@article {corcoles2017estimation, title = {On the estimation of the worst-case implant-induced RF-heating in multi-channel MRI}, journal = {Physics in Medicine and Biology}, volume = {62}, number = {12}, year = {2017}, pages = {4711}, publisher = {IOP Publishing}, author = {J C{\'o}rcoles and Zastrow, Earl and Kuster, Niels} } @conference {Corcoles20171, title = {Optimization-based strategy in multiple-channel magnetic resonance systems operating at 128 MHz to reduce radiofrequency heating induced by active implantable medical devices}, booktitle = {2017 32nd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2017}, volume = {2017-January}, year = {2017}, note = {cited By 2}, pages = {1-3}, doi = {10.23919/URSIGASS.2017.8105232}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046140205\&doi=10.23919\%2fURSIGASS.2017.8105232\&partnerID=40\&md5=2f1a69d9a5ebcca222c42b8feaf694eb}, author = {J C{\'o}rcoles and Zastrow, E. and Kuster, N.} } @article {16_AWPL_JUAN-CORCOLES_CAD_SLOTTED_ANTENNA, title = {Computer Automated Design of an Irregular Slotted Waveguide Array for Ku-Band}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {15}, year = {2016}, pages = {1593-1597}, abstract = {A computer automated design methodology to synthesize a progressive wave array antenna is presented. The proposed method is based on the generalized-scattering matrix and spherical wave expansion analysis of the array. Mutual coupling effects between radiating elements are inherently considered in the design process. A linearly polarized 24-element irregular slotted array antenna at Ku-band is presented to describe the proposed computer automated design methodology. A prototype has been manufactured to experimentally validate the antenna performance. At the design frequency (17 GHz), 15.9 dB realized gain and 97\% efficiency (excluding aluminum losses) values are achieved. Although the array is designed at a single frequency, it shows an overall experimental 7\% usable bandwidth.}, keywords = {Array antenna, computer automated design, generalized scattering matrix, slot, spherical wave expansion}, issn = {1536-1225}, doi = {10.1109/LAWP.2016.2517928}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7381600}, author = {J C{\'o}rcoles and P Sanchez-Olivares and J Rubio and J L Masa-Campos and J. Zapata} } @conference {16_URSI_JESUS-RUBIO_dao_slotted_array, title = {Dise{\~n}o Automatizado por Ordenador de una Agrupaci{\'o}n de Ranuras con Alimentaci{\'o}n en Gu{\'\i}a de Onda}, booktitle = {Simposium Nacional URSI 2016}, year = {2016}, month = {September}, abstract = {A Computer Automated Design method based on the generalized-scattering matrix and spherical wave expansion analysis is used to configure a linearly polarized 24-element slotted array antenna at Ku band. The mutual coupling effects between slots have been considered in the proposed methodology. Therefore, it is possible to remove the typical compensation step in the design process. The computing costs of the whole antenna optimization process is significantly reduced using the proposed method compared to the commercial full-wave simulation tools. An antenna prototype has been manufactured in order to experimentally validate the antenna performance. A realized gain and efficiency values of 15.9 dB and 97\% have been measured at the design frequency (17 GHz), respectively.}, author = {J C{\'o}rcoles and P Sanchez-Olivares and J Rubio and J L Masa-Campos and J. Zapata} } @article {murbach2016virtual, title = {Virtual population-based assessment of the impact of 3 Tesla radiofrequency shimming and thermoregulation on safety and B1+ uniformity}, journal = {Magnetic resonance in medicine}, volume = {76}, number = {3}, year = {2016}, pages = {986{\textendash}997}, author = {Murbach, Manuel and Neufeld, Esra and Cabot, Eugenia and Zastrow, Earl and J C{\'o}rcoles and Kainz, Wolfgang and Kuster, Niels} } @article {15_PMB_ConvexImplant, title = {Convex optimization of MRI exposure for mitigation of RF-heating from active medical implants}, journal = {Physics in Medicine and Biology}, volume = {60}, number = {18}, year = {2015}, pages = {7293}, abstract = {Local RF-heating of elongated medical implants during magnetic resonance imaging (MRI) may pose a significant health risk to patients. The actual patient risk depends on various parameters including RF magnetic field strength and frequency, MR coil design, patient{\textquoteright}s anatomy, posture, and imaging position, implant location, RF coupling efficiency of the implant, and the bio-physiological responses associated with the induced local heating. We present three constrained convex optimization strategies that incorporate the implant{\textquoteright}s RF-heating characteristics, for the reduction of local heating of medical implants during MRI. The study emphasizes the complementary performances of the different formulations. The analysis demonstrates that RF-induced heating of elongated metallic medical implants can be carefully controlled and balanced against MRI quality. A reduction of heating of up to 25 dB can be achieved at the cost of reduced uniformity in the magnitude of the $\#$$\#$IMG$\#$$\#$ [http://ej.iop.org/images/0031-9155/60/18/7293/pmb516939ieqn001.gif] {$B_{1}^{+} $} field of less than 5\%. The current formulations incorporate a priori knowledge of clinically-specific parameters, which is assumed to be available. Before these techniques can be applied practically in the broader clinical context, further investigations are needed to determine whether reduced access to a priori knowledge regarding, e.g. the patient{\textquoteright}s anatomy, implant routing, RF-transmitter, and RF-implant coupling, can be accepted within reasonable levels of uncertainty.}, url = {http://stacks.iop.org/0031-9155/60/i=18/a=7293}, author = {J C{\'o}rcoles and E Zastrow and N. Kuster} } @conference {15_EIEC_Corcoles_mutualcoupling, title = {EM field combination and optimization for RF shimming and SAR control in Magnetic Resonance transmit array systems}, booktitle = {X Iberian Meeting on Computational Electromagnetism}, year = {2015}, month = {May}, author = {J C{\'o}rcoles and E Zastrow} } @conference {15_BMES_Murbach_3Tpregnant, title = {Influence of 3T pTx body coils and their excitations on a pregnant anatomical models}, booktitle = {Biomedical Engineering Society and Food and Drug Administration Frontiers in Medical Devices Conference: Innovations in Modeling and Simulation, (2015 BMES/FDA Frontiers)}, year = {2015}, month = {May}, author = {M Murbach and E Neufeld and J C{\'o}rcoles and E Zastrow and N. Kuster} } @conference {15_ISMRM_Murbach_3Tpregnant, title = {Pregnant Anatomical Models in 3T pTx Body Coils: Evaluation of SAR and B1+ Optimization in Various Imaging Positions}, booktitle = {23rd Annual Meeting of the International Society for Magnetic Resonance in Medicine, 2015. ISMRM 2015}, year = {2015}, month = {June}, author = {M Murbach and E Neufeld and E Cabot and E Zastrow and J C{\'o}rcoles and W Kainz and N. Kuster} } @conference {15_IEEEAPS_ImplantSOCP, title = {RF shimming with implant safety control in MRI transmit arrays through second-order cone programming}, booktitle = {IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, AP-S/URSI 2015}, year = {2015}, month = {July}, author = {J C{\'o}rcoles and E Zastrow and N. Kuster} } @conference {15_EIEC_Rubio_OMP, title = {Thinned Arrays by using the orthogonal matching pursuit algorithm and spherical-wave field synthesis}, booktitle = {X Iberian Meeting on Computational Electromagnetism}, year = {2015}, month = {May}, author = {J Rubio and J C{\'o}rcoles and J F Izquierdo and R G{\'o}mez-Alcal{\'a} and J. Zapata} } @article {14_JEMWA_CORCOLES_FULL-WAVEFloquet, title = {Full-wave analysis of finite periodic cylindrical conformal arrays with Floquet spherical modes and a hybrid finite element {\textendash} generalized scattering matrix method}, journal = {Journal of Electromagnetic Waves and Applications}, volume = {28}, number = {1}, year = {2014}, month = {Jan}, pages = {102-111}, abstract = {This work reports a novel approach for the full-wave analysis of a finite conformal array made up of antennas which are periodically arranged on a metallic cylindrical surface. The analysis methodology is based on a hybrid finite element and modal analysis method, and it allows the computation of the generalized scattering matrix of the structure. In this case, spherical vector modes are used to characterize the radiating region and because of the periodic nature of the conformal array, Floquet{\textquoteright}s theory is used to render the methodology efficient and accurate. Therefore, the formulation is derived to be able to characterize the whole structure from the analysis of only one semi-period. Numerical results of arrays made up of rectangular apertures and microstrip patches are presented and compared with the ones obtained with commercial software and infinite models both for conformal and planar arrays.}, keywords = {cylindrical conformal array, finite element method, Floquet{\textquoteright}s theory, generalized scattering matrix, spherical modes}, issn = {0920-5071}, doi = {10.1080/09205071.2013.857280}, url = {http://www.tandfonline.com/doi/abs/10.1080/09205071.2013.857280$\#$.U57p9vl_vQg}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Zapata, J} } @conference {13_EIEC_RubioetAl_SphericalModesinCEM, title = {Spherical Modes in Computational Electromagnetics applied to Antenna Problems}, booktitle = {IX Iberian Meeting on Computational Electromagnetism}, year = {2013}, month = {May}, pages = {1}, abstract = {In this work we review the use of spherical modes in computational electromagnetics mainly applied to antenna problems. First, the theory of spherical modes will be reviewed. Second, the use jointly with the Finite Element Method will be exposed. Third, the application to the analysis of finite arrays will be shown. Finally, it will be presented how the spherical modes allow us to obtain an equivalent model of the antenna, in terms of infinitesimal dipoles, which increases the capabilities of the method for the analysis of finite arrays.}, author = {Rubio, J and Izquierdo, J F and Gonz{\'a}lez, M A and Gil, J M and Garc{\'\i}a, J and de la Rubia, V and J C{\'o}rcoles and Zapata, J} } @article {11_TAP_PontesCorcoles_ModalNetworkMIMO, title = {Modal Network Model for MIMO Antenna in-System Optimization}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {59}, number = {2}, year = {2011}, month = {Feb}, pages = {643-653}, abstract = {The analysis of MIMO systems is described with the aid of a novel modal network model. For this purpose the capacity performance of typical base station and mobile station antennas in a simulated macro-cellular scenario with varying antenna inter element spacings and antenna rotation will be studied. The model is based on the modal description of typical receiving and transmitting antennas. In this manner a significant simulation time reduction is achieved which allows for faster analysis and optimization. To prove this the effects of both the mobile and base station antennas are investigated. Moreover, for the more restrictive case of base station antennas, a fully modal descriptive model is proven to yield very similar results as those from measured commercial antennas. It is found that the modal approach improves simulation speed without loss of accuracy or generality. Simulations are done for the city of Karlsruhe with a three-dimensional Ray-tracing tool.}, keywords = {3D Ray-tracing tool, Antenna arrays, antenna inter element spacing, antenna optimization, antenna rotation, base station antenna, capacity performance, cellular radio, macro-cellular scenario, MIMO antenna, MIMO communication, MIMO network model, MIMO system, mobile antennas, mobile station antenna, modal network model, multiple-input multiple-output (MIMO), network theory, path-based channel models, receiving antenna, receiving antennas, spherical mode expansion, system optimization, transmitting antenna, transmitting antennas}, issn = {0018-926X}, doi = {10.1109/TAP.2010.2096179}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5654566}, author = {Pontes, J and J C{\'o}rcoles and Gonz{\'a}lez, M A and Zwick, T} } @article {11_JoCN_FahmiRuiz-CruzMansourEtAl_RecentAdvancesinFiltersSatellite, title = {Recent Advances in Filter Topologies and Realizations for Satellite Communications}, journal = {Journal of Communications and Networks}, volume = {13}, number = {6}, year = {2011}, month = {Dec}, pages = {625-632}, abstract = {This paper presents an overview of recent advances in radio frequency and microwave filter topologies for satellite communication systems. Many types of filters have been developed during the last years in order to satisfy the demands of modern applications in both terrestrial systems and onboard spacecrafts, leading to a great variety of aspects such as transfer functions, resonator implementations or coupling structures. This paper revisits some of the last advances in this area, including the modeling and full-wave simulation. Some recent designs using dual-mode cavities along with other novel implementations in ridge waveguide will be shown.