Showing papers on "Computational electromagnetics published in 2012"
Book•
06 Nov 2012
TL;DR: In this article, the authors introduce three of the most popular numerical methods for simulating electromagnetic fields: the finite difference method, the finite element method and the method of moments, focusing on how these methods are used to obtain valid approximations to the solutions of Maxwell's equations, using, for example, "staggered grids" and edge elements.
Abstract: Computational Electromagnetics is a young and growing discipline, expanding as a result of the steadily increasing demand for software for the design and analysis of electrical devices. This book introduces three of the most popular numerical methods for simulating electromagnetic fields: the finite difference method, the finite element method and the method of moments. In particular it focuses on how these methods are used to obtain valid approximations to the solutions of Maxwell's equations, using, for example, "staggered grids" and "edge elements." The main goal of the book is to make the reader aware of different sources of errors in numerical computations, and also to provide the tools for assessing the accuracy of numerical methods and their solutions. To reach this goal, convergence analysis, extrapolation, von Neumann stability analysis, and dispersion analysis are introduced and used frequently throughout the book. Another major goal of the book is to provide students with enough practical understanding of the methods so they are able to write simple programs on their own. To achieve this, the book contains several MATLAB programs and detailed description of practical issues such as assembly of finite element matrices and handling of unstructured meshes. Finally, the book aims at making the students well-aware of the strengths and weaknesses of the different methods, so they can decide which method is best for each problem. In thissecond edition, extensive computer projects are added as well as new material throughout. Reviews of previous edition: "The well-written monograph is devoted to students at the undergraduate level, but is also useful for practising engineers." (Zentralblatt MATH, 2007)
322 citations
TL;DR: A novel stochastic modeling strategy is constructed that allows assessment of the parameter variability effects induced by the manufacturing process of on-chip interconnects, demonstrating its accuracy and efficiency.
Abstract: In this paper, a novel stochastic modeling strategy is constructed that allows assessment of the parameter variability effects induced by the manufacturing process of on-chip interconnects. The strategy adopts a three-step approach. First, a very accurate electromagnetic modeling technique yields the per unit length (p.u.l.) transmission line parameters of the on-chip interconnect structures. Second, parameterized macromodels of these p.u.l. parameters are constructed. Third, a stochastic Galerkin method is implemented to solve the pertinent stochastic telegrapher's equations. The new methodology is illustrated with meaningful design examples, demonstrating its accuracy and efficiency. Improvements and advantages with respect to the state-of-the-art are clearly highlighted.
100 citations
TL;DR: In this article, the path loss exponent in cellular wireless communication is three, preceded by a slow-fading region, and followed by the fringe region, where the path-loss exponent is four.
Abstract: The objective of this paper is to illustrate that electromagnetic macro modeling can properly predict the path-loss exponent in mobile cellular wireless communication. This represents the variation of the path loss with distance from the base-station antenna. Specifically, we illustrate that the path-loss exponent in cellular wireless communication is three, preceded by a slow-fading region, and followed by the fringe region, where the path-loss exponent is four. The sizes of these regions are determined by the heights of the base-station transmitting antennas and the receiving antennas. Theoretically, this is illustrated through the analysis of radiation from a vertical electric dipole situated over a horizontal imperfect ground plane, as first considered by Sommerfeld in 1909. To start with, the exact analysis of radiation from the dipole is made using the Sommerfeld formulation. The semi-infinite integrals encountered in this formulation are evaluated using a modified saddle-point method for field points moderate to far distances away from the source point, to predict the appropriate path-loss exponents. The reflection-coefficient method is also derived by applying a saddle-point method to the semi-infinite integrals, and this is shown to not provide the correct path-loss exponent that matches measurements. The various approximations used to evaluate the Sommerfeld integrals are described for different regions. It is also important to note that Sommerfeld's original 1909 paper had no error in sign. However, Sommerfeld overlooked the properties associated with the so-called “surface-wave pole.” Both accurate numerical analyses, along with experimental data, are provided to illustrate the above statements. In addition, Okumura's experimental data, and extensive data taken from seven different base stations in urban environments at two different frequencies, validate the theory. Experimental data revealed that a macro modeling of the environment, using an appropriate electromagnetic analysis, can accurately predict the path-loss exponent for the propagation of radio waves in a cellular wireless communication scenario.
