@article {14_IEEETMTT_Leal-SevillanoYingaTaoLancasterEtAl_MicromachinedDual-BandOrthomode,
	title = {A Micromachined Dual-Band Orthomode Transducer},
	journal = {IEEE Transactions on Microwave Theory and Techniques},
	volume = {62},
	number = {1},
	year = {2014},
	month = {January},
	pages = {55-63},
	abstract = {In this paper, an orthomode transducer (OMT) for dual-band operation and optimized for stacked micromachined layers implementation is presented. The proposed design avoids the use of septums, irises, pins, or small features and minimizes the number of equal-thickness micromachined layers required. In this way, the micromachining fabrication is simplified, making the proposed design a very attractive candidate for high frequency applications and for low-cost batch production. A W-band dual-band design (one different polarization in each frequency band) with more than 10\% fractional bandwidth for each band and 30\% separation between bands is presented. In addition, proper routing and layered bends are designed for an optimum standard interfacing with the same orientation of the input/output ports. Two OMTs in a back-to-back configuration are fabricated using a thick SU-8 photo-resist micromachining process. A total of six stacked SU-8 layers, all of them with the same thickness of 635 micrometers, are used. The experimental results are coherent with the tolerance and misalignment of the process, validating the proposed novel OMT design.},
	issn = {0018-9480},
	doi = {10.1109/TMTT.2013.2292611},
	url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6678791},
	author = {C A Leal-Sevillano and YingaTao, T and Lancaster, M J and J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M}
}
@article {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}
}
@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}
}
@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 {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 {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}
}
