ACES Publication Search
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| Title: | ACES June 2009 Full Journal Download |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 4894 KB |
| Title: | ACES June 2009 Journal Front/Back Matter |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 205 KB |
| Title: | A Novel Space-Stepping Finite-Difference Frequency–Domain Method for Full Wave Electromagnetic Field Modeling of Passive Microwave Devices |
| Abstract: | In this paper a novel space-stepping finite-difference frequency-domain (SSFDFD) method is presented for the analysis of passive microwave devices. Unknown electromagnetic (EM) fields are solved from given EM fields at two initial planes space-step by space-step along a spatial direction. SSFDFD has the advantage over the traditional FDFD method in that all the EM field unknowns are local variables and the solution of a huge matrix equation is avoided. The stability condition for the SSFDFD method is derived as that for the finite-difference time-domain (FDTD) method. Application examples show that the stability condition is valid and the SSFDFD method is at least one magnitude faster than the traditional FDFD method with the same accuracy of analysis. SSFDFD has the potential to be a powerful and fast tool for full wave EM field modeling of passive microwave devices. |
| Author(s): | J. Mao, L. Jiang, S. Luo |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 347 KB |
| Title: | A Comparison Among Fast Visibility Algorithms Applied to Computational Electromagnetics |
| Abstract: | This paper presents a set of fast algorithms developed for solving the visibility problem in large complex geometric scenarios. The implemented algorithms are: Binary Space Partitioning (BSP) –based on a binary tree structure- and three new ones: Trimming Method – facets which are partially occluded are trimmed –, Cone Method – a cone emerges from the point of view to discard shadowed facets – and Pyramid Method – a pyramid is used to eliminate non-lit patches – . All the proposed algorithms are tested on a pair of scenarios for determining the field of view of electromagnetic waves in order to calculate the corresponding induced currents on the surfaces. The scenarios consist of two electrically large spheres and two PEC plates respectively where the surfaces are meshed with a variable number of flat triangular patches. The first reflection contribution is calculated using Physical Optics (PO) for both cases. The results show that the computational time can be drastically reduced by assuming small percentage of error in the computed scattered fields. |
| Author(s): | J. G. Meana, F. Las-Heras, J. Á. Martínez-Lorenzo |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 597 KB |
| Title: | UTD Shooting-and-Bouncing Extension to a PO/PTD Ray Tracing Algorithm |
| Abstract: | This paper deals with the efficient combination of three well-established electromagnetic modeling methods, a Shooting-and-Bouncing-Rays (SBR) algorithm on the basis of the Geometrical Optics (GO), a source-based calculation of scattered field strengths using Physical Optics (PO) and Physical Theory of Diffraction (PTD), and diffraction calculation on the basis of the Uniform Theory of Diffraction (UTD). While the conventional GO-PO/PTD methods are able to accurately calculate wedge contributions to scattered fields, the further propagation of diffracted rays is generally not considered in SBR approaches. Thus, the aim of this paper is to describe the implementation of diffracted rays according to the UTD concept into an SBR code. This novel implementation allows for the modeling of double diffraction and reflected-diffractedreflected paths in complex scenarios consisting of a very large number of surface elements as well as the accurate simulation of cavities. The comparison with numerically exact reference simulations proves that the proposed hybrid GO/UTD-PO/PTD algorithm yields excellent results and that the UTD-SBR extension definitely improves the simulations of the ray tracing algorithm also for realistic objects. |
| Author(s): | F. Weinmann |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 526 KB |
| Title: | On the Direct Computation of the Time-Domain Plane-Wave Reflection Coefficients |
| Abstract: | This communication compares different approximate techniques to calculate the transient reflection coefficient for TE and TM plane waves from a lossy half space in terms of accuracy, computational costs and area of validity. By varying angles of incidence and constitutive parameters of the half spaces, it is shown that approximate equations can efficiently and accurately calculate the reflection coefficients in the time domain, if the right equation and enough terms in the approximate series are chosen. To confirm these conclusions, it is considered, as a practical example, short pulses reflected by an operational Ground-Probing Radar from different half spaces. |
| Author(s): | M. F. Pantoja, A. G. Yarovoy, A. R. Bretones |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 257 KB |
| Title: | Quasi Monte Carlo Integration Technique for Method of Moments Solution of EFIE in Radiation Problems |
| Abstract: | In this work, a Quasi Monte Carlo Integration (QMCI) Technique using Halton Sequence is proposed for the Method of Moments (MoM) solution of the Electric Field Integral Equation (EFIE) in radiation problem. It is found that this scheme is capable of handling the singularity issue in the EFIE automatically and at the same time provides solution to the radiation problems very efficiently. |
| Author(s): | M. Mishra, N. Gupta |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 177 KB |
| Title: | Validation of Fast Site-Specific Mean-Value Models for Indoor Propagation |
| Abstract: | A fast assessment of the local mean value of the electric field strength throughout a floor plan is useful for the design of local-area networks. Site-specific models require coding the location of walls, doorways, and other features and modelling their structure and electrical properties. Using ray tracing to find the field strength throughout the floor plan is slow and expensive because a grid of closely-spaced points is needed to trace the rapid variations called fast fading; then the raytracing local area average is found by explicit spatial averaging, to obtain the slow fading behavior. The raytracing mean value is obtained by combining the amplitudes of the fields associated with the rays on an energy basis; widely-spaced grid points can be used because the local mean value varies slowly with position, making the calculation fast and inexpensive. The Sabine method provides a energy-balance approach for an inexpensive estimate of the local mean value field strength. This paper tests the accuracy of the fast methods (the ray-tracing mean value and the Sabine mean value) against the local area average found from dense ray tracing, and against measurements. In a 40 m2 room of roughly square floor plan, the fields from the fast methods were close to those of dense ray tracing and to the measurements. But it is shown that in a long corridor, the ray-tracing mean value and the Sabine mean value were low compared to dense ray tracing, and so these fast methods should be used with caution. |