}, keywords = {full-wave simulators, RF and microwave filters, waveguide technologies}, issn = {1229-2370}, doi = {10.1109/JCN.2011.6157479}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6157479}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @article {11_IETMAP_FahmiRuiz-CruzMansourEtAl_RecentLTCC, title = {Recent Results on Compact Broad-Band and Multi-Band LTCC Components for RF Front-Ends}, journal = {IET Microwaves, Antennas and Propagation}, volume = {5}, number = {8}, year = {2011}, month = {June}, pages = {870-876}, abstract = {Compact components for radio frequency (RF) front-ends realised in low-temperature co-fired ceramics (LTCC) are presented. The aim of this study was to highlight recent advances in realisation of different components for modern RF/microwave subsystems, stressing such attributes as compactness, wide bandwidth and operation in multiple bands. Two key components of every RF front-end are filters and couplers. To illustrate the feasibility of using LTCC technology to realise these components, several designs of filters and couplers are presented. Very compact LTCC ridge waveguide filter covering the whole US ultra-wide band is first discussed, followed by a dual-band LTCC ridge waveguide filter. Two types of wide-band couplers are shown: ridge waveguide couplers realised in LTCC and empty metallic waveguide and also a strip-line LTCC coupler. A common characteristic that will be shown is that the presented components by the authors are modelled using computer-aided design tools based on modal analysis for waveguides as well as commercially available finite-element tools. The shown examples have simulation results compared by different methods as well as some experimental results in LTCC and empty metallic waveguide, used to demonstrate the proposed approach.}, issn = {1751-8725}, doi = {10.1049/iet-map.2010.0371}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5936984\&tag=1}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @conference {10_IMS_FahmiRuiz-CruzMansourEtAl_CompactDualBandRidge, title = {Compact Wide-Band Ridge Waveguide Dual-Band Filters}, booktitle = {2010 IEEE MTT-S International Microwave Symposium Digest}, year = {2010}, month = {May}, pages = {888-891}, abstract = {A compact wide-band, dual-band filter realized in air filled metallic ridge waveguides is proposed. Dual-band filters replace doubly multiplexed filters, thus simplifying the system architecture considerably. The filter is realized in a canonical folded structure layout. Coupling sections that realize strong coupling values required for the wide-band characteristics are achieved by means of transversal sections of ridges connecting the main ridge waveguide resonators. The filter is efficiently modeled using rigorous mode matching method. The filter response is further verified using a commercially available Finite Element Method software. In addition a prototype was built and tested for verification.}, issn = {0149-645X}, doi = {10.1109/MWSYM.2010.5517525}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=05517629}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @book {10_INTECHBook_Ruiz-CruzMontejo-GaraiRebollar_CADWgDevicesbyMM, title = {Computer Aided Design of Waveguide Devices by Mode-Matching Methods (in Microwave and Millimeter Wave Technologies (ISBN: 978-953-307-083-4))}, year = {2010}, month = {Oct 2009}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M}, editor = {Zhurbenko, V} } @article {10_IEEEMWCL_ZhangRuiz-CruzZaki_WaveguideMicrostripTransition, title = {A Waveguide to Microstrip Inline Transition With Very Simple Modular Assembly}, journal = {IEEE Microwave and Wireless Components Letters}, volume = {20}, number = {9}, year = {2010}, month = {Sept.}, pages = {480-482}, abstract = {A microstrip to empty rectangular waveguide transition is presented for systems requiring a simple modular assembly with good electrical performance. The structure is based on three building blocks, involving a microstrip line to dielectric-loaded rectangular waveguide, a transition between dielectric-loaded and empty rectangular waveguides with reduced height, and a final transformer to standard waveguide. These three building blocks (segmentation based on the design point of view) are combined in three simple parts which are assembled in a straightforward modular way, without soldering. These features are very important for signal feeders requiring a large number of transitions, as the X-band phased array antenna where the proposed structure has been integrated. The concepts involved in the design and manufacturing are illustrated with a prototype showing measured return loss of 10 dB and insertion loss of 1.1 dB in the band 8.5-9.5 GHz.}, issn = {1531-1309}, doi = {10.1109/LMWC.2010.2056358}, url = {http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5545481}, author = {Zhang, Y and J A Ruiz-Cruz and Zaki, K A and Piloto, A J} } @conference {09_EuCAP_Corcoles, title = {Array design for different SLL and null directions with an interior-point optimization method from the generalized-scattering-matrix and spherical modes}, booktitle = {Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on}, year = {2009}, month = {March}, pages = {1381-1385}, abstract = {This paper presents a pattern synthesis technique for arbitrary planar arrays which can be characterized in terms of a generalized-scattering-matrix (GSM) and whose radiated field can be expressed as a spherical mode expansion (SME). The procedure yields the complex-valued excitations needed to achieve a pattern which fulfils the requirements of different sidelobe levels in different regions and several prescribed field nulls with a maximum directive gain. The formulation is based on matrix-valued functions which are computed from the GSM and the SME, so all interelement coupling effects coming from complex radiating structures used as array elements are inherently taken into account. To solve the resulting nonlinear optimization problem, a primal-dual interior-point filtering method specifically adapted to this formulation is developed. Numerical results are presented for arrays of microstrip patch antennas and dielectric resonator antennas.}, keywords = {antenna pattern, antenna radiation patterns, antenna sidelobe level, dielectric resonator antenna, dielectric resonator antennas, electromagnetic coupling, Filtering, filtering theory, generalized scattering matrix, generalized-scattering-matrix, GSM, Hessian matrices, interelement coupling effect, interior-point optimization method, Jacobian matrices, microstrip antenna arrays, Microstrip antennas, microstrip patch antenna, Microstrip resonators, nonlinear optimization, optimisation, Optimization methods, pattern synthesis technique, planar antenna array, planar antenna arrays, Planar arrays, primal-dual interior-point filtering method, Resonator filters, S-matrix theory, spherical, spherical mode expansion, Transmission line matrix methods, wave expansion}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5067872}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Rubio, J and Zapata, J} } @conference {09_IMS_FahmiRuiz-CruzZakiEtAl_CompactRidgeNRN, title = {Compact Ridge Waveguide Filters using Non-resonating Nodes}, booktitle = {2009 IEEE MTT-S International Microwave Symposium Digest}, year = {2009}, month = {June}, pages = {1337-1340}, abstract = {A ridge waveguide filter based on the nonresonating node (NRN) concept is proposed. A new coupling mechanism, suitable for this realization is introduced. The proposed coupling mechanism alleviates the need to use other complicated structures and simplify the design process significantly. Rigorous mode matching method (MMM) is used to model the filter. The filter response is further verified using another numerical technique. A prototype was built and tested. Measurement results agree well with simulation.