@article {15_TAP_RubioIzqdoCorcoles_ModalNetworkMIMO, title = {Mutual Coupling Compensation Matrices for Transmitting and Receiving Arrays}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {63}, number = {2}, year = {2015}, month = {Feb}, pages = {839-843}, abstract = {A general method to obtain a matrix which allows the compensation of mutual coupling effects in transmitting arrays for the total field in all directions is introduced. This method is independent of the numerical method used in the analysis and it can include the effect of the antenna platform. The starting point can be the active element patterns or the spherical mode expansion from spherical near-field antenna measurements. Additionally, the spherical mode expansion is also used to find a matrix which allows the compensation of mutual coupling effects in receiving arrays. Through this theory, a simple relation between the compensation matrices of the transmitting and the receiving arrays is found. As a consequence, the scattering matrix of a circuit that allows the simultaneous compensation of mutual coupling effects for the transmission and the reception problem can be easily defined. Finally, it will be shown how the capabilities of the compensation in all directions depend strongly on the array element.}, keywords = {Active element pattern, antenna array, Antenna arrays, Antenna measurements, antenna radiation patterns, finite element analysis, Mutual coupling, mutual coupling compensation, spherical mode expansion, transmitting antennas, Vectors}, issn = {0018-926X}, doi = {10.1109/TAP.2014.2382691}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6987253}, author = {Rubio, J and Izquierdo, J F and J C{\'o}rcoles} } @article {09_TAP_Corcoles_FourierSynthesis, title = {Fourier Synthesis of Linear Arrays Based on the Generalized Scattering Matrix and Spherical Modes}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {57}, number = {7}, year = {2009}, month = {July}, pages = {1944-1951}, abstract = {This paper presents a novel, simple pattern synthesis procedure for linear equispaced arrays which can be characterized by a generalized scattering matrix (GSM) and whose radiated field can be expressed as a weighted sum of shifted spherical waves. It can be viewed as an extension of the classic design techniques of the Fourier series (FS) method or the Woodward-Lawson frequency sampling method, to the case in which the individual antenna elements{\textquoteright} patterns and all interelement couplings are taken into account. The design procedure, which yields the excitations needed to achieve the desired pattern, is based on either the FS or the discrete Fourier transform (DFT) of the spherical mode expansion of the array radiated field, as well as on various properties associated to the FS or DFT coefficients. In this work, to compute the GSM of the array and the spherical mode expansion of the field, a validated hybrid full-wave methodology, based on the finite element method and rotation and translation properties of spherical waves, is used. Numerical results of different synthesized array patterns are presented for different arrays made up of dielectric resonator antennas and cavity-backed microstrip circular patches.}, keywords = {Antenna array mutual coupling, cavity-backed microstrip circular patches, dielectric resonator antennas, discrete Fourier transform, discrete Fourier transforms, discrete Fourier transforms (DFT), finite element analysis, finite element method, finite element methods, Fourier series, Fourier synthesis, Frequency, generalized scattering matrix, GSM, interelement couplings, linear antenna arrays, linear arrays, linear equispaced arrays, microstrip antenna arrays, Microstrip antennas, pattern synthesis, S-matrix theory, Sampling methods, Scattering, scattering matrices, shifted spherical waves, signal sampling, spherical mode expansion, spherical modes, Transmission line matrix methods, Woodward-Lawson frequency sampling}, issn = {0018-926X}, doi = {10.1109/TAP.2009.2021929}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=4907114}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Rubio, J} } @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_APS_CorcolesSalazar_SelfAdaptiveFEM, title = {Self-adaptive algorithms based on h-refinement applied to finite element method}, booktitle = {Antennas and Propagation Society International Symposium, 2005 IEEE}, volume = {4B}, year = {2005}, month = {July}, pages = {197-200 vol. 4B}, abstract = {Two error indicators of the solution of an electromagnetic problem by the finite element method (FEM) and two local refinement algorithms for tetrahedral meshes are developed and combined to build up different self-adaptive (h-refinement) algorithms. 2nd order curl-conforming Nedelec tetrahedral elements are used. The performance of the different methods is checked and compared by means of the electromagnetic analysis of resonant cavities.}, keywords = {2nd order curl-conforming Nedelec tetrahedral elements, cavity resonators, computational electromagnetics, Convergence, Eigenvalues and eigenfunctions, Electromagnetic analysis, electromagnetic problem, Erbium, error indicators, finite element analysis, finite element method, finite element methods, h-refinement, Least squares approximation, Maxwell equations, Performance analysis, Resonance, resonant cavities, self-adaptive algorithms, Software performance, tetrahedral meshes}, doi = {10.1109/APS.2005.1552777}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=1552777}, author = {J C{\'o}rcoles-Ortega and Salazar-Palma, M} }