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Title: ACES August 2011 Full Journal
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
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Title: ACES August 2011 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 958 KB

Title: Fast Design Optimization of Microwave Structures Using Co-Simulation-Based Tuning Space Mapping
Abstract: Tuning space mapping (TSM) expedites efficient design optimization of microwave circuits by replacing sections in the electromagnetic (EM) model with corresponding sections of designable equivalent elements. A key assumption of TSM is that these designable elements can replace their respective EM model sections without introducing significant distortion in the structureís response. This can be achieved through the co-calibrated ports technique introduced in Sonnet em. Here, we generalize the TSM algorithm. A tuning model is constructed by simulating the EM model sections separately and connecting them with the tuning components through a co-simulation process. This allows us to implement the TSM algorithm with any EM simulator. The response misalignment between the original structure and the tuning model is reduced using classical space mapping. The proposed algorithm is illustrated through the design of two microstrip filters simulated in FEKO.
Author(s): S. Koziel, J. W. Bandler
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 704 KB

Title: A Broadband Reflectarray Antenna using the Triangular Array Configuration
Abstract: A novel broadband reflectarray cell element is designed for use in several offset-fed reflectarray antennas based on square and triangular lattice. The proposed double-layer element consists of two stacked rectangular patches having two slots in non-radiating edges. Reflection phase curves are obtained by changing simultaneously the slotís length of top and bottom patch. The designed element exhibits a large phase-shift range in excess of 360o.This wideband cell element is designed to be used in a triangular lattice that eliminates the grating lobes for wideband reflectarrays composed of unit-cell larger than half-wavelength. Two 529-element square reflectarrays and two 518-element triangular reflectarray antennas were designed and simulated using CST and HFSS, for producing 20o and 35o off-broadside E-plane beams using a 20o offset feed. The 1-dB gain-bandwidth is about 30% at the center frequency of 14 GHz, and the maximum simulated gain is about 31 dBi which is equivalent to 51.5% aperture efficiency for a 20o off-broadside reflectarray based on triangular lattice configurations.
Author(s): M. Mohammadirad, N. Komjani, A. R. Sebak, M. R. Chaharmir
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 880 KB

Title: A Novel Approach for the Analysis of Electromagnetic Field with Rotating Body
Abstract: In this paper, a novel approach which combines the FDTD method with overset grid generation method is proposed for the analysis of the EM field with rotating body. The analysis is carried out together with the Lorentz transformation to comprise with the higher velocity cases. To apply the Lorentz transformation to the FDTD method, at least two frames are required, and we primitively modelled it with the overset grid generation method. With the Lorentz transformation, the time component changes at each of the grid point. The time component that has been changed by Lorentz transformation must be fixed as the numerical procedure. Through the interpolation technique, it is possible to fix the time component easily. We have previously proposed this novel approach for a stationary and uniformly moving body. Here, this analysis is further expanded and has included a more detailed discussion of the EM field interactions in a rotating environment. The numerical results show the characteristics of the EM field when the incident wave strikes the rotating body. For validation, the numerical results are compared with the theoretical results, and good agreements were obtained. The proposed novel approach has shown its consistency over higher relative velocity cases.
Author(s): S. Sahrani, H. Iwamatsu, M. Kuroda
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 1062 KB

Title: Study of the Effects of the Back Cavity on a Broadband Sinuous Antenna and an Optimized Loaded Back Cavity
Abstract: Sinuous antennas, like spiral antennas, have wideband characteristics, such as constant beam width and low axial ratio over a broad range of frequencies, and thus they are suitable for communicating in transmitting and receiving over bands of frequencies that may encompass multiple channels. In the presence of the back cavity, the performance of the sinuous antenna is affected. The purpose of this paper is to study the affects of the back cavity, and use these findings to build an optimized lossy cavity to improve the performance of the sinuous antenna. The performance of the antenna with and without the back cavity is compared to the antenna with the optimized loaded cavity.
Author(s): S. Palreddy, A. I. Zaghoul, R. Cheung
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 887 KB

Title: Investigation of a Proposed ANN-Based Array Antenna Diagnosis Technique on a Planar Microstrip Array Antenna
Abstract: In this article, a realistic neural network based method is proposed for the array antenna fault diagnosis through the utilization of array far field characteristics. Defective elements are those elements that are not excited directly by the feed lines but radiations due to the induced currents on the surface of these elements still remain. Neural network performs a nonlinear mapping between some samples of the degraded patterns and the array elements which may have caused these degradations. The proposed method is investigated on a real fabricated micro-strip planar array via its far field degraded radiation pattern measurements. A multilayer perceptron neural network trained in the back propagation mode with some samples of the simulated degraded patterns is used in an innovative manner to map the measured radiation pattern to its corresponding faulty elements configuration. After the training procedure the proposed fault diagnosis system is very fast and has a satisfactory success rate both in theory and application that makes it suitable for real time applications.
Author(s): A. R. Mallahzadeh, M. Taherzadeh
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 756 KB

