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Electromagnetic Scattering Problems (electromagnetic + scattering_problem)

Distribution by Scientific Domains

Engineering	90%

Selected Abstracts

Electromagnetic scattering problems solved by an improved spectral iteration technique

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2001
Sandra Costanzo
Abstract The spectral iteration technique is used to solve electromagnetic scattering problems. A detailed analysis is carried out to investigate the convergence properties of the procedure, and a static solution is proposed as an initial estimate of the current to solve divergence problems. Diffraction by strips is considered to validate the method. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 384,388, 2001. [source]

A study of uniform approximation of equivalent permittivity for index-modulated gratings

ELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 11 2008
Shota Sugano
Abstract It is well known that surface-relief dielectric gratings with rectangular profile can be treated by uniform approximation of the equivalent permittivity when the periodicity is very small compared with the wavelength. In optics, this phenomenon is the equivalent anisotropic effects or the form birefringence. When the periodicity is very small, the equivalent anisotropic effects will be shown in index-modulated gratings. In this paper, the uniform approximation is described for the electromagnetic scattering problem of index-modulated gratings. The scattering properties of dielectric slabs are calculated by transmission-line theory and the equivalent permittivity obtained from our proposed formulation of the uniform approximation. Scattering by index-modulated gratings is analyzed rigorously by matrix eigenvalue calculations using the Fourier expansion method and spatial harmonics expansions. When the periodicity is very small, the results are in good agreement. By investigating the difference between the equivalent permittivity and the numerical values corresponding to the permittivity of the index-modulated gratings, the conditions of applicability of the uniform approximation are shown. The equivalent anisotropic effects of various profiles are compared. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(11): 28,36, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10181 [source]

A time-marching finite element method for an electromagnetic scattering problem

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 12 2003
Tri Van
Abstract In this paper, Newmark time-stepping scheme and edge elements are used to numerically solve the time-dependent scattering problem in a three-dimensional polyhedral cavity. Finite element methods based on the variational formulation derived in Van and Wood (Adv. Comput. Math., to appear) are considered. Existence and uniqueness of the discrete problem is proved by using Babuska,Brezzi theory. Finite element error estimate and stability of the Newmark scheme are also established. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Physics-based preconditioner for iterative algorithms in multi-scatterer and multi-boundary method of moments formulations

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2002
Jürgen v. Hagen
Abstract An efficient method to solve electromagnetic scattering problems involving several metallic scatterers or bodies composed of dielectric and metallic regions is proposed. So far, the method of moments has successfully been applied to large arrays of identical scatterers when it was combined with preconditioned iterative algorithms to solve for the linear system of equations. Here, the method is generalized to geometries that are composed of several metallic elements of different shapes and sizes, and also to scatterers that are composed of metallic and dielectric regions. The method uses in its core an iterative algorithm, preferably the transpose-free quasi-minimum residual (TFQMR) algorithm, and a block diagonal Jacobi preconditioner. For best performance, the blocks for the preconditioner are chosen according to individual scatterers or groups of scatterers for the array case, and according to the electric and magnetic current basis functions for dielectric/metallic scatterers. The iterative procedure converges quickly for an optimally chosen preconditioner, and is robust even for a non-optimal preconditioner. Reported run times are compared to run times of an efficiently programmed LU factorization, and are shown to be significantly lower. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Multilevel fast multipole algorithm enhanced by GPU parallel technique for electromagnetic scattering problems

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2010
Kan Xu
Abstract Along with the development of graphics processing Units (GPUS) in floating point operations and programmability, GPU has increasingly become an attractive alternative to the central processing unit (CPU) for some of compute-intensive and parallel tasks. In this article, the multilevel fast multipole algorithm (MLFMA) combined with graphics hardware acceleration technique is applied to analyze electromagnetic scattering from complex target. Although it is possible to perform scattering simulation of electrically large targets on a personal computer (PC) through the MLFMA, a large CPU time is required for the execution of aggregation, translation, and deaggregation operations. Thus GPU computing technique is used for the parallel processing of MLFMA and a significant speedup of matrix vector product (MVP) can be observed. Following the programming model of compute unified device architecture (CUDA), several kernel functions characterized by the single instruction multiple data (SIMD) mode are abstracted from components of the MLFMA and executed by multiple processors of the GPU. Numerical results demonstrate the efficiency of GPU accelerating technique for the MLFMA. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 502,507, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24963 [source]

Shifted SSOR preconditioning technique for electromagnetic wave scattering problems

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2009
J. Q. Chen
Abstract To efficiently solve large dense complex linear system arising from electric field integral equations (EFIE) formulation of electromagnetic scattering problems, the multilevel fast multipole method (MLFMM) is used to accelerate the matrix-vector product operations. The symmetric successive over-relaxation (SSOR) preconditioner is constructed based on the near-field matrix of the EFIE and employed to speed up the convergence rate of iterative methods. This technique can be greatly improved by shifting the near-field matrix of the EFIE with the principle value term of the magnetic field integral equation (MFIE) operator. Numerical results demonstrate that this method can reduce both the number of iterations and the computational time significantly with low cost for construction and implementation of preconditioners. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1035,1039, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24254 [source]

Further comments on the performances of finite element simulators for the solution of electromagnetic problems involving metamaterials

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2006
Gaia Cevini
Abstract In this paper, we analyze the performances of three-dimensional finite element (FE) simulators in handling electromagnetic scattering problems involving metamaterials. It has already been proved that the performances of the FE method are worse than usual, when metamaterials are considered. In this work, we extend our previous analysis by providing some additional results on the precision of the FE solution and on the performances of the iterative and direct solvers typically used with FE simulators. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:2524,2529, 2006; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22008 [source]

Assessment of the performances of first- and second-order time-domain ABC's for the truncation of finite element grids

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2003
Salvatore Caorsi
Abstract In this paper we investigate the performances of first- and second-order time-domain absorbing boundary conditions (ABCs) when introduced in a finite-element algorithm to solve electromagnetic scattering problems. Attention is focused on the analysis of the ABC's absorbing characteristics when different geometries are considered for the truncation of the computational domain. Numerical results will be given by considering, as a first analysis, two-dimensional scattering problems. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 11,16, 2003 [source]

Use of wavelet transform to the method-of-moments matrix arising from electromagnetic scattering problems of 2D objects due to oblique plane-wave incidence

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2002
Jin Yu
Abstract An efficient method is presented for transforming the matrix of the method of moments obtained by the expansion of the unknown surface currents with pulse basis function and the use of point match testing to a matrix with wavelet basis and testing functions. When the electromagnetic scattering object is a dielectric or object under oblique plane-wave incidence, more than one equivalent surface current component exists at the object surface. When these currents are connected into one current vector in the method of moments, there must be some discontinuities between the current components. These discontinuities make the direct wavelet transform to the whole MoM matrix inefficient and not equivalent to the use of the wavelet functions in the expansion of the unknown currents and the testing. Therefore, the wavelet transform must be constructed in a different way to avoid these discontinuities. Here, the proper wavelet transform that is equivalent to the use of the wavelet functions in the MoM, which avoids such discontinuities, is presented. This transform is referred to as wavelet subtransform. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 130,134, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10394 [source]