89 citations
TL;DR: In this article, the equivalence principle was used to cancel the electromagnetic scattering of an object by using an array of sources by superimposing magnetic and electric surface current densities at the boundary of the object.
Abstract: Electromagnetic cloaking refers to the ability to prevent an object from scattering an incident electromagnetic field This has been accomplished in recent works by specially designed materials Another way of cloaking using sources has been known in the acoustics community In this letter, we introduce a prescription for canceling the electromagnetic scattering of an object by using an array of sources By using the equivalence principle, we show that by superimposing magnetic and electric surface current densities at the boundary of an object, the scattered fields from that object can be canceled These magnetic and electric surface currents can be discretized into electric and magnetic dipoles that are physically implementable by straight and loop wire antennas Finally, we confirm our results using numerical simulations
85 citations
TL;DR: The proposed approach employs a graphics processing unit (GPU) for both numerical integration and matrix assembly and results indicate that the GPU implementation of the matrix generation allows one to achieve speedups by a factor of 81 and 19 over the optimized single- and multi-threaded CPU-only implementations, respectively.
Abstract: This paper presents an e-cient technique for fast gener- ation of sparse systems of linear equations arising in computational electromagnetics in a flnite element method using higher order ele- ments. The proposed approach employs a graphics processing unit (GPU) for both numerical integration and matrix assembly. The per- formance results obtained on a test platform consisting of a Fermi GPU (1x Tesla C2075) and a CPU (2x twelve-core Opterons), indicate that the GPU implementation of the matrix generation allows one to achieve speedups by a factor of 81 and 19 over the optimized single- and multi-threaded CPU-only implementations, respectively.
76 citations
Posted Content•
TL;DR: Methods for electromagnetic wave propagation, based on splines and on T-splines are introduced, and the theory is extended to the case of meshes with T-junctions, leveraging on the recent theory of T- Splines.
Abstract: In this paper we introduce methods for electromagnetic wave propagation, based on splines and on T-splines. We define spline spaces which form a De Rham complex and, following the isogeometric paradigm, we map them on domains which are (piecewise) spline or NURBS geometries. We analyse their geometric structure, as related to the connectivity of the underlying mesh, and we give a physical interpretation of the fields degrees-of-freedom through the concept of control fields. The theory is then extended to the case of meshes with T-junctions, leveraging on the recent theory of T-splines. The use of T-splines enhance our spline methods with local refinement capability and numerical tests show the efficiency and the accuracy of the techniques we propose.
68 citations
TL;DR: In this paper, the authors derived analytical solutions for the magnetic fields generated by permanent magnets in terms of a magnetic vector potential and a two-dimensional (2D) polar coordinate system.
Abstract: This study is devoted to the analysis of the vibration characteristics of a permanent magnet synchronous motor (PMSM) through investigation into its electromagnetic vibration sources. For this purposed, we derive analytical solutions for the magnetic fields generated by permanent magnets (PMs) in terms of a magnetic vector potential and a two-dimensional (2-D) polar coordinate system. A 2-D permeance function is also introduced in order to consider slotting effects. The electromagnetic vibration sources such as torque ripple, cogging torque, and radial force density are analyzed using these solutions. The analytical results are validated extensively with finite element (FE) analyses. The fast Fourier transformation (FFT) analysis is employed for investigating the specific harmonic orders of the electromagnetic vibration sources that affect the vibration of the PMSM. Finally, mechanical modal analysis results and test results such as vibration measurements are obtained to confirm the validity of the analysis methods presented in this paper.
56 citations
TL;DR: The proposed MS-DDM is well suited for modeling multiple antennas conformally mounted on a large platform, where touching subregions are usually unavoidable and multiple existing CEM solvers have been successfully integrated with few minor modifications.