}, issn = {0149-645X}, doi = {0.1109/MWSYM.2009.5165952}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5165952\&isnumber=5165586}, author = {Fahmi, M M and J A Ruiz-Cruz and Zaki, K A and Mansour, R R} } @article {09_IEEETMTT_FahmiRuiz-CruzMansourEtAl_CompactRidgeWaveguideTZNRN, title = {Compact Ridge Waveguide Filters With Arbitrarily Placed Transmission Zeros Using Nonresonating Nodes}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {57}, number = {12}, year = {2009}, month = {Dec.}, pages = {3354-3361}, abstract = {Compact size ridge waveguide filters based on the nonresonating node concept are introduced to realize transfer functions with arbitrarily placed attenuation poles. Coupling mechanisms, suitable for the new realization are introduced in diverse $E$ -plane and $H$ -plane configurations and with different input-output interfaces. These coupling structures are studied and characterized in detail in order to simplify the design of the proposed filters. Rigorous mode-matching method is used to accelerate the full-wave design of the filter configurations, whose response is also verified using other numerical techniques and experimental data. To validate the proposed novel designs, a prototype has been built and tested. Measurement results agree well with the predicted theoretical simulations.}, keywords = {Attenuation poles, microwave filters, mode-matching, ridge waveguides}, issn = {0018-9480}, doi = {10.1109/TMTT.2009.2034423}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5308444\&isnumber=5340253}, author = {Fahmi, M M and J A Ruiz-Cruz and Mansour, R R and Zaki, K A} } @conference {09_IMS_MongeRuiz-CruzAnzaEtAl_HighPowerDualMode, title = {High Power analysis and design of dual-mode channel filters}, booktitle = {2009 IEEE MTT-S International Microwave Symposium Digest}, year = {2009}, month = {June}, pages = {1353-1356}, abstract = {In this paper, we present two dual-mode channel filter topologies which are able to withstand more than 600 W in Ku-Band. The two different designs (one with elliptical cavities and the other one with rectangular cavities) implement the same transfer function: four order, elliptical response centered in 12GHz, with 40MHz bandwidth and two transmission zeros. It is shown that the critical dimensions for the power-handling of these filters are the dimensions of the input-output irises. In fact, in order to rigorously obtain these conclusions and to reach these high-power levels (including margins), it is essential to use the advanced numerical techniques described in the paper to predict the multipactor effect. Moreover, the standard approach for multipactor onset prediction based on computing the voltage inside the component is shown to be too conservative and difficult to apply to many practical filter configurations.}, issn = {0149-645X}, doi = {0.1109/MWSYM.2009.5165956}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5165956\&isnumber=5165586}, author = {Monge, J and J A Ruiz-Cruz and Anza, S and Vicente, C and Zaki, K A and Montejo-Garai, J R and Rebollar, J M and Gil, J and Gimeno, B., and Boria, V E} } @article {09_IJRFMiCAE_ZhangRuiz-CruzZaki_InlineandCanonical, title = {Inline and Canonical Stripline Filters with Ridge Coupling Sections for LTCC Applications}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {19}, number = {3}, year = {2009}, month = {May}, pages = {354-363}, abstract = {Inline and canonical filters employing stripline resonators coupled by evanescent-mode ridge waveguide sections are presented. The proposed configurations are suitable choices for broadband chip filters integrated in printed circuit boards, especially for those with constraints on size and loss. Low temperature co-fired ceramic (LTCC) technology can be used to manufacture such filters. To validate the idea, prototypes of Chebyshev and elliptic function filters are designed following a systematic procedure. Stepped impedance stripline resonators are used in the Chebyshev filter to improve the spurious response. A novel canonical structure is presented for achieving high selectivity elliptic function filter responses. Rigorous mode matching method is applied to analyze and optimize all the filters, whose results are validated by commercial software.}, keywords = {bandpass, Chebyshev filter, elliptic response, LTCC, ridge waveguide, stripline}, issn = {1096-4290}, doi = {10.1002/mmce.20354}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/121582207/PDFSTART}, author = {Zhang, Y and J A Ruiz-Cruz and Zaki, K A} } @article {09_ELL_Corcoles_LPfromGSM, title = {Linear programming from generalised scattering matrix analysis of array for minimum sidelobe level and prescribed nulls}, journal = {Electronics Letters}, volume = {45}, number = {1}, year = {2009}, month = {January}, pages = {9-10}, abstract = {A pattern synthesis technique for arbitrary planar arrays which are characterised in terms of a generalised scattering matrix and whose radiated field is expressed as a spherical mode expansion is introduced. The procedure yields the complex-valued excitations to achieve a minimum-maximum sidelobe level given a specified pointing direction and mainlobe width, as well as prescribed field nulls. All inter-element coupling effects coming from complex radiating structures used as array elements are inherently taken into account. Numerical results are presented for arrays of dielectric resonator antennas.}, keywords = {Antenna arrays, arbitrary planar arrays, complex-valued excitations, dielectric resonator antennas, dielectric resonators, electromagnetic coupling, electromagnetic wave scattering, generalised scattering matrix analysis, inter-element coupling effects, linear programming, minimum sidelobe level array, minimum-maximum sidelobe level, pattern synthesis technique, prescribed nulls}, issn = {0013-5194}, doi = {10.1049/el:20092008}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=4733076}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Zapata, J} } @article {09_ELL_Corcoles_ModellingLOScoupledMIMO, title = {Modelling line-of-sight coupled MIMO systems with generalised scattering matrices and spherical wave translations}, journal = {Electronics Letters}, volume = {45}, number = {12}, year = {2009}, month = {June}, pages = {598-599}, abstract = {A model to rigorously characterise line-of-sight MIMO systems is introduced. It is based on the generalised scattering matrix of each antenna, considered as isolated, and the rotation and translation coefficients of spherical modes. The resulting channel matrix rigorously includes the exact spherical vector nature of electromagnetic propagation (which may exert a significant influence over short-range links), mutual coupling effects and real antenna reflection, transmission, reception and scattering features. Numerical results are presented for MIMO systems made up of ideal dipoles.