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Title: ACES Journal October 2015 Cover
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
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Title: ACES Journal October 2015 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 104 KB

Title: ACES Journal October 2015 Full
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 12321 KB

Title: FEKO Simulation of Multi-Resonant Low-Profile PIFA
Abstract: A passive, low-profile multi-resonant planar-inverted-F antenna (PIFA) element well-suited for portable communications is presented. The antenna combines the optimal low-profile geometry of a planar inverted-F antenna with a double-tuned structure to create a multi-resonant element with monopole-class radiation properties. The form factor and overall dimensions are held constant for comparisons to a similar single-resonant antenna in different near-field environments.
Author(s): C. W. Hearn, W. A. Davis
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 512 KB

Title: Sensitivity Analysis of the Orthorhombic Design Parameters in the Artificially Biaxially Dielectric Crystal
Abstract: A full-wave modeling and simulation analysis method is presented for performing sensitivity analysis of artificial uniaxial and biaxial crystals previously reported for study with waveguide measurement systems. Small occlusions were machined into bulk dielectric material to impose effectively biaxial material properties. Here, the primary design parameters for orthorhombic occlusions are presented. Using multivariate parameter estimation, the effective material properties are characterized in a way that is equivalent to waveguide measurement methods. The advantage in using full-wave simulation allows investigation beyond measurement and fabrication capabilities, but is still limited because of the mesh size needed to model the fine geometric sizes of the occlusions in the crystal. The analysis shows that the effects of the primary design parameters on anisotropy can achieve 2-3 dB of axial difference for the biaxially diectric crystal. Although, only the dielectric case is presented, the multivariate estimation method used to estimate the material parameters is applicable for characterizing lossy and magnetic materials.
Author(s): J. Brand, M. A. Saville
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 335 KB

Title: A Novel Wedge Diffraction Modeling Using Method of Moments (MoM)
Abstract: Scattering from edges and/or tips (i.e., diffraction) has long been modeled using different approaches. Initially, it was handled analytically using high frequency asymptotics (HFA). Parallel to the development in computer technology diffraction has begun to be modeled using numerical approaches also. Here, method of moments (MoM) is used to model the canonical wedge scattering problem and a novel, generally applicable procedure is introduced to extract diffracted fields and diffraction coefficients.
Author(s): G. Apaydin, L. Sevgi
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 841 KB

Title: Scattering Analysis of Periodic Composite Metallic and Dielectric Structures with Synthetic Basis Functions
Abstract: Synthetic basis functions method (SBFM) is used in this paper to analyze scattering properties of periodic arrays composed of composite metallic and dielectric structures based on EFIE-PMCHW equation. Compared to traditional method of moment (MoM) based on volume integral equations (VIE) or surface integral equations (SIE), SBFM uses fewer synthetic basis functions to approximate scattering properties of a target which decreases the number of unknowns as well as memory cost significantly. Auxiliary sources are introduced to imitate the mutual coupling effects between different blocks. By solving targetsí responses to these auxiliary sources, scattering solution space will be determined. Then, singular value decomposition (SVD) is adopted to extract synthetic basis functionsí coefficients matrix from scattering solution space. For periodic structures, synthetic basis functions of each block are exactly the same which means previously computed coefficients matrix can be recycled; therefore, SBFM is of great advantages in analyzing large scale periodic mixed problems.
Author(s): X. Yanlin, Y. Hu, Y. Weikang
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 895 KB

Title: An Efficient FDTD Algorithm to Analyze Skewed Periodic Structures Impinged by Obliquely Incident Wave
Abstract: An efficient wideband finite-difference time-domain (FDTD) method is proposed to analyze arbitrarily skewed periodic structures at oblique incidence. The method is free of complex step-by-step phase processing caused by the oblique incident plane wave and the stagger unit cells, and the provided periodic boundary condition (PBC) is as simple to implement as in the normal incidence case. A numerical example is simulated respectively by our method in one-time calculation over a wideband and the previous dual plane wave method requiring multiple repeated runs, which verifies the validity and efficiency of the proposed method.
Author(s): M. Bai, B. Liang, H. Ma
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 281 KB