Title: Simulation and Design of a PCB-Chassis System for Reducing Radiated Emissions
Abstract: The effects of the design parameters for a printed circuit board (PCB)-chassis system such as the slots on the chassis, the decoupling capacitors on the PCB, and the grounding posts (screws) connected between the PCB and the chassis are investigated using numerical analysis. These design parameters can affect the radiated emissions of the PCB-chassis system by changing or removing the resonances of the PCB and chassis. This numerical investigation represents a promising guideline for optimizing the number and location of grounding posts with regard to the placement of slots on a chassis and of decoupling capacitors on a PCB. The simulated results are shown to be consistent with the corresponding theoretical interpretations. Several design guides are summarized in the conclusion.
Author(s): H. H. Park, H. T. Jang, H. B. Park
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 1735 KB

Title: Hybrid of Moment Method and Mode Matching Technique for Full-Wave Analysis of SIW Circuits
Abstract: In this paper, a full wave analysis of substrate integrated waveguide (SIW) structures is presented based on the moment method in combination with the mode matching technique. Initially, input and output post pairs are terminated with two waveguide sections. Then waveguide width, as an unknown variable, is adjusted to obtain minimum reflection from the SIW. Field distribution in the structure and current density on posts as well as dispersion characteristic of the SIW are investigated. Also, by taking the advantage of the moment method, analysis of the structures with longitudinal discontinuity along the wave propagation direction is offered. Furthermore, versatile instances are analyzed and compared with experimental values, results from high frequency structure simulator (HFSS), and numerical methods in recent literature. Good agreement between the results verifies the accuracy of the hybrid method.
Author(s): R. Rezaiesarlak, M. Salehi, E. Mehrshahi
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 842 KB

Title: GTD Model Based Cubic Spline Interpolation Method for Wide-Band Frequency- and Angular- Sweep
Abstract: A hybrid frequency- and angularsweep interpolation method is proposed for the efficient analysis of the scattering over a broad frequency and angular band. This method hybridizes the cubic spline interpolation method and the GTD model. The cubic spline interpolation method is applied to interpolate the induced currents in the angular domain. The GTD model combined with the matrix pencil method is applied to parameterize the scattering centers over a wide frequency band. In order to efficiently compute electromagnetic scattering, the flexible general minimal residual (FGMRES) iterative solver is applied to compute the coefficients of Rao-Wilton- Glisson (RWG) basis functions. Therefore, a great deal of time can be saved for the calculation of frequency- and angular- sweep. Numerical results demonstrate that this hybrid method is efficient for wide-band RCS calculation with high accuracy.
Author(s): Z. Liu, R. Chen, D. Ding, L. Le
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 1518 KB

Title: A Monopole Antenna with SIR Ground for Harmonic Suppression and Bandwidth Enhancement
Abstract: A novel approach of adding a step impedance resonator (SIR) ground on the coplanar waveguide (CPW) monopole antenna has been proposed in this paper. The purpose of using the SIR ground is to suppress the harmonic radiation generated by rectifying diodes in a rectenna system and to enhance the impedance bandwidth. The measured results of the proposed antenna show that a 10-dB return loss bandwidth could reach 53% (2.32-4.05GHz) with respect to the center frequency of 3.23GHz, and all the second and third harmonics have been completely suppressed.
Author(s): Y. Zhao, L. Zhong, J. S. Hong, G. M. Zhang
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 811 KB

Title: Analysis of EM Scattering of Precipitation Particles in Dual-Band
Abstract: Simulation of EM scattering from complex precipitation particles shows great importance in both theoretical researches and practical applications. In order to analyze the scattering from raindrops in the Ku-band and Kaband, the T-matrix method is used in this paper. Firstly, a detailed analysis has been illustrated for a single homogeneous rainfall particle model in Ku-band and Ka-band. Then, scattering properties of double-layer rainfall media, such as ice-water or water-ice model, are quantitative analysis. Finally, scattering characteristics of a rainfall group by particle size distribution in a certain region is discussed. Numerical results are given to demonstrate the results of the EM scattering of precipitation particles. It is shown that studying the EM scattering of precipitation particles in Kuband and Ka-band will lead to great significance for the development of precipitation radar in the future
Author(s): J. Chen, R. Chen, Z. Liu, H. Peng, P. Shen, D. Ding
File Type: Journal Paper
Issue:Volume: 26      Number: 8      Year: 2011
Download Link:Click here to download PDF     File Size: 694 KB