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Title: ACES November 2010 Full Journal
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 2589 KB

Title: ACES November 2010 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 396 KB

Title: Grid-Based SCT Approach for the Global Electromagnetic Simulation and Design of Finite-Size and Thick Dichroďc Plate
Abstract: In the work presented in this paper, a grid-enabled environment for the scale changing technique (SCT) simulations is proposed. This approach allows the fast design of a finite size and thick dichroďc metallic mirror based on global electromagnetic simulation. The computed transmission and reflection coefficients, as well as radiation pattern, satisfying to some predefined technical requirements in X and Ka frequency bands are presented. Simulation results are shown in order to demonstrate the validity of the approach.
Author(s): F. Khalil, E. B. Tchikaya, R. Sharrock, T. Monteil, F. Coccetti, H. Aubert
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 449 KB

Title: Preconditioned MDA-SVD-MLFMA for Analysis of Multi-Scale Problems
Abstract: Multilevel fast multipole algorithm (MLFMA) has been widely used to solve electromagnetic scattering problems from the electrically large size objects. However, it consumes very large memory to store near the interaction matrix for the object with fine structures because the “low frequency breakdown” phenomenon would happen when the finest level box’s size is below 0.2 wavelengths. The matrix decomposition algorithm - singular value decomposition (MDA-SVD) is one remedy to alleviate this pressure because it has no limit of the box’s size. However, the matrix assembly time of MDA-SVD is much longer than that of the MLFMA. In this paper, a hybrid method called MDA-SVD-MLFMA is proposed to analyze multi-scale problems, which uses the main framework of MLFMA but adopts the MDA-SVD to deal with the near interaction of MLFMA. This method takes advantage of the virtues of both MLFMA and MDA-SVD and is more efficient than either conventional MLFMA or conventional MDA-SVD. An efficient preconditioning technique is combined into the inner-outer flexible generalized minimal residual (FGMRES) solver to speed up the convergence rate. Numerical results are presented to demonstrate the accuracy and efficiency of the proposed method.
Author(s): Z. N. Jiang, Z. H. Fan, D. Z. Ding, R. S. Chen, K. W. Leung
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 270 KB

Title: Parallel SAI Preconditioned Adaptive Integral Method For Analysis of Large Planar Microstrip Antennas
Abstract: An efficient parallel sparse approximate inverse (PSAI) preconditioning of the adaptive integral method (AIM) is proposed to analyze the large-scale planar microstrip antennas. The PSAI preconditioner is based on the parallelized Frobenius-norm minimization, and is used to speed up the convergence rate of the loose generalized minimal residual method (LGMRES) iterative solver. The parallel AIM is used to accelerate the required matrix vector product operations. Numerical results demonstrate that the PSAI preconditioner is effective with the AIM and can increase the parallel efficiency significantly when analyzing the large planar microstrip antennas.
Author(s): M. Li, M. Chen, W. Zhuang, Z. Fan, R. Chen
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 302 KB

Title: Well-Conditioned CFIE for Scattering from Dielectric Coated Conducting Bodies above a Half-Space
Abstract: In this paper, a well-conditioned coupled combined-field integral equation called the electric and magnetic current combined-field integral equation (JCFIE-JMCFIE) is proposed for the analysis of electromagnetic scattering from coated targets above a lossy half-space. The halfspace multilevel fast multipole algorithm (MLFMA) is used to reduce computational complexity. The inner-outer flexible generalized minimal residual method (FGMRES) was used as the iterative solver to further speed up the convergence rate. Numerical results were presented to demonstrate the accuracy and efficiency of the proposed method.
Author(s): D. Ding, J. Ge, R. Chen
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 401 KB

Title: Robust Beamforming Technique with Sidelobe Suppression Using Sparse Constraint on Beampattern
Abstract: In this paper, we propose two beamforming algorithms which impose sparse constraint on beampattern to suppress the sidelobe level and enhance robustness of the beamformer against steering vector error. The sparse constraint is given by an lp-norm, where ???2 holds. It is shown that the proposed algorithms can be solved using iterative algorithm. Computer simulations show that the proposed algorithms not only yield lower sidelobe level than that of the conventional beamformer, but also show better robustness against steering vector error than the conventional beamformers.
Author(s): Y. Zhang, H. Zhao, J. P. Lie, B. P. Ng, Q. Wan
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 563 KB

