@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}
}
@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 {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_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_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 {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}
}
@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_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 {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}
}
@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}
}
@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_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_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.}
}
@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}
}
@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}
}
@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}
}
@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}
}
@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 {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}
}
@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_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 {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}
}
@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 {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_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}
}
@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}
}
@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}
}
@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}
}
@conference {05_URSIUSA_Ruiz-CruzGentiliRebollar_Analysisofwaveguide,
	title = {Analysis of waveguide junctions by the Boundary Contour Mode-Matching Method with segmented regions},
	booktitle = {Proc. 2005 USNC/URSI National Radio Science Meeting},
	year = {2005},
	month = {July},
	pages = {1},
	abstract = {The Boundary Contour Mode-Matching method (BCMM) allows the analysis of homogeneous waveguide junctions. The basic building block of this method is an E- or H-plane structure with arbitrary contour, excited by several rectangular waveguides (the ports). The electromagnetic field inside the junction is expanded in basic solutions of the Maxwell equations as, for instance, circular waves (J.M Reiter et al., IEEE TMTT, 796-801, April 1995). In the ports, a modal series is used. The boundary conditions are imposed by means of a Galerkin method that relates the two different field expansions and leads to the Generalized Scattering Matrix (GSM) of the junction. Different improvements have been made to the method as (R. H MacPhie et al., IEEE TMTT, 232-237, Feb. 1999) and (J A Ruiz-Cruz et. al, IEE Microw. Ant. and Prop., 332-338, Oct. 2003), oriented to speed up the computation of the Galerkin method matrices. The technique has been successfully applied to different types of structures as arbitrary bends (circular, mitered,..), cavities with rounded corners and Y-junctions. In comparison with other quasi-analytical methods, this technique does not require to characterize the eigenfunctions of the junction. However, when ridged zones appear in the contour of the problem (for instance a bend with a matching element), the BCMM linear system is not well conditioned and convergent results are difficult to achieve. The aim of this contribution is to overcome the limitations of the ridged zones by means of segmenting the junction under analysis in regions which can be successfully analyzed by the BCMM. The trivial case is when the problem can be divided in two or more basic building blocks linked by waveguide ports, which can be solved by cascading the GSM of each separate block. This contribution will focus on structures, like a T-junction with an inner ridge zone, where the trivial case can not be applied and the segmented regions must be considered all together in the field-matching procedure. The formulation will use three type of expansions: a) a dedicated expansion for representing the electromagnetic field in each segmented region, b) the modal series in the ports, c) a series to describe the electric field at the interface between regions. All the amplitudes of the expansions are linked by the boundary conditions at the interfaces. A Galerkin method will provide the GSM of the junction. The results of the investigated problems will be shown in the oral presentation.},