Abstract: We proposed herein a multisolver domain decomposition method (MS-DDM), and applied it to compute the isolations among multiple antennas mounted on a large air platform at X -band frequency. The fundamental strategy of the proposed MS-DDM is to decompose the entire computational domain into many subregions based on the local material properties and geometrical features. Subsequently, we employ the most suitable computational electromagnetic (CEM) technique for each of the subregions. Moreover, the coupling between well-separated subregions is implemented through Stratton-Chu representation formulas. However, for the touching interfaces between neighboring subregions, a Robin transmission condition is introduced to mitigate the troublesome self-integral terms with weak singular kernels. The proposed MS-DDM is, therefore, well suited for modeling multiple antennas conformally mounted on a large platform, where touching subregions are usually unavoidable. Furthermore, by using the proposed MS-DDM framework, multiple existing CEM solvers have been successfully integrated with few minor modifications.
55 citations
TL;DR: In this article, an efficient implementation of the hybrid method of moments (MoM)-physical optics (PO) hybrid technique is presented to avoid the calculation of the PO contribution in matrix form for electrically large objects.
Abstract: The conventional hybrid method of moments (MoM)-physical optics (PO) technique provides a possible way to handle electrically large objects with affordable computer memory However, its efficiency is not very good because the evaluation of the PO contribution to the MoM impedance matrix is very time-consuming An efficient implementation of the iterative MoM-PO hybrid technique is presented in this paper to avoid the calculation of the PO contribution in matrix form For electrically large objects, the proposed efficient iterative MoM-PO (EI-MoM-PO) method can greatly reduce the computational time and maintain the same or better accuracy with the same number of unknowns compared with the conventional MoM-PO method Several examples of large-scale structures are analyzed by the EI-MoM-PO method, the conventional MoM-PO method, and the multilevel fast multipole algorithm The excellent efficiency and accuracy are achieved by the proposed EI-MoM-PO technique
51 citations
TL;DR: In this article, the authors re-examine the solution to this equation using the undifferentiated form of the time domain electric field integral equation (TDEFIE) and a separable approximation to the spatio-temporal convolution.
Abstract: The state of art of time domain integral equation (TDIE) solvers has grown by leaps and bounds over the past decade. During this time, advances have been made in (i) the development of accelerators that can be retrofitted with these solvers and (ii) understanding the stability properties of the electric field integral equation. As is well known, time domain electric field integral equation solvers have been notoriously difficult to stabilize. Research into methods for understanding and prescribing remedies have been on the uptick. The most recent of these efforts are (i) Lubich quadrature and (ii) exact integration. In this paper, we re-examine the solution to this equation using (i) the undifferentiated form of the time domain electric field integral equation (TDEFIE) and (ii) a separable approximation to the spatio-temporal convolution. The proposed scheme can be constructed such that the spatial integrand over the source and observer domains is smooth and integrable. As several numerical results will demonstrate, the proposed scheme yields stable results for long simulation times and a variety of targets, both of which have proven extremely challenging in the past.
50 citations
TL;DR: The radial point interpolation method (RPIM) as discussed by the authors is a meshless method based on radial basis functions, which allows to model fine geometrical details with high accuracy and facilitates the adaptation of node distributions for optimization or refinement purposes.
Abstract: Meshless methods are a promising new field in computational electromagnetics. Instead of relying on an explicit mesh topology, a numerical solution is computed on an unstructured set of collocation nodes. This allows to model fine geometrical details with high accuracy and facilitates the adaptation of node distributions for optimization or refinement purposes. The radial point interpolation method (RPIM) is a meshless method based on radial basis functions. In this paper, the current state of the RPIM in electromagnetics is reviewed. The localized RPIM scheme is summarized, and the interpolation accuracy is discussed in dependence of important parameters. A time-domain implementation is presented, and important time iteration aspects are reviewed. New formulations for perfectly matched layers and waveguide ports are introduced. An unconditionally stable RPIM scheme is summarized, and its advantages for hybridization with the classical RPIM scheme are discussed in a practical example. The capabilities of an adaptive time-domain refinement strategy based on the experiences on a frequency-domain solver are discussed. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this paper, a low-frequency approximation to the full set of the Maxwell equations is presented, where the displacement current density or induced current density are neglected depending on a priori knowledge about the dominating effects for a specific problem setup.
