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Title: December 2008 Full Journal
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 4045 KB

Title: December 2008 Journal Front/Back Matter
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 226 KB

Title: Highly Accurate Implementations of Methods for Handling Singularities on a Planar Patch
Abstract: Three methods for evaluating integrals containing the Green’s function singularity are studied from the standpoint of numerical accuracy at levels required in high order calculations. A significant source of potential error was found to be common to all methods. Suggestions for improving the accuracy of all three are proposed.
Author(s): M. M. Bibby, A. F. Peterson
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 105 KB

Title: Low-Frequency Full-Wave Finite Element Modeling Using the LU Recombination Method
Abstract: In this paper, the low-frequency instability of full-wave finite element methods (FEM) is investigated. The curl part of the FEM matrix is shown to be singular. The paper explains how low-frequency instabilities are related to this singularity. Based on this analysis, an LU recombination method is implemented in FEM to solve the low-frequency problem. This method, which has previously been applied to the method of moments (MOM), reduces the errors in the curl part of the matrix and enforces the correct gauge condition. Moreover, the method is restructured to work more efficiently for sparse finite element matrices.
Author(s): H. Ke, T. H. Hubing
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 312 KB

Title: A GPU Implementation of the 2-D Finite-Difference Time-Domain Code using High Level Shader Language
Abstract: The authors have applied a graphics processing unit (GPU) to the finite-difference timedomain (FDTD) method to realize a cost-effective and high-speed computation of an FDTD simulation. The authors used the plane wave scattering by a perfectly conducting rectangular cylinder as the model and investigated the performance of this implementation. The authors timed the computation time of the scattered electromagnetic field by the two-dimensional (2-D) FDTD method at 1,000 steps. Using a PC equipped with an Intel 3.4-GHz Pentium 4 processor and an nVIDIA Geforce 7800 GTX GPU, the authors achieved an approximately 10-fold improvement in computation speed compared with the speed of a conventional central processing unit (CPU) executing the same task.
Author(s): N. Takada, N. Masuda, T. Tanaka, Y. Abe, T. Ito
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 356 KB

Title: EM Scattering from Bodies of Revolution using the Locally Corrected Nystrom Method
Abstract: The locally corrected Nystr¨om method is applied to the magnetic field integral equation for a conducting body of revolution. A construction method is presented for the locally corrected weights for the resulting one-dimensional coupled scalar magnetic field integral equations. Special attention is paid to minimizing the cost for multi-frequency computations. Numerical results are presented for the sphere, oblate spheroid, and right circular cylinder. Good agreement with results from mature moment method codes is observed.
Author(s): A. W. Wood, J. L. Fleming
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 649 KB

Title: Numerical Solution of Electromagnetic Scattering by Multiple Cylinders
Abstract: A numerical solution based on integral equation is derived for an electromagnetic scattering from M multiple parallel cylinders. The problem is twodimensional and the integral equation is solved using the Nystr¨om method. To validate the algorithm, we compare our numerical results with the semi-analytical ones obtained from multipole expansion method.
Author(s): F. Seydou, R. Duraiswami, T. Seppanen
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 393 KB

Title: Design of a Near Field Protective Dielectric Radome “Window” for a Curved Phased Array Antenna-Axial Polarization Case
Abstract: A systematic design method of near field dielectric windows for 2D conformal fed arrays was previously developed. This developed design yielded simultaneously well-behaved element patterns in both axial and circumferential polarization. The method includes dimensioning of the window thickness to maximize the radial decay rate of the radome induced surface waves, followed by inclusion of a sufficiently large gap to decouple the surface waves from the array face. This methodology has been successfully extended to 3D with circumferential polarization according to the previously established guidelines and has provided smooth patterns in the circumferential plane, but limited the scan in the axial plane. Here we will investigate the case with axial polarization and compare the available useful scan volume to that of circumferentially polarized excitation.
Author(s): A. E. Fathy
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 942 KB

Title: Design, Modelling, and Synthesis of Radiation Pattern of Intelligent Antenna by Artificial Neural Networks
Abstract: The work presented in this paper refers to the synthesis of the radiation pattern of intelligent antennas by the artificial neural networks (ANN) based on linear antennas array supplied with coaxial lines. The method of synthesis implemented for this type of antennas makes it possible to approach with an optimal desired radiation pattern specified by a gauge with modifying amplitude, phase excitation and sources space distribution. The approach used is based on geometry of the antennas and the artificial neural networks (ANN) which are able to model the linear antennas array. Our principal contribution in this paper is the extension of a synthesis model of the radiation pattern. The developed synthesis is based on the neural networks technique.
Author(s): R. Ghayoula, N. Fadlallah, A. Gharsallah, M. Rammal
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 549 KB

Title: Optimised Design of a Printed Elliptical Spiral Antenna with a Dielectric Superstrate
Abstract: An elliptical spiral antenna embedded between a grounded dielectric substrate and superstrate is designed using a curved segment moment method employing complex images, which is driven by a marginal distribution optimisation algorithm. The spiral parameters together with substrate and superstrate permittivity and thickness values are optimised for low axial ratio and maximum gain and bandwidth. It is shown that the superstrate improves the bandwidth of the spiral.
Author(s): S. K. Khamas, G. G. Cook
File Type: Journal Paper
Issue:Volume: 23      Number: 4      Year: 2008
Download Link:Click here to download PDF     File Size: 292 KB