}, keywords = {antenna reflection, channel matrix, electromagnetic coupling, electromagnetic propagation, electromagnetic wave propagation, generalised scattering matrix, line-of-sight coupled MIMO system, MIMO communication, multiple-input multiple-output system, mutual coupling effect, S-matrix theory, spherical wave translation scheme}, issn = {0013-5194}, doi = {10.1049/el.2009.0545}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=5069759}, author = {J C{\'o}rcoles and Pontes, J and Gonz{\'a}lez, M A and Zwick, T} } @article {09_IntJRFMiCAE_CORCOLES_PerformanceUslot, title = {Performance characterization of wideband, wide-angle scan arrays of cavity-backed U-slot microstrip patch antennas}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {19}, number = {3}, year = {2009}, pages = {389{\textendash}396}, abstract = {This work looks at the use of wideband cavity-backed U-slot microstrip antennas in finite phased arrays. This configuration retains the single-patch and single-layer characteristics of conventional microstrip antenna arrays and provides a good impedance matching over wider scan angles when electrically thick substrates are used to improve the frequency bandwidth. The characteristics of finite phased arrays of U-slot rectangular microstrip patches enclosed in cylindrical cavities are analyzed from a validated hybrid methodology based on the finite element method, the modal analysis, and the properties of spherical waves. The results are compared with those obtained using an infinite array model. {\textcopyright} 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.}, keywords = {broadband U-slot patch antenna, cavity-backed microstrip antennas, finite element method, finite phased array, spherical mode expansion}, issn = {1099-047X}, doi = {10.1002/mmce.20361}, url = {http://dx.doi.org/10.1002/mmce.20361}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Rubio, J and Zapata, J} } @article {08_MwJournal_Ruiz-CruzWangZaki_AdvancesMicrowaveFilterDesign, title = {Advances in Microwave Filter Design Techniques}, journal = {Microwave Journal}, volume = {51}, number = {11}, year = {2008}, month = {November}, pages = {26-44}, issn = {0192-6225}, url = {http://www.mwjournal.com/Journal/article.asp?HH_ID=AR_6783}, author = {J A Ruiz-Cruz and Wang, C and Zaki, K A} } @article {08_MOPT_CORCOLES_CADstackedpatches, title = {Cad of stacked patch antennas through multipurpose admittance matrices from FEM and neural networks}, journal = {Microwave and Optical Technology Letters}, volume = {50}, number = {9}, year = {2008}, month = {Sep}, pages = {2411-2416}, abstract = {In this work, a novel computer-aided design methodology for probe-fed, cavity-backed, stacked microstrip patch antennas is proposed. The methodology incorporates the rigor of a numerical technique, such as finite element methods, which, in turn, makes use of a newly developed procedure (multipurpose admittance matrices) to carry out a full-wave analysis in a given structure in spite of certain physical shapes and dimensions not yet being established. With the aid of this technique, we form a training set for a neural network, whose output is the desired response of the antenna according to the value of design parameters. Last, taking advantage of this neural network, we perform a global optimization through a genetic algorithm or simulated annealing to obtain a final design. The proposed methodology is validated through a real design whose numerical results are compared with measurements with good agreement.}, keywords = {computer-aided design, finite element methods, neural networks, optimization algorithms, stacked microstrip antennas}, issn = {1098-2760}, doi = {10.1002/mop.23670}, url = {http://onlinelibrary.wiley.com/doi/10.1002/mop.23670/abstract}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Zapata, J} } @conference {08_URSIESP_Corcoles_DisenoAutomatizadoParches, title = {Dise{\~n}o automatizado de antenas de parches apilados en cavidad mediante descomposici{\'o}n de dominio en el MEF, redes neuronales y optimizaci{\'o}n global}, booktitle = {Proc. 2008 Simposium Nacional URSI (in Spanish)}, year = {2008}, month = {Sep}, pages = {1-4}, abstract = {This work reports the development of a computeraided- design methodology consisting of three steps for probe-fed cavity-backed, stacked microstrip patch antennas. In the first step, the rigour of a numerical technique such as the finite element method (FEM) to describe the electromagnetic behaviour of these structures is incorporated. The application of the FEM is carried out on a highly efficient basis through a sophisticated domain decomposition approach. From these results, a neural network (NN) is trained to output the desired response of the antenna according to the value of design parameters. Thanks to the versatily of this NN, a global optimization through simulated annealing or genetic algorithms is lastly executed to obtain a final design. The proposed methodology is validated through a real design whose numerical results are compared with measurements with good agreement.}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Zapata, J} } @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} } @article {08_IJRFMiCAE_FahmiRuiz-CruzZaki_EandH-plane, title = {E and H-plane wide-band ridge waveguide couplers}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {18}, number = {4}, year = {2008}, month = {July}, pages = {348-358}, abstract = {A systematic synthesis procedure for ridge waveguide branch line couplers in both E-plane and H-plane configurations is presented. Ridge waveguides are chosen to benefit from their wide mono-mode band and compact size compared to rectangular waveguides. Equivalent circuit parameters are used to synthesize the coupler sections. Rigorous mode matching method is used for full-wave analysis and optimization of the couplers. Ridge couplers both in empty waveguide and Low Temperature Co-fired Ceramic "LTCC" technology are designed using the proposed method and the design is verified with another numerical method. A prototype is built and its response is measured to verify the approach}, keywords = {full-wave, LTCC, mode matching, optimization, ridge waveguide}, issn = {1096-4290}, doi = {10.1002/mmce.20293}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/119140987/PDFSTART}, author = {Fahmi, M M and J A Ruiz-Cruz and Zaki, K A} } @conference {08_IMS_Ruiz-CruzZhangMontejo-GaraiEtAl_LongitudinalDual-ModeFilters, title = {Longitudinal Dual-Mode Filters in Rectangular Waveguide}, booktitle = {2008 IEEE MTT-S International Microwave Symposium Digest}, year = {2008}, month = {June}, pages = {631-634}, 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.