@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 {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} } @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} }