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Title: ACES Journal February 2017 Cover
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
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Title: ACES Journal February 2017 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 100 KB

Title: ACES Journal February 2017 Full
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 9080 KB

Title: FDTD Potentials for Dispersion Analysis of Sinusoidally Modulated Media
Abstract: A numerical study based on the finite difference time domain (FDTD) method is presented for the oblique incidence of TE modes with an emphasis on dispersion properties. The proposed medium has sinusoidally modulated dielectric permittivity. In order to truly address this scattering problem, total fieldscattered field (TFSF) approach is suggested, which yields accurate results for the electric field distribution inside the modulated medium. A comparison between analytical plots and the FDTD results reveals the ability of FDTD in rigorous analysis of band diagrams for any arbitrary value of modulation factor. In addition, a closed form formula for numerical dispersion relation is derived for the case of small modulation.
Author(s): F. M. Monavar, G. Moradi, P. Mousavi
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1992 KB

Title: An Efficient and Analytical Solution to the Integral on Truncated-Wedge ILDCs for Polygonal Surfaces
Abstract: A new method is proposed to analytically evaluate the line integral on truncated-wedge incremental length diffraction coefficients (TW-ILDCs). By utilizing the coherence of a geometry, the trailing edges can be divided into several linear segments, and the line integrals can be reduced as the two end-point contributions for each segment based on the mathematical model derived in this paper. Thus, the efficiency is greatly enhanced in comparison with the traditional numerical techniques. Numerical results for the bistatic radar cross sections show excellent performance of the proposed method both in accuracy and efficiency.
Author(s): C. Liu, X. Zhou, W. M. Yu, T. J. Cui
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1781 KB

Title: A Regularized Source Current Reconstruction Method for Reactive Near Field to Far Field Transformation
Abstract: The source current reconstruction method (SRM) is based on reconstructing equivalent current from the known electric field and can be used as a method of near field to far field transformation. In this paper for the first time the reactive near field (RNF) to far field (FF) transformation based on SRM is carefully studied. It is shown that in the RNF region, the singular values of the SRM transformation matrix can magnify the evanescent modes of RNF region and unstable the SRM iterative solvers. Therefore, in this paper for RNF/FF transformation a regularized SRM is proposed and the equivalent magnetic current of an antenna under test is reconstructed from the Tikhonov SRM equation. The regularization parameter of the Tikhonov equation is determined by the L-curve method. The effect of near field distance and noise on the accuracy of far field transformation of the proposed algorithm are studied in two different antenna simulations. It is shown that in all cases in the RNF region a regularized SRM have more stable behavior and more accurate results.
Author(s): M. Bod, R. Sarraf-Shirazi, GH. Moradi, A. Jafargholi
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 2309 KB

Title: Electromagnetic Radiation Source Identification Based on Spatial Characteristics by Using Support Vector Machines
Abstract: In the radio monitoring, electromagnetic interference diagnostics and radar detection, the electromagnetic radiation source identification (ERSI) is a key technology. A new method for ERSI was proposed. The support vector machines (SVMs) have been applied to facilitate the ERSI on the basis of the spatial characteristics of the electromagnetic radiation sources. The radiation sources were located by the triangulation method, and then their spatial characteristics were collected by a band receiver array, and converted from 3D data to 1D vector with subscripts as the inputs for the SVMs. We trained the model with these 1D vectors to enable it to identify the radiation source types with both high speed and accuracy. The identification time needs only a few seconds, which is much faster than the artificial neural networks (ANNs). The influence of parameters (e.g., noise from the ambient environment, the data collection method, the scaling method for the input data, and the penalty parameter) were discussed. The proposed method has good performance even in the noisy environments. The results were verified by a designed measurement. The proposed approach is very useful for the ERSI of unknown radiation sources in practice.
Author(s): D. Shi, Y. Gao
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1817 KB

Title: A Null Broadening Beamforming Approach Based on Covariance Matrix Expansion
Abstract: In order to improve the performance of antenna array beamforming in the case of jammer motion, a null broadening beamforming approach based on covariance matrix expansion is proposed in this paper. The covariance matrix of the array is expanded through the Kronecker product of an eye matrix and the sample covariance matrix. The steering vector of the array is also expanded. When the expanded covariance matrix is used for beamforming, more linear constraints can be constructed compared with the original sample covariance matrix, so wider and deeper nulls can be obtained with equal number of array elements, or similar performance can be obtained with fewer number of array elements. Necessary numerical procedures are provided and computation complexity is analyzed. The validity of the proposed approach is verified by theoretical analysis and simulation results.
Author(s): W. Li, Y. Zhao, Q. Ye, S. Li
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1550 KB

