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Title: ACES Journal December 2012
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 5520 KB

Title: ACES Journal December 2012 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 631 KB

Title: A Hybrid 3DMLUV-ACA Method for Scattering from a 3-D PEC Object above a 2-D Gaussian Dielectric Rough Surface
Abstract: The bistatic electromagnetic scattering from the composite model of a three-dimensional (3-D) arbitrarily shaped object located above a two -dimensional (2-D) Gaussian rough surface is analyzed in this work. The object suited above is assumed to be a perfect electric conductor (PEC) while the rough surface is dielectric. Firstly, the Poggio, Miller, Chang, Harrington, Wu and Tsai (PMCHWT) integral equations, electric field integral equation (EFIE) are implemented and extended on the rough surface and on the surface of the object respectively. Then, the method of moments (MoM) combined with Galerkin method is introduced to discretize the integral equations to the matrix form using RWG basis function. Due to the memory requirement and computational complexity of traditional MOM are O(N2 ) ( N is the number of unknowns), the rank based 3-D Multilevel UV method (3DMLUV) is employed to reduce memory and CPU time overhead. The 3DMLUV has been successfully applied in the scattering of PEC targets, however, when the object or rough surface become dielectric, the fast fill-in method proposed in Reference [19] often breaks down due to the oscillatory nature of the gradient of Green’s function. Therefore, the ACA is applied to speed up the filling of the impedance entries required in 3DMLUV because of its algebraic nature. The efficiency and accuracy of the proposed method are demonstrated in a variety of scattering problems.
Author(s): C. Li, S. Y. He, G. Q. Zhu, Z. Zhang, F. S. Deng, B. X. Xiao
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 1226 KB

Title: A Hybrid ACA-FDM for Electromagnetic Scattering from PEC Targets
Abstract: In this paper, the adaptive cross approximation (ACA) algorithm is combined with the fast dipole method (FDM) to solve the electromagnetic scattering from perfect electric conducting (PEC) targets. In the ACA-FDM, the ACA and the FDM are employed to deal with the near-group pairs and the far-group pairs respectively. Compared with the conventional FDM, the submatrices related to the interactions of the near-group pairs are efficiently compressed by the ACA, so the ACA-FDM saves CPU time and memory requirement, when the criterion for the far-group pairs becomes stricter in order to obtain relatively high accurate solutions. Numerical results about the electromagnetic scattering from PEC targets are given to demonstrate the merits of the ACA-FDM.
Author(s): X. Chen, C. Gu, X. Deng, B. Xu, Z. Li, Z. Niu
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 300 KB

Title: A Novel Single-Sided Wideband Metamaterial
Abstract: A simplified structure made of double P-like rings (DPLs), printed on only one side of a dielectric substrate was proposed. A metamaterial sample is investigated numerically and experimentally. The results clearly show that the negative refraction occurs at the transmission band, and one very wide left-handed passband is obtained. A circuit model is also carried out to be a further analysis of the DPLs unit cell.
Author(s): D. L. Jin, J. S, Hong, H. Xiong
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 567 KB

Title: Photonics Bandgap Computations using Novel Periodic Meshless Methods
Abstract: Although many numerical methods have been developed to calculate photonic bandgap structure properties, but always improvement in numerical methods is necessary to have more efficient, accurate and flexible techniques. In the present work, novel periodic meshless shape functions including so-called direct and radial shape functions are presented. The meshless approaches, based on these periodic shape functions as real-space methods, can be used for simulation of periodic structures, like photonics bandgap structures, straightforwardly. The results on band structures derived from the proposed methods are then presented, discussed and compared with those available in the literature, and a very good agreement is seen. It shows that the proposed techniques are very promising to be robust techniques in the simulation of periodic structures such as photonic problems.
Author(s): H. Razmjoo, M. Movahhedi, A. Aminian, T. Q. Bui
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 380 KB

Title: Analysis of Thin Microstrip Antennas by Meshless Methods
Abstract: In this paper, different meshless methods are applied to the analysis of microstrip antennas with thin substrate. Comparison is made between the performance of the methods with respect to convergence, CPU time and condition number of final coefficient matrix. The exact modal solution and method of moments are used for validation. The input impedance results of all methods are in agreement with each other.
Author(s): B. Honarbakhsh, A. Tavakoli
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 490 KB