Title: Modal Analysis of Frequency Selective Surface Containing Ring Loops
Abstract: Modal analysis of frequency selective surface (FSS) containing ring loops arranged periodically along any two skewed coordinates, will be calculated. In proposed modal analysis, a compatible set of orthonormal mode functions used for ring loops in addition to Floquet modes which are used in every infinite two dimensional arrays. This set of modes provides faster convergence in solving integral equation in accordance with this boundary condition problem. Calculations are compared with results of CST (Finite Integration Technique) and HFSS (Finite Element Method) full-wave simulators and they are in good agreement with each other.
Author(s): M. S. Samani, R. S. Shirazi, G. Moradi
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 468 KB

Title: Multi-Band Frequency Selective Surface Design Based on Idea of Clusters in Cellular Communication Systems
Abstract: A frequency selective surface which can provide up to 4 passbands will be proposed. The passbands are nearly independent so it simplifies the design procedure. The base of the design is according to frequency reuse in cellular communications which there are N different frequencies in one cluster. The array cells in this FSS are hexagons and the resonators on top and bottom of each cell are aperture loops. As the elements and cells are in the most geometrical symmetry, stability about polarization and angle of incidence is in the good state. As some examples, a dual-band, a triple-band and a quad-band FSS are simulated with CST software. The results are in good agreement with theoretical calculations.
Author(s): M. S. Samani, R. S. Shirazi, G. Moradi
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 987 KB

Title: Design Investigation of an X-Band SIW H-Plane Band Pass Filter with Improved Stop Band Using Neural Network Optimization
Abstract: In this paper, an X-band H-plane band pass filter based on substrate integrated waveguide (SIW) technology is introduced. Back propagation neural network (BPNN) method is applied to optimize parameters of the proposed filter. The stop band of the proposed filter is improved by cascading the H-plane filter with a low pass filter designed and implemented using defected ground structure (DGS). A prototype of the proposed filter is made and experimental results are presented and also compared with those obtained by simulation. Measured reflection coefficient and transmission coefficient in pass band are better than -20 dB and -3.7 dB respectively. Measured results agree well with those obtained by simulation.
Author(s): Z. S. Tabatabaeian, M. H. Neshati
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 1428 KB

Title: A Circular Slot UWB Antenna with Independently Tunable Quad-Band Filtering Characteristics
Abstract: An effective design method is proposed to develop an excellent performed quad-band filtering UWB antenna. A spiral-shaped stub (SSS), two T-shaped stubs (TSSs) and an arc-shaped slot (ASS) are utilized to realize the proposed quad-band filtering characteristics. The independently tunable band-notched characteristics are carried out by adjusting the dimensions of SSS, TSS and ASS respectively. The proposed quad-band filtering UWB antenna is fabricated and measured for validation. The simulated and measured results show that this antenna can provide a wide bandwidth covering 3.1-10.6 GHz with four band notched characteristics and omnidirectional radiation patterns in its H-plane, which render it suitable for indoor UWB communication applications.
Author(s): Y. Li, W. Zhang, W. Yu
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 712 KB

Title: Dual Band Bandpass Filter Using Multilayer Structure
Abstract: In this paper, a new method to design a dual band bandpass filter (BPF) is presented. This method is based on a simple principle: different substrates (dielectric constants) will result different resonant frequencies for a resonator. The basic structure of this method is studied and then a planar band pass resonator is designed to utilize in this structure. Response of the proposed dual layer filter is tuned using resonator shifting and resonator scaling. In addition to improve the filter response, resonator shifting improves the filter size. The final structure is designed, fabricated and measured and simulation results are in good agreement with measured values. The central frequencies of this dual band BPF are f1=3.85 GHz and f2=5.3 GHz and a deep transition zero at 4.57 GHz, guarantees isolation between passbands.
Author(s): S. Majidifar, S-V. Makki
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 1484 KB

Title: Nonlinear Analysis of Active Aperture Coupled Reflectarray Antenna Containing Varactor Diode
Abstract: Radiation pattern of reflectarray antenna can be controlled using varactor diode in the antenna structure, but may cause nonlinear response. Thus, it is needed to design active reflectarray antenna considering nonlinear behavior of the unit cell. However, in the past papers, active element of varactor tuned reflectarray antenna is assumed linear, while in this paper, nonlinear analysis of active reflectarray antenna is explained and an active aperture coupled reflectarray unit cell containing two varactor diodes is analyzed. Harmonic balance method is used in analyzing active unit cell using nonlinear model of the diode. Therefore, this paper shows the significance of nonlinear analysis of active reflectarray antenna, and also the effect of nonlinear element in radiation pattern is presented. By the explained method, the impact of nonlinearities on performance of reflectarrays can be investigated. Furthermore, any active reflectarray cell having active device by any nonlinear model can be used in the analysis, and the impact of parameters of the model can be studied.
Author(s): I. Aryanian, A. Abdipour, G. Moradi
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 464 KB

