Felipe Catedra

Felipe Catedra
University of Alcalá | UAH · Department of Computer Sciences

About

270
Publications
10,423
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2,407
Citations
Citations since 2016
33 Research Items
645 Citations
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120

Publications

Publications (270)
Article
Full-text available
This work details a technique tailored to the analysis of complex radome structures based on the non-overlapping separation of two different domains: antenna and radome. Both domains are analyzed isolated using the method of moments with the multilevel fast multipole algorithm (MoM-MLFMA) for the antenna domain and a modified characteristic basis f...
Article
Full-text available
A refinement for the computation of the rigorous part of the multi-level fast multipole method (MLFMM) of analyzing volumetric objects is presented. A scheme based on the fast Fourier technique (FFT) is proposed with the objective of reducing the computational resources required to accurately analyze large homogeneous and non-homogeneous dielectric...
Article
We present a new approach for the analysis and design of radome structures. It makes use of extended domain macro-basis functions obtained from the Characteristic Basis Function Method in order to represent the current distribution over the radome. This involves computational advantages due to the reduction of the number of unknowns compared to con...
Article
Full-text available
A comparison between Ma-Rokhlin-Wandzura (MRW) and double exponential (DE) quadrature rules for numerical integration of method of moments (MoM) matrix entries with singular behavior is presented for multilayer periodic structures. Non Uniform Rational B-Splines (NURBS) modelling of the layout surfaces is implemented to provide high-order descripti...
Article
This paper presents a technique for the computation of the monostatic Radar Cross Section of complex objects based on a combination of Macro-Basis Functions and the Multilevel Fast Multipole Algorithm. An initial pool of excitation-independent Macro Basis Functions are first obtained, generating the corresponding reduced coupling matrix as well as...
Article
Full-text available
Fast computation of the coefficients of the reduced impedance matrix of the method of moment (MM) is proposed by expanding the basis functions (BFs) in pulses and solving an equivalent periodic problem (EPP) for analyzing large multilayer structures with non-uniform rational basis spline (NURBS) modeling of the embedded layout. These coefficients a...
Article
Full-text available
An evaluation of monostatic radar cross section (RCS) response in the near-field range was performed for several targets with different and complex topologies. The main objective was to provide and validate an efficient tool based on electromagnetic (EM) simulations to characterize a traffic scenario. Thus, a novel method based on the combination o...
Article
Full-text available
BICGSTAB-FFT method of moment (MM) scheme is proposed to analyze several levels of planar generic layouts embedded in large multilayer structures when the layout geometries are modeled by NURBS surfaces. In this scheme, efficient computation of normalized error defined in iterative bi-conjugate gradient stabilized (BICGSTAB) method for large multil...
Article
Full-text available
In recent years, the characteristic basis function method has been developed as an efficient approach for the solution of large electromagnetic radiation or scattering problems. According to this technique, the currents over the scenario under analysis are defined using a set of pre‐computed characteristic basis functions, associated with a number...
Article
Full-text available
This work presents an efficient approach for the generation of distributed Sparse Approximate Inverse preconditioners based on the near‐field coupling information for the analysis of electromagnetic problems on large computing clusters. This scheme combines the Message Passing Interface and Open Multi‐Processing paradigms in order to minimise the C...
Article
Full-text available
In this paper, an efficient technique of computation of method of moments (MM) matrix entries for multilayer periodic structures with NURBS surface and Bézier patches modelling is proposed. An approximation in terms of constant pulses of generalized rooftop basis functions (BFs) defined on Bézier patches is proposed. This approximation leads discre...
Article
This work presents an efficient approach for the electromagnetic analysis of complex scenarios involving transmitting antennas moving along predetermined trajectories. In order to efficiently reduce the size of the problem for each position of the antenna we propose a technique based on Macro Basis Functions that are dynamically generated using a R...
Article
Full-text available
The multilevel fast multipole algorithm is a popular technique that enables the efficient solution of the method of moments (MoM) matrix equations. In this work, the authors address the adaptation of this method to the compute unified device architecture (CUDA), a relatively new computing infrastructure provided by NVIDIA, and the authors take into...
Article
This document presents a technique for the full-wave analysis of large problems using the Method of Moments, in combination with the Multilevel Fast Multipole Algorithm, based on a decomposition of the scenario into two domains using a ray-tracing analysis. These domains are computed considering the proximity to the critical points. The currents ov...
Article
Full-text available
Multi-beams antennas are currently being used for direct broadcast satellite, personal communication satellite, military communication satellite, and high-speed internet applications. In this work, a circularly polarized (CP) multi-spot beam satellite parabolic reflectarray antenna is designed to provide six spot beams at 19.7 GHz. For this purpose...