Abstract: For many technical examples, low-frequency approximations to the full set of the Maxwell equations are applicable. Commonly, either the displacement current density or the induced current density are neglected depending on a priori knowledge about the dominating effects for a specific problem setup. This leads to different subsets of the Maxwell equations describing inductive-resistive or capacitive-resistive systems, respectively. In this paper, a formulation combining both scenarios while maintaining the quasistationary assumption, i.e., without modeling wave propagation and radiation, is presented. The formulation is applied to a simple test model consisting of a bounded massive conductor embedded in a dielectric insulation.
TL;DR: A novel and efficient method of Moments matrix generation technique called the frequency and material independent reactions for the method of moments (FMIR-MoM) technique is presented, which efficiently calculates impedance matrices while sweeping through frequency, permittivity, conductivity, and/or permeability values.
Abstract: A novel and efficient method of moments (MoM) matrix generation technique called the frequency and material independent reactions for the method of moments (FMIR-MoM) technique is presented. This new matrix generation algorithm efficiently calculates impedance matrices while sweeping through frequency, permittivity, conductivity, and/or permeability values. For frequency sweeps it has computational and memory costs comparable to those of interpolation techniques. It has the advantage over interpolation techniques in that it does not divide the frequency range into segments and allows one to dynamically update the precision. The technique expands the exponential of the Green's function into a Taylor series. This allows the problem to be formulated as a summation, where each term consists of a real valued matrix depending only on the geometry (discretization), multiplied by a scalar dependent on the propagation constant. The algorithm's efficiency is obtained by calculating the geometry-dependent matrices prior to sweeping through frequency or material parameters.
TL;DR: In this paper, a general numerical algorithm, which is different from the commonly used discrete dipole approximation, the finite difference time-domain, and the surface integral equation (SIE) method, is proposed to model plasmonic nanostructures.
Abstract: The superior ability of plasmonic structures to manipulate light has propelled their extensive applications in nanophotonics techniques and devices. Computational electromagnetics plays a critical role in characterizing and optimizing the nanometallic structures. In this paper, a general numerical algorithm, which is different from the commonly used discrete dipole approximation, the finite-difference time-domain, and the surface integral equation (SIE) method, is proposed to model plasmonic nanostructures. In this algorithm, the generalized impedance boundary condition (GIBC) based on the finite element method (FEM) is formulated and converted to the SIE. The plasmonic nanostructures with arbitrary inhomogeneity and shapes are modeled by the FEM. Their complex electromagnetic interactions are accurately described by the SIE method. As a result, the near field of plasmonic nanostructures can be accurately calculated. The higher order basis functions, together with the multifrontal massively parallel sparse direct solver, are involved to provide a higher order accurate and fast solver.
TL;DR: A discontinuous Galerkin finite element method (DG-FEM) with a highly accurate time integration scheme for solving Maxwell equations is presented, but it uses coefficients that are obtained using a numerical scheme with fully controllable accuracy.
Abstract: A discontinuous Galerkin finite element method (DG-FEM) with a highly accurate time integration scheme for solving Maxwell equations is presented. The new time integration scheme is in the form of traditional predictor-corrector algorithms, PE(CE)m, but it uses coefficients that are obtained using a numerical scheme with fully controllable accuracy. Numerical results demonstrate that the proposed DG-FEM uses larger time steps than DG-FEM with classical PE(CE)m schemes when high accuracy, which could be obtained using high-order spatial discretization, is required.
TL;DR: In this paper, a full-wave, whole-system modeling of microwave imaging tomography (MWT) systems is presented to be used as the forward model in reconstruction (inverse) algorithms.