Title: Design and Fabrication of Aperture Coupled Microstrip Increased Bandwidth Antenna
Abstract: This paper presents aperture coupled microstrip antenna with three resonants. The antenna bandwidth has been enhanced due to clip in the patch edges and varies the current distribution well in order to create the third resonant. There is a compromise between radiation characteristics and the antenna bandwidth. These two factors have been optimized in designed and fabricated samples. E-plane and H-plane patterns indicate the appropriate propagation pattern of antenna is between 1.3 to 2.3 GHz frequency band, which clarifies achieved bandwidth more than 53% by using certain method in the novel one radiating element. Of course, there is bandwidth enhancement up to this limit by utilization of multiple radiating elements.
Author(s): M. J. Chashmi, H. Ghobadi, M. Oliaei
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 3081 KB

Title: Full-Wave Fast Solver for Circuit Devices Modeling
Abstract: The analysis of complex circuit components with electrically small size is an important problem for radio frequency circuit modeling. In this paper, we present a fast solver which is based on low-frequency stable integral equation and accelerated with the multilevel accelerated Cartesian expansion algorithm (MLACEA). MLACE algorithm is usually based on electric field integral equation which suffers from lowfrequency breakdown problems. To keep the algorithm stable, the augmented electric field integral equation (AEFIE) is used in our solver. Regarding the truncation order of the expansion, the efficiency and accuracy of MLACEA are investigated. By adjusting the truncation order, we can keep the algorithm in good performance. Numerical examples show the efficiency and the capability of the proposed method.
Author(s): Y. Zheng, Y. Zhao, Z. Nie, Q. Cai
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 1022 KB

Title: Firefly Algorithm for Failure Correction of Linear Array of Dipole Antennas in Presence of Ground Plane with Mutual Coupling Effects
Abstract: In this paper, firefly algorithm is utilized for the correction of radiation pattern of a linear antenna array of parallel half-wavelength dipole antennas spaced uniformly when defected completely with more than one dipole element. Mutual coupling between the antennas along has been considered along with the effect of distance between the antenna array and the ground plane on the radiation pattern. Adjustments are done in the values of the excitation voltage of the remaining nondefective elements through evolutionary algorithm such that the parameters, namely, side lobe level and maximum reflection coefficient (S11) in dB of the corrected pattern are calculated and efforts are taken to make it closer to the original pattern values. This certainly avoids replacing of defective elements. The element pattern of individual elements in the array has been assumed omnidirectional in the plane considered. Examples are shown to produce the response of the proposed approach using evolutionary algorithm for three element failures out of twenty elements in the array with the effect on various distances between the antenna array and ground plane. Even though, the method is utilized here for a linear dipole antenna array, it can be applied for other antenna array configurations also.
Author(s): R. Muralidharan, A. Vallavaraj, G. K. Mahanti
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 638 KB

Title: Lattice Boltzmann Model for Simulation of Avalanche Formation and Streamer Discharge in Breakdown of Gaseous Dielectrics
Abstract: Gas discharges play a central role in the electrical breakdown of matter, both in nature and technology. Therefore, accurate modeling and simulation of streamers in gaseous discharge processes are of particular interest. This study presents the formulation of computationally efficient models of the charge density and electric field produced by the lattice Boltzmann method. The propagation of double-headed streamers is described in 1-cm plane-to-plane geometry in pure nitrogen at atmospheric pressure by 1.5D and 2D models. The lattice Boltzmann method was successfully applied to the simulation of streamer discharges. Therefore, this scheme is a potential way of simulating gaseous discharge problems.
Author(s): N. Wang, Q. Lei
File Type: Journal Paper
Issue:Volume: 30      Number: 10      Year: 2015
Download Link:Click here to download PDF     File Size: 564 KB