Article
The concept of generating two spaced beams in dual-CP by variable rotation technique (VRT) is validated for first time by manufacturing and measuring. A reflectarray demonstrator has been designed, manufactured and tested to deviate ±10° the beam of a dual-CP multi-flared horn at 19.7 GHz. The proposed reflectarray cell for VRT is made of a conduct...
Article
A technique for the reduction of the CPU-time in the solution of scattering problems using the Characteristic Basis Function Method (CBFM) is presented. It is suitable to analyze electrically very large cases in which an iterative solution process cannot be avoided, even considering the reduction of the size of the matrix achieved by the CBFM. This...
Article
An approach for the generation of Macro Basis Functions considering the directivity of the sources and the ray-tracing characteristics of the scenario is described in this work. The number of basis functions generated is highly optimized by dynamically generating the threshold to be applied for the retrieval of the Macro Basis Functions after the a...
Article
This work presents a technique that allows a very noticeable relaxation of the computational requirements for full-wave electromagnetic simulations based on the Method of Moments. A ray-tracing analysis of the geometry is performed in order to extract the critical points with significant contributions. These points are then used to generate a reduc...
Article
A technique to reduce the CPU-time and computer memory spent in scattering electromagnetic problems when using the Characteristics Basis Function Method (CBFM) combined with the Multilevel Fast Multipole Algorithm (MLFMA) is presented. It is intended for use in very large cases where an iterative solution process cannot be avoided, even considering...
Article
An efficient approach for the generation of sparse preconditioners, tailored for the application of Macro Basis Function methods, is described in this work. The preconditioner is highly scalable and generated by computing groups of rows that share a common sparsity pattern, calculated by using a distance threshold among geometrical blocks that cont...
Article
This document presents a technique that allows an efficient selection of the number of Macro Basis Functions for each block by assigning dynamic thresholds applied after the Singular Value Decomposition of the currents induced by the Plane Wave Spectrum. It makes use of a ray-tracing pre-processing of the scenario, where a number of critical points...
Article
Full-text available
This document presents a technique for the generation of Sparse Inverse Preconditioners based on the near field coupling matrices of Method of Moments simulations where the geometry has been partitioned in terms of regions. A distance parameter is used to determine the sparsity pattern of the preconditioner. The rows of the preconditioner are compu...
Article
An improved ray-tracing method applied to high-frequency techniques such as the Uniform Theory of Diffraction (UTD) is presented. The main goal is to increase the speed of the analysis of complex structures while considering a vast number of observation directions and taking into account multiple bounces. The method is based on a combination of the...
Article
Most computer codes in Radar Cross Section (RCS) prediction use Physical Optics (PO) and Physical theory of Diffraction (PTD) combined with Geometrical Optics (GO) and Geometrical Theory of Diffraction (GTD). The latter approaches are computationally cheaper and much more accurate for curved surfaces, but not applicable for the computation of the R...
Article
A method for the rigorous computation of the electromagnetic scattering of large dielectric volumes is presented. One goal is to simplify the analysis of large dielectric targets with translational symmetries taken advantage of their Toeplitz symmetry. Then, the matrix-fill stage of the Method of Moments is efficiently obtained because the number o...
Conference Paper
The analysis of collision avoidance systems in real traffic urban scenarios represent a challenge for computational electromanetics due to its multiscale nature. An approach for solving this problem based on a combination of Multi-Level Fast Multipole Method (MLFMM), Characteristic Basis Functions (CBF), Physical Optics (PO) and Geometrical Theory...
Conference Paper
An overview of some different numerical solvers such us PO (Physical Optics) GTD (Geometrical Theory of Diffraction), UTD (Uniform Theory of Diffraction), MoM (Method of Moments), MLFMM (Multilevel Fast Multipole Method), etc, for the analysis of the electromagnetic scattering by wind turbines will be presented. The applications of these methods to...
Article
This work presents a multilevel technique developed for speeding-up efficiently the mesh generation process of large and complex bodies for electromagnetic analysis. The targets are meshed by generating intermediate meshes with elements of decreasing size edge until the desired size is reached. The technique minimizes the time of meshing any given...
Article
A new method to design Fresnel Zone Plate Antennas (FZPA) is presented in this paper. The proposed method is based on deforming a flat metallic surface in order to achieve the desired phase distribution required to point the main beam to a certain direction. The resulting shaped reflector is modeled by using parametric surfaces, since they allow fi...
Article
Full-text available
This paper presents an evolution of the challenges and solutions found in the application of techniques based on the Method of Moments until the present day. The original MoM presented very high computational restrictions that have motivated the development of more efficient approaches. The main features of these newer improvements are presented, a...
