ACES Publication Search





There are 12 search results for:



Title: ACES February 2010 Full Journal
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 3955 KB

Title: ACES February 2010 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 278 KB

Title: Whispering Gallery Mode Laser in an Elliptical Microring
Abstract: Studies on whispering gallery mode (WGM) laser in microrings have been limited to circular geometry. Elliptical microring lasers, despite their potential engineering use, have not been analyzed to guide experiments. This paper introduces a computationally efficient method for determining the WGM laser resonance and the laser field distribution in an elliptical microring. An analytical method is applied to avoid computing high order Mathieu functions. Both WGM resonant frequencies and electromagnetic (EM) field distributions are computed and presented in this paper. Computed results clearly show that the WGM laser field is concentrated on the outer surface of the microring. Results also show that the eccentricity of the ellipse affects the distribution of resonant frequencies and the laser field.
Author(s): R. Baktur, L. W. Pearson, J. M. Ballato
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 419 KB

Title: A Greenís Function Approach to Calculate Scattering Width for Cylindrical Cloaks
Abstract: The anisotropic material properties of cylindrical cloaks can be simulated using thin, concentric layers of homogeneous, isotropic material. A Green's function for a line current in the presence of a layered PEC cylinder can be used to calculate the scattering width from a cloaked PEC cylinder with a significant improvement in computational efficiency compared to solutions obtained using the finite element method.
Author(s): J. S. McGuirk, P. J. Collins, M. J. Havrilla, A. W. Wood
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 968 KB

Title: Optimum Horn Antenna Design Based On an Integration of HFSS Commercial Code and Genetic Algorithms for the Feed Application of Reflector Antennas
Abstract: The optimum design of horn antennas for the application as feeds to reflector antennas is performed utilizing a simulation tool based on an integration of HFSS commercial code as an electromagnetic computational engine and an add-on optimization scheme of genetic algorithm. This work is motivated by the need of antenna operations at multiband frequencies, where the horn antennas tend to radiate narrower beams at higher frequencies and result in inefficient uses of the reflector surface since the narrow beams will illuminate only a portion of the reflector surface. Optimum design of the horn antenna may significantly increase efficiency. The philosophy of this work is based on a fact that the currently available commercial codes are reliable and relatively accurate in the analysis with more efforts tending to enhance the computational efficiency. The quality of the antenna design will mainly rely on an effective optimization algorithm that can be and should be developed independently according to engineersí own need, since the variables and cost functions for optimization can be flexibly selected. The integration of existing analysis codes, as mentioned above, and self-developed algorithms will be most effective for an engineer in the customized antenna design. The concepts and strategies are addressed with numerical examples to validate.
Author(s): H. Chou, C. Liu, W. Liao
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 848 KB

Title: Investigation on the Electric Field Inverse Problem of HV Transmission Lines and Discussion on Its Appli
Abstract: The electric field inverse problem of high voltage transmission lines is investigated in this paper. Firstly the equations for the electric field forward problem of transmission lines were formulated, then equations for the inverse problem were formulated according to the forward problem and the least square theory. A method to solve the inverse problem is presented in the paper, in which the global regularization was used to process the ill-posed characteristic of the inverse problem. The Damped Gauss-Newton iterative method was used to search the optimum solution. A 500kV double-circuit transmission line was taken as an example for the calculations of the inverse problem. The inverse problems for different situations were calculated, including the situation when the transmission lines were in normal operation, and the situation when the transmission lines were in faulty state. The solutions to the inverse problem with and without regularization were compared in the paper, and the results indicated that the global regularization can effectively eliminate the ill-pose of the inverse problem. The electric field inverse problem can be used to confirm the electrification state of the ultra high voltage transmission lines, and also can be used in the environmental assessment tests to reduce the measurement workload.
Author(s): F. Yang, H. Wu, W. He, T. Chen, D. Nie
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 577 KB

Title: Modified Double-Ridged Antenna for 2-18 GHz
Abstract: In this paper, the design and simulation of a modified double-ridged antenna for 2-18 GHz is presented. The designed antenna has a voltage standing wave ratio (VSWR) less than 2.4 for the frequency range of 2-18 GHz and is most suitable as a feed element in the reflectors of the radar systems and EMC applications. The proposed antenna had distortion in radiation patterns in the 10-14 GHz frequency range. This problem has been modified by shaping of ridges. The proposed antenna is simulated with commercially available packages such as CST microwave studio and Ansoft HFSS in the operating frequency range. Simulation results for the VSWR, radiation patterns, and gain of the designed antenna over the frequency band 2-18 GHz are presented and discussed.
Author(s): A. R. Mallahzadeh, A. Imani
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 500 KB