| Author(s): | C. W. Trueman, D. Davis, B. Segal, W. Muneer |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 264 KB |
| Title: | Soft Computing Techniques for Free-Space Measurements of Complex Dielectric Constant |
| Abstract: | A novel method for estimating the dielectric properties of materials by applying different soft computing techniques is presented. Dielectric properties allow us to know other material characteristics such as moisture content, bio-content, chemical concentration, etc., which are of great importance on industrial or science fields. In this paper, we present a free-space measurement method along with soft computing techniques, such as Genetic Algorithms (GA) and Particle Swarm Optimization (PSO), and other approaches like Artificial Neural Networks (ANN), for estimating the dielectric properties of materials. The proposed method is validated by measurements and synthetic materials, which were generated to test the performance of these soft computing algorithms. |
| Author(s): | D. Escot, D. Poyatos, I. Montiel, M. A. Patricio |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 2444 KB |
| Title: | Application of Wavelets and Auto-Correlation-Function For Cancellation of High-Frequency EMI Noise |
| Abstract: | This paper presents a wavelet transforms and auto-correlation function based approach for the high-frequency switching noise cancellation. The noise is extracted by wavelet multi-resolution analysis. The enough features of signal in frequency and time domains are obtained by using arguments and magnitudes of complex wavelet transform as well as main frequency evaluation of auto-correlation function. The simulation results showed that the high frequency noise could be detected and reconstructed accurately and the average noise attenuation is larger than 20dB. This new method provides a multi-level process and multi-level description method for disturbance identification and cancellation. |
| Author(s): | W. Chen, X. Yang, Z. Wang |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 119 KB |
| Title: | Interpolation Algorithm for Fast Evaluation of EM Coupling between Wires |
| Abstract: | Efficient and accurate evaluation of the EM field radiated by a current flowing along a wire is essential to solve the electromagnetic coupling between arbitrary oriented wires. In this paper, a numerically efficient algorithm for the evaluation of coupling is presented. The currents along the wires are expressed in terms of local basis functions. The coupling between each two expansion functions of different wires, using an exact kernel and the Galerkin Method of Moments, requires an integration over the mantle of the radiating element and an integration over the mantle of the receiving element. The computational cost for this 2 × 2D integration is reduced by an interpolation technique. In order to reduce the number of evaluation points and to control accuracy, the interpolation technique is applied to a function that represents the difference between the electric field radiated by a wire element and the analytically known point dipole field. The proposed algorithm is implemented using already available standard routines. |
| Author(s): | C. Marasini, E. S. A. M. Lepelaars, P. A. M. Zwamborn |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 200 KB |
| Title: | Numerical Electromagnetic Analysis of GSM Tower under the Influence of Lightning Over-voltage |
| Abstract: | In the last twenty years, the widespread use of sensitive electronic devices in telecommunication systems and power systems has increased the interest in transients, in particular those caused by lightning (direct and/or indirect) strokes. Lightning over-voltage causing unpredictable and accidental interruption in these systems is a very important factor also in telecommunication systems and transmission lines. So the electromagnetic interference (EMI) analysis of different communication towers under the influence of lightning over-voltage on tall structures is necessary to avoid these unexpected interruptions. This paper presents a numerical electromagnetic simulation of direct lightning stroke for the EMI analysis of a GSM tower utilizing Method of Moments. This analysis is also a primary factor and can give approximate solution, helpful for correct EMC design of transient protection circuits for GSM base station. |
| Author(s): | M. O. Goni, M. S. I. Hossaini |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 296 KB |
| Title: | Analysis of Photonic Band Gap using Multilayer Contribution of Wave Concept Iterative Process MLC-WCIP |
| Abstract: | Microstrip elements are modeled in multilayered contribution. An iterative method based on the concept of waves is developed in a form useful for efficient computation for interacting microstrip elements, which may be located at any substrate layer and separated by a large distance. The multilayer contribution of iterative method is developed in the spatial domain. Examples for regularly shaped geometries in multilayered media are presented. These involve the optimization of a microstrip ring with a narrow gap which induces multiple reflections with a fixed phase correlation necessary to make the photonic band gap. The analysis takes into account eventual coupling parasites. Experimental measurements are performed to validate the computation. The approach involves the mixed magnetic and electric field equation technique and the wave concept iterative process which involves S-parameters extraction technique. In this sense, a program in FORTRAN has been elaborated to determine different parameters Sij characterizing the studied structure. A good agreement between numerical and reported results is important to validate the theory of the multilayer contribution of iterative method MLC-WCIP. |
| Author(s): | E. A. Hajlaoui, H. Trabelsi, A. Gharsallah, H. Baudrand |
| File Type: | Journal Paper |
| Issue: | Volume: 24 Number: 3 Year: 2009 |
| Download Link: | Click here to download PDF File Size: 281 KB |