Abstract: This letter presents a full-wave, whole-system modeling of microwave imaging tomography (MWT) systems to be used as the forward model in reconstruction (inverse) algorithms. The full geometry including antennas and their ports is simulated via a finite element method (FEM) approach. A new technique is used to compute the antenna operation in the system, which provides a general method to enforce the excitation as a specific modal distribution and to extract the voltage and current from the employed antenna. We report results for a complete microwave imaging (MWI) system with comparison between measured and simulated data.
TL;DR: In this article, a full-wave method for the electromagnetic analysis of dielectric-loaded cylindrical and coaxial waveguides and cavities is developed, and a new four-port ring network is proposed, and the mode-matching method is applied to calculate the generalized admittance matrix of this new structure.
Abstract: In this paper, a full-wave method for the electromagnetic analysis of dielectric-loaded cylindrical and coaxial waveguides and cavities is developed. For this purpose, a new four-port ring network is proposed, and the mode-matching method is applied to calculate the generalized admittance matrix of this new structure. A number of analyses on dielectric-loaded waveguide structures and cavities have been conducted in order to validate and to assess the accuracy of the new approach. The results have been compared with theoretical values, numerical modeling from the literature, and data from commercial electromagnetic simulators. The method has been also applied to the accurate determination of dielectric properties, and we provide an example of these measurements as another way to validate this new method.
TL;DR: Three spatial-interpolation-based algorithms, including the Nonuniform-Grid Interpolation Method (NGIM), the box Adaptive-Integral Method (B-AIM), and the fast periodic interpolation method (FPIM), are described to show the basic principles for optimizing GPU-accelerated fast integral-equation algorithms.
Abstract: A survey of electromagnetic integral-equation solvers, implemented on graphics processing units (GPUs), is presented. Several key points for efficient GPU implementations of integral-equation solvers are outlined. Three spatial-interpolation-based algorithms, including the Nonuniform-Grid Interpolation Method (NGIM), the box Adaptive-Integral Method (B-AIM), and the fast periodic interpolation method (FPIM), are described to show the basic principles for optimizing GPU-accelerated fast integral-equation algorithms. It is shown that proper implementations of these algorithms lead to very high computational performance, with GPU-CPU speed-ups in the range of 100-300. Critical points for these accomplishments are (i) a proper arrangement of the data structure, (ii) an “on-the-fly” approach, trading excessive memory usage with increased arithmetic operations and data uniformity, and (iii) efficient utilization of the types of GPU memory. The presented methods and their GPU implementations are geared towards creating efficient electromagnetic integral-equation solvers. They can also find a wide range of applications in a number of other areas of computational physics.
TL;DR: In this article, a new method for predicting the broadband electromagnetic (EM) wave propagation characteristics of woven fabric composites is presented. But the method is not suitable for the case of large narrow band electromagnetic resonances that occur above 30 GHz.
Abstract: We demonstrate a new method for predicting the broadband electromagnetic (EM) wave propagation characteristics of woven fabric composites. The method combines a rigorous EM model with effective media theory to predict the EM properties of structural composites from dc to 50 GHz. Experimental results are provided that demonstrate the validity of the method. We also describe the presence of large narrow band electromagnetic resonances that occur above 30 GHz. These resonances, which are shown to be guided mode resonances, can be predicted by solving a simple dispersion relation.
TL;DR: In this article, general analytical equations were developed for the calculation of electromagnetic fields due to an inclined channel directly in the time domain, where the input parameters, angle of inclination of the lightning channel and the angle at the observation point can be varied through all possible values to produce the relevant electromagnetic fields.
Abstract: This article describes general analytical equations that are developed for the calculation of electromagnetic fields due to an inclined channel directly in the time domain. The input parameters of the model, angle of inclination of the lightning channel and the angle at the observation point can be varied through all possible values to produce the relevant electromagnetic fields. The proposed model is validated with eight electromagnetic waveforms measured at close range of the lightning channel. The results of the model show good agreement with the measured data. Furthermore, the proposed equations are compatible with different channel base current functions. The equations could easily be applied in the coupling models that calculate induced voltages in conductors in the presence of lightning-generated electromagnetic fields.