Title: Two-Dimensional Pattern Scanning by Linear Phased Array with Pattern Reconfigurable Elements
Abstract: In this paper, a linear phased array with pattern reconfigurable elements is studied to perform a two-dimensional pattern scanning. Compared with the traditional linear array, the new linear array can scan the patterns in two-dimensional directions??i.e. -direction and -direction. The results indicate that the main beam of the proposed array can continuously scan from =30o to =150 o in the E-plane by adjusting the feed phases of reconfigurable elements and from =-50o to =50o in the H-plane by switching the elements operating states.
Author(s): Y. Bai, S. Xiao, B. Wang, S. Gao
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 374 KB

Title: Size Reduction and Harmonic Suppression of Parallel Coupled-Line Bandpass Filters Using Defected Ground Structure
Abstract: A novel miniaturized parallel coupledline bandpass filter with suppression of second, third and fourth harmonic frequencies, is demonstrated in this paper. The new filter is based on the slow-wave effect of the Defected Ground Structure (DGS) to achieve size minimization, while the spurious responses are eliminated by the band-rejection property of the DGS unit. These features offer the classical parallel coupled-line bandpass filter simultaneous compactness and wide stopband performance. Using the proposed DGS unit, does not require the filter parameters to be recalculated and, this way, the classical design methodology for microstrip parallel coupled-line filters can still be used. As an example, a 2.0 GHz parallel coupledline filter has been designed and measured in order to show the validity of the proposed DGS. Compared with the conventional parallel coupledline bandpass filters, the second, third and fourth measured spurious responses are suppressed to - 45, -43 and -34 dB, respectively. In addition, the size of the prototype filter is reduced by 20% compared to that of the conventional parallel coupled-line filter.
Author(s): F. Karshenas, A. R. Mallahzadeh, J. Rashed-Mohassel
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 346 KB

Title: Design and Analysis of Microstrip Photonic Band Gap Filter for Suppression of Periodicity
Abstract: A design for a microstrip band reject filter is presented in this paper. The proposed filter is compact in structure and provides an accurate band gap. Optimized length is applied to photonic band gap (PBG) structures etched in the ground plane for suppressing periodicity in the frequency response. Detailed analysis of the frequency response of the conventional microstrip filter along with the PBG filter has been carried out in this paper.
Author(s): R. N. Baral, P. K. Singhal
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 224 KB

Title: Capacity Investigations of MIMO Systems in Correlated Rician Fading Channel Using Statistical Clustered Modelling
Abstract: In this paper the capacity of MIMO systems is investigated for different realistic propagation scenarios in Rician fading channel. A nonparametric stochastic model is presented and is used to develop the spatial fading correlation. Uplink statistical MIMO channel is assumed with Laplacian angular energy distributed over multi-clusters situations. Radio waves that are gathered in several clusters distributed over the space domain are assumed to exhibit different power profiles. Capacity investigations for both uniform linear array (ULA) and uniform circular array (UCA) for single cluster and multi-clustered assumptions are presented. The optimum selections of number of elements and spacing between elements are discussed for different values of Angle of Arrival (AoA) and Azimuth Spread (AS). Also, the impact of K factor of the Rician distribution for single and multi-clusters environments is studied under different propagation scenarios.
Author(s): M. A. Mangoud
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 269 KB

Title: Parallelization of MLFMA with Composite Load Partition Criteria and Asynchronous Communication
Abstract: This paper describes an efficient parallelization of the multi-level fast multipole algorithm (MLFMA) for fast solution of very large scale electromagnetic scattering problems. Computation in the MLFMA can be divided into several stages. To accomplish load balance at any time, load partition criteria are adjusted according to different features of every phase. Meanwhile, an asynchronous communication method is designed to overlap the communication with computation and thus the communication cost in parallelization is reduced. Numerical results show that good parallel efficiency is obtained in the presented parallelization of MLFMA. With our parallel MLFMA, a scattering problem with nearly 5, 300, 000 unknowns is solved in about six hours using 8 CPUs on SGI O350 server.
Author(s): H. Zhao, J. Hu, Z. Nie
File Type: Journal Paper
Issue:Volume: 25      Number: 2      Year: 2010
Download Link:Click here to download PDF     File Size: 379 KB