } @conference {15_EUCAP_EDUARDOGARCIA_patcharray2x2, title = {2 {\texttimes} 2 stacked patch array with corporate SIW feeding network}, booktitle = {Antennas and Propagation (EUCAP), 2015 9th European Conference on}, year = {2015}, month = {April}, pages = {1-4}, abstract = {A linearly polarized 2x2 patch array fed by a corporate Substrate Integrated Waveguide network for Ku band is presented. The utilization of a corporate topology in the feeding network prevents the antenna from suffering an unintended main lobe tilt dispersion. Nevertheless, the interelement spacing increases, and so does the Side-Lobe Level. Reducing this spacing implies closer discontinuities, such as bends and T-junctions. This degrades the reflection coefficient. Hence, a tradeoff solution has been designed and manufactured, achieving a Side-Lobe Level better than -11 dB and a measured bandwidth similar to the expected in the simulation stage, being 4.1 \% at -10 dB. The measured gain reaches 13.27 dB, which corresponds to an 86\% radiation efficiency.}, keywords = {antenna, array, corporate feed, linear polarization., SIW, stacked patch}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {15_URSI_EDUARDO-GARCIA_patcharray2x2, title = {Agrupaci{\'o}n Plana de Doble Parche Apilado con Alimentaci{\'o}n Corporativa sobre SIW}, booktitle = {Simposium Nacional URSI 2015}, year = {2015}, month = {September}, abstract = {In this work, a planar stacked patch array for Ku band fed by a fully corporate Substrate Integrated Waveguide network is proposed. Corporate topology prevents an unintended main beam steering effect that reduces the antenna bandwidth in progressive wave structures. Nevertheless, an increase in the spacing between radiating elements occurs, worsening the Side- Lobe Level figure. A reduction in such spacing implies closer discontinuities, namely bends and power dividers, and thus reflection coefficient is degraded. Therefore, a tradeoff solution is presented, where a measured Side-Lobe Level better that -11 dB and 4.1\% reflection bandwidth are achieved, showing good agreement with the simulated results. A measured gain of 13.27 dBi is attained, corresponding to an 86\% radiation efficiency.}, author = {E Garcia-Marin and J L Masa-Campos and P Sanchez-Olivares} } @conference {15_URSI_PAULA-SANCHEZ_conformalomniarray, title = {Conformal Patch Array Antenna at 3.5 GHz for Omnidirectional Coverage}, booktitle = {Simposium Nacional URSI 2015}, year = {2015}, month = {September}, abstract = {A conformal patch array antenna with an omnidirectional pattern in the azimuth plane at S band is presented. A theoretical study of the ripple generated in the omnidirectional radiation pattern according to the number of faces that conform the array has been analyzed. A six faced prism 3D structure has been chosen following a maximum 3 dB ripple criteria in the omnidirectional radiation pattern. A rectangular microstrip patch fed by a microstrip line has been designed as the single radiating element. To feed each radiating element an equal power division feeding network has been designed in microstrip technology. Several prototypes have been manufactured and measured. Finally, the entire conformal array has been assembled on a regular hexagonal prism fabricated in Polylactic acid material using a 3D printer to validate the theoretical and the simulation results. Higher field ripple than expected in the omnidirectional radiating pattern has been obtained in the experimental results, demonstrating that the 3 dB beamwidth of the single radiating element is a critical parameter to design for a good 3D array performance.}, author = {P P Sanchez-Dancausa and J L Masa-Campos and P Sanchez-Olivares} } @conference {15_URSI_JORGE_INVITADA, title = {Desarrollo de componentes pasivos con divisi{\'o}n/combinaci{\'o}n de potencia para sistemas de comunicaciones}, booktitle = {Simposium Nacional URSI 2015}, year = {2015}, month = {September}, abstract = {This paper addresses the development of passive devices for communication systems working at the microwave frequency band, but also at millimeter-wave and terahertz frequencies. A brief review of different types of passive devices that the authors have been developed for different applications will be made. The paper will be focused on the devices for the last stage of the transmitter/receiver chain in communications systems, where the antennas and other components such as filters, multiplexers, polarizers, dividers/combiners, etc are an essential part. The application of these devices to power combination techniques will be also outlined, which can be used in high-power amplification, but also in other problems as antenna arrays.}, author = {B Taha-Ahmed and J C{\'o}rcoles-Ortega and R V Haro-Baez and C A Leal-Sevillano and J L Masa-Campos and J R Montejo-Garai and E Garcia-Marin and A Mor{\'a}n-L{\'o}pez and L Polo-Lopez and J M Rebollar-Machain and J A Ruiz-Cruz and P Sanchez-Olivares} } @conference {15_APCASE_RAULHARO_divradial, title = {Development of Radial Waveguide Dividers with Large Number of Ports}, booktitle = {Computer Aided System Engineering (APCASE), 2015 Asia-Pacific Conference on}, year = {2015}, month = {July}, pages = {58-62}, abstract = {Power division/combination is a very important function for achieving high-performance power amplification in microwave and millimeter-wave systems, allowing the use of simpler individual amplifiers to provide microwave/millimeter wave high power signals. In this paper we address the development of divider/combiners in waveguide technology for large number of ports. Radial waveguide dividers will be studied, starting from the S-parameters representing the N-port waveguide junction, and ending with the full-wave simulations. Two different designs in this technology are studied. The experimental evaluation will come from a prototype at Ku-band, fabricated and tested in order to validate the design.}, keywords = {antenna, array, corporate feed, linear polarization., SIW, stacked patch}, author = {R V Haro-Baez and J L Masa-Campos and J A Ruiz-Cruz and P Sanchez-Olivares and E V Carrera} } @conference {15_BMES_Murbach_3Tpregnant, title = {Influence of 3T pTx body coils and their excitations on a pregnant anatomical models}, booktitle = {Biomedical Engineering Society and Food and Drug Administration Frontiers in Medical Devices Conference: Innovations in Modeling and Simulation, (2015 BMES/FDA Frontiers)}, year = {2015}, month = {May}, author = {M Murbach and E Neufeld and J C{\'o}rcoles and E Zastrow and N. Kuster} } @conference {15_ISMRM_Murbach_3Tpregnant, title = {Pregnant Anatomical Models in 3T pTx Body Coils: Evaluation of SAR and B1+ Optimization in Various Imaging Positions}, booktitle = {23rd Annual Meeting of the International Society for Magnetic Resonance in Medicine, 2015. ISMRM 2015}, year = {2015}, month = {June}, author = {M Murbach and E Neufeld and E Cabot and E Zastrow and J C{\'o}rcoles and W Kainz and N. Kuster} } @article {47_PARCHE_GUIA_RECTANGULAR_ MOTL_PRADEEP, title = {Waveguide Fed Circular Microstrip Patch Antenna for Ku Band Applications}, journal = {Microwave and Optical Technology Letters}, volume = {57}, number = {3}, year = {2015}, pages = {585-589}, abstract = {This paper presents the design and development of a waveguide fed microstrip patch antenna for Ku band applications. A circular patch is fed by using a conventional WR-51 rectangular waveguide ended with a feeding slot capacitively coupled to the radiating patch. The design is optimized using the electromagnetic software CST Microwave Studio. The antenna is fabricated and the measured results are compared with simulations. The achieved bandwidth of the manufactured antenna is approximately 16.2 - 18.4 GHz, and a maximum gain of 5.7 dBi. The comparison of measured and simulated results shows good agreement except in the prediction of the surface wave effects propagated in the antenna substrate.}, keywords = {circular patch, Ku band, rectangular waveguide, slotted ground plane}, issn = {0895-2477}, doi = {10.1002/mop.28904}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.28904/full}, author = {P Kumar and J L Masa-Campos} } @article {14_IET_SERGIO-CASAS_rwpatcharray, title = {Design and characterisation model for a linearly polarised patch array fed by serial rectangular waveguide network}, journal = {IET Microwaves, Antennas \& Propagation}, volume = {8}, number = {14}, year = {2014}, month = {November}, pages = {1204-1210}, abstract = {A novel method for considering radiating structures independently to their feeding networks is presented. The integration of both parts separately designed suffers a critical misalignment with the theoretical behaviour caused by the mutual coupling effects between adjacent elements. This method analyses radiated near E-field monitors to adjust the whole antenna after joining both independently designed parts. A linearly polarised patch array fed by a rectangular waveguide with internal coupling patches for X band (11{\textendash}12 GHz) has been designed to validate the method performance. A double stacked microstrip patch structure with an integrated phase compensation microstrip line has been used as radiating element. The coupling patches inside the waveguide are connected to the external radiating patches by means of metallic probes. The presented method requires changes in the feeding structure as in the radiating elements. Several prototypes have been manufactured and measured: the feeding waveguide structure connectorised, the radiating patches connectorised, the union of both with SMA transitions and the final integration into the complete antenna. 18.5 dBi gain and 85\% efficiency peak values, as well as 6\% usable bandwidth have been experimentally achieved.}, issn = {1751-8725}, doi = {10.1049/iet-map.2013.0379}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6955144}, author = {S Casas-Olmedo and J L Masa-Campos and P Sanchez-Olivares} } @conference {14_URSI_SERGIO-CASAS_rwpatcharray, title = {Design Method of Linear Patch Arrays Fed by Waveguide Feeding Networks}, booktitle = {Simposium Nacional URSI 2014}, year = {2014}, month = {September}, abstract = {A novel method for considering radiating structures independently to their feeding networks is presented. The integration of both parts separately designed suffers a critical misalignment with the theoretical behavior caused by the mutual coupling effects between adjacent elements. This method analyses radiated near E-field monitors to adjust the whole antenna after joining both independently designed parts. A Linearly Polarized Patch Array fed by a Rectangular Waveguide with internal coupling patches for X band (11 GHz - 12 GHz) has been designed to validate the method performance. A double stacked microstrip patch structure with an integrated phase compensation microstrip line has been used as radiating element. The coupling patches inside the waveguide are connected to the external radiating patches by means of metallic probes. The presented method requires changes in the feeding structure as in the radiating elements. Several prototypes have been manufactured and measured: the feeding waveguide structure connectorized, the radiating patches connectorized, the union of both with SMA transitions, and the final integration into the complete antenna. 18.5 dBi gain and 85\% efficiency peak values have been experimentally achieved.}, author = {S Casas-Olmedo and J L Masa-Campos and P Sanchez-Olivares} } @article {26_UWB_Pradeep_MOTL, title = {Dual polarized microstrip patch antennas for ultra-wideband applications}, journal = {Microwave and Optical Technology Letters}, volume = {56}, number = {9}, year = {2014}, month = {Sep.}, pages = {2174 - 2179}, abstract = {This article presents a novel design of dual polarized microstrip patch antennas for ultra-wideband (UWB) applications. Two antennas are designed for different frequency band of UWB. Both antennas are loaded together and the combined antenna is designed for the entire UWB. The designed antenna is optimized using CST Microwave Studio simulator. The antennas are fed by a 50-? coaxial probe. Both antennas are fabricated and measurement of return loss and radiation pattern is performed. The VSWR 2:1 bandwidth of individual designed Antenna I and Antenna II is 3.1{\textendash}5.2 GHz and 4.9{\textendash}11.5 GHz, respectively. The comparison between simulated results and measured results shows good agreement}, keywords = {dual polarization, microstrip antenna, reflection coefficient, ultra wideband}, issn = {0895-2477}, doi = {10.1002/mop.28504}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.28504/pdf}, author = {P Kumar and J L Masa-Campos} } @article {14_IEEETMTT_Leal-SevillanoYingaTaoLancasterEtAl_MicromachinedDual-BandOrthomode, title = {A Micromachined Dual-Band Orthomode Transducer}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {62}, number = {1}, year = {2014}, month = {January}, pages = {55-63}, abstract = {In this paper, an orthomode transducer (OMT) for dual-band operation and optimized for stacked micromachined layers implementation is presented. The proposed design avoids the use of septums, irises, pins, or small features and minimizes the number of equal-thickness micromachined layers required. In this way, the micromachining fabrication is simplified, making the proposed design a very attractive candidate for high frequency applications and for low-cost batch production. A W-band dual-band design (one different polarization in each frequency band) with more than 10\% fractional bandwidth for each band and 30\% separation between bands is presented. In addition, proper routing and layered bends are designed for an optimum standard interfacing with the same orientation of the input/output ports. Two OMTs in a back-to-back configuration are fabricated using a thick SU-8 photo-resist micromachining process. A total of six stacked SU-8 layers, all of them with the same thickness of 635 micrometers, are used. The experimental results are coherent with the tolerance and misalignment of the process, validating the proposed novel OMT design.}, issn = {0018-9480}, doi = {10.1109/TMTT.2013.2292611}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6678791}, author = {C A Leal-Sevillano and YingaTao, T and Lancaster, M J and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {48_propagacion_loss_indoor_3_frecuencias_cesar_WPC, title = {Narrowband Short Range Directive Channel Propagation Loss in Indoor Environment at Three Frequency Bands}, journal = {Wireless Personal Communication}, volume = {78}, number = {1}, year = {2014}, month = {Sep.}, pages = {507 - 520}, abstract = {Propagation loss models for indoor environment are presented. The narrowband directive channel propagation loss in indoor environment at three frequency bands namely (2.4, 3.3 and 5.5) GHz is measured. Sets of directive panel antennas are used in the measurements. RF signal generator and a spectrum analyzer are used in the measurement campaign. It is found that propagation loss is sensitive to the scenario configuration. It is noticed that the propagation loss can be modelled by a single slope propagation model or two slopes propagation model.}, keywords = {Directive channel, Propagation loss, Single slope propagation model, two slope propagation model}, issn = {1022-0038}, doi = {10.1007/s11277-014-1764-5}, url = {http://link.springer.com/article/10.1007/s11277-014-1764-5}, author = {B Taha-Ahmed and J L Masa-Campos and C A Naranjo-Hidalgo} } @conference {14_EuCAP_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_NovelDual-BandSingle, title = {Novel Dual-Band Single Circular Polarization Antenna Feeding Network for Satellite Communications}, booktitle = {Proc. 2014 European Conference on Antennas and Propagation (EuCap)}, year = {2014}, month = {Apr.}, pages = {1-5}, abstract = {In this paper a novel dual-band single circular polarization antenna feeding network for satellite communications is presented. The novel antenna feed chain1 is composed of two elements or subsystems, namely a diplexer and a bi-phase polarizer. In comparison with the classic topology based on an orthomode transducer and a dual-band polarizer, the proposed feed chain presents several advantages, such as compactness, modular design of the different components, broadband operation and versatility in the subsystems interconnection. The design procedure of this new antenna feed configuration is explained. Different examples of antenna feeding networks at 20/30 GHz are presented. It is pointed out the excellent results obtained in terms of isolation and axial ratio.}, keywords = {antenna, Circular polarization, diplexer, dual-band, K/Ka band, multibeam, orthomode transducer, polarizer, satellite communications, waveguide}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {14_TAP_SANCHEZ-OLIVARES_PFC, title = {Novel Four Cross Slot Radiator With Tuning Vias for Circularly Polarized SIW Linear Array}, journal = {Antennas and Propagation, IEEE Transactions on}, volume = {62}, number = {4}, year = {2014}, month = {April}, pages = {2271-2275}, abstract = {A substrate integrated waveguide (SIW) linear array is presented with a new circularly polarized (CP) element. The single radiator consists of four cross tilted slots. In addition, a pair of tuning metallic vias is included to improve the reflection of longest slots. A 16-element antenna prototype with -26-dB Taylor distribution and 1.5\% residual power was designed, manufactured and measured to verify the new slot performance in an array configuration. A 17-dB peak gain, 1.86-dB axial ratio and 80\% radiation efficiency were experimentally achieved at 17 GHz. A 3\% usable bandwidth was obtained owing to frequency main beam tilt dispersion.}, keywords = {16-element antenna prototype, antenna, Antenna measurements, antenna radiation patterns, array configuration, Arrays, circular polarization (CP), circularly polarized element, circularly polarized linear array, Couplings, four cross slot radiator, four cross tilted slots, frequency 17 GHz, frequency main beam tilt dispersion, linear antenna arrays, linear array, metallic vias, microwave antenna arrays, radiation efficiency, Reflection, single radiator, SIW linear array, slot, slot antenna arrays, substrate integrated waveguide, substrate integrated waveguide (SIW), substrate integrated waveguides, Substrates, Taylor distribution, Tuning, tuning via, tuning vias}, issn = {0018-926X}, doi = {10.1109/TAP.2014.2299823}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6710164}, author = {P Sanchez-Olivares and J L Masa-Campos} } @conference {14_EuMC_Ruiz-CruzFahmiMansour_Single-PoleMultiple-ThrowWaveguide, title = {Single-Pole Multiple-Throw Waveguide Switch for Twelve Output Ports}, booktitle = {Proc. 44th European Microwave Conference}, year = {2014}, issn = {978-1-61284-235-6}, author = {J A Ruiz-Cruz and Fahmi, M M and Mansour, R R} } @article {13_IEEETHz_Leal-SevillanoCooperRuiz-CruzEtAl_225GHzCircularPolDuplexer, title = {A 225 GHz Circular Polarization Waveguide Duplexer Based on a Septum Orthomode Transducer Polarizer}, journal = {IEEE Transactions on Terahertz Science and Technology}, volume = {3}, number = {5}, year = {2013}, month = {Sep.}, pages = {574-583}, abstract = {In this paper, we present the modeling and experimental validation of an efficient, compact, and high-isolation waveguide duplexer operating at 225 GHz. While duplexers based on ferrite circulators are key components of many monostatic radar systems, at W-band frequencies and above the performance of waveguide circulators rapidly deteriorates. The design presented here uses a ferrite-free duplexing concept based on transmitting and receiving in orthogonal circular polarizations. The circular polarization is efficiently generated in waveguide using a septum orthomode transducer polarizer, leading to a compact device with a single horn antenna. The complete duplexer is designed using efficient numerical algorithms, resulting in a fabricated device with a measured 10\% fractional bandwidth, a return loss better than 20 dB, isolation of 30 dB, and insertion loss below 1 dB.}, keywords = {Circular polarization, duplexer, orthomode transducer, terahertz}, issn = {2156-342X}, doi = {10.1109/TTHZ.2013.2264317}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6525512}, author = {C A Leal-Sevillano and Cooper, K B and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {13_DESE_Masa-CamposRuiz-CruzCorcoles-OrtegaEtAl_AntenasplanasBajasPerdidas, title = {Antenas planas con redes de alimentaci{\'o}n de bajas p{\'e}rdidas y control de apuntamiento para aplicaciones de defensa y seguridad}, booktitle = {Congreso Nacional de I+D en Defensa y Seguridad}, year = {2013}, month = {Nov}, pages = {1-8}, abstract = {En el presente art{\'\i}culo se presentan distintas opciones de antenas de bajo perfil, bajas p{\'e}rdidas y apuntamiento variable seg{\'u}n la banda de operaci{\'o}n de los sistemas de defensa y seguridad. Empezando por las antenas enteramente en tecnolog{\'\i}a impresa, pasando por las gu{\'\i}as de onda sobre sustrato y las gu{\'\i}as de ondas met{\'a}licas, los dise{\~n}os mostrados ofrecen un buen rendimiento en ganancia adecuado a la banda de frecuencias. Varios prototipos han sido implementados y testeados en banda S, X y Ku para validar las ideas planteadas.}, author = {J L Masa-Campos and J A Ruiz-Cruz and J C{\'o}rcoles-Ortega and B Taha-Ahmed and P Sanchez-Olivares and P Pascual-Garcia} } @conference {13_EuMC_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_CompactBroadbandCouplersMagicT, title = {Compact Broadband Couplers Based on the Waveguide Magic-T Junction}, booktitle = {Proc. 43rd European Microwave Conference}, year = {2013}, issn = {978-1-61284-235-6}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {13_CSTUGM_Montejo-GaraiRuiz-CruzLeal-SevillanoEtAl_DesignofDual-PolarizationDiplexers, title = {Design of Dual-Polarization Diplexers Based on Enhanced Turnstile Junctions}, booktitle = {2013 CST European User Group Meetings}, year = {2013}, month = {May}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and C A Leal-Sevillano and Rebollar, J M} } @conference {13_Montejo-GaraiRuiz-CruzLeal-SevillanoEtAl_DesignofDual-PolarizationwithFreqDsicrimi, title = {Design of Dual-Polarization Waveguide Devices with Frequency Discrimination}, booktitle = {2013 IEEE MTT-S International Microwave Symposium Digest}, year = {2013}, month = {June}, pages = {1-4}, abstract = {The goal of this workshop is to introduce the main topologies for devices handling both the frequency discrimination and dual-polarization at the same time. The particular issues that have to be taken into account when addressing the dual-polarization operation along with frequency discrimination in waveguide components will be studied. Antenna feeders with simultaneous linear or circular polarization working at frequency bands with very large separation will be discussed.