@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 {12_URSIUSA_Leal-SevillanoRuiz-CruzMontejo-GaraiEtAl_DesignFiltersWband,
	title = {Design of waveguide filters at W-band by means of machining techniques},
	booktitle = {Proc. 2012 USNC/URSI National Radio Science Meeting},
	year = {2012},
	month = {July},
	pages = {1},
	abstract = {A common part of many microwave systems is the routing of the signal between the circuit devices performing the different functions of the system (frequency discrimination, power combining, frequency conversion, signal amplifying {\^a}{\texteuro}{\textbrokenbar}). The optimum configuration of these individual devices may lead to a system layout where the interfaces of the different blocks are not aligned or even are in different planes. Thus, the routing network must have waveguide transformers, bends, and twists to be able to accommodate the signal between the different blocks. These elements have a simple function, although a careful design may be required for broadband applications. Moreover, in satellite communications, mass and volume must be kept to a minimum and compactness is highly pursued. A possible solution in these cases is to integrate some of these functions in the routing network elements or even in the input/output of the components. In this work, several waveguide devices will be shown with integrated compact elements for waveguide matching and polarization rotation. Since different functions are integrated in the same device, transitions are avoided and the total length is reduced. Very compact structures for waveguide twists have been developed in Asao et al., "A compact 90-degree twist using novel ridged waveguide for integrated waveguide subsystems," Proc. 36th EuMC, 2006 and Kirilienko et al. {\^a}{\texteuro}{\oe}Compact 90{\^A}{\textordmasculine} Twist formed by a Double-Corner-cut Square Waveguide Section{\^a}{\texteuro}, IEEE TMTT, 2008). Other structures used here will be based on Ruiz-Cruz et al., {\^a}{\texteuro}{\oe}Multi-Section Bow-Tie Steps for Full-Band Waveguide Polarization Rotation{\^a}{\texteuro}, IEEE MWCL, July 2010. The design and evaluation of the different components will be addressed in the presentation, with devices in mixed E/H plane configuration, bends and transformers. When integrating different functions in the same device, some undesired resonances may appear in the structure. Therefore, accurate CAD tools are required for simulating the response and taking into account the mode excitations inside the structure. A precise fabrication is required for having good experimental results, which will be shown in the presentation.},
	author = {C A Leal-Sevillano and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M}
}
@conference {12_URSIESP_Leal-SevillanoMontejo-GaraiMaolongEtAl_DisenoWFilterSU8,
	title = {Dise{\~n}o de un Filtro de Respuesta El{\'\i}ptica en Banda W Fabricado Mediante la Tecnolog{\'\i}a de Foto Resina SU-8},
	booktitle = {Proc. 2012 Simposium Nacional URSI (in Spanish)},
	year = {2012},
	month = {Sept.},
	pages = {1-4},
	abstract = {Waveguide polarizers are essential devices in feeders for radio transmission systems with circular polarization. In this paper two different dual-band polarizers are designed and compared. The structure of both polarizers is based on the classical corrugated rectangular waveguide. This structure can be analyzed very efficiently like an H-plane and an E-plane problem. The Mode-Matching technique, in combination with global search algorithms, is used for the full-wave analysis and optimization of the polarizers. In the first polarizer, the height of the corrugations is designed according to a taper-type shape. For the second polarizer, no restrictions in the height of the corrugations are imposed and all the dimensions are optimized. The performance of both polarizers is compared, showing certain improvement in terms of polarization purity for the second one.},
	author = {C A Leal-Sevillano and Montejo-Garai, J R and Ke Maolong and Lancaster, M. J and J A Ruiz-Cruz and Rebollar, J M}
}
@conference {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}
}
@conference {10_URSIUSA_Ruiz-CruzMontejo-GaraiRebollarEtAl_DesignandEvaluation,
	title = {Design and Evaluation of a Ka-band Antenna Feeder with Broadband Dual-Polarization Performance},
	booktitle = {Proc. 2010 USNC/URSI National Radio Science Meeting},
	year = {2010},
	month = {July},
	pages = {14},
	abstract = {New telecommunication satellite services have increased the demand on antenna feed systems with more stringent requirements in both the electrical and mechanical parts. In fact, one of the main goals for RF hardware onboard spacecrafts is the reduction of size and volume, at the expense of more complex design of the components. Thus, the use of a single antenna for several frequency bands is very common and the antenna feeder has to separate (or to combine, depending on the transmission/reception scheme) the different signals involved in the system. The frequency separation is carried out with multiplexers. Moreover, in many systems, dual polarization is used in order to have a more efficient use of the electromagnetic spectrum, using ortho-mode transducers (OMTs) for the polarization discrimination. In a very common scheme, the OMTs are attached by the common port to the antenna and by the other dedicated ports to the diplexers. This is the type of antenna feed network developed in this communication, for two Ka sub-bands centered in 21.7 and 28.7 GHz, respectively, with 4\% and 6\% fractional bandwidth, approximately. The developed OMT is based on a double symmetry junction (Boifot et al, "Simple and broadband orthomode transducer," IEE Proc. H Microw., Ant. and Prop., vol. 137, no. 6, pp. 396-400, Dec 1990.). In its simpler version, it has a metallic septum and full height vertical pins to match the vertical polarization. The effect of these pins will be studied. The routing network is another important part of the device, with a great impact on the size of the component and in the manufacturing method (see for instance Ruiz-Cruz et al. "Full-wave modeling and optimization of Boifot junction ortho-mode transducers," Int. J RFMiCAE, vol. 18, no. 4, pp. 303-313, July 2008). These different alternatives will be studied in the presentation. The diplexers are based on E-plane bifurcations with well-known low-pass and high-pass filters. The dimensions of the waveguides connecting the ortho-mode transducer and the waveguide diplexers are non-standard, in order to reduce the total feeder length, since transitions to standard waveguides are avoided. The diplexer is manufactured without any tuning element. Therefore, accurate CAD tools are required for the design, along with a precisely controlled fabrication.The design and evaluation of the different components will be addressed in the presentation, showing the experimental measurements, the expected simulated responses and the critical points found in the development of the antenna feeder.},
	author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Mart{\i}n, M J and Garc{\'\i}a, V}
}
@conference {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}
}
@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}
}
@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 {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 {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}
}
