@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 {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_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}
}
@article {15_TAP_Corcoles_RLAQCQP,
	title = {Reactively Loaded Array Pattern Synthesis as a Quadratically Constrained Quadratic Program},
	journal = {Antennas and Propagation, IEEE Transactions on},
	volume = {63},
	number = {11},
	year = {2015},
	month = {Nov},
	pages = {5219-5224},
	abstract = {The pattern synthesis problem of maximizing the gain at a scanning direction subject to a maximum sidelobe level for a reactively loaded antenna array is formulated as a quadratically constrained quadratic program (QCQP). This formulation is derived from the scattering matrix and the active element patterns of the array considering both fed and loaded antennas as ports. Since the resulting QCQP is nonconvex, the loads are computed from the solution of the semidefinite relaxation of the problem by forcing the feasibility of the constraints in a meaningful physical sense, i.e., by explicitly imposing passive or purely reactive loads. Numerical results of dipole arrays with various configurations are presented and compared to previous works.},
	keywords = {Antenna arrays, Antenna pattern synthesis, antenna radiation patterns, Arrays, dipole antenna arrays, dipole array, Gain, Loaded antennas, optimization, Optimization methods, Ports (Computers), QCQP, quadratic programming, quadratically constrained quadratic program, reactively loaded array pattern synthesis, reconfigurable antennas, S-matrix theory, scattering matrix, semidefinite (SD) programming, semidefinite programming, semidefinite relaxation, sidelobe level, sidelobe supression},
	issn = {0018-926X},
	doi = {10.1109/TAP.2015.2478487},
	author = {J C{\'o}rcoles}
}
@conference {15_IEEEAPS_ImplantSOCP,
	title = {RF shimming with implant safety control in MRI transmit arrays through second-order cone programming},
	booktitle = {IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, AP-S/URSI 2015},
	year = {2015},
	month = {July},
	author = {J C{\'o}rcoles and E Zastrow and N. Kuster}
}
@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 {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 {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 {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}
}
@conference {06_IMS_ZhangRuiz-CruzZaki_RidgeWaveguideCoupled,
	title = {Ridge Waveguide Coupled Stripline Resonator Filters and Multiplexers},
	booktitle = {2006 IEEE MTT-S International Microwave Symposium Digest},
	year = {2006},
	month = {June},
	pages = {681-684},
	abstract = {Stripline resonator bandpass filters with evanescent-mode coupling sections by ridge waveguides are introduced in this paper. Such filters have very compact cross sections, which makes them suitable choices for some integrated systems having cross section constraints. Low Temperature Co-fired Ceramic (LTCC) technology can be employed to build such filters for PCB systems. It is also possible to manufacture them in air-filled metallic structures. Two filter design examples by Mode Matching Method (MMM) are given in this paper. Stepped impedance line resonators are used in one example to improve the spurious. The presented filters can also be applied for multiplexer applications using stripline junctions. One diplexer design example for LTCC application is presented to show the feasibility.},
	issn = {0149-645X},
	doi = {10.1109/MWSYM.2006.249724},
	url = {http://ieeexplore.ieee.org/iel5/4014788/4014789/04014995.pdf?tp=\&isnumber=\&arnumber=4014995},
	author = {Zhang, Y and J A Ruiz-Cruz and Zaki, K A}
}
@conference {06_IMS_ZhangRuiz-CruzZaki_RidgeWaveguideDivider,
	title = {Ridge Waveguide Divider Junctions for Wide-Band Multiplexer Applications},
	booktitle = {2006 IEEE MTT-S International Microwave Symposium Digest},
	year = {2006},
	month = {June},
	pages = {1225-1228},