Title: A Frequency-Dependent Hybrid Implicit-Explicit FDTD Scheme for Dispersive Materials
Abstract: A frequency-dependent hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method for dispersive materials is presented. This method has higher computation efficiency than the conventional FDTD method, because the time step in this method is only determined by two space discretizations. The accuracy of this method is demonstrated by computing the incident at a planar air-water interface over a wide frequency band including the effects of the frequency-dependent permittivity of water.
Author(s): J. Chen, A. Zhang
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 168 KB

Title: Adaptive Mixed-Form Fast Multipole Method for the Analysis of Electromagnetic Scattering
Abstract: To analyze an electrically large object with local fine structures, the conventional mixed form fast multipole algorithm requires that the boxes of the finest level are all with the same size, which belongs to the low-frequency region. This scheme is deficient since the mesh size is limited by the box size of the finest level, which is related to the finest parts of the object. In this paper, an efficient adaptive grouping scheme is introduced into a mixed-form fast multipole algorithm. In an adaptive mixed-form fast multipole algorithm, the number of unknowns in each non-empty box of the finest level is almost the same which results in the box of the finest level may be in a different frequency regime with a different size. Hence multipole expansions are employed, if the boxes located in the low frequency regime while the plane wave expansions are employed if the boxes located in the mid-frequency regime. Numerical results are given to show that the proposed approach is efficient to analyze the objects with many fine structures.
Author(s): H. Chen, Z. H. Fan, R. S. Chen, Z. N. Jiang, M. M. Li
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 378 KB

Title: Improved Microstrip Folded Tri-Section Stepped Impedance Resonator Bandpass Filter using Defected Ground Structure
Abstract: In this paper, a study of a microwave microstrip bandpass filter (BPF), based on folded tri-section stepped impedance resonator (FTSIR) and defected ground structure (DGS) is presented. Based on the resonance characteristics of a stepped impedance resonator (SIR), the first spurious resonant frequency can be tuned over a wide range by adjusting its structure parameters. The SIR bandpass filter is designed to have a quasi-elliptic function response and a wide upper stopband. Furthermore, five ground slots (DGS) are used in order to omit the first spurious resonant frequency. Compared to similar microstrip filter without defected ground, the simulated performances of this novel structure indicate some functional advantages. To validate the design and analysis, a prototype of the bandpass filter with DGS was fabricated and measured. It is shown that the measured and simulated performances are in a good agreement.
Author(s): N. M. Garmjani, N. Komjani
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 442 KB

Title: Impact of the Mobile Phone Dimensions on the Hearing Aids Compatibility
Abstract: In this work, we have investigated the influence of the mobile phone physical dimensions on the hearing aids compatibility (HAC). In our study, we have considered an inverted F antenna (IFA) and a planar inverted F antenna (PIFA) both fitting into a typical candy bar mobile phone. We have used a generic cubical head model to investigate the user impact on the near fields (NF). The field values are obtained by using the finite difference time domain (FDTD) method. We have observed significant difference in the peak field values between free space and with the head included although only free space values are specified in the relevant standard. Important outcome for the physical dimensions of the mobile phone is that the increase of the length of the handset significantly decreases the peak H value.
Author(s): I. B. Bonev, O. Franek, M. Christensen, G. F. Pedersen
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 239 KB

Title: Parametric Analysis of Multi Source Feeding Flare Rolling and Corrugating Effects for H-Plane Horn Radiator
Abstract: In this paper, radiation characteristics of H-plane sectoral horn antenna are treated systematically by investigation of the multi source feeding, flare wall rolling and corrugating effects. The analytical regularization method (ARM) is used to solve the problem of E-polarized wave diffraction in a fast and accurate way. The numerical procedure is initially verified by the analytical solutions, and the calculated field patterns are presented for the selected horn antenna configurations. Proper choices of the geometrical parameters, such as source position, back wall shape, multi source feed, metal thickness, and ridged and corrugated flares are proposed for the designers to reach high directivity, narrow beam, and suppressed side and back lobe levels.
Author(s): A. S. Turk, O. Yurduseven
File Type: Journal Paper
Issue:Volume: 25      Number: 11      Year: 2010
Download Link:Click here to download PDF     File Size: 449 KB