Early computational electromagnetics

The author discusses the early history of computational electromagnetics from the late 1940s. In particular Illiac and Ordvac are discussed     

Low-frequency computational electromagnetics for antenna analysis

An overview of computational methods for modeling the low-frequency electromagnetic characteristics of antennas is given. Presented first is a brief analytical background that forms the basis for numerically solving low-frequency antenna problems using the method of moments. Next discussed are extensions to modeling perfectly conducting objects in free space, followed by a consideration of some computational issues that affect model accuracy, efficiency, and utility. A variety of representative applications is given to illustrate various aspects of modeling and capabilities that are currently available. A fairly extensive bibliography is included     

Integer lattice gas automata for computational electromagnetics

Integer lattice gas automata (ILGA) are combined with the transmission-line matrix (TLM) method to yield a new electromagnetic-field computation algorithm using very low-precision integer variables. Lattice gas automata can be evaluated using look-up tables on special-purpose hardware and do not require floating-point arithmetic. In this paper, we present a TLM motivated ILGA with emphasis placed on algorithms that demonstrate minimal dissipation     

Multi-grid interface in computational electromagnetics

An elegant and accurate technique of interfacing segments of a uniform computational mesh with different spatial resolution is described. The technique is illustrated in the time-domain for a TLM mesh. Results show that a seamless interface is achieved between different mesh areas, thus allowing multi-scale problems to be accurately mapped onto the mesh.     

High-order Runge-Kutta multiresolution time-domain methods for computational electromagnetics

In this paper we introduce a class of Runge-Kutta multiresolution time-domain (RK-MRTD) methods for problems of electromagnetic wave propagation that can attain an arbitrarily high order of convergence in both space and time. The methods capitalize on the high-order nature of spatial multiresolution approximations by incorporating time integrators with convergence properties that are commensurate with these. More precisely, the classical MRTD approach is adapted here to incorporate mth-order m-stage low-storage Runge-Kutta methods for the time integration. As we show, if compactly supported wavelets of order N are used (e.g., the Daubechies D/sub N/ functions) and m=N, then the RK-MRTD methods deliver solutions that converge with this overall order; a variety of examples illustrate these properties. Moreover, we further show that the resulting algorithms are well suited to parallel implementations, as we present results that demonstrate their near-optimal scaling.     

A selective survey of computational electromagnetics

Some of the tools used in computational electromagnetics are placed into perspective with respect to the different kinds of approaches that may be used and their computer-resource requirements. Particular attention is paid to numerical models based on integral and differential equations. After a brief background discussion, some of the analytical and numerical issues involved in developing a computer model are reviewed. Some practical considerations are included from the viewpoint of computer-resource requirements, followed by a discussion of some ways by which computer time might be reduced. The presentation concludes with a brief examination of validation and error checking. The emphasis throughout is on review and summarization rather than detailed exposition     

电磁场数值计算中的内插和外推

内插和外推算法是电磁场领域的常用算法，它在天线设计、微波技术、雷达目标散射建模等各种电磁场计算领域都要用到。因此内插和外推算法的成功应用，直接关系到电磁场数值计算技术的计算效率。文章主要介绍了内插和外推算法在电磁场数值计算中的应用背景，提出了当前所面临的问题；列举了一些常用的内插和外推算法以及国内外一些新算法的应用，介绍了作者在这方面的工作以及一些看法。     

Expansion of existing EM workbench for multiple computational electromagnetics codes

An "EM workbench" is described. It has a modular, code-independent architecture and a common design environment. The technique for integrating new EM codes is demonstrated with a method-of-moments code specialized for circularly symmetric feed horns, and with a new hybrid DFT-MoM (discrete Fourier transform - method of moments) code for finite-boundary planar phased arrays. The use of a common design environment for all codes takes advantage of common infrastructure and utility software, and minimizes the learning-curve penalty for using a new EM code capability.     

Research in computational electromagnetics at the University ofMichigan

The history of the Radiation Laboratory at the University of Michigan is briefly recounted, and its present composition of staff, faculty, and graduate students is described. Research in electromagnetic scattering at the laboratory is reviewed, covering high-frequency scattering and two- and three-dimensional numerical simulation. Work on passive monolithic circuits and antennas, including numerical modeling of planar discontinuities and antennas, planar discontinuities and transitions, and antenna feeding networks, is discussed     

Hierarchical parallelisation strategy for multilevel fast multipole algorithm in computational electromagnetics

A hierarchical parallelisation of the multilevel fast multipole algorithm (MLFMA) for the efficient solution of large-scale problems in computational electromagnetics is presented. The tree structure of MLFMA is distributed among the processors by partitioning both the clusters and the samples of the fields appropriately for each level. The parallelisation efficiency is significantly improved compared to previous approaches, where only the clusters or only the fields are partitioned in a level.     

EM programmer's notebook-benchmark radar targets for the validationof computational electromagnetics programs

Low- and high-frequency measurements are presented of five differently shaped targets: the NASA almond, ogive, double ogive, cone-sphere, and cone-sphere with gap. These were measured from 700 MHz to 16 GHz. The metallic targets are made of aluminum, and were cut by a numerically controlled mill to maintain the surface precision. Except for the almond target, all the targets were made in two parts and joined by sleeves and screws. The measurements are computational electromagnetics (CEM) validation measurements for the Electromagnetic Code Consortium (EMCC)     

EM programmer's notebook-benchmark plate radar targets for thevalidation of computational electromagnetics programs

In February, 1989, a Computational Electromagnetics (CEM) validation measurement program was initiated by the Electromagnetic Code Consortium (EMCC), to fabricate and test several small radar cross-section (RCS) range models, in order to generate RCS reference data for validating existing and future codes. As part of the validation effort, the EMCG defined various sets of three- and two-dimensional targets. Measured data are presented here for five of the 3D plate targets. They are a wedge-cylinder plate, a wedge-plate cylinder, a plate cylinder, a 2×3.5 λ flat plate, and a wedge-cylinder with a gap     