	author = {J A Ruiz-Cruz and Gentili, G G and Rebollar, J M}
}
@article {05_IEEETMTT_Ruiz-CruzSabbaghZakiEtAl_Canonicalridgewaveguide,
	title = {Canonical ridge waveguide filters in LTCC or metallic resonators},
	journal = {IEEE Transactions on Microwave Theory and Techniques},
	volume = {53},
	number = {1},
	year = {2005},
	month = {Jan.},
	pages = {174-182},
	abstract = {A new physical realization of an elliptic function filter response is proposed for achieving compact size, wide bandwidth, wide spurious free stopband and high-selectivity performance. The filter configuration can be implemented in conventional waveguide technology or embedded in a multilayer low-temperature co-fired ceramic structure for integration with other circuitry in a chip module. The filter is analyzed using rigorous mode matching. To validate the concept, prototypes of four- and six-cavity elliptic filters are designed following a systematic procedure. Approximate synthesis is used to obtain initial dimensions of the filter and the desired optimum response is obtained by means of a final full-wave optimization. The results are verified with other numerical methods and with the measurements of a fourth-order waveguide filter.},
	keywords = {band-pass filters, canonical ridge waveguide filters, cavity resonator filters, ceramics, chip module, circuit optimisation, elliptic filters, elliptic function filter response, four cavity elliptic filters design, fourth order waveguide filter, full-wave optimization, metallic resonators, microwave filters, mode matching, multilayer low temperature cofired ceramic structure, multilayers, numerical methods, prototypes, resonators, ridge waveguides, six cavity elliptic filters design, spurious free stopband filter, waveguide filters band pass filters, waveguide technology},
	issn = {0018-9480},
	doi = {10.1109/TMTT.2004.839324},
	url = {http://ieeexplore.ieee.org/iel5/22/30125/01381687.pdf?tp=\&arnumber=1381687\&isnumber=30125},
	author = {J A Ruiz-Cruz and El Sabbagh, M A and Zaki, K A and Rebollar, J M and Zhang, Y}
}
@article {05_IJRFMiCAE_Ruiz-CruzRebollar_Eigenmodesofwaveguides,
	title = {Eigenmodes of waveguides using a boundary contour mode-matching method with an FFT scheme},
	journal = {International Journal of RF and Microwave Computer-Aided Engineering},
	volume = {15},
	number = {3},
	year = {2005},
	month = {May},
	pages = {286-295},
	abstract = {An efficient boundary contour mode-matching method (BCMM) is applied to the analysis of hollow waveguides whose cross section is enclosed by curved and planar boundaries. The TE and TM modes are expressed in terms of circular waves whose cutoff wavenumber and amplitudes are the unknowns of the problem.. The boundary conditions are imposed with a new line-integral extended over the closed contour. The weighting functions introduced and the use of the transformations between plane and circular waves avoid the conventional numerical integrations. In addition, the conversion between the different field representations is accelerated due to the use of the fast Fourier transform (FFT). Finally, the numerical results are shown as a comparison of our approach with other numerical methods},
	keywords = {boundary contour mode-matching method, eigenmodes, FFT},
	issn = {1096-4290},
	doi = {10.1002/mmce.20082},
	url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/110429941/PDFSTART},
	author = {J A Ruiz-Cruz and Rebollar, J 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}
}
@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}
}
@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}
}
@conference {04_IMS_Ruiz-CruzElZakiEtAl_Full-wavedesignof,
	title = {Full-wave design of canonical ridge waveguide filters},
	booktitle = {2004 IEEE MTT-S International Microwave Symposium Digest},
	volume = {2},
	year = {2004},
	month = {June},
	pages = {603-606},
	abstract = {A new physical realization of an elliptic function filter response is proposed for achieving compact size, wide bandwidth, wide spurious free stop band and high selectivity performance. The canonical ridge waveguide filter configuration is analyzed using rigorous mode-matching. To validate the concept, a prototype that realizes the coupling matrix of a canonical four cavity elliptic filter is designed following a systematic procedure. Approximate synthesis is used to obtain initial dimensions of the filter and the desired optimum response is obtained by means of a final full-wave optimization. The results are verified with other numerical method and a prototype will be built for testing.},