}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and C A Leal-Sevillano and Rebollar, J M} } @conference {13_EuMC_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_Dual-BandBi-PhasePolarizerNonOMT, title = {Dual-Band Bi-Phase Waveguide Polarizer for a Novel Feeder Network without Orthomode Transducer}, booktitle = {Proc. 43rd European Microwave Conference}, year = {2013}, issn = {978-1-61284-235-6}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {13_URSIUSA_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_EquivalentcircuitofMultiaperture, title = {Equivalent circuit of multi-aperture waveguide irises and its application in the design of compact filters}, booktitle = {Proc. 2013 USNC/URSI National Radio Science Meeting}, year = {2013}, month = {July}, pages = {11}, abstract = {Equivalent circuits of waveguide discontinuities and volumes were use in the past for the design of microwave devices, N Marcuvitz, "Waveguide Handbook". Nowadays, most of this waveguide structures can be analyzed and optimized using rigorous full-wave methods (either numerical or quasi-analytical) with acceptable computation times. Nevertheless, an accurate equivalent circuit provides physical insight of the structure. This additional electromagnetic knowledge might lead to the design of new high-performance waveguide components. Moreover, non-ideal behaviors commonly obtained in experimental measurements, such as narrow band spike resonances, can be explained by means of accurate equivalent circuits. This work is divided in two parts: first an accurate and wide-band equivalent circuit of multi-aperture waveguide irises is determined; then this equivalent circuit is applied in the synthesis of compact waveguide filters, including pseudo-elliptical band-pass, dual band and stop-band filters. The proposed equivalent circuit of multi-aperture irises (with an arbitrary number of apertures) is based on an in deep electromagnetic analysis of the possible resonances of these structures. Two different kind of resonances are possible, either implementing a refection zero (resonances) or a transmission zero (antiresonances). The equivalent circuit is a parallel admittance with a circuit topology given by any of the classical one-port LC realizations, G C Temes and J. W. LaPatra, "Introduction to Circuit Synthesis and Design". The values of the circuit elements are entirely determined by the singular points (resonances and antiresonances) obtained in the full-wave analysis. Modeling of different multi-aperture waveguide irises by means of the proposed equivalent circuit, including experimental results of a five apertures iris, will be addressed in the presentation. Some designs of waveguide filters using the particular case of two-fold symmetric irises with three apertures will be presented. The design discussion will be focused on a systematic synthesis method based on the accurate modeling of the waveguide irises.}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @article {13_JEMWA_Leal-SevillanoMontejo-GaraiRuiz-CruzEtAl_ExperimentalcomparisonofWBandFilters, title = {Experimental comparison of waveguide filters at W-band implemented by different machining processes and split-block}, journal = {Journal of Electromagnetic Waves and Applications}, volume = {27}, number = {18}, year = {2013}, month = {Oct}, pages = {2390-2394}, abstract = {The aim of this work is to explore different machining processes and different split-block, getting important experimental information for the design of passive waveguide components at W-band. To this end, two all-pole response filters are machined by different techniques: electro-discharge and milling, and split-block: H-plane and E-plane. Some interesting results, obtained in the design, fabrication, and measure of waveguide filters at W-band, such as tolerances of the different processes and level of insertion loss, are reported.}, keywords = {antena de parche, microstrip, ranura, red de alimentaci{\'o}n}, issn = {0920-5071}, doi = {http://dx.doi.org/10.1080/09205071.2013.851011}, author = {C A Leal-Sevillano and Montejo-Garai, J R, and J A Ruiz-Cruz and Rebollar, J M} } @conference {13_URSIESP_Mecia-OlivaGrajal-de-la-FuenteBadolatoEtAl_Experimentalradarimager300GHz, title = {Experimental radar imager with sub-cm range resolution at 300 GHz}, booktitle = {Proc. 2013 Simposium Nacional URSI (in Spanish)}, year = {2013}, month = {Sept.}, pages = {1-7}, abstract = {This paper presents a high range resolution radar sensor working in the submillimeter-wave band for standoff detection and security applications. Low-cost technologies have been properly selected in order to implement a versatile and easily scalable radar system. A large operational bandwidth, required for high range resolution, is attained by means of a frequency multiplication-based architecture. This radar system sweeps a bandwidth of 27 GHz. The final application allows the generation of 3D images by means of the radar front-end integrated with a bifocal ellipsoidal Gregorian reflector system. The scene of interest is elliptically scanned at a standoff range of 8 m. In addition, some of the design and fabrication techniques of components at the millimeter and submillimeter-wave bands are presented.}, author = {Mecia-Oliva, B and Grajal-de-la-Fuente, J and Badolato, A and Garcia-Pino, A and Besada-Sanmartin, J L and C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {13_AWPL_GARCIA-VALVERDE_PFC, title = {Linear Patch Array Over Substrate Integrated Waveguide for Ku-Band}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {12}, year = {2013}, pages = {257-260}, abstract = {A linearly polarized patch array with direct probe feed over substrate integrated waveguide (SIW) network (LP-PASIW) for Ku-band is presented. A double-stacked microstrip patch structure has been used as radiating elements. Internal SIW coupling patches are placed inside the SIW to obtain the desired radiation pattern. The internal coupling and external radiating patches are connected by means of copper vias. A mutual coupling model is also proposed to adjust the radiation and reflection properties of the array. An antenna prototype has been manufactured and measured. At 17.7 GHz, 16 dBi and 80\% peak gain and efficiency values are obtained. Although a 10\% reflection bandwidth (17-18.6 GHz) is achieved, the usable bandwidth is reduced to 3\% due to array beam tilt dispersion.}, keywords = {antenna feeds, antenna prototype, antenna radiation patterns, Antennas, array beam tilt dispersion, Arrays, bandwidth 17 GHz to 18.6 GHz, Brain modeling, Couplings, direct probe feed, double-stacked microstrip patch structure, Double-stacked patch, efficiency 80 percent, electromagnetic wave polarisation, external radiating patches, frequency 17.7 GHz, hybrid LSM$^{{rm y}{\textquoteright}}$ mode, internal coupling patches, internal SIW coupling patches, linearly polarized patch array, LP-PASIW, microstrip antenna arrays, microwave antenna arrays, Mutual coupling, mutual coupling model, radiating elements, radiation pattern, Reflection, substrate integrated waveguide (SIW), substrate integrated waveguide network, substrate integrated waveguides, Substrates, waveguide antenna arrays}, issn = {1536-1225}, doi = {10.1109/LAWP.2013.2245623}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6451111\&tag=1}, author = {D Garcia-Valverde and J L Masa-Campos and P Sanchez-Olivares and B Taha-Ahmed and J C{\'o}rcoles} } @article {22_materialsPIER-M, title = {Material{\textquoteright}s Insertion Loss at 2.4, 3.3 and 5.5 GHz Bands}, journal = {PIER-M: Progress in Electromagnetics Research M}, volume = {30}, year = {2013}, month = {Mar.}, pages = {1-10}, abstract = {The insertion loss of different materials is measured at 2.4, 3.3 and 5.5 GHz bands. Directive antennas with a nominal gain of 19 dB are used in the measurement campaign. The height of the antennas has been selected to have the minimum possible reflection from around surfaces. Metallic door with porthole window, metallic grid, glass window, human beings and tree{\textquoteright}s insertion loss are measured. The metallic grid presents a band pass filter function with a resonance frequency between 3.2 to 3.3 GHz. Other materials have an insertion loss that increases with the increment of the operating frequency.}, issn = {1937-8726}, doi = {10.2528/PIERM13022803}, url = {http://www.jpier.org/PIERM/pierm30/01.13022803.pdf}, author = {B Taha-Ahmed and I {\'A}lvarez-Calvo and J L Masa-Campos} } @article {23_materialsPIER-L, title = {Material{\textquoteright}s Insertion Loss in Three Frequency Bands}, journal = {PIER-L: Progress in Electromagnetics Research Letters}, volume = {39}, year = {2013}, month = {Apr.}, pages = {199-205}, abstract = {The insertion loss of different materials is measured at 2.4, 3.3 and 5.5 GHz bands. Directive antennas with a nominal gain of 19 dB are used in the measurement campaign. The height of the antennas has been selected to have the minimum possible reflection from around surfaces. Thick concrete wall, thick concrete column and tree{\textquoteright}s insertion loss are measured. It is noticed that the insertion loss increases with the increment of the operating frequency. For tress, the insertion loss for the leafless tress is 6 to 10 dB lower than the deciduous trees.}, issn = {1937-6480}, doi = {10.2528/PIERL13040906}, url = {http://www.jpier.org/PIERL/pierl39/20.13040906.pdf}, author = {B Taha-Ahmed and I {\'A}lvarez-Calvo and J L Masa-Campos} } @article {13_IETMAP_Montejo-GaraiRuiz-CruzLeal-SevillanoEtAl_ModelingofDual-PolarizationDiplexers, title = {Modeling of Dual-Polarization Diplexers Based on Enhanced Multiport Turnstile Junctions}, journal = {IET Microwaves, Antennas and Propagation}, volume = {7}, number = {7}, year = {2013}, month = {May}, pages = {485-492}, abstract = {The modelling of waveguide diplexers working simultaneously with two dual-polarisation signals is presented in this study. The proposed network is an ortho-mode junction with six physical ports based on an enhanced multiport turnstile junction. This structure is excited at the common port coming from the antenna, by two signals at different frequency bands which are required to be discriminated into dedicated ports. The added functionality of the structure presented in this work is that each frequency band can also allocate two orthogonal polarisations (dual linear or dual circular) with a very large separation between bands (fractional bandwidth larger than 55\%), using two different waveguiding concepts. The first one is based on confining the high frequencies at the centre of the axial path. The second one is just the dual, diverting the high frequencies to the outer boundaries of the axial path. The proposed structures, whose modelling and design will be addressed, are suited for low insertion loss and high-power applications, since they do not use metallic pins, irises or small waveguide sections. Moreover, as consequence of the introduced waveguiding concepts, they are very compact and short in the axial direction, which is crucial for this type of feeders in satellite applications.}, keywords = {antenna feeds, multifrequency antennas, multiplexing equipment, multiport networks, waveguide junctions}, issn = {1751-8725}, doi = {10.1049/iet-map.2012.0424}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6552358}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and C A Leal-Sevillano and Rebollar, J M} } @article {13_IEEEMWCL_Leal-SevillanoReckJung-KubiakEtAl_SiliconMicromachinedCanonicalTHz, title = {Silicon Micromachined Canonical E-Plane and H-Plane Bandpass Filters at the Terahertz Band}, journal = {IEEE Microwave and Wireless Components Letters}, volume = {23}, number = {6}, year = {2013}, month = {June}, pages = {288-290}, abstract = {In this letter, several bandpass filters operating in the WR-1.5 band (500 to 750 GHz) are presented. The deep reactive ion etching (DRIE) silicon micromachining process is used for the fabrication of the filters. Two canonical filter topologies based on E- and H-plane are implemented. The work presented here has two specific objectives: a) to get important fabrication process parameters, such as tolerances, vertical angles, surface roughness, and repeatability and b) to validate the proper working of the waveguide filters in the terahertz band. These filters do not have any tuning element. Experimental results show better than 10 dB return loss and approximately 1 and 2.5 dB insertion loss (for 6\% fractional bandwidth) for the E- and H-plane topology, respectively. The obtained results are in agreement with fabrication tolerances of 2 micrometers and vertical angles deviations up to 3{\^A}{\textdegree}.}, keywords = {Deep reactive ion etching (DRIE), filter, micromachining, terahertz, WR-15}, issn = {1531-1309}, doi = {10.1109/LMWC.2013.2258097}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6509458}, author = {C A Leal-Sevillano and Reck, T J and Jung-Kubiak, C and Chattopadhyay, G. and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {13_IMS_Ruiz-CruzFahmiMansour_Single-PoleSix-ThrowWaveguideSwitch, title = {Single-Pole Six-Throw Waveguide Switch Embedded in a Seven Port Loaded Junction}, booktitle = {2013 IEEE MTT-S International Microwave Symposium Digest}, year = {2013}, month = {Nov}, pages = {1-4}, abstract = {A waveguide switch with six states involving seven ports is presented in this paper. It consists of a common port that feeds perpendicularly six output routing branches placed in the same plane. The switch is based on actuating short circuit loads in six ridge waveguide branches. It avoids the use of complex rotary systems to provide path switching, resulting in an extremely compact profile and simplifying the manufacturing. The concept is presented based on rigorous full-wave simulations and experimental results of a Ku-band SP6T, which is designed, built and tested. The experimental proof of this new switch integrates the transitions to SMA outputs and the short-circuit loads. It shows measured return loss better than 25 dB in a 12\% fractional bandwidth in the best state and 20 dB in an 8\% bandwidth in the worst state. The isolation of this prototype is at least 32 dB, with insertion loss of 0.3-0.4 dB.}, author = {J A Ruiz-Cruz and Fahmi, M M and Mansour, R R} } @article {13_PIERC_Sanchez-OlivaresMasa-CamposRuiz-CruzEtAl_SIW2DPlanar4CrossSlotsTuningvias, title = {SIW 2D Planar Array with Four Cross Slots Radiator and Tuning Vias}, journal = {Progress In Electromagnetics Research C}, volume = {40}, year = {2013}, pages = {83-92}, abstract = {A Substrate Integrated Waveguide (SIW) planar array is presented using a right handed circularly polarized (RHCP) element with four crossed tilted radiating slots. In addition, a pair of metallic tuning vias is included to really improve the reflection of longest slots. A corporate feeding network over SIW has been designed for distributing the input signal to 128 radiating elements, divided into 8 progressive wave linear arrays of 16 elements each. The designed planar array has been manufactured and measured to verify the antenna performance. 25.5 dB gain, 2.33 dB axial ratio, as well as 85\% radiation efficiency values have been experimentally achieved at 17 GHz. A 3\% usable bandwidth (16.75-17.25 GHz) is obtained due to the typical frequency main beam tilt dispersion in the elevation plane of the progressive wave arrays.}, issn = {1937-8718}, doi = {10.2528/PIERC13040905}, url = {http://www.jpier.org/PIERC/pier.php?paper=13040905}, author = {P Sanchez-Olivares and J L Masa-Campos and J A Ruiz-Cruz and B Taha-Ahmed} } @conference {APS-URSI-2013, title = {SIW patch array with internal coupling patches}, booktitle = {Antennas and Propagation Society International Symposium (APSURSI), 2013 IEEE}, year = {2013}, month = {July}, pages = {1800-1801}, abstract = {A Substrate Integrated Waveguide (SIW) has been used to feed a progressive wave linear array of 16 double stacked patches. The amplitude and phase performance has been achieved by means of coupling patches, which are placed inside the SIW. An antenna prototype has been manufactured with a multilayer PCB structure. 16 dBi and 80 \% peak gain and efficiency values at 17.7 GHz have been measured. A 10\% reflection bandwidth (17 - 18.6 GHz) is achieved, although the usable bandwidth is reduced to 3\% due to the typical array beam tilt dispersion of this kind of designs.}, keywords = {Antenna measurements, antenna prototype, Antennas, array beam, Arrays, bandwidth 17 GHz to 18.6 GHz, Couplings, double stacked patches, Gain, internal coupling patches, linear antenna arrays, microstrip antenna arrays, Nonhomogeneous media, PCB structure, printed circuits, progressive wave linear array, SIW patch array, substrate integrated waveguide, substrate integrated waveguides, Substrates, tilt dispersion}, issn = {1522-3965}, doi = {10.1109/APS.2013.6711559}, author = {J L Masa-Campos and D Garcia-Valverde and P Sanchez-Olivares and B Taha-Ahmed} } @conference {13_URSI_SANCHEZ-OLIVARES_tuningvias, title = {Tuning Vias Four Cross Slot Planar Array over Substrate Integrated Waveguide}, booktitle = {Simposium Nacional URSI 2013}, year = {2013}, month = {September}, abstract = {A Substrate Integrated Waveguide (SIW) planar array is presented using a circularly polarized (CP) four crossed tilted radiating slots. In addition, a pair of metallic tuning vias is included to really improve the reflection of longest slots. A corporate feeding network over SIW has been designed for distributing the input signal to 128 radiating elements, divided into eight 16-elements progressive wave linear arrays. The designed planar array has been manufactured and measured to verify the antenna performance. 25.5 dB peak gain, 2.33 dB axial ratio and 85\% radiation efficiency values have been experimentally achieved at 17 GHz. Although the specified operation band is 16.3 to 17.7 GHz (Ku band), a 3\% usable bandwidth is obtained due to the typical frequency main beam tilt dispersion in the elevation plane of the progressive wave antennas.}, author = {P Sanchez-Olivares and J L Masa-Campos} } @conference {12_URSIUSA_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_DesignFiltersWband, title = {Design of waveguide filters at W-band by means of machining techniques}, booktitle = {Proc. 2012 USNC/URSI National Radio Science Meeting}, year = {2012}, month = {July}, pages = {1}, abstract = {A common part of many microwave systems is the routing of the signal between the circuit devices performing the different functions of the system (frequency discrimination, power combining, frequency conversion, signal amplifying {\^a}{\texteuro}{\textbrokenbar}). The optimum configuration of these individual devices may lead to a system layout where the interfaces of the different blocks are not aligned or even are in different planes. Thus, the routing network must have waveguide transformers, bends, and twists to be able to accommodate the signal between the different blocks. These elements have a simple function, although a careful design may be required for broadband applications. Moreover, in satellite communications, mass and volume must be kept to a minimum and compactness is highly pursued. A possible solution in these cases is to integrate some of these functions in the routing network elements or even in the input/output of the components. In this work, several waveguide devices will be shown with integrated compact elements for waveguide matching and polarization rotation. Since different functions are integrated in the same device, transitions are avoided and the total length is reduced. Very compact structures for waveguide twists have been developed in Asao et al., "A compact 90-degree twist using novel ridged waveguide for integrated waveguide subsystems," Proc. 36th EuMC, 2006 and Kirilienko et al. {\^a}{\texteuro}{\oe}Compact 90{\^A}{\textordmasculine} Twist formed by a Double-Corner-cut Square Waveguide Section{\^a}{\texteuro}, IEEE TMTT, 2008). Other structures used here will be based on Ruiz-Cruz et al., {\^a}{\texteuro}{\oe}Multi-Section Bow-Tie Steps for Full-Band Waveguide Polarization Rotation{\^a}{\texteuro}, IEEE MWCL, July 2010. The design and evaluation of the different components will be addressed in the presentation, with devices in mixed E/H plane configuration, bends and transformers. When integrating different functions in the same device, some undesired resonances may appear in the structure. Therefore, accurate CAD tools are required for simulating the response and taking into account the mode excitations inside the structure. A precise fabrication is required for having good experimental results, which will be shown in the presentation.}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {12_URSIESP_Leal-SevillanoMontejo-GaraiMaolongEtAl_DisenoWFilterSU8, title = {Dise{\~n}o de un Filtro de Respuesta El{\'\i}ptica en Banda W Fabricado Mediante la Tecnolog{\'\i}a de Foto Resina SU-8}, booktitle = {Proc. 2012 Simposium Nacional URSI (in Spanish)}, year = {2012}, month = {Sept.}, pages = {1-4}, abstract = {Waveguide polarizers are essential devices in feeders for radio transmission systems with circular polarization. In this paper two different dual-band polarizers are designed and compared. The structure of both polarizers is based on the classical corrugated rectangular waveguide. This structure can be analyzed very efficiently like an H-plane and an E-plane problem. The Mode-Matching technique, in combination with global search algorithms, is used for the full-wave analysis and optimization of the polarizers. In the first polarizer, the height of the corrugations is designed according to a taper-type shape. For the second polarizer, no restrictions in the height of the corrugations are imposed and all the dimensions are optimized. The performance of both polarizers is compared, showing certain improvement in terms of polarization purity for the second one.}, author = {C A Leal-Sevillano and Montejo-Garai, J R and Ke Maolong and Lancaster, M. J and J A Ruiz-Cruz and Rebollar, J M} } @conference {12_IMS_Ruiz-CruzFahmiMansour_Dual-ResonanceComblineResonator, title = {Dual-Resonance Combline Resonator for Dual-Band Filters}, booktitle = {2009 IEEE MTT-S International Microwave Symposium Digest}, year = {2012}, month = {June}, pages = {1-3}, abstract = {A novel combline resonator is introduced in this paper for realizing compact microwave dual-band filters. The basic resonator is based on the well-known combline topology, where an additional metallic conductor is introduced for having two TEM modes. The resonant frequencies of the two asynchronous TEM resonant modes are controlled by the length of the two concentric conductors and their spacing. The proposed structure is employed to realize a dual-band filter, where each combline resonator provides one resonant mode per pass-band. The control of the filter parameters, such as pass-band bandwidths and band separation, is addressed. These filters harness the advantages of combline technology for dual-band filters, using the compactness provided by the proposed resonator. A complete design is introduced. Simulations as well as experimental results are presented showing excellent agreement, thus validating the proposed concept.