A look at some challenging problems in computational electromagnetics

Recent years have seen a spectacular increase in our capability to model, simulate the performance of, and design complex electromagnetic systems. Much progress has been made in enhancing the available numerical techniques, viz., the method of moments (MoM), the finite-element method (FEM), and the finite-difference time-domain (FDTD) or its variants. Great strides have recently been made in enlarging the scope of MoM via the use of the fast multipole method (FMM), which has made it feasible for us to solve problems that require the handling of 106 degrees of freedom, or even higher, and distributed processing has enabled the FDTD to handle upward of 109 degrees of freedom on a moderate-size computing platform. Despite this recent progress, many practical computational electromagnetic (CEM) modeling problems of interest present formidable challenges, and the search for numerically efficient techniques to solve large problems involving complex structures continues unabated. The objectives of this paper are to identify some of these challenging problems encountered by the author during the last five years, and to present the results of application of a technique called CBFM - developed at the EMC Laboratory at Penn State - that has been found useful for addressing them.     

Grid computing for electromagnetics: a beginner's guide with applications

The demand for computing power in computational electromagnetics (CEM) is continuously increasing. Meanwhile, cooperative engineering is becoming more and more present in daily research and development workflows. Projects are often developed by teams, which interact remotely, and need tighter and tighter connectivity. Grid computing (GC), from the perspective of progress in computer networks, seems a promising way to satisfy both the need of high-performance computing platforms, and the requirements for effective cooperative computing. In this paper, researchers involved in CEM are introduced to grid computing, and to the use of grid computing for CEM. Two real applications are proposed, with a critical discussion on potential benefits and drawbacks with respect to alternative strategies.     

Magneto-dielectrics in electromagnetics: concept and applications

In this paper, the unique features of periodic magneto-dielectric meta-materials in electromagnetics are addressed. These materials, which are arranged in periodic configurations, are applied for the design of novel EM structures with applications in the VHF-UHF bands. The utility of these materials is demonstrated by considering two challenging problems, namely, design of miniaturized electromagnetic band-gap (EBG) structures and antennas in the VHF-UHF bands. A woodpile EBG made up of magneto-dielectric material is proposed. It is shown that the magneto-dielectric woodpile not only exhibits band-gap rejection values much higher than the ordinary dielectric woodpile, but also for the same physical dimensions it shows a rejection band at a much lower frequency. The higher rejection is a result of higher effective impedance contrasts between consecutive layers of the magneto-dielectric woodpile structure. Composite magneto-dielectrics are also shown to provide certain advantages when used as substrates for planar antennas. These substrates are used to miniaturize antennas while maintaining a relatively high bandwidth and efficiency. An artificial anisotropic meta-substrate having /spl mu//sub r/>/spl epsiv//sub r/, made up of layered magneto-dielectric and dielectric materials is designed to maximize the bandwidth of a miniaturized patch antenna. Analytical and numerical approaches, based on the anisotropic effective medium theory (AEMT) and the finite-difference time-domain (FDTD) technique, are applied to carry out the analyzes and fully characterize the performance of finite and infinite periodic magneto-dielectric meta-materials integrated into the EBG and antenna designs.     

Conduction current crossing domain boundaries in heterogeneoushybrid computational electromagnetics formulation

A heterogeneous hybrid computational electromagnetics method is presented that permits conduction currents to cross the boundary between different computational domains. The method uses a standard frequency-domain moment-method program and the finite-difference time-domain method to compute the fields in the two regions. Several validation cases are examined and the results compared with available data     

Using object-oriented and literate-programming techniques for the development of a computational electromagnetics library

Code maintenance is perhaps the most time-consuming problem in developing source code for various purposes. The increased complexity of computational-electromagnetics (CEM) simulation software makes this task even more difficult and tedious. The current paper proposes a sophisticated approach for a significant performance improvement in CEM code-maintenance tasks, with the fusion of object-oriented and literate-programming techniques. A case study concerning the development of a CEM library is thoroughly analyzed and presented. Various aspects of computational efficiency have been examined in order to estimate the costs of developing object-oriented CEM programs. The aim of the analysis is to stress the advantages of the above-mentioned techniques, and to provide useful guidelines for effective implementation of CEM programs with reusable, extensible, self-documented source code.     

On the design of numerical methods [computational electromagnetics]

Many terms and ideas used in numerical methods have their origin in analytical mathematics. Despite the well-known discrepancies between number spaces of computers and those of mathematics, the consequences of applying mathematical theorems to numerical methods and the importance of physical reasoning are often underestimated. It is demonstrated that terms known from analytic considerations and goals like orthogonal basis functions and small condition numbers of matrices can be misleading, and can prevent engineers from designing useful codes for computational electromagnetics and similar tasks. Introducing a priori knowledge in numerical codes requires open structures, and often leads to ill-conditioned matrices. Thus, it is important to develop and apply methods for handling matrices such as the generalized point matching used in the multiple multipole (MMP) code instead of the projection technique used in many method of moments (MoM) codes     

Digital signal processing for video applications

Digital video signal processing is one result of the fast progress in NMOS-VLSI techniques. The attractions of using digital data processing methods in an analog application field are the availability of CAD tools for the design of digital ICs and the integration of digital filter functions. Besides the key components such as microcomputers, A/D, and D/A converters, the digital filter techniques are the most important functions in this application field. It is demonstrated that digital signal processing is not only restricted to amplitude modulated video signals, but also that frequency modulated signals can be processed and methods for FM modulation and demodulation have been developed.