@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 {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 {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}
}
@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}
}