}, issn = {0149-645X}, doi = {10.1109/MWSYM.2012.6259436}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6259436}, author = {J A Ruiz-Cruz and Fahmi, M M and Mansour, R R} } @article {12_IEEEMWCL_Leal-SevillanoMontejo-GaraiRuiz-CruzEtAl_Low-LossEllipticalResponse, title = {Low-Loss Elliptical Response Filter at 100 GHz}, journal = {Microwave and Wireless Components Letters, IEEE}, volume = {22}, number = {9}, year = {2012}, month = {September}, pages = {459 -461}, abstract = {The design, method of fabrication and experimental validation of a pseudo-elliptical four-poles asymmetric response filter at 100 GHz with 10\% of fractional bandwidth is presented. The designed filter is part of an image radar system and must fulfill stringent specifications. The proposed topology and method of fabrication improves the out of band rejection above the pass band in comparison with other classical structures, while keeping a low insertion loss level. A two-fold geometry for implementing a transmission zero is proposed, avoiding the excitation of the first higher order mode and easing the manufacturing without any tuning element. A low-cost milling process is used for the fabrication of the device. The final design fulfills the desired specifications and presents 0.6 dB of insertion loss level at 100 GHz. The excellent agreement between simulations and measurements at this frequency band in both, return loss and insertion loss, is pointed out.}, keywords = {Asymmetric, band-pass filters, elliptic filters, extracted pole, Fabrication, fabrication method, filter, filtering theory, fractional bandwidth, frequency 100 GHz, higher order mode, image radar system, Insertion loss, loss 0.6 dB, Loss measurement, low insertion loss level, low loss, low-cost milling process, low-loss elliptical response filter, microwave filters, millimetre wave filters, Milling, out of band rejection, pseudo-elliptical four-poles asymmetric response filter, Radar, return loss, transmission zero, two-fold geometry, W-band}, issn = {1531-1309}, doi = {10.1109/LMWC.2012.2212237}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6268297\&tag=1}, author = {C A Leal-Sevillano and Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @conference {12_IMS_DaneshmandA.FahmiEtAl_MEMSMultiportSwitches, title = {MEMS Multiport Switches and Switch Matrices for Satellite Applications}, booktitle = {2012 IEEE MTT-S International Microwave Symposium Digest}, year = {2012}, month = {June}, pages = {1-4}, issn = {0149-645X}, author = {Daneshmand, M and Fomani, A A and Fahmi, M M and J A Ruiz-Cruz and Mansour, R R} } @conference {12_CSTUGM_Montejo-GaraiLeal-SevillanoRuiz-CruzEtAl_MultipactionBreakdownPrediction, title = {Multipaction Breakdown Prediction of Passive Microwave Devices with CST Particle-Studio}, booktitle = {2012 CST European User Group Meetings}, year = {2012}, month = {May}, keywords = {CST}, author = {Montejo-Garai, J R and C A Leal-Sevillano and J A Ruiz-Cruz and Rebollar, J M} } @article {19_Propagation5.6GHzPIER-C, title = {Propagation Loss Measurement due to Miscellaneous Phenomenon at 5.6 GHz Band}, journal = {PIER-C: Progress in Electromagnetics Research C}, volume = {32}, year = {2012}, month = {Oct.}, pages = {207-220}, abstract = {In this work, the propagation loss due to diffraction and insertion losses for indoor scenario at 5.6 GHz band are measured using directive antenna and a Vector Network Analyzer (VNA). It is shown that the insertion loss of a metallic door with porthole window varies from several dB due to the propagation loss via the porthole glass up to 50 dB due to the diffraction by the porthole boards when the line between the transmitting antenna and receiving one is outside the porthole glass. It is shown that the insertion loss of a 12 cm brick wall is 4.8 dB for vertical polarization while it is 6.3 dB for horizontal polarization. Also it is shown the diffraction loss due single or double concrete columns depends on the distance between the transmitting and receiving antennas.}, issn = {1937-8718}, doi = {10.2528/PIERC12072304}, url = {http://www.jpier.org/PIERC/pierc32/16.12072304.pdf}, author = {B Taha-Ahmed and J L Masa-Campos and F Fern{\'a}ndez-Campillo} } @article {17_WimaxWIRELESSCOM, title = {Propagation Path Loss and Materials Insertion Loss in Indoor Environment at WiMAX Band of 3.3 to 3.6 GHz}, journal = {Wireless Personal Communication}, volume = {66}, number = {2}, year = {2012}, month = {Sep.}, pages = {251 - 260}, abstract = {The purpose of this study is to characterize the indoor channel for IEEE 802.16 (WiMAX) at 3.3{\textendash}3.6 GHz frequency. This work presents a channel model based on measurements conducted in commonly found scenarios in buildings. These scenarios include closed corridor, wide corridor and semi open corridor. Path loss equations are determined using log-distance path loss model and a Rayleigh multipath induced fading, Normal multipath induced fading or a combination of both. A numerical analysis of measurements in each scenario was conducted and the study determined equations that describe path loss for each scenario. Propagation loss is given for 300 MHz bandwidth. This work also represents the insertion loss of different materials and the obstruction loss due the existence of human beings between the transmitting antenna and the receiving one.}, keywords = {Indoor propagation, Normal multipath induced fading, Rayleigh multipath induced fading, WiMAX}, issn = {1022-0038}, doi = {10.1007/s11277-011-0335-2}, url = {http://link.springer.com/article/10.1007/s11277-011-0335-2}, author = {B Taha-Ahmed and J L Masa-Campos and Lalueza-Mayordomo, J M} } @article {12_IEEEMWCL_Leal-SevillanoMontejo-GaraiMaolongEtAl_Pseudo-EllipticalResponseFilterSU8, title = {A Pseudo-Elliptical Response Filter at W-Band Fabricated with Thick SU-8 Photo-Resist Technology}, journal = {IEEE Microwave and Wireless Components Letters}, volume = {22}, number = {3}, year = {2012}, month = {March}, pages = {105-107}, abstract = {The design and experimental validation of a pseudo-elliptical response filter at W-Band is presented. A micromachining technique based on the thick SU-8 photo-resist is used to construct the filter. The optimized structure is specially well-suited for the implementation of filters with transmission zeros by means of micromachining techniques, since the extracted poles are implemented by simple stubs without irises. Furthermore, a novel topology based on the use of only three SU-8 layers is presented. This new topology, which includes a novel optimized input/output routing, can be potentially used for the design of high-performance devices with a fast and low-cost production. A fourth-order filter with two transmission zeros has been fabricated (bandwidth 5\%), presenting 1.2 dB of insertion loss. This level of loss is equivalent to the actual state-of-art for micromachined filters at W-band, in spite of the reduced height and the split block in the H-plane used in the presented design.}, issn = {1531-1309}, doi = {http://dx.doi.org/10.1109/LMWC.2012.2183861}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=\&arnumber=6157647\&contentType=Journals+\%26+Magazines\&sortType\%3Dasc_p_Sequence\%26filter\%3DAND\%28p_IS_Number\%3A6166715\%29}, author = {C A Leal-Sevillano and Montejo-Garai, J R and Ke Maolong and Lancaster, M. J and J A Ruiz-Cruz and Rebollar, J M} } @conference {12_ESA_Montejo-GaraiRuiz-CruzRebollar_RecentResultsFiltersWBand, title = {Recent Results on Waveguide Filters at W-Band}, booktitle = {Proc. 2012 ESA Microwave Technology and Techniques Workshop}, year = {2012}, month = {Nov.}, pages = {1-6}, author = {C A Leal-Sevillano and Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @article {12_RS_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_RigorousanalysisofParallelPlateTEMtoPolariton, title = {Rigorous analysis of the parallel plate waveguide: From the transverse electromagnetic mode to the surface plasmon polaritons}, journal = {Radio Science}, volume = {47}, number = {RS0NO2}, year = {2012}, month = {February}, pages = {1-8}, abstract = {This paper presents an analysis of the parallel plate waveguide, based on a hybrid mode formulation. The nonideal metallic conductors of the waveguide are treated as a media characterized by an equivalent permittivity. The frequencies of interest in the presented analysis are at the terahertz band (from 300 GHz to 30 THz), and appropriate models are used for the correct characterization of metallic conductors at these frequencies. The behavior of the electromagnetic field of the fundamental mode is studied in a wide frequency range. At low frequencies (microwave regime) the fundamental mode is the well-known transverse electromagnetic (TEM) mode; as frequency increases, the electromagnetic field changes significantly and a surface wave or surface plasmon polariton (SPP) behavior is observed at the highest frequencies of the terahertz band. This paper shows a unified formulation that explains this transformation in the electromagnetic field behavior.}, issn = {0018-9480}, doi = {doi:10.1029/2011RS004838}, url = {http://onlinelibrary.wiley.com/doi/10.1029/2011RS004838/pdf}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {18_Propagation5.5GHzPIER, title = {Short Range Propagation Model For a Very Wideband Directive Channel at 5.5 GHz Band}, journal = {PIER - Progress in Electromagnetics Research}, volume = {130}, year = {2012}, month = {Sep.}, pages = {319-346}, abstract = {In this work, the propagation loss of three short range directive channels at 5.5 GHz is measured using different directive antennas and a Vector Network Analyzer (VNA). Results are given for a channel bandwidth of 300 MHz which will be the future channel bandwidth of IEEE 802.11 ac system. It has been noted that the multipath induced fading tends to have Normal Distribution at low distance between the transmitting and the reception antennas. At higher distances, it tends to have Normal distribution plus Rayleigh one. Channel Impulse response (CIR) is also measured indicating that the main contribution is due to the direct ray and the one reflected from the floor. The human being obstruction causes an extra propagation loss of 2 to 10 dB depending on its distance from the transmitting antenna.}, issn = {1559-8985}, doi = {10.2528/PIER12060509}, url = {http://www.jpier.org/PIER/pier130/16.12060509.pdf}, author = {B Taha-Ahmed and F Fern{\'a}ndez-Campillo and J L Masa-Campos} } @conference {12_EUCAP_SANCHEZ-OLIVARES_16siw, title = {Slot radiator with tuning vias for circularly polarized SIW linear array}, booktitle = {Antennas and Propagation (EUCAP), 2012 6th European Conference on}, year = {2012}, month = {March}, pages = {3716-3720}, abstract = {A 16-element circularly polarized (CP) Substrate Integrated Waveguide (SIW) linear array antenna with -26 dB Taylor distribution and 2\% residue power at 17 GHz is designed. The single element consists of four crossed inclined radiating slots. In this configuration, reflection goals on the linear array are not fully achieved. For this reason a tuning element is included on some of the individual radiating elements, which consists of a pair of metallic vias that greatly enhances the reflection of longest slots. Therefore, the antenna reflection is also improved. A global antenna prototype is manufacture to check the new slot element performance in an array configuration. The specified operation band is 16.3 to 17.7 GHz.}, keywords = {16-element circularly-polarized SIW linear array antenna, antenna radiation patterns, antenna reflection, Arrays, circular polarization (CP), electromagnetic wave polarisation, frequency 16.3 GHz to 17.7 GHz, linear antenna arrays, metallic vias, prototypes, radiating elements, Reflection, slot antenna arrays, Slot antennas, Slot array antenna, slot radiator, slot reflection, substrate integrated waveguide, substrate integrated waveguide (SIW), substrate integrated waveguides, Substrates, Taylor distribution, Tuning, tuning element, tuning via, tuning vias}, doi = {10.1109/EuCAP.2012.6205816}, author = {P Sanchez-Olivares and J L Masa-Campos} } @conference {12_ICEAA_Montejo-GaraiLeal-SevillanoRuiz-CruzEtAl_SymmetricalResponseFilterBartlett, title = {Symmetrical Response Filter Design Applying the Bartlett{\^a}{\texteuro}{\texttrademark}s Theorem and Using Riblet{\^a}{\texteuro}{\texttrademark}s Couplers}, booktitle = {Proc. International Conference on Electromagnetics in Advanced Applications (ICEAA)}, year = {2012}, month = {Sep.}, pages = {1-4}, keywords = {corrugated waveguide, dual-band, mode-matching, optimization, Waveguide polarizers}, author = {Montejo-Garai, J R and C A Leal-Sevillano and J A Ruiz-Cruz and Rebollar, J M} } @article {12_FED_Montejo-GaraiLeal-SevillanoRuiz-CruzEtAl_SynthesisanddesignPlasma, title = {Synthesis and design of waveguide band-stop filters without out-of-band spurious responses for plasma diagnosis}, journal = {Fusion Engineering and Design}, volume = {89}, number = {9}, year = {2012}, month = {September}, pages = {1662-1666}, issn = {0920-3796}, doi = {10.1016}, url = {http://www.sciencedirect.com/science/article/pii/S0920379612003146}, author = {Montejo-Garai, J R and C A Leal-Sevillano and J A Ruiz-Cruz and Rebollar, J M and Estrada, T} } @article {12_IEEETMTT_Ruiz-CruzFahmiMansour_Triple-ConductorComblineResonators, title = {Triple-Conductor Combline Resonators for Dual-Band Filters With Enhanced Guard-Band Selectivity}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {60}, number = {12}, year = {2012}, month = {December}, pages = {3969-3979}, abstract = {Novel combline resonators and filters with enhanced dual-band characteristics are introduced in this paper. The proposed resonator is made up of three metallic conductors: an inner post, an intermediate conductor, and an enclosure. This structure provides two asynchronous resonant modes that can be used for realizing compact microwave dual-band filters. Such dual-band filters offer the low cost, compact size, and ease of manufacturing features of traditional combline resonator filters, with additional size reduction due to the fact that a single physical cavity provides two electrical resonators. In addition, the new cavity introduces a transmission zero in the guard-bands enhancing the filter selectivity, while keeping a simple and compact inline topology. The design of filters based on this novel resonator is discussed, starting with the resonator circuit model, the coupling scheme, and the complete filter design methodology. Simulations as well as experimental results of a tenth-order $(2 times 5)$ dual-band filter with a measured rejection level in excess of 100 dB in the guard-band are presented to show the concept.}, keywords = {Dual-resonance TEM-mode filters, multiband filters, multiconductor combline, re-entrant cross section}, issn = {0018-9480}, doi = {10.1109/TMTT.2012.2223482}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6354010}, author = {J A Ruiz-Cruz and Fahmi, M M and Mansour, R R} } @conference {12_IMS_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_UpperFrequencyLimit, title = {Upper Frequency Limit of the Power Loss Method for the Estimation of Ohmic Losses in Hollow Metallic Waveguides}, booktitle = {2012 IEEE MTT-S International Microwave Symposium Digest}, year = {2012}, month = {June}, pages = {1-4}, issn = {0149-645X}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {11_EuMC_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_CADDual-BandPolarizersCorrugatedRectWg, title = {CAD for Dual-Band Polarizers in Corrugated Rectangular Waveguide}, booktitle = {Proc. 41st European Microwave Conference}, year = {2011}, month = {Oct.}, pages = {822-825}, abstract = {Waveguide polarizers are essential devices in feeders for radio transmission systems with circular polarization. In this paper two different dual-band polarizers are designed and compared. The structure of both polarizers is based on the classical corrugated rectangular waveguide. This structure can be analyzed very efficiently like an H-plane and an E-plane problem. The Mode-Matching technique, in combination with global search algorithms, is used for the full-wave analysis and optimization of the polarizers. In the first polarizer, the height of the corrugations is designed according to a taper-type shape. For the second polarizer, no restrictions in the height of the corrugations are imposed and all the dimensions are optimized. The performance of both polarizers is compared, showing certain improvement in terms of polarization purity for the second one.}, keywords = {corrugated waveguide, dual-band, mode-matching, optimization, Waveguide polarizers}, issn = {978-1-61284-235-6}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=224789}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {11_IMS_Ruiz-CruzFahmiMansour_Compactfour-portRectWgSwitches, title = {Compact four-port rectangular waveguide switches based on simple short circuit loads}, booktitle = {2011 IEEE MTT-S International Microwave Symposium Digest}, year = {2011}, month = {June}, pages = {1-4}, abstract = {Four-port rectangular waveguide switches presented in this paper are based on alternating simple short and open circuit loads in the waveguide path. The proposed concept eliminates the use of bulky rotary mechanisms to provide path switching. The device layout is very simple and compact and is presented for C-, R- and T-type switches. The experimental performance of a T-type switch shows a return loss better than 23 dB from 13 to 14.5 GHz, insertion loss of 0.3 $\#$x2013;0.4 dB and isolation of 28 dB.}, issn = {0149-645X}, doi = {10.1109/MWSYM.2011.5973154}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5973154}, author = {J A Ruiz-Cruz and Fahmi, M M and Mansour, R R} } @conference {11_IMS_Ruiz-CruzFahmiDaneshmandEtAl_CompactreconfigurableWgCircularPol, title = {Compact reconfigurable waveguide circular polarizer}, booktitle = {2011 IEEE MTT-S International Microwave Symposium Digest}, year = {2011}, month = {June}, pages = {1-4}, abstract = {A waveguide circular polarizer with reconfigurable polarization sense is proposed in this paper. The polarizer can be switched between right and left hand circular polarization. The polarization sense is controlled by RF MEMS switches, which commute between two states for allowing or blocking adequately two different signal paths inside the waveguide structure. The polarizer is made up of three building blocks, involving E-plane waveguide MEMS SP2T switch, ridge to waveguide transitions and a septum-orthomode transducer. A switchable Ku-band polarizer prototype is designed and tested as a proof of concept. The experimental performance shows acceptable return losses and axial ratio levels in the 12.7 to 14.8 GHz band (15.3\% fractional bandwidth). The proposed structure is compact and is useful for applications that require fast polarization switching.}, issn = {0149-645X}, doi = {10.1109/MWSYM.2011.5972872}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5972872}, author = {J A Ruiz-Cruz and Fahmi, M M and Daneshmand, M and Mansour, R. R} } @conference {11_EIEC_Montejo-GaraiLeal-SevillanoRuiz-CruzEtAl_DesignofContiguous-BandOMUX, title = {Design of Contiguous-Band Elliptic-Response Manifold Output Multiplexers by Efficient Cancellation of Reactive Impedance Parts}, booktitle = {Proc. VIII Encuentro Ib{\'e}rico de Electromagnetismo Computacional (in Spanish)}, year = {2011}, month = {Nov.}, pages = {1}, abstract = {In recent years, there has been an increasing demand for satellite communication channels with a complex response, motivated by a most effective use of the radiofrequency spectrum. This means that more channels have to be combined in the output multiplexer (OMUX) after power amplification. In this paper, a synthesis technique based on the Cauer ladder development has been developed to design the singly terminated filters for manifold multiplexers. A procedure for the synthesis and design of contiguous band manifold output multiplexers based on singly terminated filters with elliptic response is considered. The zero shifting technique leads to the synthesis of a driving{\^a}{\texteuro}{\textquotedblleft}point impedance including transmission zeros at finite real frequencies. The synthesized canonical forms have different topologies, number of reactive constant elements and reactive part of the driving impedances with different frequency responses. These characteristics have been intensively analyzed to find the most suitable combination in the multiplexing process to match the channels to the manifold. Using the methodology presented in this work a four-channel multiplexer for Ku-band operation has been designed, manufactured and measured. The input{\^a}{\texteuro}{\textquotedblleft}output ports are standard WR75. The prototype has been manufactured in brass using low-cost milling technique and is formed in one block where all the cavities and irises have the same height. The unloaded Q for the brass cavities is 2500 and therefore the expected insertion losses at central frequency of the higher channel are approximately 2.5 dB. The final paper will show a comparison between the full-wave simulation using the mode-matching method (including losses) and the measurements of the input reflection coefficient and the transmission of the manufactured multiplexer.}, author = {Montejo-Garai, J R and C A Leal-Sevillano and J A Ruiz-Cruz and Rebollar, J M and Rogla, L and Sobrino, S} } @conference {11_URSIESP_Montejo-GaraiLeal-SevillanoRuiz-CruzEtAl_DisenoOMUXCancelacion, title = {Dise{\~n}o de Multiplexores Manifold de Salida y Banda Contigua con Respuesta El{\'\i}ptica Mediante la Cancelaci{\'o}n Eficiente de la Parte Reactiva de la Impedancia}, booktitle = {Proc. 2011 Simposium Nacional URSI (in Spanish)}, year = {2011}, month = {Sept.