Article
This work deals with the design, analysis, and measurement of a novel multibeam reflector feed at X band. The whole system is composed of a five-horn array and two layers of electromagnetic bandgap (EBG) material. The goal of this antenna is to obtain high gain over a wide bandwidth, while maintaining a compact size. An efficient optimization proce...
Article
Full-text available
This paper proposes a hybrid technique for treating electromagnetic problems of scattering and radiation in which the source structure is described as an array of antennas. This strategy is based on the combination of the rigorous method multilevel fast multipole algorithm (MLFMA) and the high frequency technique geometrical theory of diffraction (...
Chapter
Nowadays, the parallelization of computer codes plays a very important role, because it enables codes to run on multiple processors, resulting in considerable time-saving if the algorithm scales efficiently as the number of processors is increased progressively. The CBFM is specially well-suited for parallelization. In this chapter, it is showed so...
Article
A metal-only Fresnel zone plate antenna (FZPA) to operate at millimetre wave frequency bands is presented in this work. The proposed antenna is a very attractive alternative to parabolic reflectors and reflectarrays because of its several advantages such as low profile, low cost, easy to manufacture and lossless. A centre-fed Fresnel zone plate who...
Article
Full-text available
The characteristic basis function method (CBFM) is a popular technique for efficiently solving the method of moments (MoM) matrix equations. In this work, we address the adaptation of this method to a relatively new computing infrastructure provided by NVIDIA, the Compute Unified Device Architecture (CUDA), and take into account some of the limitat...
Article
The analysis of dielectric volumes by using the Moment Method is presented in this paper. The discretization with tetrahedrons or hexahedra are the most common techniques for analyzing dielectric volumes with this technique. The simplest methods for the mesh generation and the analysis work with flat elements (every faces of the tetrahedrons or hex...
Article
A novel optimization method to design the layout of printed reflectarrays for multibeam operation is presented in this paper. The proposed approach allows using different classes of cell elements to design the layout of reflectarrays. Therefore, phase curves do not have to fulfill the requirement of having a phase range wider than 360°. The dimensi...
Chapter
An efficient technique for solving large electromagnetic problems, called Characteristic Basis Function Method (CBFM), is presented. It is a rigorous technique, based on Method of Moments (MoM), which can solve electrically very large problems using less computer resources than MoM. The key step in the CBFM consists of defining a relatively small n...
Article
This letter investigates the effect of varying the feed position along the focal axis on the performance of a conformed Fresnel zone reflector. Bandwidth and aperture efficiency are analyzed by illuminating the proposed reflector antenna with a pyramidal horn at Ku band. The antenna under study is a new type of Fresnel zone plate antenna that, comp...
Article
Full-text available
The rapid growth in wireless communications has led to the need for an effective way to evaluate the radio propagation. Dense urban areas and indoor spaces tend to be complex environments that require a lot of obstacles to be modeled. In such environments, the radio propagation is an extremely complex phenomenon and ray tracing techniques have been...
Conference Paper
A new tool for the analysis and design of radomes using multicore processors is presented. The radomes can be defined by multilayer structures with embedded Frequency Selective Surfaces (FSS). Radome with metallic layers with arbitrarily shaped can be also analyzed. Four different approaches can be used for the analyses of the radomes: Iterative Ph...
Article
An offset-fed reflectarray antenna composed of single-layer elements based on the combination of circular and square concentric rings of variable size is presented in this paper. The characteristics of the elementary cells have been optimized providing a lineal phase curve with a phase range higher than 360 degrees. The 297 x 297 mm reflectarray ha...
Conference Paper
This paper presents the latest developments in NewFasant Suite: the Reflectarray module to design, analyze and optimize reflectarray antennas, the Ultra-conformed Reflector module to create and simulate conformed reflectors that can fit any complex shape, and the Radome module to design and analyze radomes. The three new modules are presented with...
Article
This work presents the design and analysis of a modified Fresnel zone plate reflector for broadband operation. A new technology based on slight deformations on a flat metallic surface is applied to obtain the geometrical model of the proposed flat reflector antenna. In comparison with reflectarrays, Fresnel zone reflectors are lossless, low cost, e...
Conference Paper
The main goal of this paper is to characterize the radio channel propagation model of studying the impulse response. The observation points have been located along two different areas in the city of Madrid, to analyse LOS and NLOS paths. In order to obtain accurate results the geometry has been modelled with NURBS surfaces, since these allow us to...
Conference Paper
In order to satisfy the demand of the automotive industry about anti-collision systems, related to the protection of pedestrians and drivers, this paper proposes the development of an algorithm that achieves a dynamic analysis of urban scenarios. Typically, some objects of these scenarios can have a translation and/or rotation movement. For each sa...