	keywords = {band-pass filters, coupling matrix, elliptic filters, elliptic function filter, filtering theory, full-wave design, full-wave optimization, mode matching, mode-matching, waveguide filters canonical ridge waveguide filters, wide bandwidth, wide spurious free stop band},
	issn = {0149-645X},
	doi = {10.1109/MWSYM.2004.1336056},
	url = {http://ieeexplore.ieee.org/iel5/9277/29472/01336056.pdf?tp=\&isnumber=\&arnumber=1336056},
	author = {J A Ruiz-Cruz and El Sabbagh, M A and Zaki, K A and Rebollar, J 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 {04_URSIUSA_Ruiz-CruzRebollar_Interpretationofresonance,
	title = {Interpretation of resonance at inclined multi-aperture rectangular iris with arbitrary locations in rectangular waveguide},
	booktitle = {Proc. 2004 USNC/URSI National Radio Science Meeting},
	year = {2004},
	month = {June},
	pages = {45},
	abstract = {Alternative interpretation of resonance of two-apertures iris in terms of the excitation of a TEM field of the structure was proposed by the authors of this contribution at (2003 USNC/URSI Symp., 226). This alternative interpretation proposed is very simple and useful to design bandpass filters with some improved stopband attenuation as it has been proposed at (L. Mospan, VIII Int. Conf. MMET, 503-505, 2000) and more recently at (A A Kirilenko, MSMW{\textquoteright}2001 Symposium, 690-692). Moreover, this interpretation could be useful to prevent some spurious resonances that arise at some rectangular waveguide devices, therefore helping the designer to improve their electrical performances. In this paper, with the main aim to confirm our alternative interpretation of the resonance in terms of a TEM field excitation, we consider a modification of the previous ones: a new iris structure composed by inclined multi-aperture rectangulars. The single inclined aperture was analytically analysed at (R Yang and A S Omar, IEEE Trans. MTT- 41, 1461-1463), and the inclined multi-aperture iris by means of the Generalised Scattering Matrix of generalised 2-port discontinuity concept (J M Rebollar, IEE Proc., 1-7, 1988). The analysis of the scattering parameters joint to a visualisation of the electromagnetic field vectors in the structure are employed to discuss and validate the interpretation of the resonance. As a first example, an iris with only two rectangular apertures is considered. The excitation of the only one TEM-resonance is analysed vs. the inclination between the apertures and the waveguide walls. A second example of an iris with three rectangular apertures is analysed too. The excitation of the two TEM-resonances of this iris it is also studied. Quantitative results for the resonance frequency positions and field plots at these frequency points for the above mentioned examples will be presented. The obtained results for the inclined two/three-apertures irises validate the interpretation of resonances in terms of the excited TEM fields.},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@conference {04_APS_Ruiz-CruzZakiRebollar_Mode-matchinganalysisof,
	title = {Mode-matching analysis of a coaxial-to-stripline discontinuity applied to the modeling of a coaxial probe},
	booktitle = {Proc. 2004 IEEE Antennas and Propagation Society International Symposium},
	volume = {2},
	year = {2004},
	month = {June},
	pages = {2139-2142},
	abstract = {The paper presents the analysis of the discontinuity between a coaxial and a generalized stripline waveguide and its application to the characterization of a probe inside a rectangular waveguide. The probe is modeled by a stripline whose inner conductor is stepped. For thin probes, just a reduced number of sections is needed and its characterization can be obtained very efficiently. The mode-matching technique is employed for analyzing the basic discontinuity, and the inner cross products between the modes are computed by means of the Bessel-Fourier series, reducing the computation time with respect to a pure numerical integration. The simulation results are compared with those obtained by other numerical techniques.},