}, pages = {1-4}, abstract = {A procedure for the synthesis and design of contiguous band manifold output multiplexers based on singly terminated filters with elliptic response is presented. The zero-shifting technique leads to the synthesis of a driving-point impedance including transmission zeros at finite real frequencies. The synthesized canonical forms have different topologies, number of reactive constant elements and reactive part of the driving impedances with different frequency responses. These characteristics have been intensively analyzed to find the most suitable combination in the multiplexing process to match the channels to the manifold. A Ku-band four-channel elliptic-response multiplexer has been designed in H-plane rectangular waveguide, manufactured and measured in order to show the proposed approach.}, author = {Montejo-Garai, J R and C A Leal-Sevillano and J A Ruiz-Cruz and Rebollar, J M and Rogla, L and Sobrino, S} } @conference {11_URSIESP_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_DisenoyOptimizacionPolariz, title = {Dise{\~n}o y Optimizaci{\'o}nn de Polarizadores Doble-Banda en Gu{\'\i}a Rectangular Corrugada}, booktitle = {Proc. 2011 Simposium Nacional URSI (in Spanish)}, year = {2011}, month = {Sept.}, pages = {1-4}, abstract = {Waveguide polarizers are essential devices in feeders for radio transmission systems with circular polarization. In this paper two different dual-band polarizers are designed and compared. The structure of both polarizers is based on the classical corrugated rectangular waveguide. This structure can be analyzed very efficiently like an H-plane and an E-plane problem. The Mode-Matching technique, in combination with global search algorithms, is used for the full-wave analysis and optimization of the polarizers. In the first polarizer, the height of the corrugations is designed according to a taper-type shape. For the second polarizer, no restrictions in the height of the corrugations are imposed and all the dimensions are optimized. The performance of both polarizers is compared, showing certain improvement in terms of polarization purity for the second one.}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {11_IEEETMTT_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_FieldCircularHollowWgNonIdealConductorsMwtoThz, title = {Field Propagation in Circular Hollow Waveguides with Non-Ideal Metallic Conductors from Microwaves to Terahertz Frequencies}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {59}, number = {12}, year = {2011}, month = {Dec}, pages = {3013-3022}, abstract = {A general and rigorous formulation is proposed for the analysis of hollow metallic waveguides from the gigahertz to the terahertz band. The analysis is based on a hybrid mode formulation and the Drude model for the dielectric permittivity of metallic conductors. The obtained results for the circular waveguide are compared with the classical microwave approach (surface impedance approximation or Leontovich condition). The validity range of the surface impedance approximation in both the propagation constant and the electromagnetic field pattern is studied. As a consequence, a direct relation between the error in the propagation constant and the electromagnetic field configuration is shown. Moreover, this formulation shows the evolution in the field pattern: from TE=TM modes at microwaves to the so-called Surface Plasmon Polariton at terahertz frequencies}, keywords = {Drude, hybrid mode, Leontovich, modal solution, surface impedance, Surface Plasmon Polariton (SPP), surface wave, terahertz, waveguides}, issn = {0018-9480}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6065772\&tag=1}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {11_IEEETMTT_Ruiz-CruzFahmiMansour_GeneralizedMulti-PortWgSwicthesShortCktLoads, title = {Generalized Multi-Port Waveguide Switches Based on Multiple Short-Circuit Loads in Power Divider Junctions}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {59}, number = {12}, year = {2011}, month = {December}, pages = {3347 - 3355}, abstract = {This paper presents a new concept for multiport waveguide switches based on short-circuit loads integrated in power-divider ridge-waveguide junctions. The switching is achieved by means of actuating short and open circuit loads in the waveguide path of a ridge waveguide, eliminating the need of bulky rotors, which are typically used in conventional waveguide switches. A complete class of single-pole N -throw switches (N up to 4) is presented based on this concept. Furthermore, the concept is employed to demonstrate highly compact C-, R-, and T-type waveguide switches by integrating different power-divider junctions in a seamless manner. The T-type case involves three states that provide the maximum flexibility for realizing advanced switch matrices for signal routing. A T-type waveguide switch is built and measured for validating the concept. To our knowledge, this paper marks the first time R- and T-type waveguide switches are demonstrated without the need to use a bulky rotary junction}, keywords = {multi-port ridge waveguide divider, rectangular waveguide switch, redundancy switch matrix, short-circuit loaded ridge waveguide, SPNT, three-state switch}, issn = {0018-9480}, doi = {10.1109/TMTT.2011.2170089}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6069588}, author = {J A Ruiz-Cruz and Fahmi, M M and Mansour, R R} } @article {11_IEEEMWCL_Montejo-GaraiRuiz-CruzRebollar_In-lineEPlaneBandStop, title = {In-line Pure E-Plane Waveguide Band-Stop Filter with Wide Spurious-Free Response}, journal = {IEEE Microwave and Wireless Components Letters}, volume = {21}, number = {4}, year = {2011}, month = {April}, pages = {209-211}, abstract = {A new compact pure E-plane waveguide structure is proposed for coupling band-rejection cavities to the main rectangular waveguide in bandstop in-line filters. This coupling structure reduces drastically the unwanted resonances in filters with a very large pass band requirement. Moreover, it has some additional advantages. First, unlike typical inductive irises, large coupling coefficients can be implemented. Second, a pure E-plane configuration is achieved, which simplifies the manufacturing and also reduces significantly the computational effort. Third, in the design, by means of distributed model circuits, the rejection cavities are individually designed and connected by phase shifters maintaining the E-plane layout. Experimental validation is demonstrated by a pseudoelliptic fifth-order bandstop filter centered at 28 GHz and 2\% fractional stop band. It is free of spurious resonances in the full Ka-band.}, issn = {1531-1309}, doi = {10.1109/LMWC.2011.2105468}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5723025\&tag=1}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M and Estrada, T.} } @article {15_RadialLineIEEE, title = {Linearly Polarized Radial Line Patch Antenna With Internal Rectangular Coupling Patches}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {8}, year = {2011}, month = {Aug.}, pages = {3049 - 3052}, abstract = {A linearly polarized radial line patch antenna with internal coupling patches is presented. A non-resonant antenna structure has been designed, with a 0.68 ?0 radial spacing between element rings. A uniform amplitude and phase feed scheme has been implemented. Therefore, a phase compensation microstrip structure (external to the radial waveguide) has been included for a broadside radiation beam. Likewise, a compensation method has been used to avoid internal reflection problems in the waveguide. An antenna prototype has been built. 28.2 dBi gain and 70\% efficiency peak values have been measured at DBS band, with reasonable agreement between simulations and measurements.}, keywords = {Internal rectangular coupling patch, microstrip phase compensation line, radial line patch antenna (RLPA)}, issn = {0018-926X}, doi = {10.1109/TAP.2011.2158945}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5784312}, author = {J L Masa-Campos and Sierra-P{\'e}rez, M} } @conference {11_MULCOPINN_Montejo-GaraiLeal-SevillanoRuiz-CruzEtAl_MultipactorpredictionBandStopFilters, title = {Multipactor prediction in waveguide band-stop filters with wideband spurious-free response}, booktitle = {Proc. International workshop on Multipactor, Corona and Passive Intermodulation (MULCOPIM)}, year = {2011}, month = {Sep.}, pages = {1-6}, keywords = {corrugated waveguide, dual-band, mode-matching, optimization, Waveguide polarizers}, url = {http://mulcopim.webs.upv.es/programme.html}, author = {Montejo-Garai, J R and C A Leal-Sevillano and J A Ruiz-Cruz and Rebollar, J M and Estrada, T} } @article {11_IETMAP_Ruiz-CruzMontejo-GaraiRebollar_OptimalFeeders, title = {Optimal configurations for integrated antenna feeders with linear dual polarization and multiple frequency bands}, journal = {IET Microwaves, Antennas and Propagation}, volume = {5}, number = {8}, year = {2011}, month = {June}, pages = {1016-1022}, abstract = {Different configurations for the antenna feeder of advanced microwave subsystems are introduced, working in several schemes which combine multiple frequency bands with two linear orthogonal polarisations. The aim of this study is to highlight state-of-art research results on different waveguide components for modern radio frequency (RF)/microwave subsystems, stressing the impact of the selected architecture in the whole system in both the electrical performance and the volume and size of the feeder. Two are the key components of this type of RF/microwave feeder: the ortho-mode transducer for polarisation discrimination and the multiplexers for separating the frequency bands. It will be shown that a careful study of the whole feeder architecture can simplify in some cases the individual components, with the consequent benefit in electric performance and size reduction. The computer-aided design of the presented architectures is outlined, showing examples for different applications and comparing numerical simulations by different methods with experimental results.}, issn = {1751-8725}, doi = {10.1049/iet-map.2010.0363}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5937003}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {11_JoCN_FahmiRuiz-CruzMansourEtAl_RecentAdvancesinFiltersSatellite, title = {Recent Advances in Filter Topologies and Realizations for Satellite Communications}, journal = {Journal of Communications and Networks}, volume = {13}, number = {6}, year = {2011}, month = {Dec}, pages = {625-632}, abstract = {This paper presents an overview of recent advances in radio frequency and microwave filter topologies for satellite communication systems. Many types of filters have been developed during the last years in order to satisfy the demands of modern applications in both terrestrial systems and onboard spacecrafts, leading to a great variety of aspects such as transfer functions, resonator implementations or coupling structures. This paper revisits some of the last advances in this area, including the modeling and full-wave simulation. Some recent designs using dual-mode cavities along with other novel implementations in ridge waveguide will be shown.}, keywords = {full-wave simulators, RF and microwave filters, waveguide technologies}, issn = {1229-2370}, doi = {10.1109/JCN.2011.6157479}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6157479}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @article {11_IETMAP_FahmiRuiz-CruzMansourEtAl_RecentLTCC, title = {Recent Results on Compact Broad-Band and Multi-Band LTCC Components for RF Front-Ends}, journal = {IET Microwaves, Antennas and Propagation}, volume = {5}, number = {8}, year = {2011}, month = {June}, pages = {870-876}, abstract = {Compact components for radio frequency (RF) front-ends realised in low-temperature co-fired ceramics (LTCC) are presented. The aim of this study was to highlight recent advances in realisation of different components for modern RF/microwave subsystems, stressing such attributes as compactness, wide bandwidth and operation in multiple bands. Two key components of every RF front-end are filters and couplers. To illustrate the feasibility of using LTCC technology to realise these components, several designs of filters and couplers are presented. Very compact LTCC ridge waveguide filter covering the whole US ultra-wide band is first discussed, followed by a dual-band LTCC ridge waveguide filter. Two types of wide-band couplers are shown: ridge waveguide couplers realised in LTCC and empty metallic waveguide and also a strip-line LTCC coupler. A common characteristic that will be shown is that the presented components by the authors are modelled using computer-aided design tools based on modal analysis for waveguides as well as commercially available finite-element tools. The shown examples have simulation results compared by different methods as well as some experimental results in LTCC and empty metallic waveguide, used to demonstrate the proposed approach.}, issn = {1751-8725}, doi = {10.1049/iet-map.2010.0371}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5936984\&tag=1}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @conference {11_URSIGAAS_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_RigorousAnalysisofParallelPlate, title = {Rigorous Analysis of the Parallel-Plate Waveguide by the Hybrid Mode Formulation:From the TEM mode to the Surface Plasmon Polariton}, booktitle = {Proc. 2011 URSIGAAS}, year = {2011}, month = {August}, pages = {1-4}, abstract = {This paper presets an analysis of the parallel-plate waveguide, based on an hybrid mode formulation. The nonideal metallic conductors of the waveguide are treated as a media characterized by an equivalent permittivity. The frequencies of interest in the presented analysis are at the terahertz band (from 300 GHz to 30 THz) and appropriate models are used for the correct characterization of metallic conductors at these frequencies. The behavior of the electromagnetic field of the fundamental mode is studied in a wide frequency range. At low frequencies (microwave regime) the fundamental mode is the well-known TEM mode; as frequency increases, the electromagnetic field changes significantly and a surface wave or Surface Plasmon Polariton (SPP) behavior is observed at the highest frequencies of the terahertz band. This paper shows an unified formulation that explains this transformation in the electromagnetic field behavior.}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {11_MEE_OfliCrespo-ValeroRuiz-CruzEtAl_SEMCADXMicrowaveWg, title = {SEMCAD X Microwave: Enhanced Simulation of Waveguide Structures}, journal = {Microwave Engineering Europe}, volume = {September}, year = {2011}, pages = {12-15}, abstract = {A general and rigorous formulation is proposed for the analysis of hollow metallic waveguides from the gigahertz to the terahertz band. The analysis is based on a hybrid mode formulation and the Drude model for the dielectric permittivity of metallic conductors. The obtained results for the circular waveguide are compared with the classical microwave approach (surface impedance approximation or Leontovich condition). The validity range of the surface impedance approximation in both the propagation constant and the electromagnetic field pattern is studied. As a consequence, a direct relation between the error in the propagation constant and the electromagnetic field configuration is shown. Moreover, this formulation shows the evolution in the field pattern: from TE=TM modes at microwaves to the so-called Surface Plasmon Polariton at terahertz frequencies}, issn = {0332-1649}, url = {http://www.microwave-eetimes.com/en/magazine/mwee-2010.html}, author = {Ofli, E and Crespo-Valero, P and J A Ruiz-Cruz and C A Leal-Sevillano and Montejo-Garai, J R and Rebollar, J M} } @article {11_IJoE_Ruiz-CruzMontejo-GaraiRebollar_Short-slotArbPowerDiv, title = {Short-slot E- and H-plane waveguide couplers with an arbitrary power division ratio}, journal = {International Journal of Electronics}, volume = {98}, number = {1}, year = {2011}, note = {falta pos en JCR de su a{\~n}o}, month = {Jan.}, pages = {11-24}, abstract = {Short-slot couplers are a particular type of waveguide directional coupler commonly used due to their compact size in comparison with other waveguide configurations. The common short-slot Riblet coupler is used as a 3 dB hybrid (equal power division to the coupled and the through ports) in microwave networks supporting high power and providing good performance over a moderate bandwidth. In this article, the general case of short-slot couplers with arbitrary power division is presented, in E- or H-plane configuration. Moreover, it is shown that the port closer to the input can handle either more or less power than the further port, depending on the design parameters and the length of the main guide of the coupler. Several designs in E- and H-plane are shown to introduce the concept. In addition, two experimental prototypes, with either rectangular waveguide interfaces or coaxial input/output, are manufactured and tested showing good agreement with the expected results.}, issn = {0020-7217}, doi = {10.1080/00207217.2010.488913}, url = {http://www.informaworld.com/smpp/content~db=all~content=a931813059~frm=titlelink}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {11_IEEETMTT_Ruiz-CruzFahmiFouladiEtAl_WaveguideAntennaFeedersReconfDualCircPol, title = {Waveguide Antenna Feeders with Integrated Reconfigurable Dual Circular Polarization}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {59}, number = {12}, year = {2011}, month = {December}, pages = {3365 - 3374}, abstract = {Waveguide antenna feeders with reconfigurable circular polarization sense are proposed in this paper. They can be switched between right and left hand circular polarization, without any mechanical rotation between the feeder and the antenna. Two types of feeders are presented. The polarizer works with a single switchable polarization for each state. The dual feeder can work with both polarizations at the same frequency band simultaneously, each one associated with a different rectangular waveguide port. The polarization sense is controlled by metallic posts that block or open the signal paths connecting the rectangular ports with a septum-orthomode polarizer. These posts are automated with piezo-motors integrated in the structure, leading to a very compact layout, reduced size, and practical for applications with diverse switching speed. The proof of concept and the automation are shown with experimental Ku-band prototypes.}, keywords = {piezo-motor controlled feeder, polarization switch, Reconfigurable antenna feeder, waveguide septum OMT-polarizer}, issn = {0018-9480}, doi = {10.1109/TMTT.2011.2170581}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6068261}, author = {J A Ruiz-Cruz and Fahmi, M M and Fouladi, S and Mansour, R R} } @conference {11_URSIUSA_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_WaveguideDeviceswithTwist, title = {Waveguide Devices with Integrated Polarization Twist for Broadband Applications}, booktitle = {Proc. 2011 USNC/URSI National Radio Science Meeting}, year = {2011}, month = {July}, pages = {1}, abstract = {A common part of many microwave systems is the routing of the signal between the circuit devices performing the different functions of the system (frequency discrimination, power combining, frequency conversion, signal amplifying {\^a}{\texteuro}{\textbrokenbar}). The optimum configuration of these individual devices may lead to a system layout where the interfaces of the different blocks are not aligned or even are in different planes. Thus, the routing network must have waveguide transformers, bends, and twists to be able to accommodate the signal between the different blocks. These elements have a simple function, although a careful design may be required for broadband applications. Moreover, in satellite communications, mass and volume must be kept to a minimum and compactness is highly pursued. A possible solution in these cases is to integrate some of these functions in the routing network elements or even in the input/output of the components. In this work, several waveguide devices will be shown with integrated compact elements for waveguide matching and polarization rotation. Since different functions are integrated in the same device, transitions are avoided and the total length is reduced. Very compact structures for waveguide twists have been developed in Asao et al., "A compact 90-degree twist using novel ridged waveguide for integrated waveguide subsystems," Proc. 36th EuMC, 2006 and Kirilienko et al. {\^a}{\texteuro}{\oe}Compact 90{\^A}{\textordmasculine} Twist formed by a Double-Corner-cut Square Waveguide Section{\^a}{\texteuro}, IEEE TMTT, 2008). Other structures used here will be based on Ruiz-Cruz et al., {\^a}{\texteuro}{\oe}Multi-Section Bow-Tie Steps for Full-Band Waveguide Polarization Rotation{\^a}{\texteuro}, IEEE MWCL, July 2010. The design and evaluation of the different components will be addressed in the presentation, with devices in mixed E/H plane configuration, bends and transformers. When integrating different functions in the same device, some undesired resonances may appear in the structure. Therefore, accurate CAD tools are required for simulating the response and taking into account the mode excitations inside the structure. A precise fabrication is required for having good experimental results, which will be shown in the presentation.}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {11_CavitydipoleJEMWA, title = {Broadband Cavity-Backed Bow-Tie Dipole Antenna with 90{\textdegree} Horizontal Coverage for American and European Cellular Systems}, journal = {Journal of Electromagnetic Waves and Applications}, volume = {24}, number = {8-9}, year = {2010}, month = {Jan.}, pages = {1089 - 1101}, abstract = {A cavity-backed bow-tie dipole antenna is presented as base station antenna for wide band American and European cellular communication systems (1.7{\textendash}2.17 GHz). A beam widening of the horizontal plane is achieved by the cavity aperture reduction and the inclusion of a metallic support between the cavity floor and the antenna reflector plane. The structure design procedure is exposed, and a reasonable agreement between simulations and measurements is obtained. Single antenna and medium gain array prototypes have been manufactured and tested. A 35\% reflection bandwidth and an 85{\textdegree} to 95{\textdegree} sector coverage is achieved in the desired operation band.