}, keywords = {Dual-Mode cavities, elliptic filter response, rectangular waveguide filter}, issn = {0149-645X}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=4632911\&isnumber=4632906}, author = {J A Ruiz-Cruz and Zhang, Y and Montejo-Garai, J R and Rebollar, J M and Zaki, K A} } @conference {08_EIEC_CorcolesetAl_OptimizationIPM, title = {Optimization of coupled antenna arrays characterized by spherical modes by means of an interior-point filtering method}, booktitle = {VI Iberian Meeting on Computational Electromagnetism}, year = {2008}, month = {Oct}, pages = {1}, abstract = {In this work, we present a novel method for the efficient optimization of arbitrary planar array excitations. This method, which inherently takes into account every array element pattern as well as all interelement couplings, allows the maximization of the directive or power gain of an arbitrary planar array scanned at whichever direction, subject to constraints on the maximum sidelobe level, the maximum crosspolar level, the minimum aperture illumination efficiency, the setting of null pointing directions or a dynamic range ratio control. Numerical examples of arrays with canonical geometries, composed of microstrip patches or dielectric resonator antennas and covering a wide variety of requirements are presented.}, author = {J C{\'o}rcoles and Gonz{\'a}lez, M A and Rubio, J and Zapata, J} } @conference {07_IMS_ZhangZakiRuiz-CruzEtAl_AnalyticalSynthesisof, title = {Analytical Synthesis of Generalized Multi-band Microwave Filters}, booktitle = {2007 IEEE MTT-S International Microwave Symposium Digest}, year = {2007}, month = {June}, pages = {1273-1276}, abstract = {An analytical procedure is presented for the synthesis of generalized multi-band filters. The procedure is applicable to both symmetric and asymmetric frequency responses and effective for any number of passbands and stopbands. An optimum equal-ripple performance is obtained in each passband and stopband. Prescribed real or complex transmission zeros can also be employed in the multi-band filtering function.}, keywords = {band-pass filters, band-stop filters, generalized multiband microwave filters, microwave filtersfrequency responses, optimum equal-ripple performance, passbands, stopbands}, issn = {0149-645X}, doi = {10.1109/MWSYM.2007.380425}, url = {http://ieeexplore.ieee.org/iel5/4263706/4263707/04264064.pdf?tp=\&isnumber=\&arnumber=4264064}, author = {Zhang, Y and Zaki, K A and J A Ruiz-Cruz and Atia, A E} } @conference {07_IMS_Ruiz-CruzZhangRebollarEtAl_TEMMode-MatchingAnalysis, title = {TEM Mode-Matching Analysis of Multi-coupled Strip-line Filters}, booktitle = {2007 IEEE MTT-S International Microwave Symposium Digest}, year = {2007}, month = {June}, pages = {541-544}, abstract = {The analysis of multi-coupled strip-line filters by the mode-matching method is studied for different input/output excitations. The aim is to compare the computational effort of two different options and to propose the most suitable formulation for the design of some strip-line filters. It is shown that a suitable segmentation of the structure is essential for obtaining good numerical results. In fact, if the optimum segmentation is selected, a mode-matching analysis using only TEM modes can resemble the full-wave response, with shorter computation time. Hence, this approach can be very useful in design and different examples are shown to validate it, using other numerical methods and measurements of a ten order filter.}, keywords = {microwave filters, mode matching, multicoupled strip-line filter design, optimum structure segmentation, strip line filtersTEM mode-matching analysis}, issn = {0149-645X}, doi = {10.1109/MWSYM.2007.380546}, url = {http://ieeexplore.ieee.org/iel5/4263706/4263707/04263871.pdf?tp=\&isnumber=\&arnumber=4263871}, author = {J A Ruiz-Cruz and Zhang, Y and Rebollar, J M and Zaki, K A and Montejo-Garai, J R and Piloto, A J} } @article {07_IEEEMWCL_Ruiz-CruzZhangZakiEtAl_Ultra-WidebandLTCCRidge, title = {Ultra-Wideband LTCC Ridge Waveguide Filters}, journal = {IEEE Microwave and Wireless Components Letters}, volume = {17}, number = {2}, year = {2007}, month = {Feb.}, pages = {115-117}, abstract = {The design and experimental validation of an ultra-wideband (UWB) filter in a low temperature co-fired ceramic (LTCC) is presented. The bandpass filter uses ridge waveguide resonators realized in LTCC by printing parallel planar conductors for the top and bottom walls and closely spaced metal filled vias for the lateral walls. Filter coupling scheme and stripline transitions are developed for the UWB requirement. The mode-matching method is used in their design. The LTCC via effect and the measurement setup are also addressed. Finally, experimental results of a nine-order filter (design passband from 3 to 9GHz) are presented}, keywords = {band-pass filters, bandpass filter, filter coupling scheme, low temperature co fired ceramic, LTCC, metal filled vias, mode matching method, nine order filter, planar conductors, ridge waveguide filters, ridge waveguide resonators, ridge waveguides, stripline transitions, ultra wideband filter, waveguide filters3 to 9 GHz}, issn = {1531-1309}, doi = {10.1109/LMWC.2006.890333}, url = {http://ieeexplore.ieee.org/iel5/7260/4079621/04079639.pdf?tp=\&isnumber=4079621\&arnumber=4079639\&punumber=7260}, author = {J A Ruiz-Cruz and Zhang, Y and Zaki, K A and Piloto, A J and Tallo, J} } @article {07_IJRFMiCAE_Ruiz-CruzMontejo-GaraiRebollarEtAl_Waveguidefilterswith, title = {Waveguide filters with elliptical function response: Overview and results of different implementations}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {17}, number = {1}, year = {2007}, month = {Jan.}, pages = {63-69}, abstract = {Some recent implementations of waveguide filters with elliptical response are presented in this paper. The goal is to describe the main aspects involved in the computer-aided design of elliptic waveguide filters, which are commonly used at microwave and millimeter-wave frequencies by their high selectivity, low insertion loss, and high power-handling capabilities. Three different examples based on crosscoupled cavities and the extracted-pole procedure are used to illustrate the main ideas, with their corresponding experimental results. A comparative table summarizes the main features of the presented filters.}, keywords = {Bandpass Waveguide Filters, Design, Extracted Poles, N-Transmission Zeros, Order Filters, resonators}, issn = {1096-4290}, doi = {10.1002/mmce.20198}, url = {http://www3.interscience.wiley.com/cgi-bin/fulltext/113493159/PDFSTART}, author = {J A Ruiz-Cruz and Montejo-Garai, J R and Rebollar, J M and Zaki, K A} } @conference {06_IMS_ZhangRuiz-CruzZaki_RidgeWaveguideCoupled, title = {Ridge Waveguide Coupled Stripline Resonator Filters and Multiplexers}, booktitle = {2006 IEEE MTT-S International Microwave Symposium Digest}, year = {2006}, month = {June}, pages = {681-684}, abstract = {Stripline resonator bandpass filters with evanescent-mode coupling sections by ridge waveguides are introduced in this paper. Such filters have very compact cross sections, which makes them suitable choices for some integrated systems having cross section constraints. Low Temperature Co-fired Ceramic (LTCC) technology can be employed to build such filters for PCB systems. It is also possible to manufacture them in air-filled metallic structures. Two filter design examples by Mode Matching Method (MMM) are given in this paper. Stepped impedance line resonators are used in one example to improve the spurious. The presented filters can also be applied for multiplexer applications using stripline junctions. One diplexer design example for LTCC application is presented to show the feasibility.