	keywords = {coaxial probe modeling, coaxial waveguide, coaxial waveguides, coaxial-to-stripline discontinuity, computation time, Fourier series, mode matching, mode-matching analysis, numerical integration, rectangular waveguide, strip line discontinuities Bessel-Fourier series, stripline waveguide},
	issn = {0-7803-8302-8},
	doi = {10.1109/APS.2004.1330633},
	url = {http://ieeexplore.ieee.org/iel5/9253/29356/01330633.pdf?tp=\&isnumber=\&arnumber=1330633},
	author = {J A Ruiz-Cruz and Zaki, K A and Rebollar, J M}
}
@conference {03_URSIUSA_Ruiz-CruzRebollar_alternativeinterpretationof,
	title = {An alternative interpretation of resonance of two-aperture irises in rectangular waveguide},
	booktitle = {Proc. 2003 USNC/URSI National Radio Science Meeting},
	year = {2003},
	month = {June},
	pages = {226},
	abstract = {The multiple aperture irises present some interest for the design of low cost bandpass filters with some improved stopband attenuation. Approximate estimation of the rejection resonance position based on circuit theory modelling, joint to a circuital interpretation was proposed by (N G Paterson, Electron Lett, 592-594, 1976). An accurate electromagnetic estimation of such rejection resonance was presented at (R. Yang, IEEE Trans. MTT, 1369-1373, 1993). An interpretation of the nature of this resonance for two-aperture in terms of a pair of natural oscillations in the open-waveguide type structure was presented at (A A Kirilenko, IEEE Trans. MTT, 1419-1421, 2000). Application for a new type of bandstop filter with three-aperture irises was presented at (L. Mospan, VIII Int. Conf. MMET, 503-505, 2000). In this paper, we present and alternative interpretation of resonance of two-apertures iris in terms of the excitation of the TEM mode of the structure. The mentioned TEM mode considers the strip between the two irises as one conductor and the wide walls of rectangular waveguide as the second conductor of the transmission line. This transmission line is short-circuited at both ends and its total length is approximately the wide of the iris. An accurate fullwave electromagnetic simulation joint to a visualisation of the electric and magnetic field vectors in the structure are employed to discuss and validate this interpretation. We consider that this alternative interpretation is very simple and useful from the designer point of view, specially to prevent spurious resonance in a variety of devices that use the mentioned multi-aperture iris structure. Quantitative results of resonance frequency positions and field plots at these frequency points for different structures will be presented.},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@conference {03_APS_Ruiz-CruzRebollar_BCMManalysisof,
	title = {BCMM analysis of short-slot waveguide couplers with an FFT algorithm},
	booktitle = {Proc. 2003 IEEE Antennas and Propagation Society International Symposium},
	volume = {2},
	year = {2003},
	month = {June},
	pages = {1193-1196},
	abstract = {In this contribution, the analysis of the short-slot directional waveguide couplers by means of a boundary contour mode-matching method (BCMM method) is presented. A new formulation is proposed that uses the FFT to improve the efficiency of the technique. The advantages and difficulties of the application of the BCMM for solving this kind of structure are also discussed. Simulated results are compared with those obtained by other numerical techniques. Experimental measurements are shown.},
	keywords = {BCMM method, boundary contour mode-matching method, boundary-value problems, fast Fourier transforms, FFT algorithm, measurements, mode matching, numerical techniques, short-slot directional waveguide couplers, short-slot waveguide couplers, slot lines, waveguide couplers BCMM analysis},
	issn = {0-7803-7846-6},
	doi = {10.1109/APS.2003.1219449},
	url = {http://ieeexplore.ieee.org/iel5/8636/27400/01219449.pdf?tp=\&isnumber=\&arnumber=1219449},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@conference {03_URSIESP_Ruiz-CruzRebollar_Calculodemodos,
	title = {Calculo de modos en guias de onda mediante un metodo BCMM basado en el uso de la FFT},
	booktitle = {Proc. 2003 Simposium Nacional URSI (in Spanish)},
	year = {2003},
	month = {Sept.},
	pages = {1-4},