TL;DR: A fast wideband integral equation (IE) solver combining the multilevel interpolatory fast Fourier transform accelerated approach (MLIPFFT) with theMultilevel fast multipole method (MLFMM) is discussed and a method for MLIPFFt extrapolation error reduction based on fine level interpolation domain spreading is introduced.
Abstract: A fast wideband integral equation (IE) solver combining the multilevel interpolatory fast Fourier transform accelerated approach (MLIPFFT) with the multilevel fast multipole method (MLFMM) is discussed. On electrically fine levels within an oct-tree multilevel structure, coupling computations are performed by MLIPFFT. This method is based on a 3D Lagrange factorization of the pertinent Green's functions with a smooth approximation error in space and it does not suffer a low frequency breakdown as known from MLFMM. For high frequency integral equation problems, MLIPFFT has decreased computational efficiency as the Nyquist theorem requires increasing numbers of samples in 3 dimensions. Due to a transition from the interpolation point based MLIPFFT source/receive formulation towards an appropriate k-space representation at a certain level within the oct-tree, the high frequency efficient MLFMM can be employed for coarse levels. The hybrid algorithm is hence well suited for fast wideband integral equation solutions. Both, mixed-potential and direct-field formulations are considered. Furthermore, a method for MLIPFFT extrapolation error reduction based on fine level interpolation domain spreading is introduced. In several numerical examples, the performance of the proposed algorithm is demonstrated.
TL;DR: A novel sparse approximate inverse (SAI) preconditioner in multilevel fashion is proposed to accelerate the convergence rate of Krylov iterations for solving -matrices system in electromagnetic applications, and a group of parallel fast direct solvers are developed for dealing with multiple right-hand-side cases.
Abstract: Hierarchical (-) matrices method is a general mathematical framework providing a highly compact representation and efficient numerical arithmetic. When applied in integral-equation- (IE-) based computational electromagnetics, -matrices can be regarded as a fast algorithm; therefore, both the CPU time and memory requirement are reduced significantly. Its kernel independent feature also makes it suitable for any kind of integral equation. To solve -matrices system, Krylov iteration methods can be employed with appropriate preconditioners, and direct solvers based on the hierarchical structure of -matrices are also available along with high efficiency and accuracy, which is a unique advantage compared to other fast algorithms. In this paper, a novel sparse approximate inverse (SAI) preconditioner in multilevel fashion is proposed to accelerate the convergence rate of Krylov iterations for solving -matrices system in electromagnetic applications, and a group of parallel fast direct solvers are developed for dealing with multiple right-hand-side cases. Finally, numerical experiments are given to demonstrate the advantages of the proposed multilevel preconditioner compared to conventional “single level” preconditioners and the practicability of the fast direct solvers for arbitrary complex structures.
TL;DR: In this paper, the spectral lineshapes of the quantum well infrared photodetector (QWIP) geometries were analyzed using a rigorous electromagnetic field model and the model was used to optimize the detector structures for 12-micron pixel pitch focal plane arrays.
Abstract: Rigorous electromagnetic field modeling is applied to calculate the quantum efficiency of various quantum well infrared photodetector (QWIP) geometries. We found quantitative agreement between theory and experiment for corrugated-QWIPs, grating-coupled QWIPs, and enhanced-QWIPs, and the model explains adequately the spectral lineshapes of the quantum grid infrared photodetectors. After establishing our theoretical approach, we used the model to optimize the detector structures for 12-micron pixel pitch focal plane arrays.
TL;DR: In this article, the authors present guidelines and quantitative recipes for adoptions of optimal higher order parameters for computational electromagnetics (CEM) modeling using the method of moments and the finite element method.