}, issn = {0920-5071}, doi = {10.1163/156939310791586115}, url = {http://www.tandfonline.com/doi/pdf/10.1163/156939310791586115}, author = {J L Masa-Campos and Rubio-Mayordomo, J M} } @conference {10_IMS_FahmiRuiz-CruzMansourEtAl_CompactDualBandRidge, title = {Compact Wide-Band Ridge Waveguide Dual-Band Filters}, booktitle = {2010 IEEE MTT-S International Microwave Symposium Digest}, year = {2010}, month = {May}, pages = {888-891}, abstract = {A compact wide-band, dual-band filter realized in air filled metallic ridge waveguides is proposed. Dual-band filters replace doubly multiplexed filters, thus simplifying the system architecture considerably. The filter is realized in a canonical folded structure layout. Coupling sections that realize strong coupling values required for the wide-band characteristics are achieved by means of transversal sections of ridges connecting the main ridge waveguide resonators. The filter is efficiently modeled using rigorous mode matching method. The filter response is further verified using a commercially available Finite Element Method software. In addition a prototype was built and tested for verification.}, issn = {0149-645X}, doi = {10.1109/MWSYM.2010.5517525}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=05517629}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @book {10_INTECHBook_Ruiz-CruzMontejo-GaraiRebollar_CADWgDevicesbyMM, title = {Computer Aided Design of Waveguide Devices by Mode-Matching Methods (in Microwave and Millimeter Wave Technologies (ISBN: 978-953-307-083-4))}, year = {2010}, month = {Oct 2009}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M}, editor = {Zhurbenko, V} } @conference {10_URSIUSA_Ruiz-CruzMontejo-GaraiRebollarEtAl_DesignandEvaluation, title = {Design and Evaluation of a Ka-band Antenna Feeder with Broadband Dual-Polarization Performance}, booktitle = {Proc. 2010 USNC/URSI National Radio Science Meeting}, year = {2010}, month = {July}, pages = {14}, abstract = {New telecommunication satellite services have increased the demand on antenna feed systems with more stringent requirements in both the electrical and mechanical parts. In fact, one of the main goals for RF hardware onboard spacecrafts is the reduction of size and volume, at the expense of more complex design of the components. Thus, the use of a single antenna for several frequency bands is very common and the antenna feeder has to separate (or to combine, depending on the transmission/reception scheme) the different signals involved in the system. The frequency separation is carried out with multiplexers. Moreover, in many systems, dual polarization is used in order to have a more efficient use of the electromagnetic spectrum, using ortho-mode transducers (OMTs) for the polarization discrimination. In a very common scheme, the OMTs are attached by the common port to the antenna and by the other dedicated ports to the diplexers. This is the type of antenna feed network developed in this communication, for two Ka sub-bands centered in 21.7 and 28.7 GHz, respectively, with 4\% and 6\% fractional bandwidth, approximately. The developed OMT is based on a double symmetry junction (Boifot et al, "Simple and broadband orthomode transducer," IEE Proc. H Microw., Ant. and Prop., vol. 137, no. 6, pp. 396-400, Dec 1990.). In its simpler version, it has a metallic septum and full height vertical pins to match the vertical polarization. The effect of these pins will be studied. The routing network is another important part of the device, with a great impact on the size of the component and in the manufacturing method (see for instance Ruiz-Cruz et al. "Full-wave modeling and optimization of Boifot junction ortho-mode transducers," Int. J RFMiCAE, vol. 18, no. 4, pp. 303-313, July 2008). These different alternatives will be studied in the presentation. The diplexers are based on E-plane bifurcations with well-known low-pass and high-pass filters. The dimensions of the waveguides connecting the ortho-mode transducer and the waveguide diplexers are non-standard, in order to reduce the total feeder length, since transitions to standard waveguides are avoided. The diplexer is manufactured without any tuning element. Therefore, accurate CAD tools are required for the design, along with a precisely controlled fabrication.The design and evaluation of the different components will be addressed in the presentation, showing the experimental measurements, the expected simulated responses and the critical points found in the development of the antenna feeder.}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Mart{\i}n, M J and Garc{\'\i}a, V} } @conference {10_PIERSym_Ruiz-CruzCrespo-ValeroMosig_EfficientCADMultiCoupled, title = {Efficient Computer Aided Design of Compact Multi-Coupled Stripline Resonators Filters}, booktitle = {Proc. 2010 Progress in Electromagnetic Research Symposium (PIERS)}, year = {2010}, month = {March}, pages = {1}, author = {J A Ruiz-Cruz and Crespo-Valero, P and Mosig, J R} } @article {10_ELMG_Montejo-GaraiRuiz-CruzRebollar_EfficientOMUXSingleTerminated, title = {Efficient Design of Contiguous-Band Elliptic-Response Manifold Output Multiplexers with Single-Terminated Filters}, journal = {Electromagnetics}, volume = {30}, number = {8}, year = {2010}, note = {falta pos en JCR de su a{\~n}o}, month = {November}, pages = {644-659}, abstract = {A procedure for the synthesis and design of contiguous-band manifold output multiplexers based on singly terminated filters with an elliptic response is presented. An extension of the Cauer ladder development using the zero-shifting technique leads to the synthesis of a driving-point impedance, including transmission zeros at finite real frequencies. The synthesized canonical forms have different topologies, number of reactive constant elements, and reactive part of the driving impedance, which have been compared to find the most suitable combination in the multiplexing process to match the channels to the manifold. The study proposed here is very important for improving the design process, and it is illustrated with four different multiplexer configurations and implemented with different pole-extraction orders in the ladder singly terminated filters. The multiplexer design has been divided into tasks with low computational effort extensively using the circuit model. Thus, the final full-wave optimization is significantly reduced, since the starting point is closer to the required specification. Finally, a Ku-band four-channel elliptic-response multiplexer has been designed in the H-plane rectangular waveguide, manufactured and measured in order to show the proposed approach.}, keywords = {H-plane, mode matching, transmission zero}, issn = {0272-6343}, doi = {10.1080/02726343.2010.524879}, url = {http://www.informaworld.com/smpp/content~db=all?content=10.1080/02726343.2010.524879}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @article {13_WiMaxUWBCOMNEC, title = {Impact of Ultra Wide Band emission on WiMAX systems at 2.5 and 3.5 GHz}, journal = {Computer Networks}, volume = {54}, number = {10}, year = {2010}, month = {Jul.}, pages = {1573 - 1583}, abstract = {In this work, results of an analytical analysis to assess the effect of Ultra Wide Band (UWB) emissions on the Worldwide Interoperability for Microwave Access system (WiMAX) are presented. The WiMAX range is evaluated with and without the UWB interference. Free space propagation model is used to calculate the UWB signal power that interferes with WiMAX systems. It is shown that, for the case of single UWB transmitter, WiMAX system can easily tolerate UWB interference when the UWB EIRP is ?83 dBm/MHz or less for a distance between the UWB transmitter and the WiMAX receiver of 1 m or higher at 3.5 GHz frequency in order to have only 5\% range reduction. To make this possible, multi band UWB should not transmit in the first and the second bands. This will have a detrimental effect on UWB technology. For 2.5 GHz WiMAX, the range reduction will be 5\% when the UWB EIRP is ?87 dBm/MHz.}, keywords = {Ultra Wide Band, WiMAX}, issn = {0895-2477}, doi = {10.1016/j.comnet.2009.12.010}, url = {http://ac.els-cdn.com/S1389128610000058/1-s2.0-S1389128610000058-main.pdf?_tid=8a83fdde-f571-11e3-b545-00000aacb35e\&acdnat=1402935555_c627df1d584d191e69c83ea871741f2b}, author = {B Taha-Ahmed and J L Masa-Campos and J A Ruiz-Cruz} } @article {10_COMNET_AhmedMasa-CamposRuiz-Cruz_ImpactUWBonWiMax2p5and3p5, title = {Impact of Ultra Wide Band Emission on WiMAX Systems at 2.5 and 3.5 GHz}, journal = {Computer Networks}, volume = {54}, number = {10}, year = {2010}, month = {January}, pages = {1573-1583}, abstract = {In this work, results of an analytical analysis to assess the effect of Ultra Wide Band (UWB) emissions on the Worldwide Interoperability for Microwave Access system (WiMAX) are presented. The WiMAX range is evaluated with and without the UWB interference. Free space propagation model is used to calculate the UWB signal power that interferes with WiMAX systems. It is shown that, for the case of single UWB transmitter, WiMAX system can easily tolerate UWB interference when the UWB EIRP is -83 dBm/MHz or less for a distance between the UWB transmitter and the WiMAX receiver of 1 m or higher at 3.5 GHz frequency in order to have only 5\% range reduction. To make this possible, multi band UWB should not transmit in the first and the second bands. This will have a detrimental effect on UWB technology. For 2.5 GHz WiMAX, the range reduction will be 5\% when the UWB EIRP is -87 dBm/MHz.}, issn = {1389-1286}, doi = {10.1016/j.comnet.2009.12.010}, url = {http://www.sciencedirect.com/science/article/pii/S1389128610000058}, author = {Ahmed, B T and J L Masa-Campos and J A Ruiz-Cruz} } @article {10_IEEEMWCL_Ruiz-CruzMontejo-GaraiRebollar_MultiSectionBowTie, title = {Multi-Section Bow-Tie Steps for Full-Band Waveguide Polarization Rotation}, journal = {IEEE Microwave and Wireless Components Letters}, volume = {20}, number = {7}, year = {2010}, month = {July}, pages = {375-377}, abstract = {A new compact multi-section structure for broadband waveguide polarization rotation is presented. The twist component is based on cascading multiple steps with bow-tie shape geometry, which are progressively rotated between the input and output rectangular waveguides. The twists show an excellent performance in the full operating frequency band, which is controlled with the number of sections and their shapes and can be designed for any rotation angle. Moreover, the bow-tie sections are very short and compact and can be easily manufactured, being well-suited for satellite applications. The proposed configuration is shown with design tables and curves for different rotation angles. Two 90{\^A}{\textdegree} twists in WR75 waveguide have been tested, showing measured return losses of 30 dB (one section) and 40 dB (two sections) from 10 to 15 GHz with a total length of 5.6 mm and 8.6 mm, respectively.}, issn = {1531-1309}, doi = {10.1109/LMWC.2010.2049428}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5481983}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {10_EIEC_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_NewModelSIW, title = {A New Model for the Electromagnetic Characterization of SIW}, booktitle = {Proc. VII Encuentro Ib{\'e}rico de Electromagnetismo Computacional (in Spanish)}, year = {2010}, month = {Apr.}, pages = {1-4}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {10_URSIESP_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_NuevoModeloparaSIW, title = {Nuevo Modelo para la Caracterizaci{\'o}n Electromagn{\'e}tica de SIW}, booktitle = {Proc. 2010 Simposium Nacional URSI (in Spanish)}, year = {2010}, month = {Sept.}, pages = {1-4}, abstract = {The Substrate Integrated Waveguide has been proposed as an alternative to planar technology in very high frequencies of the submilimeter band and in the teraherz band. For the correct analysis and design of devices like couplers, filters or antennas an accurate model for the characterization of SIW is needed. In this contribution a new model for electromagnetic characterization of SIW is proposed. The model is based on the analysis of a closed waveguide, which simulates the behavior of an open structure. For the correct simulation of the open structure a dielectric material is adjusted. Finally a pass-band filter in SIW technology is analyzed in order to verify the proposed model.}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {12_RFindoorWiMaxJEMWA, title = {RF Propagation in Indoor Environment at WiMAX Band of 3.5 GHz}, journal = {Journal of Electromagnetic Waves and Applications}, volume = {24}, number = {17-18}, year = {2010}, month = {Jan.}, pages = {2495 - 2508}, abstract = {The purpose of this study is to characterize the indoor channel for IEEE 802.16 (WiMAX) at 3.5 GHz frequency band. This paper presents a channel model based on measurements conducted in commonly found scenarios in buildings. These scenarios include narrow corridor, wide corridor (a passage) and semi open corridor. Path loss equations are determined using log-distance path loss model and a Gaussian (Normal) or Rayleigh fading. Sometimes a combination of both fadings takes place. A numerical analysis of the measurements in each scenario was conducted, and the study determined equations that described path loss for each scenario. Propagation loss for a 20 MHz bandwidth is given. Our contribution is to show for the first time that indoor fading can be represented by Normal, Rayleigh or a combination of both.}, issn = {0920-5071}, doi = {10.1163/156939310793675826}, url = {http://www.tandfonline.com/doi/pdf/10.1163/156939310793675826}, author = {J L Masa-Campos and Lalueza-Mayordomo, J M and B Taha-Ahmed} } @conference {10_EuCAP_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_SimpleModelsTHz, title = {Simple Models For The Analysis Of Waveguiding Systems At The Terahertz Band Using Classical Microwave Approaches}, booktitle = {Proc. 2010 European Conference on Antennas and Propagation (EuCap)}, year = {2010}, month = {Apr.}, pages = {1-5}, abstract = {Recently the terahertz band has focused so much attention from many research groups with the aim of designing full systems. The first task before designing devices in this band is to characterize waveguide systems. In this contribution the analysis of different waveguides systems in the terahertz band is presented. The analysis is based on a hybrid mode formulation and the Drude model for the dielectric permittivity of the metallic conductor. A comparison between the exact results obtained with this last formulation and those using classical microwave approaches (surface impedance approximation or Leontovich{\^A}{\textasciiacute}s condition) is done in order to determine the validity range of the approximations in both the propagation constant and the electromagnetic field pattern.}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=05505379}, author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {10_IEEETMTT_Medina-MenaMesa-LedesmaRuiz-CruzEtAl_StudyEOTCircularWg, title = {Study of Extraordinary Transmission in a Circular Waveguide System}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {58}, number = {6}, year = {2010}, month = {June}, pages = {1532-1542}, abstract = {Extraordinary transmission through periodic distributions of sub-wavelength holes made in opaque screens has been demonstrated and exhaustively studied along the last decade. More recently, extraordinary transmission has also been predicted and experimentally observed through electrically small diaphragms located inside hollow pipe waveguides. This last phenomenon cannot be explained in terms of surface waves excited along the periodic system (the so-called surface plasmon polaritons). Transverse resonances can be invoked, however, as a sound explanation for extraordinary transmission in this kind of systems. In this paper, a simple waveguide system, exhibiting exactly the same behavior previously observed in periodic 2-D arrays of holes, is analyzed in depth. Analogies and differences with the periodic case are discussed. The theoretical and experimental results reported in this paper provide strong evidence in favor of the point of view emphasizing the concept of impedance matching versus surface wave excitation. The role of material losses is discussed as an important practical issue limiting the maximum achievable subwavelength transmission level. Most of our conclusions can be applied to both periodic arrays of holes and diaphragms in closed waveguides.}, issn = {0018-9480}, doi = {10.1109/TMTT.2010.2048254}, url = {http://ieeexplore.ieee.org/search/srchabstract.jsp?tp=\&arnumber=5462973\&queryText\%3Dmedina+ruiz-cruz\%26openedRefinements\%3D*\%26searchField\%3DSearch+All}, author = {Medina-Mena, F and Mesa-Ledesma, F and J A Ruiz-Cruz and Rebollar, J M and Montejo-Garai, J R} } @article {09_ELET_Ruiz-CruzMontejo-GaraiRebollarEtAl_C-BandOMT, title = {C-Band Orthomode Transducer for Compact and Broadband Antenna Feeders}, journal = {Electronics Letters}, volume = {45}, number = {16}, year = {2009}, month = {July}, pages = {813-814}, abstract = {The design and evaluation of a compact C-band orthomode transducer for dual polarisation satellite communications is presented, covering the bands 3.7-4.2 GHz and 5.925-6.425 GHz (54\% of fractional bandwidth separation). Over such a broadband, the main difficulty is to obtain a compact structure able to fulfil the stringent satellite specifications with minimum longitudinal length. The proposed configuration, validated with a tested prototype, also reduces the number of connections and parts in the fabrication, decreasing the passive intermodulation risk and the mass and volume}, issn = {0013-5194}, doi = {10.1049/el.2009.1034}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5191333\&isnumber=5191328?tag=1}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Montero, J M} } @conference {09_IMS_FahmiRuiz-CruzZakiEtAl_CompactRidgeNRN, title = {Compact Ridge Waveguide Filters using Non-resonating Nodes}, booktitle = {2009 IEEE MTT-S International Microwave Symposium Digest}, year = {2009}, month = {June}, pages = {1337-1340}, abstract = {A ridge waveguide filter based on the nonresonating node (NRN) concept is proposed. A new coupling mechanism, suitable for this realization is introduced. The proposed coupling mechanism alleviates the need to use other complicated structures and simplify the design process significantly. Rigorous mode matching method (MMM) is used to model the filter. The filter response is further verified using another numerical technique. A prototype was built and tested. Measurement results agree well with simulation.}, issn = {0149-645X}, doi = {0.1109/MWSYM.2009.5165952}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5165952\&isnumber=5165586}, author = {Fahmi, M M and J A Ruiz-Cruz and Zaki, K A and Mansour, R R} } @article {09_IEEETMTT_FahmiRuiz-CruzMansourEtAl_CompactRidgeWaveguideTZNRN, title = {Compact Ridge Waveguide Filters With Arbitrarily Placed Transmission Zeros Using Nonresonating Nodes}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {57}, number = {12}, year = {2009}, month = {Dec.}, pages = {3354-3361}, abstract = {Compact size ridge waveguide filters based on the nonresonating node concept are introduced to realize transfer functions with arbitrarily placed attenuation poles. Coupling mechanisms, suitable for the new realization are introduced in diverse $E$ -plane and $H$ -plane configurations and with different input-output interfaces. These coupling structures are studied and characterized in detail in order to simplify the design of the proposed filters. Rigorous mode-matching method is used to accelerate the full-wave design of the filter configurations, whose response is also verified using other numerical techniques and experimental data. To validate the proposed novel designs, a prototype has been built and tested. Measurement results agree well with the predicted theoretical simulations.}, keywords = {Attenuation poles, microwave filters, mode-matching, ridge waveguides}, issn = {0018-9480}, doi = {10.1109/TMTT.2009.2034423}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5308444\&isnumber=5340253}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @conference {09_URSIUSA_Ruiz-CruzMontejo-GaraiRebollar_DesignDualBandOMTLargeSepBands, title = {Design of a Dual-Band Ortho-Mode Transducer for Satellite Communications with Large Separation between Bands}, booktitle = {Proc. 2009 USNC/URSI National Radio Science Meeting}, year = {2009}, month = {June}, pages = {1}, abstract = {Ortho-Mode Transducers (OMTs) are devices used in satellite communication systems to discriminate the two orthogonal signals received or transmitted by a dual-polarization antenna. For linear polarization, they set a signal path between the vertical polarization in the common port and a monomode port dedicate for that polarization. The horizontal polarization, also found in the common port, follows a different path till another dedicated port. Thus, the OMT, usually implemented in waveguide technology in satellite applications, has three physical ports and four electrical ports (the common one hosts the two orthogonal polarizations). The advantage of using such devices is that they increase the capacity information of the satellite link, since the two polarizations can share the same frequency band. The main features to control in the design of an OMT are the return and insertion losses, the isolation between polarizations and the power handling capabilities. The bandwidth is a critical parameter and it is in close relation to the symmetry of the physical structure of the OMT (see for instance G. Pelosi, R Nesti, and G G Gentili, {\^a}{\texteuro}\~{}{\^a}{\texteuro}\~{}Orthomode transducers,{\^a}{\texteuro}{\texttrademark}{\^a}{\texteuro}{\texttrademark} Encyclopedia of RF and Microwave Eng., Wiley, New York, 2005). The Computer Aided Design (CAD) of the OMT is another aspect to take into account. In our work, the OMT is divided into building blocks which are designed individually. They are analyzed with a full-wave method which provides its Generalized Admittance Matrix (GAM) or Generalized Scattering Matrix (GSM). The interaction of the building blocks is considered in a second stage. This design procedure will be described in the presentation. The compactness of the mechanical structure can be also a very significant aspect of the OMT selection. Different alternatives using Boifot and Turnstile junctions have been compared. In addition, the OMT construction will be also discussed, since it is very important to reduce the number of parts to be connected. More waveguide flanges increase the losses, the risk of passive intermodulation and limit the maximum power to transmit. These different aspects will be seen in the presentation, with focus on an OMT in C-band with more than 40\% separation between bands. The experimental measurements of a manufactured prototype will be shown.}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {9_DualPolarizerPIER, title = {Dual Linear/Circular Polarized Plannar Antenna with Low Profile Double-Layer Polarizer of 45{\textpm} Tilted Metallic Strips for WIMAX Applications}, journal = {PIER - Progress in Electromagnetics Research}, volume = {98}, year = {2009}, month = {Oct.