Title: Radar Cross Section Reduction of Microstrip Antenna Using Dual-Band Metamaterial Absorber
Abstract: This paper deals with the design and experimental verification of a dual-band metamaterial radar absorbing structure for the reduction of radar cross section (RCS) of a microstrip antenna. A Metamaterial Absorber (MMA) is designed to work in X-band with absorption rate near 100%. To demonstrate the effective performance of the proposed structure, its influence on RCS and performance of a microstrip antenna is investigated. According to the numerical and measurement results, one can find that the designed antenna shows dual-band RCS reduction within X-band for wide incident angles, while the radiation characteristics of the antenna are sustained without undesired changes.
Author(s): A. Shater, D. Zarifi
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1792 KB

Title: Noise Suppression Detection Method Based on Time Reversed Signal Waveform Similarity
Abstract: A novel time reversal detection (TRD) algorithm for noise suppression is presented. The targets can be located accurately by analyzing the crosscorrelation character of TR echo signals received by subarrays. Compared with conventional TR algorithm, the performance of proposed method is superior, especially under low signal-to-noise ratio (SNR) condition.
Author(s): B. Li
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1735 KB

Title: A Compact Microstrip Lowpass Filter with Flat Group-delay and Ultra High Figure-of-Merit
Abstract: This paper presents a new design of a microwave low pass filter (LPF) using coupled stepped impedance patches. The designed LPF has specifications such as ultra sharp roll-off, ultra wide stopband, low insertion-loss and high return-loss in the passband. The designed LPF has -3 dB cut-off frequency of 1.38 GHz. The transition-band is 0.12 GHz that is from 1.38 to 1.50 GHz with the attenuation levels of -3 and -20 dB, respectively. Maximum insertion-loss at about 80% of the passband is 0.1 dB. The simulation and experimental results are close to each other. The proposed LPF achieved to a remarkable figure-of-merit of 171622.
Author(s): M. Hayati, M. Ekhteraei, F. Shama
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1805 KB

Title: Compact Wideband Parallel-Coupled Microstrip Line Bandpass Filter with In-Line Structure
Abstract: A compact wideband microstrip bandpass filter constructed by a parallel-coupled microstrip line and a parallel-connected half-wavelength (?g/2) microstrip line is proposed in this letter. The proposed bandpass filter showcases wideband bandpass response with four transmission zeros within the operating bandwidth from DC to 2f0 (f0 center frequency). The transmission zeros located at DC and 2f0 are inherently generated by the parallel-coupled microstrip line while the other two are realized by the parallel-connected ?g/2 microstrip line. For validation, a wideband bandpass filter centered at 4.15 GHz with bandwidth of 3 GHz is designed, fabricated and measured. The size of the in-line bandpass filter is 0.27?g0.045?g, which features very compact size and can be integrated conveniently with other microwave components.
Author(s): C. Shao, Y. Li, L. Wang, C. Jin
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1809 KB

Title: LTCC Wideband Bandpass Filter Based on Multi-layered Coupling
Abstract: A novel wideband bandpass filter (BPF) based on multi-layered coupling using low temperature co-fired ceramic (LTCC) technology is proposed. Four folded quarter-wavelength layered coupled lines are distributed in 3D space to achieve compact circuit structure. Two transmission zeros near edges of the passband response can be easily realized by the two quarter-wavelength open/short coupled lines. Besides over 15-dB out-of-band rejection, the insertion loss of less than 0.7 dB is realized in the passband. A prototype with 3-dB fractional bandwidth of 25.7% operated at 2.95 GHz is designed and fabricated.
Author(s): X. Gao, W. Feng, W. Che
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1987 KB

Title: Compact Modified Quarter Mode Substrate Integrated Waveguide Resonator and Its Application to Filters Design
Abstract: A novel compact modified quarter mode substrate integrated waveguide (QMSIW) resonator is proposed. The dominant resonant mode of the proposed resonator is TE101 mode. Using modified QMSIW resonator can reduce 97.3% in size with respect to its corresponding substrate integrated waveguide (SIW) counterpart. With the new coupling structures, the miniaturized cavity can be properly arranged in the filter design to minimize the footprint of the circuit. Two novel filters using compact modified QMSIW cavity are designed, and these proposed compact filters are fabricated to prove the predicted results in experiments, in which good agreement is obtained.
Author(s): Y.-Z. Zhu, W.-X. Xie, X. Deng, Y.-F. Zhang
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1878 KB

Title: Waveguide Filter Modeling and Simulation using Mode-matching, Fullwave Network Analysis and Swarm Optimization
Abstract: This paper presents the modeling of waveguide bandpass filter synthesis. It consists of a combination of the most appropriate and reliable methods and techniques of analysis, simulation and optimization used in determined order and leading to a fast and accurate method of filter synthesis. An example of a forth-order filter synthesis is given, employing a symmetric configuration and symmetric response. The obtained results, reference measurement and commercial software simulator results are compared for validation.
Author(s): I. Bouchachi, J. Mateu, M. L. Riabi
File Type: Journal Paper
Issue:Volume: 32      Number: 2      Year: 2017
Download Link:Click here to download PDF     File Size: 1964 KB