Article
An extremely low cross-polarization reflectarray antenna is presented. The new reflectarray antenna is composed of one simple layer of variable sized T-crosses embedded in a homogeneous dielectric medium. A full wave code based on the Moment Method has been used to perform the analyses. The proposed antenna is an excellent candidate for many applic...
Article
This communication presents two efficient approaches for the electromagnetic field analysis of complex 3D bodies. The first method can provide a fast and accurate analysis of arbitrary metallic and dielectric/magnetic structures and combines the moment method (MM), the multilevel fast multipole algorithm (MLFMA), physics optics (PO) and the charact...
Article
In this paper, we propose a technique for the electromagnetic analysis of large objects considering the interactions between separate parts of the geometry (which in this context will be referred to as domains). A number of unknowns is associated to each domain, and only the basis functions included within the same domain are considered fully coupl...
Article
Different schemes for the parallelization of a new algorithm to accelerate the Ray-Tracing for computing the electrical field radiated from or scattered by complex objects using high frequency techniques are presented. This algorithm is based on a combination of the Angular ZZ-Buffer (AZB), the Space Volumetric Partitioning (SVP) and the A*Heuristi...
Article
Full-text available
This paper presents a complete assessment to the interferences caused in the nearby radio systems by wind turbines. Three different parameters have been considered: the scattered field of a wind turbine, its radar cross-section (RCS), and the Doppler shift generated by the rotating movements of the blades. These predictions are very useful for the...
Article
Full-text available
An efficient approach for the analysis of surface conformed reflector antennas fed arbitrarily is presented. The near field in a large number of sampling points in the aperture of the reflector is obtained applying the Geometrical Theory of Diffraction (GTD). A new technique named Master Points has been developed to reduce the complexity of the ray...
Article
This paper presents the design and analysis of a broadband high gain reflectarray antenna based on a novel radiating element, named spiral cross, that has been investigated showing high performance capabilities. The unit cell and the reflectarray antenna have been analyzed by using a full-wave Moment Method code. The proposed antenna exhibits excel...
Article
Cited By (since 1996):2, Export Date: 28 November 2013, Source: Scopus, CODEN: JCSOE, Language of Original Document: English, Correspondence Address: Tayebi, A.; Department of Computer Science, University of Alcalá, Alcalá de Henares, Madrid, 28805, Spain; email: hamid.tayebi@uah.es, References: Devireddy, B., Yu, A., Yang, F., Elsherbeni, A.Z., Ga...
Conference Paper
A new technique to optimize the performance of the analysis of open objects with the Method of Moments is presented in this work. The objective is to convert these objects, which should be simulated with the Electric Field Integral Equation, to objects made of two parallel near layers that can be considered as a closed volume and, therefore, analys...
Conference Paper
New modules and features included in NEWFASANT computer suite are described. NEWFASANT is an electromagnetic simulator parallelized for multiprocessors. The tool includes its own Graphical User Interface, Geometrical Editor, parallelized multilevel meshers, visualizations features and parameter optimization features. The code permits analysis and d...
Article
A compact dual-band equatorial helical antenna for TTC (telemetry, tracking, and control) applications in satellites is presented. The network feeding system of the antenna was also designed, analyzed, and measured to achieve circular polarization. A Moment Method code was used to evaluate the performance of both the helical antenna and the feed-ci...
Conference Paper
Conference code: 94243, Export Date: 28 November 2013, Source: Scopus, Art. No.: 6348503, CODEN: IAPSB, doi: 10.1109/APS.2012.6348503, Language of Original Document: English, Correspondence Address: Gomez, J.; Computer Science Department, University of Alcalá, Alcalá de Henares, Madrid, Spain; email: josefa.gomezp@uah.es, References: Hu, S., Liu, Z...
Conference Paper
A technique based on Characteristics Basis Function Method (CBFM) combined with Multilevel Fast Multipole Algorithm (MLFMA) is presented. The goal of the technique is to reduce the CPU-time and computer memory spent in electromagnetic problems solution. The technique kernel is to use he only the CBFs with a significant excitation. Results show that...
Conference Paper
Useful techniques and features included in NEWFASANT computer tool are described. NEWFASANT is parallelized for multiprocessors/GPUs computers and can treat metallic, dielectric and magnetic material. The tool includes its own Graphical User Interface, Geometrical Editor, parallelized multilevel meshers for surfaces and volumes, visualizations feat...
Conference Paper
An approach for computing efficiently monostatic and/or bistatic radar cross section of complex target on an infinite perfect electric conductor or dielectric ground plane is presented. The approach is based on Physical Optics and Equivalent Currents Method together with the Image Theory. The last one is used to obtain the scattering from the targe...