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Title: ACES Journal July 2012
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 5271 KB

Title: ACES Journal July 2012 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 635 KB

Title: Analysis of Composite Scattering from a Target Above/Below a Dielectric Rough Surface using Higher Order Basis Functions
Abstract: In this paper, the validity of four types of higher order basis functions for analyzing the 3D EM scattering from the target and dielectric rough surface is investigated. Although the higher order basis functions can reduce the number of unknowns significantly, the iterative solution time may increase with the order of the basis because the matrix condition numbers deteriorates with the basis order increase. This may be relative to: (a) The truncation of the dielectric rough surface and the interaction between the object and the rough surface; (b) the properties of the basis functions adopted. In this paper, a variety of models including a rough surface only, an object above or below the rough surface are investigated with different higher order basis functions. The program is based on the Poggio-Miller-Chang- Harrington-Wu-Tsai (PMCHW) integral equations. The multilevel fast multipole algorithm (MLFMA) and flexible generalized minimal residual (FGMRES) techniques are used to further accelerate the iteration solution.
Author(s): Y. An, R. S. Chen, P. Xu, Z. Liu, L. Zha
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 799 KB

Title: The Meshless Local Boundary Equation Method
Abstract: A method similar to the local boundary integral equation method that preserves its properties and is free from singular integrals is proposed. The approach is based on selection of the weighting functions from a homogeneous solution of the problem rather than the fundamental solution. Many examples of 2D Laplace and Helmholtz equations and 3D vector wave equation are presented for verification. The method shows optimistic performance over piecewise smooth boundaries. Radial basis functions of thin plate spline type are used for meshless discretization. The dependable performance of the proposed method provides a hopeful applicability to numerical solutions of partial differential equations.
Author(s): B. Honarbakhsh, A. Tavakoli
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 734 KB

Title: PEC Condition Implementation for the Novel Weakly Conditionally Stable Finite-Difference Time-Domain Method
Abstract: The perfect-electric-conductor (PEC) condition implementation for the novel weakly conditionally stable finite-difference time-domain (NWCS-FDTD) method is discussed in this paper. It shows that the method that the PEC condition is directly incorporated within the tri-diagonal matrix is more accurate and the burden on the computation efficiency is trivial. The theory proposed in this article is validated through numerical example.
Author(s): J. Chen, J. Wang, C. Tian
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 618 KB

Title: Analysis and Application of Inverse Detecting Method Based on Local Electric Field
Abstract: This paper investigates the timeefficient fault detection problem with applications in electric fields. A novel inverse approach based on a non-trivial combination of the fast multipole scheme and traditional simulation charge method is proposed. The fundamental principle is to take several samples of the intensity in the given local electric field at properly selected known locations nearby. Electric accessories are then used to analyze the signals in the framework of the traditional simulation charge method. Moreover, a new genetic algorithm, combined with the Tikhonov regularization, is proposed to further speed up the inverse process of fault detection in electric fields. The performance of the proposed approach is evaluated by the simulation results for the computation of the distribution of voltages in 110 kV high-voltage insulator lines. The superiority of the new inverse approach, in terms of time efficiency and accuracy for fault detection, is demonstrated by the simulation results. The present work aims to stimulate future studies on fault detection in electric fields.
Author(s): Z. Zhang, Z. Zhu, Q. Xin, X. Xie, J. Lei, S. Huang
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 668 KB

Title: Low RCS Antenna Design Using Genetic Algorithm Combined with Tabu List
Abstract: In this paper, a simple and efficient approach is presented to reduce the radar cross section (RCS) of patch antennas with defected ground structures (DGSs). This approach consists of an optimization algorithm, which combines a genetic algorithm (GA) with tabu list, and electromagnetic field solver. A tabu list, embedded into the GA frame, defines the acceptable neighborhood region of parameters and screens out the bad individuals. Thus, the repeats of search are avoided and the amount of electromagnetic simulation is largely reduced. Moreover, the whole design procedure is auto-controlled by programming the VBScript language. A patch antenna example is provided to verify the accuracy and efficiency of the proposed design method.
Author(s): X. Zhu, W. Shao, J. L. Li
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 673 KB