	abstract = {Ridge waveguide divider junctions are introduced and applied to wide-band multiplexer applications. A rigorous analysis and optimization process by mode matching method (MMM) is employed to design the junctions that yield low reflection coefficient in common port and almost equal transmission coefficients in the other two ports over a wide frequency band. Two design examples of wide-band diplexer and triplexer using such junctions are presented. All the components involved in the diplexer/triplexer designs are rigorously modeled and cascaded by MMM. Optimization procedures by MMM are also applied in these two designs to improve the performance. Multiplexers using such junctions can be built in either metallic form or low-temperature co-fired ceramic (LTCC) technology},
	keywords = {low-temperature co-fired ceramics, mode matching, mode matching method, multiplexing equipment, ridge waveguide divider junctions, ridge waveguides, waveguide junctionsLTCC technology, wide-band diplexer, wide-band multiplexer applications, wide-band triplexer},
	issn = {0149-645X},
	doi = {10.1109/MWSYM.2006.249431},
	url = {http://ieeexplore.ieee.org/iel5/4014788/4014789/04015143.pdf?tp=\&isnumber=\&arnumber=4015143},
	author = {Zhang, Y and J A Ruiz-Cruz and Zaki, K A}
}
@conference {06_EuMC_Ruiz-CruzZhangFahmiEtAl_RidgeWaveguideElliptic,
	title = {Ridge Waveguide Elliptic Filters in Narrow-Wall Canonical Configuration},
	booktitle = {Proc. 36th European Microwave Conference},
	year = {2006},
	month = {Sept.},
	pages = {1080-1082},
	abstract = {A new canonical ridge waveguide structure is proposed to design elliptic filter responses. The non-adjacent cavities are coupled by windows situated at the common narrow-wall of the ridge waveguide enclosures. This new configuration provides positive and negative cross couplings using evanescent rectangular waveguides and metallic strips, respectively. The full-wave analysis of the structure is carried out by a rigorous mode matching method. The design is based on circuit synthesis and full-wave optimization. Finally, the proposed structure is elucidated with the design of a four-pole filter and it is validated with the commercial HFSS software},
	keywords = {circuit synthesis, elliptic filters, four-pole filter, full-wave optimization, metallic strips, mode matching, mode matching method, narrow-wall canonical configuration, negative cross couplings, network synthesis, nonadjacent cavities, positive cross couplings, rectangular waveguides, ridge waveguide elliptic filters, ridge waveguides, waveguide filtersHFSS software},
	issn = {2-9600551-6-0},
	doi = {10.1109/EUMC.2006.281121},
	url = {http://ieeexplore.ieee.org/iel5/4057701/4057702/04058011.pdf?tp=\&isnumber=\&arnumber=4058011},
	author = {J A Ruiz-Cruz and Zhang, Y and Fahmi, M M and Zaki, K A}
}
@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_IMS_Ruiz-CruzZhangZakiEtAl_Ridgewaveguidebranch-line,
	title = {Ridge waveguide branch-line directional couplers for wideband applications and LTCC technology},
	booktitle = {2005 IEEE MTT-S International Microwave Symposium Digest},
	year = {2005},
	month = {June},
	pages = {1219-1222},
	abstract = {A new branch-line directional coupler is proposed for achieving wide bandwidth. The device is implemented in ridge waveguide to exploit its wide monomode band. It can be physically realized either in empty ridge waveguide or in LTCC for integration in a chip module. Two prototypes of two and five branches are designed following a systematic procedure. An appropriate equivalent circuit provides initial dimensions and the desired optimum response is obtained by means of a final full-wave optimization based on the rigorous and efficient mode-matching method. The results are verified with the finite element method of the HFSS software and a prototype will be manufactured for testing},
	keywords = {branch-line directional couplers, chip module integration, directional couplers, equivalent circuits, finite element analysis, finite element method, full-wave optimization, mode matching, mode-matching method, optimisation, ridge waveguides, ridge waveguidesLTCC technology, wide monomode band},
	issn = {01490-645X},
	doi = {10.1109/MWSYM.2005.1516896},
	url = {http://ieeexplore.ieee.org/iel5/10171/32491/01516896.pdf?tp=\&isnumber=\&arnumber=1516896},
	author = {J A Ruiz-Cruz and Zhang, Y and Zaki, K A and Piloto, A J and Rebollar, J M}
}