}, pages = {221-231}, abstract = {A low profile double-layer polarizer structure is presented for planar patch antennas to obtain circular polarization in 3.5 GHz WiMAX band (3.4-3.6 GHz?5.7\% bandwidth). Each polarizer layer is composed of 45{\textordmasculine} tilted metallic strips on a printed circuit. A bandwidth widening is obtained due to a significant reduction of the distance between polarizer and patches. The associated effects from the interaction of the two structures have been studied. A 2x2 array prototype has been implemented and measured, with a 8\% average bandwidth in reflection and dual linear/circular polarization.}, issn = {1559-8985}, doi = {10.2528/PIER09092406}, url = {http://www.jpier.org/PIER/pier98/13.09092406.pdf}, author = {J L Masa-Campos and Gonz{\'a}lez-Fern{\'a}ndez, F} } @article {09_APL_Medina-MenaRuiz-CruzMesa-LedesmaEtAl_ExpEOTNoPlasmons, title = {Experimental verification of extraordinary transmission without surface plasmons}, journal = {Applied Physics Letters}, volume = {95}, number = {7}, year = {2009}, month = {August}, pages = {1-3}, abstract = {This letter provides an experimental demonstration of extraordinary transmission in a closed waveguide system loaded with an electrically small diaphragm. This is a situation where the standard surface plasmon polariton (SPP) theory does not apply. The theoretical explanation is then based on the concept of impedance matching. This concept has previously been applied by some of the authors to account for enhanced transmission in situations where surface plasmon theory can be used: periodic arrays of small holes or slits in flat metal screens. The experiment in this letter supports the impedance matching model, valid for when SPPs are present or not}, keywords = {impedance matching, light transmission, optical waveguides, periodic structures, polaritons, surface electromagnetic waves, surface plasmons}, issn = {0003-6951}, doi = {10.1063/1.3206738}, url = {http://apl.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf\&id=APPLAB000095000007071102000001\&idtype=cvips}, author = {Medina-Mena, F and J A Ruiz-Cruz and Mesa-Ledesma, F and Montejo-Garai, J R and Rebollar, J M and Marques-Sillero, R} } @conference {09_IMS_MongeRuiz-CruzAnzaEtAl_HighPowerDualMode, title = {High Power analysis and design of dual-mode channel filters}, booktitle = {2009 IEEE MTT-S International Microwave Symposium Digest}, year = {2009}, month = {June}, pages = {1353-1356}, abstract = {In this paper, we present two dual-mode channel filter topologies which are able to withstand more than 600 W in Ku-Band. The two different designs (one with elliptical cavities and the other one with rectangular cavities) implement the same transfer function: four order, elliptical response centered in 12GHz, with 40MHz bandwidth and two transmission zeros. It is shown that the critical dimensions for the power-handling of these filters are the dimensions of the input-output irises. In fact, in order to rigorously obtain these conclusions and to reach these high-power levels (including margins), it is essential to use the advanced numerical techniques described in the paper to predict the multipactor effect. Moreover, the standard approach for multipactor onset prediction based on computing the voltage inside the component is shown to be too conservative and difficult to apply to many practical filter configurations.}, issn = {0149-645X}, doi = {0.1109/MWSYM.2009.5165956}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5165956\&isnumber=5165586}, author = {Monge, J and J A Ruiz-Cruz and Anza, S and Vicente, C and Zaki, K A and Montejo-Garai, J R and Rebollar, J M and Gil, J and Gimeno, B., and Boria, V E} } @article {7_Stacked_Patch_X_bandMOTL, title = {Monopulse beam-scanning planar array antenna in L band}, journal = {Microwave and Optical Technology Letters}, volume = {51}, number = {6}, year = {2009}, month = {Jun.}, pages = {1419-1424}, abstract = {A planar antenna is presented as part of a Signal Identification System working at 1.06 GHz. The antenna presents a monopulse radiation pattern. Likewise, a scanning of the main beam direction is achieved in a {\textpm}45{\textdegree} azimuth coverage. A limited 3 dB amplitude drop of the received signal at the edges of the angular scanning area is only permitted. Furthermore, a broad beamwidth is required in the single element of the array. A rectangular linearly polarized double stacked patch has been then designed, with a significant size reduction in the nonresonant length, to increase the azimuth beamwidth of the array single element. The whole antenna structure is composed of 18 elements, which have been distributed in six columns of three patches per column. The feeding network of the array has been developed in microstrip technology, with small individual circuits connected by coaxial cables, to reduce the global losses of the system. The designed compact antenna and the transmitting and receiving equipments will be placed inside a POD on the top part of an airplane. A prototype antenna has been manufactured and measured in three different beam pointing directions. Satisfactory results have been achieved in the entire frequency band.}, keywords = {beam-scanning array, monopulse system, stacked patch}, issn = {0895-2477}, doi = {10.1002/mop.23516}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.23516/abstract}, author = {J L Masa-Campos and S{\'a}nchez-Sevilleja, S and Dom{\'\i}nguez-Grano-de-Oro, C and Sierra-P{\'e}rez, M and Fernandez-Jambrina, J L} } @article {8_ParallelplateIEEE, title = {Parallel Plate Patch Antenna With Internal Rectangular Coupling Patches and TEN0 Mode Excitation}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {57}, number = {7}, year = {2009}, month = {Jul.}, pages = {2185-2189}, abstract = {A parallel plate waveguide antenna is presented with microstrip patches as radiating elements. Rectangular patches are also placed inside the waveguide as coupling field structures from the waveguide to the radiating elements. The connections from the coupling to the radiating patches are made by means of vias. The field propagated along the parallel plate waveguide corresponds to a high order TE mode, creating virtual smaller rectangular waveguides in the parallel plate structure. An antenna prototype has been manufactured and measured. A 60\% efficiency and 27 dBi antenna gain were obtained; with a 6.5\% reflection bandwidth. Nevertheless, the resonant behaviour becomes evident in the radiation pattern measurements.}, keywords = {Microstrip coupling horizontal lines, parallel plate waveguide, patch antenna, virtual waveguide}, issn = {0018-926X}, doi = {10.1109/TAP.2009.2021969}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=4907131}, author = {J L Masa-Campos and Klinger, S and Sierra-P{\'e}rez, M} } @conference {09_URSIESP_Montejo-GaraiRuiz-CruzRebollar_SintElipSinglyMux, title = {S{\'\i}ntesis de Filtros El{\'\i}pticos Single-Terminated Sim{\'e}tricos y Asim{\'e}tricos para Multiplexaci{\'o}n}, booktitle = {Proc. 2009 Simposium Nacional URSI (in Spanish)}, year = {2009}, month = {Sept.}, pages = {1-4}, abstract = {An extension of the Cauer ladder development for synthesizing singly-terminated filters with symmetric and asymmetric responses is presented. Basically, a driving{\^a}{\texteuro}{\textquotedblleft}point immittance including reactive constant elements is carried out in such a way that provides the transmission zeros. The reactive constant elements are introduced into the synthesis for two reasons. The first is to considerer the possibility of the asymmetric position of transmission zeros in the real frequency axis. The second one is to obtain canonical forms, i.e. networks with the minimum number of elements in the case of symmetrical responses. In order to validate the proposed method, a filter with asymmetrical response has been synthesized, comparing different topologies for its use in multiplexers. This fact is illustrated with a Ku-band elliptic response diplexer designed in H-plane rectangular waveguide.}, url = {http://w3.iec.csic.es/ursi/articulos_modernos/Cantabria2009/files/Sintesis_URSI_20091240904977.pdf}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @conference {09_CNES_Montejo-GaraiRuiz-CruzRebollar_DiplexerAsymmetricSingly, title = {Synthesis and Design of a Diplexer with Asymmetric Singly-Terminated Elliptic Ladder Filters}, booktitle = {Proc. 2009 Int. Workshop on Microwave Filters CNES-ESA}, year = {2009}, month = {Nov.}, pages = {1-6}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @article {09_IJRFMiCAE_Montejo-GaraiRuiz-CruzRebollar_SynthesisSinglyEllipticLadderFilters, title = {Synthesis of Symmetric and Asymmetric Singly-Terminated Elliptic Ladder Filters for Multiplexing Applications}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {19}, number = {4}, year = {2009}, month = {July}, pages = {443-452}, abstract = {An extension of the Cauer ladder development for synthesizing singly terminated filters with symmetric and asymmetric responses is presented. Basically, a driving-point immittance including reactive constant elements is carried out in such a way that provides the transmission zeros. The reactive constant elements are introduced into the synthesis for two reasons. The first is to consider the possibility of the asymmetric position of transmission zeros in the real frequency axis. The second one is to obtain canonical forms, i.e. networks with the minimum number of elements in the case of symmetrical responses. To validate the proposed method, a filter with asymmetrical response has been synthesized, comparing different topologies for its use in multiplexers. This fact is illustrated with a Ku-band elliptic response diplexer designed in H-plane rectangular waveguide. {\^A}{\textcopyright} 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.}, keywords = {diplexer, filter synthesis, pole removal, singly terminated, zero-shifting}, issn = {1096-4290}, doi = {10.1002/mmce.20366}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/122322557/PDFSTART}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @conference {09_URSIESP_MedinaRuiz-CruzMesaEtAl_EOTSinPlasmones, title = {Transmisi{\'o}n Extraordinaria sin Plasmones de Superficie}, booktitle = {Proc. 2009 Simposium Nacional URSI (in Spanish)}, year = {2009}, month = {Sept.}, pages = {1-4}, abstract = {This letter reports on the experimental demonstration of the extraordinary transmission (ET) phenomenon in a closed waveguide system having a diaphragm with an electrically small hole in it. The theoretical explanation for this phenomenon, which has formerly been studied only in periodically perforated screens, is here based on the concept of impedance matching. The concept of impedance matching is an alternative explanation to the surface plasmon polariton (SPP) theory and also accounts for ET through periodically perforated screens. The main difference between the two approaches lies on the fact that SPP{\textquoteright}s are not present in the proposed non-periodic system (an arbitrary cross section closed waveguide), and therefore it is not clear how the SPP-based theory could be applied. On the contrary, the simple equivalent circuit model resulting from the impedance matching point of view leads to numerical predictions that agree very satisfactorily with the experimental results.}, url = {http://w3.iec.csic.es/ursi/articulos_modernos/Cantabria2009/files/EOTSinSPP_FMedina_URSI09_v11241453622.pdf}, author = {Medina-Mena, F and J A Ruiz-Cruz and Mesa-Ledesma, F L and Montejo-Garai, J R and Rebollar, J M and Marques-Sillero, R} } @article {10_GEODAMOTL, title = {Triangular planar array of a pyramidal adaptive antenna for satellite communications at 1.7 GHz}, journal = {Microwave and Optical Technology Letters}, volume = {51}, number = {11}, year = {2009}, month = {Nov.}, pages = {2633 - 2639}, abstract = {Nowadays, satellite communications are basic for the human lifestyle. In this way, a smart, conformal, and multiarray antenna (GEODA) is being developed in order to receive signals from several satellites simultaneously in the 1.7 GHz working band. An adaptive beam system is able to follow the signals from the satellite constellation. The complex structure of the antenna is based in a 3D composition of planar arrays with triangular shape. These arrays are divided into subarrays of three patches (Cells), composing the single control element for the arrays main beam direction management. Fifteen cells (45 radiating elements) compose each triangular array of the GEODA antenna. In this article, a triangular array prototype is implemented and measured. Likewise, an individual characterization of the array components is presented.}, keywords = {adaptive antenna, branch-line coupler, double stacked patch, planar array}, issn = {0895-2477}, doi = {10.1002/mop.24692}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.24692/abstract}, author = {J L Masa-Campos and Montesinos-Ortego, I and Sierra-P{\'e}rez, M} } @article {08_PIER_Ruiz-CruzMontejo-GaraiRebollar_CompactKuTriplexer, title = {Compact Full Ku-Band Triplexer With Improved E-Plane Power Divider}, journal = {Progress in Electromagnetic Research}, volume = {86}, year = {2008}, month = {October}, pages = {39-51}, abstract = {An improved E-plane power divider for compact waveguide triplexers with large separation between channels is presented. The configuration of the divider aims to exploit the different behavior of the device for frequency bands with large separation, leading to a very asymmetric E-plane junction. H-plane filters with inductive windows are used for each channel, in order to obtain reduced insertion losses and lower sensitivity than in metal-insert E-plane filters. The resultant triplexer configuration is very compact, and its design is analyzed and optimized by Mode-Matching. The experimental results of a full Ku-band prototype for communications satellite systems show a very good agreement with the expected simulated response.}, issn = {1559-8985}, doi = {10.2528/PIER08082803}, url = {http://ceta.mit.edu/pier/pier86/03.08082803.pdf}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Sobrino, S.} } @conference {08_URSIUSA_Ruiz-CruzMontejo-GaraiRebollar_ComparisonofDifferent, title = {Comparison of Different Models to Obtain the Dispersion Diagrams of Transmission Lines at Terahertz Frequencies}, booktitle = {Proc. 2008 USNC/URSI National Radio Science Meeting}, year = {2008}, month = {July}, pages = {1}, abstract = {Transmission lines for microwave through terahertz frequencies present an increasing interest for many research groups involved in the modelling of systems operating at these frequencies. In the theoretical characterization of waveguides at terahertz frequencies, the microwave engineering community must address two main challenges: a) the behaviour of metal conductors at this broad bandwidth requires a more evolved model than the constant conductivity model used at microwaves frequencies, and b) the Leontovich{\^A}{\textasciiacute}s conditions (surface impedance conductor model), widely used at lower frequencies to predict the conductor losses and the attenuation constant of the different waveguide modes, may not be accurate enough at frequencies in the terahertz range. In order to quantify the accuracy of the Leontovich{\^a}{\texteuro}{\texttrademark}s model, in this communication an analytic analysis for the parallel plate waveguide is proposed. It is based on a rigorous matching of the different field expressions at the interface between regions of the waveguide. For the conductor, it uses the model proposed in L Solymar classic book (Lectures on electrical properties of material, 1990, Oxford Science Pub). This model has shown its validity, for the authors, as far as a thousand of terahertzs, predicting very accurately the Surface Plasmon Polaritons on metallic surfaces (a dual structure of the parallel plate waveguide considered in this work, M Mansuripur et al., OPN April 2007, pp. 44-49). The propagation constant for fundamental (TM00 or quasi-TEM) and higher order modes (TM01 and TE01) are calculated by solving the corresponding characteristic equations (R E Collin, {\^a}{\texteuro}{\oe}Field theory of guided waves{\^a}{\texteuro} , 1991, IEEE Press), which provide the dispersion diagrams of the modes. The field pattern of the modes could be also obtained. A comparison between the dispersion diagrams obtained with the classical approach (Leontovich{\^a}{\texteuro}{\texttrademark}s approximation) and with the fullwave solution for different parallel plate dimensions will be presented. The errors for both phase and attenuation constants are quantified giving a precise idea on the validity of the different models from an engineering point of view. The results will be given for the fundamental and higher order modes.}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {08_URSIUSA_Ruiz-CruzMontejo-GaraiRebollar_DesignandFull-Wave, title = {Design and Full-Wave Optimization of a Ku-Band Rectangular Waveguide Triplexer}, booktitle = {Proc. 2008 USNC/URSI National Radio Science Meeting}, year = {2008}, month = {July}, pages = {1}, abstract = {Triplexers are devices widely used on communication systems for either splitting a signal into three different sub-bands associated to three different ports or combining three sub-bands into a signal with a broader frequency range. This frequency discrimination facility of the triplexers allows the use of the same antenna for different frequency bands, achieving an important reduction of mass and volume in the hardware equipment. Moreover, in satellite communication systems, the triplexer design is constrained to very stringent electrical requirements. The main features to control are the selectivity of the channels, the insertion losses and the power handling capability. In addition, a very accurate Computer-Aided Design (CAD) is necessary to reduce/avoid the need for tuning screws or any additional adjustments, which limit the maximum power to transmit, generate Passive InterModulation (PIM) products and increase the Multiplaction risk, raising the cost of the device in the design and experimental stages of the device. A triplexer consists of the following elements: a power divider and three channel filters. There are a wide variety of possibilities for these elements (see for instance J Uher et al., {\^a}{\texteuro}{\oe}Waveguide Components for antenna feed systems: Theory and CAD{\^a}{\texteuro}, Artech House, Chap.3). The selection of a particular topology is mainly determined by the channel bandwidths, frequency separation between channels, selectivity, return loss and off-band rejection. The physical configuration of the antenna feed system is another important aspect, since it usually must be very compact. In the presentation, different alternatives will be shown. One of them is the manifold configuration, with two filters in perpendicular to the manifold axis and one inline. Other option is to use an E-plane trifurcation with H-plane filters, with may provide lower insertion losses than E-plane filters. Another import asset when studying triplexer configurations is the possibility to address the CAD of the structure by means of Mode-Matching tools, since they are well-known for their accuracy and efficiency. A comparison between these different aspects will be given in the presentation, with focus on a triplexer with bands centered in 13.1, 14.12 and 18.25 GHz. The expected simulated results will be compared with the experimental measurements of a manufactured prototype for satellite applications.}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {08_URSIESP_Gonzalez-Fernandez_Disenodeantenas, title = {Dise{\~n}o de antenas impresas de banda ancha con polarizador para sistemas WiMAX a 3.5GHz y comunicaciones por sat{\'e}lite en banda {\^a}{\texteuro}\~{}X{\^a}{\texteuro}{\texttrademark}}, booktitle = {Proc. 2008 Simposium Nacional URSI (in Spanish)}, year = {2008}, month = {Sept.}, pages = {1-4}, abstract = {Mobile communications terminals are strongly affected by multi-path reflection waves, so phase error can be quite important in this case. Circular polarization (CP) is used to avoid this problem, mainly caused by reflection on buildings and ground surface. The proposed antenna with parasitic strip elements as polarizer has the advantage to be robust, low cost and easy to fabricate with conventional materials and printed circuit technology. Two prototypes are exposed, WiMAX and X band, whose measures results verify the CP and show that good return loss and axial ratio characteristics have been obtained.}, url = {http://w3.iec.csic.es/ursi/paginas/index_congresosreali.htm}, author = {Gonz{\'a}lez-Fern{\'a}ndez, F and J L Masa-Campos and Castro, M T and J A Ruiz-Cruz} } @conference {08_URSIESP_Ruiz-CruzZhangMontejo-GaraiEtAl_Disenodefiltros, title = {Dise{\~n}o de filtros dual-mode longitudinales en gu{\'\i}a de onda rectangular}, booktitle = {Proc. 2008 Simposium Nacional URSI (in Spanish)}, year = {2008}, month = {Sept.}, pages = {1-4}, abstract = {Dual-Mode filters are used in applications where low mass and volume are required. In this paper, the Computer Aided Design of a new rectangular waveguide filter structure is proposed for achieving the dual-mode operation. It preserves the longitudinal inline topology used in the classical circular waveguide configuration, which can provide quasi-elliptic function responses. However, it has no coupling or tuning screws and it is exclusively made up of sections of aligned rectangular waveguides. This leads to a very efficient full-wave analysis based on the Mode-Matching method. The proposed CAD is illustrated with a four order prototype, whose results are compared with other numerical technique.