Title: A Novel Dual Narrow Band-Notched CPW-Fed UWB Slot Antenna with Parasitic Strips
Abstract: A novel and compact 5.2/5.8GHz dual narrow band-notched ultra wideband (UWB) slot antenna with inverted U-shaped parasitic strips is presented. The band notches of this antenna fed by a coplanar waveguide (CPW) are realized by two pairs of inverted U-shaped parasitic strips. Each pair consists of two separate strips which are similar and close to each other. And dual narrow rejected properties in the lower WLAN band (5.15-5.35GHz) and upper WLAN band (5.725- 5.825GHz) are obtained. The size of the proposed antenna is 24 24 1 mm3. The simulated and measured results show that the antenna design exhibits an operating bandwidth (VSWR < 2) from 2.8 to 12 GHz excluding the rejected bands.
Author(s): X. L. Ma, W. Shao, G. Q. He
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 1093 KB

Title: Application of Inductive Loadings for the Dual and Broad Banding of CPW-Fed Ring Antennas
Abstract: The broad banding of a printed ring antenna is achieved through inductive loadings by open-circuited radial line sections distributed around its periphery. The bandwidth of the stub loaded ring antenna is significantly enhanced without minor degradation of its radiation patterns, which may be realized by the appropriate design of widths, lengths, and angular spacings of open circuited radial lines. Dual-band performance can also be obtained by the application of the proposed method. The proposed antenna configuration is verified by computer simulation together with fabrication and measurement.
Author(s): H. Oraizi, B. Rezaei
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 2720 KB

Title: Accurate Modeling of a Patterned Ground and its Application to Microwave Filters
Abstract: A patterned ground and its exactly equivalent lumped circuit model are analyzed in depth in this paper. Characteristics of the introduced patterned ground include providing the finite attenuation pole and reflection pole near the cutoff frequency, thus effectively improving the frequency-response selectivity. The basic unit cell and its performance are first studied. A circuit theory-based lumped model is then introduced. To verify the developed equivalent model, a prototype low-pass filter using three cascaded cells is designed. Results of the prototype filter show a good consistency between the experiment and theory.
Author(s): W. Shao, J. L. Li
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 885 KB

Title: Scattering by Chiral Lossy Metamaterial Elliptic Cylinders
Abstract: Electromagnetic fields are expressed in terms of appropriate complex angular and a rigorous solution to the problem of scattering of a plane wave from a chiral lossy metamaterial circular or elliptic cylinder is presented in this paper using the method of separation of variables. The incident scattered as well as the transmitted radial Mathieu functions with expansion coefficients. The incident field expansion coefficients are known, but the scattered and transmitted field expansion coefficients are to be determined. Imposing the boundary conditions at the surface of the chiral lossy metamaterial elliptic cylinder enables the determination of the unknown expansion coefficients. Results are presented as normalized scattering widths for circular and elliptic cylinders of different sizes and chiral lossy metamaterial materials, and for both TE and TM polarizations of the incident wave, to show the effects of these on scattering cross widths.
Author(s): A. K. Hamid
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 657 KB

Title: Effects of Surface Roughness on Lossy Rectangular Waveguide
Abstract: The integral equation method combined with the surface-impedance boundary condition is applied for the analysis of propagation characteristics of rough lossy metal waveguides. The surface roughness of waveguide is random, and the statistical properties associated to the wall roughness are consistent with a Gaussian random process. The effects of the waveguide parameters on the propagation constant and attenuation constant are discussed rigorously, including the frequency, the standard deviation of height and correlation length of the Gaussian roughness. The results show that, as the increases of correlation length and frequency, the propagation constant is increased and the attenuation constant is decreased; while as the increase of the standard deviation, the trends of the propagation constant and the attenuation constant are just opposite.
Author(s): J. Chen, B. Huang
File Type: Journal Paper
Issue:Volume: 27      Number: 7      Year: 2012
Download Link:Click here to download PDF     File Size: 713 KB