Title: Single Snapshot 2D-DOA Estimation in Impulsive Noise Environment using Linear Arrays
Abstract: This paper considers single snapshot two dimensional direction-of-arrival (2D-DOA) estimation in impulsive noise environment employing linear arrays. 2D-DOA estimation is realized in two steps. Firstly, the 2D-DOA estimation problem is decomposed into two independent one dimensional direction-of-arrival (1D-DOA) estimation problems. The 1D-DOA estimation is derived using the support vector regression based basis selection algorithm. Secondly, an over-complete dictionary is designed based on amplitude information of sources, and angle pairing is accomplished in perspective of basis selection. Validity and advantages of the proposed algorithm are shown through computer simulations
Author(s): Y. Zhang, H. Zhao, Q. Wan
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 1056 KB

Title: Spherical Aperture-Coupled Antennas with Parasitic Element
Abstract: Theory and experiment of spherical aperture-coupled antennas with parasitic elements are presented in this paper. Current distributions on slot and conformal patches are calculated using spatial domain electric and magnetic Dyadic Green's Functions (DGFs). Electromagnetic fields for such a structure have been calculated with the aid of linear Rao-Wilton-Glisson (RWG) triangular basis functions and by converting spherical DGFs to Cartesian DGFs. In order to validate the proposed method, a prototype of this antenna is fabricated and tested. The effect of parasitic element on antenna characteristics such as gain and radiation pattern is investigated. Good agreement between the results shows accuracy and high convergence speed of the presented method.
Author(s): J. S. Meiguni, M. Kamyab, A. Hosseinbeig
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 476 KB

Title: Enhanced Bandwidth Ultra-Wideband Small Monopole Antenna with Variable Band-Stop Function
Abstract: In this paper a novel ultra wideband monopole antenna with frequency band-stop performance is designed and manufactured. The proposed antenna consists of square radiating patch with a T-shaped ring slot and ground plane with two G-shaped slots. In the proposed structure, by cutting two G-shaped slots in the ground plane, additional resonance is excited and hence much wider impedance bandwidth can be produced, especially at the higher band. In order to create band-rejected function we use a T-shaped ring slot in the radiating patch. The fabricated antenna has the frequency band of 2.95 to over 15.65 GHz with a rejection band around 5.13-5.91 GHz. Good return loss and radiation pattern characteristics are obtained in the frequency band of interest. Simulated and measured results are presented to validate the usefulness of the proposed antenna structure for UWB applications.
Author(s): M. T. Partovi, N. Ojaroudi, M. Ojaroudi, N. Ghadimi
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 878 KB

Title: A Novel Compact UWB Antenna with Triple Band-Notches for WiMAX/ WLAN/ ITU Bands
Abstract: A novel compact Ultra-Wideband (UWB) antenna with triple band-notched characteristics is presented. The antenna patch consists of several circular rings and a small circle. The antenna has a compact size of 25 × 20 mm2, which has been printed on a Rogers RO4003 substrate. Moreover, the proposed antenna has been successfully fabricated and measured, showing broadband matched impedance (2.8 up to more than 20GHz, VSWR? 2); almost stable gain and good omnidirectional radiation patterns.
Author(s): M. M. Abdollahi, H. R. Dalili Oskouei, M. Akbari, M. Mighani
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 993 KB

Title: Band-Notched Small Monopole Antenna using Triple E-Shaped Structures for UWB Systems
Abstract: In this letter, a novel ultra wideband monopole antenna with frequency band-stop performance is designed and manufactured. The proposed antenna consists of two E-shaped structures in the radiating patch with a rotated Eshaped slot in the ground plane. The rotated Eshaped slot increases the bandwidth that provides a wide usable fractional bandwidth of more than 110% (3.05-11.50 GHz). In order to create bandrejected function, we use an E-shaped structure in the radiating patch and also by inserting a rotated coupled E-shaped strip we can improve bandnotched performance and a frequency notch band of 5.07–5.92 GHz has been achieved. Good return loss and radiation pattern characteristics are obtained in the frequency band of interest. Simulated and measured results are presented to validate the usefulness of the proposed antenna structure for UWB applications.
Author(s): N. Ojaroudi, Sh. Amiri, F. Geran, M. Ojaroudi
File Type: Journal Paper
Issue:Volume: 27      Number: 12      Year: 2012
Download Link:Click here to download PDF     File Size: 570 KB