}, issn = {0149-645X}, doi = {10.1109/MWSYM.2006.249724}, url = {http://ieeexplore.ieee.org/iel5/4014788/4014789/04014995.pdf?tp=\&isnumber=\&arnumber=4014995}, author = {Zhang, Y and J A Ruiz-Cruz and Zaki, K A} } @conference {06_IMS_ZhangRuiz-CruzZaki_RidgeWaveguideDivider, title = {Ridge Waveguide Divider Junctions for Wide-Band Multiplexer Applications}, booktitle = {2006 IEEE MTT-S International Microwave Symposium Digest}, year = {2006}, month = {June}, pages = {1225-1228}, abstract = {Ridge waveguide divider junctions are introduced and applied to wide-band multiplexer applications. A rigorous analysis and optimization process by mode matching method (MMM) is employed to design the junctions that yield low reflection coefficient in common port and almost equal transmission coefficients in the other two ports over a wide frequency band. Two design examples of wide-band diplexer and triplexer using such junctions are presented. All the components involved in the diplexer/triplexer designs are rigorously modeled and cascaded by MMM. Optimization procedures by MMM are also applied in these two designs to improve the performance. Multiplexers using such junctions can be built in either metallic form or low-temperature co-fired ceramic (LTCC) technology}, keywords = {low-temperature co-fired ceramics, mode matching, mode matching method, multiplexing equipment, ridge waveguide divider junctions, ridge waveguides, waveguide junctionsLTCC technology, wide-band diplexer, wide-band multiplexer applications, wide-band triplexer}, issn = {0149-645X}, doi = {10.1109/MWSYM.2006.249431}, url = {http://ieeexplore.ieee.org/iel5/4014788/4014789/04015143.pdf?tp=\&isnumber=\&arnumber=4015143}, author = {Zhang, Y and J A Ruiz-Cruz and Zaki, K A} } @conference {06_EuMC_Ruiz-CruzZhangFahmiEtAl_RidgeWaveguideElliptic, title = {Ridge Waveguide Elliptic Filters in Narrow-Wall Canonical Configuration}, booktitle = {Proc. 36th European Microwave Conference}, year = {2006}, month = {Sept.}, pages = {1080-1082}, abstract = {A new canonical ridge waveguide structure is proposed to design elliptic filter responses. The non-adjacent cavities are coupled by windows situated at the common narrow-wall of the ridge waveguide enclosures. This new configuration provides positive and negative cross couplings using evanescent rectangular waveguides and metallic strips, respectively. The full-wave analysis of the structure is carried out by a rigorous mode matching method. The design is based on circuit synthesis and full-wave optimization. Finally, the proposed structure is elucidated with the design of a four-pole filter and it is validated with the commercial HFSS software}, keywords = {circuit synthesis, elliptic filters, four-pole filter, full-wave optimization, metallic strips, mode matching, mode matching method, narrow-wall canonical configuration, negative cross couplings, network synthesis, nonadjacent cavities, positive cross couplings, rectangular waveguides, ridge waveguide elliptic filters, ridge waveguides, waveguide filtersHFSS software}, issn = {2-9600551-6-0}, doi = {10.1109/EUMC.2006.281121}, url = {http://ieeexplore.ieee.org/iel5/4057701/4057702/04058011.pdf?tp=\&isnumber=\&arnumber=4058011}, author = {J A Ruiz-Cruz and Zhang, Y and Fahmi, M M and Zaki, K A} } @article {05_IEEETMTT_Ruiz-CruzSabbaghZakiEtAl_Canonicalridgewaveguide, title = {Canonical ridge waveguide filters in LTCC or metallic resonators}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {53}, number = {1}, year = {2005}, month = {Jan.}, pages = {174-182}, abstract = {A new physical realization of an elliptic function filter response is proposed for achieving compact size, wide bandwidth, wide spurious free stopband and high-selectivity performance. The filter configuration can be implemented in conventional waveguide technology or embedded in a multilayer low-temperature co-fired ceramic structure for integration with other circuitry in a chip module. The filter is analyzed using rigorous mode matching. To validate the concept, prototypes of four- and six-cavity elliptic filters are designed following a systematic procedure. Approximate synthesis is used to obtain initial dimensions of the filter and the desired optimum response is obtained by means of a final full-wave optimization. The results are verified with other numerical methods and with the measurements of a fourth-order waveguide filter.}, keywords = {band-pass filters, canonical ridge waveguide filters, cavity resonator filters, ceramics, chip module, circuit optimisation, elliptic filters, elliptic function filter response, four cavity elliptic filters design, fourth order waveguide filter, full-wave optimization, metallic resonators, microwave filters, mode matching, multilayer low temperature cofired ceramic structure, multilayers, numerical methods, prototypes, resonators, ridge waveguides, six cavity elliptic filters design, spurious free stopband filter, waveguide filters band pass filters, waveguide technology}, issn = {0018-9480}, doi = {10.1109/TMTT.2004.839324}, url = {http://ieeexplore.ieee.org/iel5/22/30125/01381687.pdf?tp=\&arnumber=1381687\&isnumber=30125}, author = {J A Ruiz-Cruz and El Sabbagh, M A and Zaki, K A and Rebollar, J M and Zhang, Y} } @conference {05_APS_ZhangZakiRuiz-Cruz_Dualmodebandpass, title = {Dual mode bandpass filter with asymmetric transfer function}, booktitle = {Proc. 2005 IEEE Antennas and Propagation Society International Symposium}, volume = {2B}, year = {2005}, month = {July}, pages = {634-637}, abstract = {We demonstrate the feasibility of dual mode implementation of an asymmetric elliptic filter. A filter which has four poles and one transmission zero is synthesized from the general Chebyshev transfer function. The ideal electrical network of the longitudinal form is then obtained through several "rotation" operations on the initial coupling matrix. Finally, the dual mode circular waveguides are adopted to realize the ideal network.}, keywords = {asymmetric elliptic filter, asymmetric transfer function, band-pass filters, Chebyshev filters, circular waveguides, coupling matrix, dual mode bandpass filter, dual mode circular waveguides, elliptic filters, ideal network, microwave filters, poles, poles and zeros, rotation operations, transfer function matrices, transmission zero, waveguide filters Chebyshev transfer function}, issn = {0-7803-8884-4}, doi = {10.1109/APS.2005.1552092}, url = {http://ieeexplore.ieee.org/iel5/10402/33057/01552092.pdf?tp=\&isnumber=\&arnumber=1552092}, author = {Zhang, Y and Zaki, K A and J A Ruiz-Cruz} } @conference {05_IMS_FahmiRuiz-CruzZakiEtAl_LTCCwide-bandcanonical, title = {LTCC wide-band canonical ridge waveguide filters}, booktitle = {2005 IEEE MTT-S International Microwave Symposium Digest}, year = {2005}, month = {June}, pages = {249-252}, abstract = {A canonical LTCC ridge waveguide filter for wide-band application is proposed. A new coupling scheme is employed to achieve the values of the cross couplings needed to increase the bandwidth. The change of the realization of the coupling sections from rectangular to narrow ridge waveguide is shown to eliminate detrimental undesired cross coupling. To validate the concept, rigorous mode matching method is used for full-wave analysis and optimization of a six pole filter. The response is verified with another numerical method, and a prototype is constructed for testing.