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Dive into the research topics where Juan M. Rius is active.

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Featured researches published by Juan M. Rius.


IEEE Transactions on Antennas and Propagation | 1993

High-frequency RCS of complex radar targets in real-time

Juan M. Rius; M. Ferrando; L. Jofre

This paper presents a new and original approach for computing the high-frequency radar cross section (RCS) of complex radar targets in real time with a 3-D graphics workstation. The aircraft is modeled with I-DEAS solid modeling software using a parametric surface approach. High-frequency RCS is obtained through physical optics (PO), method of equivalent currents (MEC), physical theory of diffraction (PTD), and impedance boundary condition (IBC). This method is based on a new and original implementation of high-frequency techniques which the authors have called graphical electromagnetic computing (GRECO). A graphical processing approach of an image of the target at the workstation screen is used to identify the surfaces of the target visible from the radar viewpoint and obtain the unit normal at each point. High-frequency approximations to RCS prediction are then easily computed from the knowledge of the unit normal at the illuminated surfaces of the target. The image of the target at the workstation screen (to be processed by GRECO) can be potentially obtained in real time from the I-DEAS geometric model using the 3-D graphics hardware accelerator of the workstation. Therefore, CPU time for RCS prediction is spent only on the electromagnetic part of the computation, while the more time-consuming geometric model manipulations are left to the graphics hardware. This hybrid graphic-electromagnetic computing (GRECO) results in real-time RCS prediction for complex radar targets. >


IEEE Antennas and Propagation Magazine | 1993

GRECO: graphical electromagnetic computing for RCS prediction in real time

Juan M. Rius; M. Ferrando; L. Jofre

An innovative approach to computing the high-frequency radar cross sections (RCSs) of complex radar targets in real time, using a 3-D graphics workstation, is presented. The target (typically, an aircraft) is modeled with the I-IDEAS solid-modeling software, using a parametric-surface approach. The high-frequency RCS is obtained through physical optics (PO), the method of equivalent currents (MEC), the physical theory of diffraction (PTD), and the impedance boundary condition (IBC) techniques. The CPU time for the RCS prediction is spent only on the electromagnetic part of the computation, while the more time-consuming geometric-model manipulations are left to the graphics hardware.<<ETX>>


IEEE Transactions on Microwave Theory and Techniques | 1991

Cylindrical geometry: a further step in active microwave tomography

Antoni Broquetas; J. Romeu; Juan M. Rius; Antonio R. Elias-Fuste; Angel Cardama; L. Jofre

A prototype imaging system for active microwave tomography using cylindrical geometry has been developed, making it possible to obtain images of the dielectric properties of biological targets at 2.45 GHz. This configuration allows a fast exploration of body slices placed along the array axis, in a way similar to that of present X-ray scanners. The electromagnetic compatibility (EMC) of this approach is critical because the strongly attenuated received fields are measured on the same array which is being used to emit a high-level illuminating signal. Therefore, carefully designed high-frequency architectures and detection techniques are necessary. The system requires no mechanical movements to illuminate the body from multiple directions (views) and measure the scattered fields. In this way, a complete data set consisting of 64 views is acquired in 3 s using low-power illumination. The system is described, and images obtained with biological phantoms and actual bodies are presented. >


IEEE Transactions on Antennas and Propagation | 2011

Multiscale Compressed Block Decomposition for Fast Direct Solution of Method of Moments Linear System

Alex Heldring; Juan M. Rius; José M. Tamayo; J. Parron; Eduard Ubeda

The multiscale compressed block decomposition algorithm (MS-CBD) is presented for highly accelerated direct (non iterative) solution of electromagnetic scattering and radiation problems with the method of moments (MoM). The algorithm is demonstrated to exhibit N2 computational complexity and storage requirements scaling with N1.5, for electrically large objects. Several numerical examples illustrate the efficiency of the method, in particular for problems with multiple excitation vectors. The largest problem presented in this paper is the monostatic RCS of the NASA almond at 50 GHz, for one thousand incidence angles, discretized using 442,089 RWG basis functions. Being entirely algebraic, MS-CBD is independent of the Greens function of the problem.


IEEE Transactions on Antennas and Propagation | 2001

On the testing of the magnetic field integral equation with RWG basis functions in method of moments

Juan M. Rius; Eduard Ubeda; J. Parron

For electromagnetic analysis using method of moments (MoM), three-dimensional (3-D) arbitrary conducting surfaces are often discretized in Rao, Wilton and Glisson basis functions. The MoM Galerkin discretization of the magnetic field integral equation (MFIE) includes a factor /spl Omega//sub 0/ equal to the solid angle external to the surface at the testing points, which is 2/spl pi/ everywhere on the surface of the object, except at the edges or tips that constitute a set of zero measure. However, the standard formulation of the MFIE with /spl Omega//sub 0/=2/spl pi/ leads to inaccurate results for electrically small sharp-edged objects. This paper presents a correction to the /spl Omega//sub 0/ factor that, using Galerkin testing in the MFIE, gives accuracy comparable to the electric field integral equation (EFIE), which behaves very well for small sharp-edged objects and can be taken as a reference.