}, url = {http://w3.iec.csic.es/ursi/paginas/index_congresosreali.htm}, author = {J A Ruiz-Cruz and Zhang, Y and Montejo-Garai, J R and Rebollar, J M and Zaki, K A} } @article {08_IJRFMiCAE_Ruiz-CruzMontejo-GaraiRebollar_Full-wavemodelingand, title = {Full-wave modeling and optimization of Boifot junction ortho-mode transducers}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {18}, number = {4}, year = {2008}, month = {July}, pages = {303-313}, abstract = {The full-wave design of broadband ortho-mode transducers based on the Boifot junction has two main aspects: an efficient analysis method and a design process divided into tasks with relatively low computational effort. In the analysis part, a rigorous mode-matching technique has been developed to obtain the generalized admittance matrix of the Boifot junction. The other elements of the device are also analyzed by mode-matching. With respect to the design, the proposed procedure starts with the optimization of the individual building blocks of the device. Their interaction is also taken into account in a systematic process. The analysis and design methods have been validated with other numerical methods and an experimental prototype}, keywords = {Boifot ortho-mode transducer, full-wave optimization, generalized admittance matrix, mode-matching}, issn = {1096-4290}, doi = {10.1002/mmce.20287}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/119140992/PDFSTART}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {08_IMS_Ruiz-CruzZhangMontejo-GaraiEtAl_LongitudinalDual-ModeFilters, title = {Longitudinal Dual-Mode Filters in Rectangular Waveguide}, booktitle = {2008 IEEE MTT-S International Microwave Symposium Digest}, year = {2008}, month = {June}, pages = {631-634}, abstract = {Dual-Mode filters are used in applications where low mass and volume are required. In this paper, the Computer Aided Design of a new rectangular waveguide filter structure is proposed for achieving the dual-mode operation. It preserves the longitudinal inline topology used in the classical circular waveguide configuration, which can provide quasi-elliptic function responses. However, it has no coupling or tuning screws and it is exclusively made up of sections of aligned rectangular waveguides. This leads to a very efficient full-wave analysis based on the Mode-Matching method. The proposed CAD is illustrated with a four order prototype, whose results are compared with other numerical technique.}, keywords = {Dual-Mode cavities, elliptic filter response, rectangular waveguide filter}, issn = {0149-645X}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=4632911\&isnumber=4632906}, author = {J A Ruiz-Cruz and Zhang, Y and Montejo-Garai, J R and Rebollar, J M and Zaki, K A} } @conference {08_EIEC_Ruiz-CruzMontejo-GaraiRebollar_Modelosparala, title = {Modelos para la caracterizaci{\'o}n de l{\'\i}neas de transmisi{\'o}n en Terahercios}, booktitle = {Proc. VI Encuentro Ib{\'e}rico de Electromagnetismo Computacional (in Spanish)}, year = {2008}, month = {Oct.}, pages = {1-6}, abstract = {Los medios de transmisi{\'o}n y en particular las l{\'\i}neas de transmisi{\'o}n presentan cada vez un mayor inter{\'e}s en frecuencias de las bandas de Terahercios, para su posible aplicaci{\'o}n en el dise{\~n}o de dispositivos. Para las bandas de frecuencia cl{\'a}sicas utilizadas en la ingenier{\'\i}a de radiofrecuencia (30 MHz - 300 GHz), el comportamiento de los materiales met{\'a}licos con los que se construyen las l{\'\i}neas de transmisi{\'o}n suele corresponderse con el de un buen conductor (corrientes de conducci{\'o}n mucho mayores que corrientes de desplazamiento), y la caracterizaci{\'o}n electromagn{\'e}tica de las mismas (constante de propagaci{\'o}n e impedancia caracter{\'\i}stica) utiliza en la mayor parte de las situaciones ciertas aproximaciones basadas en el cumplimiento de las condiciones de Leontovich (condici{\'o}n de impedancia superficial en la superficie del conductor). Siendo todo ello, de particular importancia para la caracterizaci{\'o}n de la constante de atenuaci{\'o}n. Sin embargo, a medida que la frecuencia de trabajo sube, el comportamiento de los materiales met{\'a}licos se aleja del modelo de conductor utilizado por la ingenier{\'\i}a de radiofrecuencia y dejan de poder realizarse las aproximaciones mencionadas. Estos cambios, adem{\'a}s de afectar a la configuraci{\'o}n del propio campo electromagn{\'e}tico, tambi{\'e}n pueden afectar de manera significativa la predicci{\'o}n de las p{\'e}rdidas en la l{\'\i}nea, caracter{\'\i}stica de primordial importancia en ingenier{\'\i}a de comunicaciones. El objetivo del presente trabajo es presentar un an{\'a}lisis riguroso de algunas geometr{\'\i}as de l{\'\i}nea de transmisi{\'o}n y comparar los resultados con los obtenidos por los modelos cl{\'a}sicos de la ingenier{\'\i}a de radiofrecuencia para intentar establecer algunos l{\'\i}mites de los mismos. Para ello se propone: 1) utilizar un modelo m{\'a}s preciso para la descripci{\'o}n de los materiales met{\'a}licos y en particular el modelo de Drude (Lectures on electrical properties of material, 1990, Oxford Science Pub) y 2) realizar un an{\'a}lisis electromagn{\'e}tico preciso, tanto para el modo fundamental como para los modos superiores, de geometr{\'\i}as cl{\'a}sicas de l{\'\i}neas de transmisi{\'o}n. La validez del modelo utilizado queda justificada por la precisi{\'o}n con la que predice en frecuencias de miles de terahercios los denominados "Surface Plasmon Polaritons" sobre superficies met{\'a}licas, recientemente publicados (M. Mansuripur et al., OPN April 2007, pp. 44-49). Esta estructura es dual de la l{\'\i}nea de transmisi{\'o}n de placas paralelas, que ser{\'a} utilizada en nuestros an{\'a}lisis. Se calculan la constante de propagaci{\'o}n del modo fundamental (TM00 {\'o} casi-TEM) y de los primeros modos superiores (TM01 y TE01) resolviendo la correspondiente ecuaci{\'o}n caracter{\'\i}stica del medio de transmisi{\'o}n (R E Collin, {\^a}{\texteuro}{\oe}Field theory of guided waves{\^a}{\texteuro} , 1991, IEEE Press). Se presentar{\'a} una comparaci{\'o}n entre los diagramas de dispersi{\'o}n obtenidos mediante la aproximaci{\'o}n de Leontovich y el an{\'a}lisis riguroso, para tratar de obtener los rangos de validez de las aproximaciones.}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {6_Monopulse_L_BandMOTL, title = {Monopulse beam-scanning planar array antenna in L band}, journal = {Microwave and Optical Technology Letters}, volume = {50}, number = {7}, year = {2008}, month = {Jul.}, pages = {1812-1819}, abstract = {A planar antenna is presented as part of a Signal Identification System working at 1.06 GHz. The antenna presents a monopulse radiation pattern. Likewise, a scanning of the main beam direction is achieved in a {\textpm}45{\textdegree} azimuth coverage. A limited 3 dB amplitude drop of the received signal at the edges of the angular scanning area is only permitted. Furthermore, a broad beamwidth is required in the single element of the array. A rectangular linearly polarized double stacked patch has been then designed, with a significant size reduction in the nonresonant length, to increase the azimuth beamwidth of the array single element. The whole antenna structure is composed of 18 elements, which have been distributed in six columns of three patches per column. The feeding network of the array has been developed in microstrip technology, with small individual circuits connected by coaxial cables, to reduce the global losses of the system. The designed compact antenna and the transmitting and receiving equipments will be placed inside a POD on the top part of an airplane. A prototype antenna has been manufactured and measured in three different beam pointing directions. Satisfactory results have been achieved in the entire frequency band.}, keywords = {beam-scanning array, monopulse system, stacked patch}, issn = {0895-2477}, doi = {10.1002/mop.23516}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.23516/abstract}, author = {J L Masa-Campos and S{\'a}nchez-Sevilleja, S and Dom{\'\i}nguez-Grano-de-Oro, C and Sierra-P{\'e}rez, M and Fernandez-Jambrina, J L} } @conference {07_URSIESP_Ruiz-CruzMontejo-GaraiRebollarEtAl_CADdeOMTs, title = {CAD de OMTs (Ortho-Mode Transducers) de Banda Ancha Basados en la Uni{\'o}n B{\o}ifot}, booktitle = {Proc. 2007 Simposium Nacional URSI (in Spanish)}, year = {2007}, month = {Sept.}, pages = {1-4}, abstract = {This paper proposes a CAD tool for wideband OMTs based on the B{\o}ifot junction which has two interesting features. First, the OMT routing branches use well-known waveguide elements, such as truncated E-plane bends, which can be efficiently analyzed by Mode-Matching (MM) methods and can achieve wideband performance. Second, a MM technique is presented for the four-port Boifot junction, which provides its generalized multimode characterization. As a result, the whole OMT is segmented into different regions, yielding an efficient CAD tool for its optimum design. The analysis method and the designed OMT have been validated with other numerical methods and experimental results.}, url = {http://w3.iec.csic.es/ursi/articulos_desde_2007/la_laguna_2007/PDF/p208.pdf}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Montesano, C E and Mart{\i}n, M J and Naranjo-Masi, M} } @article {4_Omni_antenna_parasiticstripsMOTL, title = {Circularly polarized omnidirectional millimeter wave monopole with parasitic strip elements}, journal = {Microwave and Optical Technology Letters}, volume = {49}, number = {3}, year = {2007}, month = {Mar.}, pages = {664-668}, abstract = {A circularly polarized omnidirectional millimeter wave monopole with parasitic strip elements for a system of arrival signal direction detection in millimeter band is presented. As a consequence of the radiation pattern requirements, the proposed antenna consists of a conical skirt monopole with a polarizer radome. The polarizer converts a wave from linear to circular polarization. The proposed antenna has the advantage to be robust, low cost, and easy to fabricate with conventional materials and printed circuit technology. The study presents simulation and experimental results obtained with an antenna prototype that validate the design.}, keywords = {arrival signal direction detection system, Circular polarization, millimeter antenna, omnidirectional antenna}, issn = {0895-2477}, doi = {10.1002/mop.22237}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.22237/abstract}, author = {Fern{\'a}ndez, J M and J L Masa-Campos and Sierra-P{\'e}rez, M} } @conference {07_APS_Ruiz-CruzMontejo-GaraiRebollarEtAl_DesignofRiblet-type, title = {Design of Riblet-type couplers for Ka band applications}, booktitle = {Proc. 2007 IEEE Antennas and Propagation Society International Symposium}, year = {2007}, month = {June}, pages = {4276-4279}, abstract = {The full-wave modeling and design of short-slot Riblet waveguide couplers are addressed in this contribution. These types of directional couplers are commonly used by their compact size in comparison with other waveguide configurations. The main features of the Riblet coupler are discussed and its modeling with different input/output excitations is described. Two different designs are shown, with either rectangular waveguide input/output ports or coaxial interfaces. The expected simulated results of two manufactured prototypes operating at 19 GHz are compared with their experimental measurements.}, keywords = {coaxial interfaces, directional couplers, directional couplersRiblet-type couplers, frequency 19 GHz, full-wave modeling, input/output excitations, rectangular waveguide input/output ports, short-slot Riblet waveguide couplers}, issn = {1-4244-0878-4}, doi = {10.1109/APS.2007.4396486}, url = {http://ieeexplore.ieee.org/iel5/4395409/4395410/04396486.pdf?tp=\&isnumber=\&arnumber=4396486}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Daganzo, A I and Hidalgo-Carpintero, I} } @conference {07_URSIESP_Ruiz-CruzMontejo-GaraiRebollarEtAl_DisenodeAcopladores, title = {Dise{\~n}o de Acopladores Tipo Riblet en Banda Ka}, booktitle = {Proc. 2007 Simposium Nacional URSI (in Spanish)}, year = {2007}, month = {Sept.}, pages = {1-4}, abstract = {The full-wave modelling and design of short-slot Riblet waveguide couplers are addressed in this contribution. These types of directional couplers are commonly used by their compact size in comparison with other waveguide configurations. The main features of the Riblet coupler are discussed and its modeling with different input/output excitations is described. Two different designs are shown, with either rectangular waveguide input/output ports or coaxial interfaces. The expected simulated results of two manufactured prototypes operating at 19 GHz are compared with their experimental measurements.}, url = {http://w3.iec.csic.es/ursi/articulos_desde_2007/la_laguna_2007/PDF/p206.pdf}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Daganzo, A I and Hidalgo-Carpintero, I} } @article {5_Omni_antenna_slotsMOTL, title = {Omnidirectional circularly polarized slot antenna fed by a cylindrical waveguide in millimeter band}, journal = {Microwave and Optical Technology Letters}, volume = {49}, number = {3}, year = {2007}, month = {Mar.}, pages = {638-642}, abstract = {A circularly polarized slotted array antenna is presented. The array is fed by a circular waveguide propagating the TM01, to properly generate the required polarization. An omnidirectional azimuth radiation pattern is obtained, as well as a ?10{\textdegree}/+30{\textdegree} elevation antenna coverage. Low losses are achieved because of the waveguide feed. The slot array is mechanized over the metallic wall of the circular waveguide. Furthermore, the antenna presents a solid and rigid mechanical structure, which guarantees an optimum and repetitive response in a manufacturing process. A prototype antenna has been designed and measured. Satisfactory results have been obtained. The slotted array takes part from a signal detection system centered in 36.85 GHz.}, keywords = {Circular polarization, conformal slotted waveguide array, transversal magnetic mode, waveguide to coaxial transition}, issn = {0895-2477}, doi = {10.1002/mop.22207}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.22207/abstract}, author = {J L Masa-Campos and Fern{\'a}ndez, J M and Sierra-P{\'e}rez, M} } @conference {07_IMS_Ruiz-CruzZhangRebollarEtAl_TEMMode-MatchingAnalysis, title = {TEM Mode-Matching Analysis of Multi-coupled Strip-line Filters}, booktitle = {2007 IEEE MTT-S International Microwave Symposium Digest}, year = {2007}, month = {June}, pages = {541-544}, abstract = {The analysis of multi-coupled strip-line filters by the mode-matching method is studied for different input/output excitations. The aim is to compare the computational effort of two different options and to propose the most suitable formulation for the design of some strip-line filters. It is shown that a suitable segmentation of the structure is essential for obtaining good numerical results. In fact, if the optimum segmentation is selected, a mode-matching analysis using only TEM modes can resemble the full-wave response, with shorter computation time. Hence, this approach can be very useful in design and different examples are shown to validate it, using other numerical methods and measurements of a ten order filter.}, keywords = {microwave filters, mode matching, multicoupled strip-line filter design, optimum structure segmentation, strip line filtersTEM mode-matching analysis}, issn = {0149-645X}, doi = {10.1109/MWSYM.2007.380546}, url = {http://ieeexplore.ieee.org/iel5/4263706/4263707/04263871.pdf?tp=\&isnumber=\&arnumber=4263871}, author = {J A Ruiz-Cruz and Zhang, Y and Rebollar, J M and Zaki, K A and Montejo-Garai, J R and Piloto, A J} } @article {07_IJRFMiCAE_Ruiz-CruzMontejo-GaraiRebollarEtAl_Waveguidefilterswith, title = {Waveguide filters with elliptical function response: Overview and results of different implementations}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {17}, number = {1}, year = {2007}, month = {Jan.}, pages = {63-69}, abstract = {Some recent implementations of waveguide filters with elliptical response are presented in this paper. The goal is to describe the main aspects involved in the computer-aided design of elliptic waveguide filters, which are commonly used at microwave and millimeter-wave frequencies by their high selectivity, low insertion loss, and high power-handling capabilities. Three different examples based on crosscoupled cavities and the extracted-pole procedure are used to illustrate the main ideas, with their corresponding experimental results. A comparative table summarizes the main features of the presented filters.}, keywords = {Bandpass Waveguide Filters, Design, Extracted Poles, N-Transmission Zeros, Order Filters, resonators}, issn = {1096-4290}, doi = {10.1002/mmce.20198}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/113493159/PDFSTART}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Zaki, K A} } @conference {06_CNES_Ruiz-CruzMontejo-GaraiRebollar_Comparisonofdifferent, title = {Comparison of different technologies to implement finite transmission zeros in cavity waveguide filters}, booktitle = {Proc. 2006 Int. Workshop on Microwave Filters CNES-ESA}, year = {2006}, month = {Oct.}, pages = {1-2}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {06_IMS_Ruiz-CruzMontejo-GaraiRebollarEtAl_ComputerAidedDesign, title = {Computer Aided Design of Wideband Orthomode Transducers based on the Boifot Junction}, booktitle = {2006 IEEE MTT-S International Microwave Symposium Digest}, year = {2006}, month = {June}, pages = {1173-1176}, abstract = {A CAD tool based on the Boslashifot junction is proposed for the design of wideband orthomode transducers (OMTs). It has two interesting features. First, the OMT routing branches use well-known waveguide elements, such as truncated E-plane bends, which can be efficiently analyzed by mode-matching (MM) methods and can achieve wideband performance. Second, a MM technique is presented for the four-port Boslashifot junction, which provides its generalized multimode characterization. As a result, the whole OMT is segmented into different regions, yielding an efficient CAD tool for its optimum design. The analysis method and the designed OMT have been validated with other numerical methods and experimental results}, keywords = {CAD, computer aided design, four-port junction, mode matching, mode-matching methods, OMT routing branches, transducers, waveguide componentsCAD tool, waveguide elements, wideband orthomode transducers}, issn = {0149-645X}, doi = {10.1109/MWSYM.2006.249400}, url = {http://ieeexplore.ieee.org/iel5/4014788/4014789/04015130.pdf?tp=\&isnumber=\&arnumber=4015130}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Montesano, C E and Mart{\i}n, M J and Naranjo-Masi, M} } @conference {06_EuMC_Montejo-GaraiRuiz-CruzRebollarEtAl_DesignofSelf-Equalised, title = {Design of Self-Equalised Elliptic Filter Channels in Ka-Band Implemented in Rectangular H-Plane Waveguide}, booktitle = {Proc. 36th European Microwave Conference}, year = {2006}, month = {Sept.}, pages = {1087-1090}, abstract = {In this article, a systematic design procedure for the design of self-equalised elliptic filters in H-plane configuration is presented. Such a configuration in tends to be an alternative to the classical dual-mode circular waveguide configuration in Ka band, with the aim in mind of reducing cost and computation time. In order to decrease the insertion loss the TE105 will be used. A sixth order filter with two transmission zeros at finite real frequencies and two zeros for equalisation has been designed, manufactured and measured. The results make clear the validity of the proposed configuration}, keywords = {dual mode circular waveguide, elliptic filter channels, elliptic filters, Ka-band, microwave filters, Milling, mode matching, poles and zeros, rectangular waveguide, rectangular waveguides, self-equalised filter, systematic design procedure, waveguide filtersH-plane configuration}, issn = {2-9600551-6-0}, doi = {10.1109/EUMC.2006.281123}, url = {http://ieeexplore.ieee.org/iel5/4057701/4057702/04058013.pdf?tp=\&isnumber=\&arnumber=4058013}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M and Onoro-Navarro, A. and Hidalgo-Carpintero, I and Padilla-Cruz, M J} } @conference {06_URSIESP_Montejo-GaraiRuiz-CruzRebollar_Disenodefiltros, title = {Dise{\~n}o de filtros de Canal El{\'\i}pticos y Autoecualizados en Banda Ka implementados en gu{\'\i}a rectangular plano H}, booktitle = {Proc. 2006 Simposium Nacional URSI (in Spanish)}, year = {2006}, month = {Sept.}, pages = {1-3}, abstract = {In this article, a systematic design procedure for the design of self-equalized elliptic filters in H-plane configuration is presented. Such a configuration intends to be an alternative to the classical dual-mode circular wave guide configuration in Ka band, with the aim in mind of reducing cost and computation time. In order to decrease the insertion loss the TE105 will be used. A sixth order filter with two transmission zeros at finite real frequencies and two zeros for equalization has been designed, manufactured and measured. The results make clear the validity of the proposed configuration.}, url = {http://w3.iec.csic.es/ursi/articulos_oviedo_2006/articulos/sesionMOP-III-13small.pdf}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @conference {06_URSIUSA_Ruiz-CruzMontejo-GaraiRebollar_RelativeConvergenceProblem, title = {Relative Convergence Problem in the Mode-Matching Analysis of Stripline Interdigital Filters with Different Input-Output Coupling}, booktitle = {Proc. 2006 USNC/URSI National Radio Science Meeting}, year = {2006}, month = {July}, pages = {1}, abstract = {Interdigital filters are used in microwave frequencies by their wide spurious-free response and their highly symmetric frequency response, which can be used to design filters with very flat group delay. They are TEM mode filters made up of a number of metallic rods or strips enclosed by a box and positioned consecutively along z-direction (see Fig. 1). The input/output of the filter can be transversal (Fig. 1.a) or longitudinal (Fig. 1.b) to the resonating strips, depending on the required interfaces and filter bandwidth. The approximate design of interdigital filters is found in Matthaei et al. classic book (Microwave Filters, Impedance-Matching Networks and Coupling Structures, Artech House, 1980). A full-wave analysis method is required in order to take into account parasitic effects of the physical implementation such as the coupling between non-adjacent lines or the enclosure box. This communication addresses the Mode-Matching analysis (MM) of the structures in Fig. 1, which is applied as follows. Firstly, the structure is segmented into a number of uniform waveguides along a specific direction (x in Fig.1.a and z in Fig. 1.b), whose TE, TM and TEM mode spectrum can be calculated either analytically or numerically. Secondly, the Generalized Scattering Matrix (GSM) that characterizes each basic step between two consecutive waveguides of different cross sections is calculated. Finally, all the individual GSMs are cascaded adequately to obtain the overall filter response. Although this procedure is applied to the configurations in Fig. 1, its implementation leads to significant numerical differences for the structures with perpendicular (along x) and longitudinal (along z) excitation. Basically, the analysis in Fig.1.a involves TEMx modes, which model the total field in the structure adequately. However, the field in the resonators in Fig.1.b is obtained by summing up TEz and TMz modes, which leads to convergence difficulties. The results of the investigated relative convergence problems [T. Itoh, Numerical Techniques {\^a}{\texteuro}{\textbrokenbar}, John Wiley, 1989] will be shown in the oral presentation.