Abstract: General guidelines and quantitative recipes for adoptions of optimal higher order parameters for computational electromagnetics (CEM) modeling using the method of moments and the finite element method are established and validated, based on an exhaustive series of numerical experiments and comprehensive case studies on higher order hierarchical CEM models of metallic and dielectric scatterers. The modeling parameters considered are: electrical dimensions of elements (h -refinement), polynomial orders of basis functions (p-refinement), orders of Gauss-Legendre integration formulas (integration accuracy), and geometrical (curvature) orders of elements in the model. The goal of the study, which is the first such study of higher order parameters in CEM, is to reduce the dilemmas and uncertainties associated with the great modeling flexibility of higher order elements, basis and testing functions, and integration procedures (this flexibility is the principal advantage but also the greatest shortcoming of the higher order CEM), and to ease and facilitate the decisions to be made on how to actually use them, by both CEM developers and practitioners.
TL;DR: A new parallel Vlasov-Maxwell solver is developed by adopting a stable but less dissipative scheme for time integration of conservation laws, which has successfully achieved a high scalability on massively parallel supercomputers with multicore scalar processors.
Abstract: Numerical schemes for solving the Vlasov-Maxwell system equations are studied. For studies of cross-scale coupling between fluid-scale dynamics and particle-scale kinetics in collisionless plasma, both highly scalable kinetic code and huge supercomputer are essential. In the present study, a new parallel Vlasov-Maxwell solver is developed by adopting a stable but less dissipative scheme for time integration of conservation laws. The new code has successfully achieved a high scalability on massively parallel supercomputers with multicore scalar processors. The new code has been applied to 2P3V (two dimensions for position and three dimensions for velocity) problems of cross-scale plasma processes such as magnetic reconnection, Kelvin-Helmholtz instability, and interaction between the solar wind and an asteroid.
TL;DR: In this article, a new mesh generation method utilizing magnetic flux lines in two-dimensional electromagnetic field problem was proposed, in which it is possible to distribute elements with different densities suitable for the electromagnetic field distribution.
Abstract: To solve electromagnetic field problems by the finite element method, it is necessary for a user to make a mesh in preprocess. However, the made mesh is usually different from that made by the other users, since it depends on the user's experience and knowledge. The mesh strongly affects the accuracy of the analysis result. The adaptive finite element method has been researched in order to address this problem. In this paper, we propose a new mesh generation method utilizing magnetic flux lines in two-dimensional electromagnetic field problem. Utilizing the magnetic flux lines computed with a rough mesh, it is possible to distribute elements with different densities suitable for the electromagnetic field distribution.
29 Mar 2012
TL;DR: This paper aims to provide a tutorial on computational electromagnetics, and simple MATLAB codes for sophisticated investigation of analytical and well-known numerical models, and the problem of propagation inside a parallel-plate waveguide is used.
Abstract: This paper aims to provide a tutorial on computational electromagnetics (CEM), and simple MATLAB codes for sophisticated investigation of analytical and well-known numerical models. The problem of propagation inside a parallel-plate waveguide is used for this purpose.
TL;DR: In this article, a generalized equivalence integral equation (GEIE) approach is proposed to formulating scattering from essentially convex closed surfaces, which invokes the generalized surface field equivalence to partially fill the volume originally occupied by the scatterer with judiciously selected materials.
Abstract: A generalized equivalence integral equation (GEIE) approach to formulating scattering from essentially convex closed surfaces is proposed. The GEIE approach invokes the generalized surface field equivalence to partially fill the volume originally occupied by the scatterer with judiciously selected materials, as opposed to the conventional replacement of the scatterer by the free space. The type and shape of the material inclusions can be selected to allow for a numerically efficient construction of the modified Green's function. Introduction of impenetrable and lossy materials confines the field interaction along the scatterer surface and reduces the coupling between the distant parts of the scatterer, which essentially makes the impedance matrix banded. The presence of lossy materials also resolves the nonuniqueness problem of the electric and magnetic field integral equations by eliminating the internal resonances. The formulation provides a pathway for developing fast iterative and direct electromagnetic integral equation solvers.