}, keywords = {canonical ridge waveguide filters, ceramic packaging, coupling scheme, coupling sections, full-wave analysis, mode matching, mode matching method, narrow ridge waveguide, optimisation, ridge waveguides, six pole filter, waveguide filters LTCC, wide-band filters}, issn = {01490-645X}, doi = {10.1109/MWSYM.2005.1516572}, url = {http://ieeexplore.ieee.org/iel5/10171/32491/01516572.pdf?tp=\&isnumber=\&arnumber=1516572}, author = {Fahmi, M M and J A Ruiz-Cruz and Zaki, K A and Piloto, A J} } @conference {05_IMS_Ruiz-CruzZakiMontejo-GaraiEtAl_Rectangularwaveguideelliptic, title = {Rectangular waveguide elliptic filters with capacitive and inductive irises and integrated coaxial excitation}, booktitle = {2005 IEEE MTT-S International Microwave Symposium Digest}, year = {2005}, month = {June}, pages = {269-272}, abstract = {CAD of rectangular waveguide filters with elliptic responses is described. The configuration uses capacitive and inductive irises in order to achieve the different coupling signs required to synthesize finite transmission zeros in the rejection bands. The input and output ports are realized by a coaxial probe that directly excites the input/output cavities. The analysis is done by the efficient mode-matching method, in order to allow a final full-wave optimization taking into account all the higher order mode interactions. The CAD results are verified with the HFSS and a filter was manufactured for testing.}, keywords = {band-stop filters, capacitive iris, circuit CAD, coaxial probe, coaxial waveguides, elliptic filters, finite transmission zeros, full-wave optimization, higher order mode interactions, inductive iris, input ports, integrated coaxial excitation, mode matching, mode-matching method, optimisation, output ports, rectangular waveguide filter, rectangular waveguides, rejection bands, waveguide filters CAD}, issn = {01490-645X}, doi = {10.1109/MWSYM.2005.1516577}, url = {http://ieeexplore.ieee.org/iel5/10171/32491/01516577.pdf?tp=\&isnumber=\&arnumber=1516577}, author = {J A Ruiz-Cruz and Zaki, K A and Montejo-Garai, J R and Rebollar, J M} } @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 {04_IMS_LiuRuiz-CruzWangEtAl_extremelywidebandridge, title = {An extremely wideband ridge waveguide filter}, booktitle = {2004 IEEE MTT-S International Microwave Symposium Digest}, volume = {2}, year = {2004}, month = {June}, pages = {615-618}, abstract = {An extremely wideband ridge waveguide filter is presented. The fractional bandwidth of the filter can be greater than 115\%. An input and output transition from ridge waveguide to stripline and then to coax is also designed. The analysis is done with mode matching method and verified with Ansoft HFSS. For validation purpose, a test filter with pass band from 3 GHz to 9 GHz has been designed. The results by both mode matching method and Ansoft HFSS are presented. Excellent agreement is obtained. The test filter is designed using air filled ridge waveguide; however the same design procedure can be equally applied to other manufacturing techniques such as LTCC.}, keywords = {air filled ridge waveguide, fractional bandwidth, mode matching, mode matching method, ridge waveguides, strip lines, stripline, waveguide filters 3 to 9 GHz, wideband ridge waveguide filter}, issn = {0149-645X}, doi = {10.1109/MWSYM.2004.1336059}, url = {http://ieeexplore.ieee.org/iel5/9277/29472/01336059.pdf?tp=\&isnumber=\&arnumber=1336059}, author = {Liu, Z M and J A Ruiz-Cruz and Wang,C and Zaki, K A} } @conference {04_IMS_Ruiz-CruzElZakiEtAl_Full-wavedesignof, title = {Full-wave design of canonical ridge waveguide filters}, booktitle = {2004 IEEE MTT-S International Microwave Symposium Digest}, volume = {2}, year = {2004}, month = {June}, pages = {603-606}, abstract = {A new physical realization of an elliptic function filter response is proposed for achieving compact size, wide bandwidth, wide spurious free stop band and high selectivity performance. The canonical ridge waveguide filter configuration is analyzed using rigorous mode-matching. To validate the concept, a prototype that realizes the coupling matrix of a canonical four cavity elliptic filter is designed following a systematic procedure. Approximate synthesis is used to obtain initial dimensions of the filter and the desired optimum response is obtained by means of a final full-wave optimization. The results are verified with other numerical method and a prototype will be built for testing.}, keywords = {band-pass filters, coupling matrix, elliptic filters, elliptic function filter, filtering theory, full-wave design, full-wave optimization, mode matching, mode-matching, waveguide filters canonical ridge waveguide filters, wide bandwidth, wide spurious free stop band}, issn = {0149-645X}, doi = {10.1109/MWSYM.2004.1336056}, url = {http://ieeexplore.ieee.org/iel5/9277/29472/01336056.pdf?tp=\&isnumber=\&arnumber=1336056}, author = {J A Ruiz-Cruz and El Sabbagh, M A and Zaki, K A and Rebollar, J M} } @conference {04_APS_Ruiz-CruzZakiRebollar_Mode-matchinganalysisof, title = {Mode-matching analysis of a coaxial-to-stripline discontinuity applied to the modeling of a coaxial probe}, booktitle = {Proc. 2004 IEEE Antennas and Propagation Society International Symposium}, volume = {2}, year = {2004}, month = {June}, pages = {2139-2142}, abstract = {The paper presents the analysis of the discontinuity between a coaxial and a generalized stripline waveguide and its application to the characterization of a probe inside a rectangular waveguide. The probe is modeled by a stripline whose inner conductor is stepped. For thin probes, just a reduced number of sections is needed and its characterization can be obtained very efficiently. The mode-matching technique is employed for analyzing the basic discontinuity, and the inner cross products between the modes are computed by means of the Bessel-Fourier series, reducing the computation time with respect to a pure numerical integration. The simulation results are compared with those obtained by other numerical techniques.}, keywords = {coaxial probe modeling, coaxial waveguide, coaxial waveguides, coaxial-to-stripline discontinuity, computation time, Fourier series, mode matching, mode-matching analysis, numerical integration, rectangular waveguide, strip line discontinuities Bessel-Fourier series, stripline waveguide}, issn = {0-7803-8302-8}, doi = {10.1109/APS.2004.1330633}, url = {http://ieeexplore.ieee.org/iel5/9253/29356/01330633.pdf?tp=\&isnumber=\&arnumber=1330633}, author = {J A Ruiz-Cruz and Zaki, K A and Rebollar, J M} }