	abstract = {The TE and TM modes of a homogeneous cylindrical waveguide are calculated by an efficient Boundary Contour Mode-Matching Method (BCMM). The electromagnetic fields are described with a series of circular cylindrical waves whose cutoff wavenumber and amplitudes are obtained by imposing the boundary conditions. The field-matching procedure is facilitated by a new line integral extendedover the closed contour and the use of the transformation between plane and circular waves. The conversion betweenthe different field representations is carried out by means of a Fast Fourier Transform (FFT), resulting in a very efficient method.},
	url = {http://w3.iec.csic.es/ursi/articulos_coruna_2003/actas_pdf/SESION\%201/S1.\%20Aula\%202.2/1454\%20-\%20CALCULO.pdf},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@article {03_IEEPMAP_Ruiz-CruzEstebanRebollar_Efficientboundarycontour,
	title = {Efficient boundary contour mode-matching method of H- and E-plane junctions by fast Fourier transform algorithm},
	journal = {IEE Proceedings Microwaves, Antennas and Propagation},
	volume = {150},
	number = {5},
	year = {2003},
	month = {Oct.},
	pages = {332-338},
	abstract = {An efficient boundary contour mode-matching method (BCMM) is applied to the analysis of H- and E-plane junctions with planar and circular boundaries. The proposed approach is based on the use of the fast Fourier transform (FFT) to improve an analytical BCMM method. The electromagnetic field inside the structure is expressed in terms of circular waves, whereas in the rectangular ports a modal expansion is used. Depending on the shape of the contour, the original field expansion is rewritten in plane waves or in other sets of circular waves, replacing the conventional numerical integrations by a new, more suitable procedure. Finally, the transformation between the different expansions is carried out by means of the FFT, increasing notably the efficiency of the method. The presented formulation is verified by comparing simulated results with those obtained by other numerical techniques},
	keywords = {boundary contour mode-matching method, circular boundary, circular waves, coupling integrals, efficient method, electromagnetic field, electromagnetic fields, fast Fourier transform algorithm, fast Fourier transforms, FFT algorithm, field expansion, fullwave analysis, H-plane junctions, junction matrix, mode matching, planar boundary, plane waves, simulated results, waveguide junctions E-plane junctions},
	issn = {1350-2417},
	doi = {10.1049/ip-map:20030775},
	url = {http://ieeexplore.ieee.org/iel5/2196/28221/01262347.pdf?tp=\&isnumber=\&arnumber=1262347},
	author = {J A Ruiz-Cruz and Esteban,J and Rebollar, J M}
}
@conference {03_EIEC_Ruiz-CruzRebollar_Interpretaciondelas,
	title = {Interpretaci{\'o}n de las resonancias de irises multiapertura y su aplicaci{\'o}n al dise{\~n}o de filtros},
	booktitle = {Proc. III Encuentro Ib{\'e}rico de Electromagnetismo Computacional (in Spanish)},
	year = {2003},
	month = {Dec.},
	pages = {1-4},
	abstract = {La utilizaci{\'o}n de irises multiapetura para el dise{\~n}o de filtros paso banda presenta inter{\'e}s tanto por su bajo coste y reducido volumen como por la posibilidad de obtener mejores prestaciones el{\'e}ctricas en particular consiguiendo una mayor atenuaci{\'o}n fuera de la banda de paso. Diferentes aproximaciones se han venido realizando para predecir las resonancias producidas por estos elementos, desde las m{\'a}s cl{\'a}sicas y secillas aproximaciones circuitales [1], hasta las m{\'a}s precisas y recientes caracterizaciones electromagn{\'e}ticas de onda completa [2]. Adem{\'a}s de la caracterizaci{\'o}n precisa de estas resonancias, resulta de inter{\'e}s poseer una interpretaci{\'o}n f{\'\i}sica de las mismas, tanto por poseer un conocimiento m{\'a}s profundo de las mismas, como por la ayuda que pueda presentar al dise{\~n}o de dispositivos. En esta direcci{\'o}n han aparecido dos trabajos [3] y [4] en los que se interpretan las resonancias en t{\'e}rminos de "oscilaciones naturales" en la estructura abierta as{\'\i} como una generalizaci{\'o}n de dichos irises multiapertura para el dise{\~n}o de filtros. En esta contribuci{\'o}n, se presenta una interpretaci{\'o}n alternativa de las resonancias de los irises multiapertura en t{\'e}rminos de la excitaci{\'o}n de campos de tipo TEM que pueden aparecer en la estructura. En el caso m{\'a}s sencillo de un iris con dos aperturas, el campo tipo TEM considerado viene soportado por dos conductores, que en este caso ser{\'\i}an el strip existente entre las dos aperturas del iris y las propias paredes de la guia. Esta "l{\'\i}nea de transmisi{\'o}n" se encontrar{\'\i}a cortocircuitada en sus extremos y por tanto su longitud total se corresponder{\'\i}a con el ancho de las aperturas. Nos encontramos por tanto con una l{\'\i}nea de transmisi{\'o}n cortocircuitada que deber{\'\i}a presentar una resonancia a la frecuencia en que su longitud sea lambda/2. Una caracterizaci{\'o}n precisa, un estudio de las excitaciones de dichos campos resonantes, as{\'\i} como una visualizaci{\'o}n de los mismos servir{\'a} para confirmar la validez de la interprestaci{\'o}n que se propone en esta contribuci{\'o}n. Se presentar{\'a} un amplio abanico de resultados para validar la interpretaci{\'o}n propuesta. Esta sencilla interpretaci{\'o}n de las resonancias puede resultar de gran utilidad tanto a la hora de utilizarlas para el dise{\~n}o de filtros, como para impedir la aparic{\'o}n de esp{\'u}rios en otros dispositivos en gu{\'\i}a.},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@conference {02_URSIESP_Ruiz-CruzRebollar_Analisisdeuniones,
	title = {An{\'a}lisis de uniones en gu{\'\i}a de onda plano E y H mediante el m{\'e}todo BCMM y el uso de la FFT},
	booktitle = {Proc. 2002 Simposium Nacional URSI (in Spanish)},
	year = {2002},
	month = {Sept.},
	pages = {519-520},
	abstract = {The Boundary Contour Mode-Matching Method (BCMM) is applied to the analysis of H- and E- plane junctions with planar and circular boundaries. The proposed approach is based on the use of the Fast Fourier Transform (FFT) to improve an analytical BCMM method, increasing notably the efficiency of the technique. The presented formulation is verified by comparing simulated results with those obtained by other numerical techniques.},
	url = {http://w3.iec.csic.es/ursi/articulos_alcalahenares_2002/sesiones/sesion6.pdf},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@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}
}
@conference {01_URSIESP_Ruiz-CruzRebollar_Propiedadesdela,
	title = {Propiedades de la matriz de dispersi{\'o}n generalizada de uniones y discontinuidades en gu{\'\i}a de onda},
	booktitle = {Proc. 2001 Simposium Nacional URSI (in Spanish)},
	year = {2001},
	month = {Sept.},
	pages = {9-10},
	abstract = {The Generalized Scattering Matrix (GSM) is an usual way to characterize a waveguide junction. Regardless of the geometry and the technique used to calculate it, the GSM has some properties that are slightly different from the circuital ones due to the presence of evanescent modes. In this paper theseproperties are reviewed and its relation with the GSM of a transversal discontinuity obtained by Mode-Matching (MM) is investigated. In this particular case, the properties can never be used to check that the analysis has been carried out rightly.},
	url = {http://w3.iec.csic.es/ursi/articulos_villaviciosaodon_2001/articulos/178.pdf},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@conference {00_URSIESP_Ruiz-CruzRebollar_CADdeanalisis,
	title = {CAD de an{\'a}lisis de discontinuidades entre gu{\'\i}as el{\'\i}pticas y rectangulares},
	booktitle = {Proc. 2000 Simposium Nacional URSI (in Spanish)},
	year = {2000},
	month = {Sept.},
	pages = {91-92},
	abstract = {A software tool has been developed in order to analyse microwave devices in which elliptical waveguides are present. The numerical technique employed is the Mode-Matching method, which requires knowing the modal spectrum of the elliptical guide. A set of discontinuities between rectangular, circular, and elliptical waveguides is studied in order to validate the computer codes.},
	url = {http://w3.iec.csic.es/ursi/articulos_zaragoza_2000/ursi2000/trabajos/cm0267.pdf},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
@conference {00_EIEC_RebollarRuiz-Cruz_Propiedadesdela,
	title = {Propiedades de la matriz de dispersi{\'o}n generalizada de discontinuidades y uniones en medios de transmisi{\'o}n},
	booktitle = {Proc. I Encuentro Ib{\'e}rico de Electromagnetismo Computacional (in Spanish)},
	year = {2000},
	month = {July},
	pages = {11},
	author = {Rebollar, J M and J A Ruiz-Cruz}
}
@conference {00_MMS_Ruiz-CruzRebollar_Somepropertiesof,
	title = {Some properties of generalized matrices and their application to the Mode-Matching technique},
	booktitle = {Proc. 2000 International Mediterranean Microwave Symp.},
	year = {2000},
	month = {May},
	pages = {62-65},
	author = {J A Ruiz-Cruz and Rebollar, J M}
}