IEEE Transactions on Antennas and Propagation | 2008

Fast Iterative Solution of Integral Equations With Method of Moments and Matrix Decomposition Algorithm – Singular Value Decomposition

Juan M. Rius; J. Parron; A. Heldring; José M. Tamayo; Eduard Ubeda

The multilevel matrix decomposition algorithm (MLMDA) was originally developed by Michielsen and Boag for 2D TMz scattering problems and later implemented in 3D by Rius et al. The 3D MLMDA was particularly efficient and accurate for piece-wise planar objects such as printed antennas. However, for arbitrary 3D problems it was not as efficient as the multilevel fast multipole algorithm (MLFMA) and the matrix compression error was too large for practical applications. This paper will introduce some improvements in 3D MLMDA, like new placement of equivalent functions and SVD postcompression. The first is crucial to have a matrix compression error that converges to zero as the compressed matrix size increases. As a result, the new MDA-SVD algorithm is comparable with the MLFMA and the adaptive cross approximation (ACA) in terms of computation time and memory requirements. Remarkably, in high-accuracy computations the MDA-SVD approach obtains a matrix compression error one order of magnitude smaller than ACA or MLFMA in less computation time. Like the ACA, the MDA-SVD algorithm can be implemented on top of an existing MoM code with most commonly used Greens functions, but the MDA-SVD is much more efficient in the analysis of planar or piece-wise planar objects, like printed antennas.


IEEE Transactions on Antennas and Propagation | 2007

Fast Direct Solution of Method of Moments Linear System

Alex Heldring; Juan M. Rius; José M. Tamayo; J. Parron; Eduard Ubeda

A fast direct (non iterative) solution method for the method of moments (MoM) in electromagnetics is proposed. The method uses the well known matrix decomposition method (MDA) and singular value decomposition (SVD) to achieve block-wise compression of the MoM impedance matrix, followed by a block-wise LU factorization that preserves the initial compression. A number of examples are presented involving problems ranging from ten to seventy thousand unknowns.


IEEE Transactions on Geoscience and Remote Sensing | 2006

On the Usage of GRECOSAR, an Orbital Polarimetric SAR Simulator of Complex Targets, to Vessel Classification Studies

Gerard Margarit; Jordi J. Mallorqui; Juan M. Rius; Jesus Sanz-Marcos

This paper presents a synthetic aperture radar (SAR) simulator that is able to generate polarimetric SAR (POLSAR) and polarimetric inverse SAR data of complex targets. It solves the electromagnetic problem via high-frequency approximations, such as physical optics and the physical theory of diffraction, with notable computational efficiency. In principle, any orbital monostatic sensor working at any band, resolution, and operating mode can be modeled. To make simulations more realistic, the targets bearing and speed are considered, and for the particular case of vessels, even the translational and rotational movements induced by the sea state. All these capabilities make the simulator a powerful tool for supplying large amounts of data with precise scenario information and for testing future sensor configurations. In this paper, the usefulness of the simulator on vessel classification studies is assessed. Several simulated polarimetric images are presented to analyze the potentialities of coherent target decompositions for classifying complex geometries, thus basing an operational algorithm. The limitations highlighted by the results suggest that other approaches, like POLSAR interferometry, should be explored


IEEE Transactions on Antennas and Propagation | 2006

Novel monopolar MFIE MoM-discretization for the scattering analysis of small objects

Eduard Ubeda; Juan M. Rius

We present a novel method of moments (MoM)-magnetic field integral equation (MFIE) discretization that performs closely to the MoM-EFIE in the electromagnetic analysis of moderately small objects. This new MoM-MFIE discretization makes use of a new set of basis functions that we name monopolar Rao-Wilton-Glisson (RWG) and are derived from the RWG basis functions. We show for a wide variety of small objects -curved and sharp-edged-that the new monopolar MoM-MFIE formulation outperforms the conventional MoM-MFIE with RWG basis functions.


Microwave and Optical Technology Letters | 1999

Multilevel matrix decomposition algorithm for analysis of electrically large electromagnetic problems in 3-D

Juan M. Rius; J. Parron; Eduard Ubeda; Juan R. Mosig

Reference LEMA-ARTICLE-1999-010doi:10.1002/(SICI)1098-2760(19990805)22:3 3.0.CO;2-2 Record created on 2006-11-30, modified on 2016-08-08

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Eduard Ubeda

Polytechnic University of Catalonia

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A. Heldring

Polytechnic University of Catalonia

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José M. Tamayo

Polytechnic University of Catalonia

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J. Parron

Autonomous University of Barcelona

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J. Romeu

Polytechnic University of Catalonia

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Angel Cardama

Polytechnic University of Catalonia

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Ivan Sekulic

Polytechnic University of Catalonia

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Alex Heldring

Delft University of Technology

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Alex Heldring

Delft University of Technology

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Juan R. Mosig

École Polytechnique Fédérale de Lausanne

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