}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {06_MOTL_Ruiz-CruzMontejo-GaraiRebollarEtAl_Verycompactortho-mode, title = {Very compact ortho-mode transducers with double septum configuration}, journal = {Microwave and Optical Technology Letters}, volume = {48}, number = {4}, year = {2006}, month = {Apr.}, pages = {765-767}, abstract = {This paper describes the analysis and design results of a very compact ortho-mode transducer (OMT) for dual-polarization communication systems. The presented configuration introduces an additional double septum in the conventional structure, not reported previously, which provides a number of advantages for some of the usual requirements of this type of OMTs. Specifically, the double-septum configuration enhances the performance of the OMT in two interrelated aspects: (i) it contributes to reduce the size of the axial branch of the OMT preventing the power transfer between horizontal modes at the axial and common ports; (ii) it facilitates the matching of the horizontal polarization between the lateral and common ports. The presented design leads to a very interesting structure for coping with competitive specifications. The proposed structure is validated using a prototype onboard the Hispasat 1D satellite.}, keywords = {generalized admittance matrix, generalized scattering matrix, mode-matching, ortho-mode, septum}, issn = {0895-2477}, doi = {10.1002/mop.21468}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/112467840/PDFSTART}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Montesano, C E and Mart{\i}n, M J} } @article {3_CouplingJMOEA, title = {Coupling Characterization and Compensation Model for Antenna Arrays}, journal = {Journal of Microwaves, Optoelectronics and Electromagnetic Applications}, volume = {4}, number = {2}, year = {2005}, month = {Dec.}, pages = {95-110}, abstract = {Coupling is an important aspect to be considered in the design process of antenna arrays. The real feeding radiated coefficients can be quite different from the theoretical ones because of this effect. In this paper, a characterization and compensation model is presented. This procedure is capable of matching each element of the array. All the parameters of the array coupling model are obtained through the measurement of scattering parameters and radiation patterns of the individual elements. Some practical applications to linear patch arrays are presented.}, issn = {1516-7399}, url = {http://www.jmoe.org/site-number?id=3}, author = {J L Masa-Campos and Fern{\'a}ndez, J M and Sierra-Casta{\~n}er, M and Sierra-P{\'e}rez, M} } @article {05_IEEETMTT_Montejo-GaraiRuiz-CruzRebollar_Full-WaveDesignof, title = {Full-Wave Design of H-Plane Contiguous Manifold Output Multiplexers Using the Fictitious Reactive Load Concept}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {53}, number = {8}, year = {2005}, month = {Aug.}, pages = {2628-2632}, abstract = {In this paper, a new procedure for the design of contiguous band manifold output multiplexers in$H$-plane configuration is presented. Such a configuration eliminates the slots between the T-junctions and the filters allowing high power handling, as well as dramatically reducing the risk of multipactor. This paper pursues the division of the design into tasks with low computational effort. The approach comprises: 1) the singly terminated synthesis of the channel filters and their corresponding full-wave responses; 2) the manifold design using fictitious reactive loads simulating the phase response of every channel out of its corresponding band; and 3) the final full-wave optimization of the whole structure using the simulated-annealing method. In order to validate the above procedure, a five-channel$Ku$-band multiplexer has been designed, manufactured, and measured.}, keywords = {mode matching, multiplexer, simulated annealing, singly terminated filter}, issn = {0018-9480}, doi = {10.1109/TMTT.2005.852749}, url = {http://ieeexplore.ieee.org/iel5/22/32085/01492665.pdf?tp=\&isnumber=\&arnumber=1492665}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @conference {05_EIEC_Montejo-GaraiRuiz-CruzRebollar_Implementaciondefiltros, title = {Implementaci{\'o}n de filtros con ceros de transmisi{\'o}n mediante polos extra{\'\i}dos en tecnolog{\'\i}a plano-H}, booktitle = {Proc. IV Encuentro Ib{\'e}rico de Electromagnetismo Computacional (in Spanish)}, year = {2005}, month = {Sept.}, pages = {1-5}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @conference {05_URSIESP_Montejo-GaraiRuiz-CruzRebollar_NuevoMetodode, title = {Nuevo M{\'e}todo de Dise{\~n}o de Multiplexores de Salida en Configuraci{\'o}n Manifold y Estructura Plano-H}, booktitle = {Proc. 2005 Simposium Nacional URSI (in Spanish)}, year = {2005}, month = {Sept.}, pages = {1-4}, abstract = {In this communication, a new procedure for the design of contiguous band manifold output multiplexers in H-plane configuration is presented. Such a configuration eliminates the slots between the T-juntions and the filters allowing high power handling as well as reducing dramatically the risk of multipactor. This work pursues the division of the design into taskswith low computational effort. The approach comprises the following steps: a) the singly-terminated synthesis of the channel filters and their corresponding full-wave responses, b) the manifold design using fictitious reactive loads simulating the phase response of every channel out of its corresponding band, c) the final full-wave optimisation of the whole structure. In order to validate the above procedure a five{\^a}{\texteuro}{\textquotedblleft}channel Kuband multiplexer has been designed, manufactured and measured.}, url = {http://w3.iec.csic.es/ursi/articulos_gandia_2005/articulos/CM4/315.pdf}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @article {2_RadiallineMOTL, title = {Radial Line Planar Antenna with Microstrip Feeding Coupling Lines}, journal = {Microwave and Optical Technology Letters}, volume = {46}, number = {4}, year = {2005}, month = {Aug.}, pages = {305-311}, abstract = {Radial-line antennas are an excellent choice for a high-gain and efficient design, as they present an easy manufacturing process due to their planar structure. In this paper, a new feeding mechanism, from the transmitting radial waveguide to the radiating elements, is proposed. This coupling structure is based on microstrip lines placed inside the radial waveguide and connected to each radiating patch. By changing the dimensions of the microstrip lines, it is possible to achieve the desired feeding configuration. In order to check the validity of the new feeding mechanism, coupled field measurements are done in the radial waveguide. Likewise, a prototype antenna is manufactured in order to evaluate the behavior of the microstrip coupling lines when the radiating patches are connected to them. The results obtained from this prototype are presented and discussed and future research is proposed.}, keywords = {double stacked patch antenna, microstrip coupling lines, radial line planar antenna (RLPA)}, issn = {0895-2477}, doi = {10.1002/mop.20973}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.20973/abstract}, author = {J L Masa-Campos and Sierra-P{\'e}rez, M} } @conference {05_IMS_Ruiz-CruzZakiMontejo-GaraiEtAl_Rectangularwaveguideelliptic, title = {Rectangular waveguide elliptic filters with capacitive and inductive irises and integrated coaxial excitation}, booktitle = {2005 IEEE MTT-S International Microwave Symposium Digest}, year = {2005}, month = {June}, pages = {269-272}, abstract = {CAD of rectangular waveguide filters with elliptic responses is described. The configuration uses capacitive and inductive irises in order to achieve the different coupling signs required to synthesize finite transmission zeros in the rejection bands. The input and output ports are realized by a coaxial probe that directly excites the input/output cavities. The analysis is done by the efficient mode-matching method, in order to allow a final full-wave optimization taking into account all the higher order mode interactions. The CAD results are verified with the HFSS and a filter was manufactured for testing.}, keywords = {band-stop filters, capacitive iris, circuit CAD, coaxial probe, coaxial waveguides, elliptic filters, finite transmission zeros, full-wave optimization, higher order mode interactions, inductive iris, input ports, integrated coaxial excitation, mode matching, mode-matching method, optimisation, output ports, rectangular waveguide filter, rectangular waveguides, rejection bands, waveguide filters CAD}, issn = {01490-645X}, doi = {10.1109/MWSYM.2005.1516577}, url = {http://ieeexplore.ieee.org/iel5/10171/32491/01516577.pdf?tp=\&isnumber=\&arnumber=1516577}, author = {J A Ruiz-Cruz and Zaki, K A and Montejo-Garai, J R and Rebollar, J M} } @conference {05_URSIUSA_Ruiz-CruzMontejo-GaraiRebollar_Simpleequivalentcircuit, title = {Simple equivalent circuit of multi-aperture rectangular iris in rectangular waveguide}, booktitle = {Proc. 2005 USNC/URSI National Radio Science Meeting}, year = {2005}, month = {July}, pages = {1}, abstract = {The rejection produced by a multi-apertures iris can be a very useful tool in the design of some kind of filters: a) band pass filters with some improved stop band attenuation as it has been proposed at (A A Kirilenko, MSMW{\textquoteright}2001 Symposium, 690-692), and b) harmonic rejection filters for the dominant and higher waveguide modes (A A Kirilenko,IEEE MTT-S Digest, 373-376). An alternative interpretation of the resonance of this multi-apertures iris in terms of the excitation of a Transverse Electro-Magnetic field (TEM) of the structure has been proposed by the authors of this contribution at (2003 USNC/URSI Symp., 226) and ( 2004 USNC/URSI Symp., 45). Moreover, this interpretation can be useful to control and prevent some spurious resonance that arise at some rectangular waveguide devices, therefore helping the designer to improve their electrical performances. In this paper, with the main aim to implement an efficient computer aided design tool for waveguide filters, a simple equivalent circuit in terms of lumped elements is proposed for multi-apertures iris with the mentioned resonant TEM behaviour. As an example of the proposed equivalent circuit, a classical band pass filter of asymmetrical inductive windows have been modified by introducing slots in the irises to obtain additional stop band attenuation out of band response. This additional attenuation band is achieved without increasing the number of cavities of the filter, therefore with the same dimensions and very similar insertion losses at its band pass. Further information regarding the design process for the Ka-band filter, and results such as fullwave response and the relative convergence problem of the analysis will be commented in the oral presentation.}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {05_EuMC_Montejo-GaraiRuiz-CruzRebollar_Synthesisanddesign, title = {Synthesis and design of a manifold triplexer implemented in a three layer rectangular H-plane waveguide}, booktitle = {Proc. 35th European Microwave Conference}, volume = {1}, year = {2005}, month = {Oct.}, pages = {1-4}, abstract = {In this article, a new procedure for the design and construction of a contiguous band manifold triplexer in H-plane configuration is presented. Such a configuration eliminates the slots between the T-junctions and the filters allowing high power handling as well as reducing dramatically the risk of multipactor. In addition, the device has been manufactured using a three layer sandwich configuration. In this way, the classical milling machine has been replaced by a wire-electric-milling one. The rounded corners are removed and consequently the tuning process is practically eliminated. In order to validate the above performance, a Ku-band triplexer has been designed, manufactured and measured.}, keywords = {contiguous band manifold triplexer, microwave devices, multiplexing equipment, rectangular waveguides, slot lines Ku-band triplexer, three layer rectangular H-plane waveguide, three layer sandwich configuration, wire-electric-milling machine}, issn = {2-9600551-2-8}, doi = {10.1109/EUMC.2005.1608801}, url = {http://ieeexplore.ieee.org/iel5/10686/33788/01608801.pdf?tp=\&isnumber=\&arnumber=1608801}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} } @article {05_IEEETMTT_Montejo-GaraiRuiz-CruzRebollarEtAl_Synthesisanddesign, title = {Synthesis and design of in-line N-order filters with N real transmission zeros by means of extracted poles implemented in low-cost rectangular H-plane waveguide}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {53}, number = {5}, year = {2005}, month = {May}, pages = {1636-1642}, abstract = {In this paper, an extension to the extracted pole technique for synthesizing N-order filters with N-transmission zeros at real frequencies is presented. In addition, a new bandpass rectangular waveguide H-plane low-cost configuration filter for high-power low-loss application (patent pending) that implements a filtering function with finite real frequency transmission zeros is proposed. This structure operates as a resonant cavity in transmission at central frequency of the bandpass and simultaneously introduces a controlled transmission zero out of the bandpass. Since every double-controlled electrical behavior cavity introduces a transmission zero, it is possible to introduce as many transmission zeros as the order of the filtering function. In order to validate the synthesis procedure and the new structure, different filters have been designed: a second-order filter with two transmission zeros, a third-order filter with one transmission zero, a fourth-order filter with two transmission zeros, and finally, an eighth-order filter with two transmission zeros. The last two have been manufactured, showing an excellent agreement between the measurement and theoretical simulation.}, keywords = {band-pass filters, double-controlled electrical behavior cavity, eighth-order filter, extracted pole technique, filter synthesis, filtering function, finite real frequency transmission zeros, fourth-order filter, in-line N-order filters, network synthesis, planar waveguides, poles and zeros, rectangular H-plane waveguide, rectangular waveguides, resonant cavity, second-order filter, third-order filter, waveguide filters bandpass rectangular waveguide H-plane filter}, issn = {0018-9480}, doi = {10.1109/TMTT.2005.847053}, url = {http://ieeexplore.ieee.org/iel5/22/30829/01427966.pdf?tp=\&isnumber=\&arnumber=1427966}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M and Padilla-Cruz, M J and Onoro-Navarro,A and Hidalgo-Carpintero, I} } @article {04_WSEAS_Ruiz-CruzMontejo-GaraiRebollar_Applicationofsimulated, title = {Application of the simulated annealing for waveguide filters with complicated frequency response}, journal = {WSEAS Transactions on Mathematics}, volume = {3}, number = {4}, year = {2004}, note = {Acceptance Rate = (Number of Accepted Papers) / (Number of Submitted Papers) *100 = 13.45\%, SCImago: 0.039}, month = {Oct.}, pages = {807-812}, abstract = {A design approach for microwave waveguide filters with complicated response is proposed. It uses a combination of analytical filter synthesis theory, a very efficient"fullwave" analysis method of the structure and the Simulated Annealing (SA) optimization algorithm. Instead of a single optimization of the whole structure, the knowledge of the analytical synthesis of the filter allows todivide the optimization into more straightforward partial problems. In this way, the filter is segmented into sections that are optimized to match the partial frequency responses obtained from the analytical synthesis procedure. These optimized sections are a very useful starting point to overcome the difficulties of the final optimization of the whole structure. These ideas areapplied to the design of two waveguide filters with sophisticated response. The obtained results show the efficiency of the presented approach.}, keywords = {microwave waveguide filters, optimization, simulated annealing., synthesis theory}, issn = {1109-2769}, url = {http://www.worldses.org/journals/mathematics/mathematics-october2004.doc}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {04_URSIESP_Ruiz-CruzMontejo-GaraiRebollar_Disenoymedida, title = {Dise{\~n}o y medida de un filtro dual-mode en cavidad el{\'\i}ptica}, booktitle = {Proc. 2004 Simposium Nacional URSI (in Spanish)}, year = {2004}, month = {Sept.}, pages = {1-4}, abstract = {This work presents the design and results of a Dual-Mode waveguide filter implemented with elliptic cavities and rectangular irises. A four-order elliptic filter responseis designed in X band, centered in 11.8 GHz and bandwidth of 100 MHz. The analysis is made by rigorous Mode-Matching with a basic building block based on the discontinuity between an elliptic and a rectangular waveguide. An experimental prototype is built and measured. Good agreement is obtained between theory and experimental data.}, url = {http://w3.iec.csic.es/ursi/articulos_barcelona_2004/articulos/ursi0115.pdf}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @article {1_CouplingmodelMOTL, title = {Estimation of the patch-array-coupling model through radiated-field measurements}, journal = {Microwave and Optical Technology Letters}, volume = {43}, number = {1}, year = {2004}, month = {Oct.}, pages = {59-65}, abstract = {In the design process of array antennas, coupling is one of the most important elements to be considered. The real feeding-radiated coefficients can be quite different from the theoretical ones because of this effect. In this paper, a characterization method is presented that allows each element to be matched from the array. All the parameters of the array-coupling model are obtained through the measurement of scattering parameters and radiation patterns. Two practical applications for a linear patch array are presented.}, keywords = {array, coupling, patch antenna, planar antenna}, issn = {0895-2477}, doi = {10.1002/mop.20375}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.20375/abstract}, author = {Fern{\'a}ndez, J M and J L Masa-Campos and Sierra-Casta{\~n}er, M and Castellanos, D and Sierra-P{\'e}rez, M} } @conference {04_CNES_Montejo-GaraiRuiz-CruzRebollarEtAl_Highpower-lowloss, title = {High power-low loss band pass rectangular waveguide H-plane filters with finite real frequency transmission zeros}, booktitle = {Proc. 2004 Int. Workshop on Microwave Filters CNES-ESA}, year = {2004}, month = {Sept.}, pages = {1-2}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M and Padilla-Cruz, M J and O{\~n}oro-Navarro A Hidalgo-Carpintero, I} } @conference {02_APS_Ruiz-CruzMontejo-GaraiRebollar_Characterisationofwaveguide, title = {Characterisation of waveguide discontinuities with finite wall conductivity}, booktitle = {Proc. 2002 IEEE Antennas and Propagation Society International Symposium}, volume = {4}, year = {2002}, month = {June}, pages = {428-431}, abstract = {In this paper, a procedure is proposed to evaluate the generalised scattering matrix of waveguide discontinuities with finite wall conductivity. This approach is applied to evaluate the insertion losses in several waveguide structures of Chebyshev bandpass filters. These numerical results are compared with those obtained with other numerical methods and with measurements, validating the proposed procedure.}, keywords = {band-pass filters, Chebyshev filters, electromagnetic wave scattering, finite wall conductivity, generalised scattering matrix, insertion losses, numerical methods, S-matrix theory, waveguide discontinuities, waveguide filters, waveguide theory Chebyshev bandpass filters}, issn = {0-7803-7330-8}, doi = {10.1109/APS.2002.1017013}, url = {http://ieeexplore.ieee.org/iel5/7931/21884/01017013.pdf?tp=\&isnumber=\&arnumber=1017013}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {01_ISS_Ruiz-CruzMontejo-GaraiRebollar_Somepropertiesof, title = {CAD of dual-mode filters with elliptical cavities}, booktitle = {Proc. 11th International Travelling Summer School on Microwaves and Lightwaves}, year = {2001}, month = {July}, pages = {11}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M} } @conference {01_EIEC_Montejo-GaraiRuiz-CruzRebollar_Comparacionentrediferentes, title = {Comparaci{\'o}n entre diferentes t{\'e}cnicas para el c{\'a}lculo de p{\'e}rdidas de inserci{\'o}n en filtros}, booktitle = {Proc. II Encuentro Ib{\'e}rico de Electromagnetismo Computacional (in Spanish)}, year = {2001}, month = {Dec.}, pages = {1}, abstract = {El c{\'a}lculo de p{\'e}rdidas de inserci{\'o}n debido a la utilizaci{\'o}n de conductores reales para dispositivos pasivos de microondas en general y filtros en particular es una cuesti{\'o}n de gran importancia no s{\'o}lo te{\'o}rica, sino tambi{\'e}n pr{\'a}ctica. En particular para filtros de aplicaciones espaciales, esta especificaci{\'o}n puede llegar a ser una de las complicadas de satisfacer obligando en muchos casos a utilizar modos resonantes distintos del fundamental [1]. En este trabajo se presenta un estudio comparativo entre diferentes t{\'e}cnicas para determinar las p{\'e}rdidas y su comparaci{\'o}n con medidas experimentales. Las diferentes t{\'e}cnicas empleadas en este trabajo para su comparaci{\'o}n son: a) aproximaci{\'o}n circuital, en la que se considera simplemente la atenuaci{\'o}n del modo de resonancia del filtro [2], b) M{\'e}todo de Adaptaci{\'o}n Modal considerando las p{\'e}rdidas en los obst{\'a}culos- discontinuidades que constituyen la estructura real del filtro [3]. En esta t{\'e}cnica se considera que se satisfacen las condiciones de Leontovich en las paredes de la discontinuidad para realizar su posterior caracterizaci{\'o}n mediante GSM. c) M{\'e}todo Adaptaci{\'o}n Modal Multipuerta, propuesto en este trabajo y que considera el obst{\'a}culo-discontinuidad como nuevas gu{\'\i}as rellenas de material conductor. Se caracteriza el obst{\'a}culo mediante la Matriz de Dispersi{\'o}n Generalizada Multimodo Multipuerta y por {\'u}ltimo, d) M{\'e}todo de Elementos Finitos, haciendo uso de software comercial [4] Los resultados te{\'o}ricos de las t{\'e}cnicas enumeradas han sido comparados con medidas de diferentes filtros paso banda trabajando en las bandas X, K y Ka, y dise{\~n}ados para diferentes equipos embarcados en sat{\'e}lites. La comparaci{\'o}n realizada conduce a resultados calificables de entre curiosos y extra{\~n}os, y por el momento sin una explicaci{\'o}n que pueda considerarse satisfactoria. Todo ello, corrobora parcialmente los resultados de [3] para otras geometr{\'\i}as.}, author = {Montejo-Garai, J R and J A Ruiz-Cruz and Rebollar, J M} }