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Title: ACES Journal July 2018 Cover
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: ACES Journal July 2018 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: ACES Journal July 2018 Full
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Domain Decomposition Scheme in Newmark-Beta-FDTD for Dispersive Grating Calculation
Abstract: In this work, an efficient domain decomposition scheme is introduced into the unconditionally stable finite-difference time-domain (FDTD) method based on the Newmark-Beta algorithm. The entire computational domain is decomposed into several subdomains, and thus the large sparse matrix equation produced by the implicit FDTD method can be divided into some independent small ones, resulting in a fast speed lower-upper decomposition and backward substitution. The domain decomposition scheme with different subdomain schemes and different subdomain numbers is studied. With a generalized auxiliary differential equation (ADE) technique, the extraordinary optical transmission through a periodic metallic grating with bumps and cuts is investigated with the domain decomposition Newmark-Beta-FDTD. Compared with the traditional ADE-FDTD method and the ADENewmark- Beta-FDTD method, the results from the proposed method show its accuracy and efficiency.
Author(s): S.-B. Shi, W. Shao, K. Wang
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: An Interpolation Scheme for Green’s Function and its Application in Method of Moment
Abstract: An interpolation scheme is put forward to accelerate the calculation of free space Green’s function. Through theoretical analysis, a universal rule on how to build value lists for the phase item of Green’s function is discussed. And this rule can guarantee accuracy of the interpolation scheme. Accuracy and efficiency of the scheme are verified in the calculation of impedance matrix for method of moment. Besides, this scheme can also be applied to other applications which contain the calculation of Green’s functions and is especially useful for the analysis of large scale problems. Moreover, this scheme can be combined with other existing improved approaches of method of moment.
Author(s): Y. Xu, H. Yang, X. Liu, R. Shen
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: An Empirical Formula for Resonant Frequency Shift due to Jerusalem-Cross FSS with Substrate on One Side
Abstract: An empirical formula for calculating the shifted resonant frequencies of Jerusalem-cross frequency selective surfaces (FSSs) with different substrates is derived based on extensive calculations made on widely varying in shifted dual resonant frequencies for substrates with different relative dielectric constants and thickness. The coefficients in the empirical formula were determined by using least-square curve fitting technique to fit 672 sets of shifted resonant frequencies obtained by the HFSS simulator. Numerical results of shifted resonant frequencies obtained from the empirical formula are generally in good agreement with those calculated by the HFSS simulator and measurement. The average error in the shifted resonant frequencies is less than 5 percent. The empirical formula thus provides a simple, inexpensive, and quick method for obtaining optimum geometrical parameters of a dual-band Jerusalem-cross FSS with a substrate consisting of different dielectric constants and thickness for arbitrarily specifying two resonant frequencies.
Author(s): H.-Y. Chen, S.-H. Wen
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: The Human Body Modelled by Canonical Geometric Shapes for the Analysis of Scattered E-fields
Abstract: The objective of this paper is to propose a simplified model of a human body to be used in electromagnetic problems involving high frequency field scattering. Canonical geometric shapes, analytically described, represent the body. The accuracy of the model was tested comparing the field scattered by the simplified body representation with the one scattered by a more realistic phantom. At first, the influence of anatomical details of the body was analysed, comparing the electromagnetic field reflected by a realistic human head with the backscattering of spheres and of an ellipsoid. A second test concerns the human body, modelled by sphere, parallelepiped and cylinders. In this case, the possibility of reconstructing a wideband pulse scattered by the whole body with the superposition of pulses scattered by its separated parts was demonstrated. Both analyses were carried out in the frequency range 3- 5 GHz using a full wave numerical simulator.
Author(s): G. Manfredi, V. Di Mattia, P. Russo, A. De Leo, G. Cerri
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Design and Implementation of Dual Band Microstrip Patch Antenna for WLAN Energy Harvesting System
Abstract: Since the demand for self-sustained wireless systems is increasing, there is a trend towards RF energy harvesting. It is a key solution to energize the low power systems such as the Internet of Things (IoT) devices without replacing the batteries periodically. This paper presents the design and analysis of RF energy harvesting system that consists of dual-band microstrip patch antenna operating at 2.4 GHz and 5.8 GHz, an impedance matching network, 4-stage voltage doubler and a storing circuit. The antenna is designed using ADS Agilent and sonnet suites software that provides a directivity of 5.5 dBi and 6.3 dBi at 2.4 GHz and 5.8 GHz respectively. The measured results of the fabricated antenna are well agreement with the simulated results. Simulated results show that for an input received power of 10 mW, the proposed system can provide 4.5 mW power at the output of 4-stage voltage rectifier with an overall efficiency of 45%.
Author(s): O. Amjad, S. W. Munir, S. T. Imeci, A. O. Ercan
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: A Compact Tunable Triple Stop-Band Filter Based on Different Defected Microstrip Structures
Abstract: A compact triple stop-band filter based on different defected microstrip structures is proposed, fabricated and measured to filter out the undesired narrowband signal interferences against UWB systems. A meander line slot (MLS), a U-shaped slot (USS) and a spur line (SL) are etched on a 50-Ohm microstrip line to achieve the expected triple stop-band function and to provide a good tunable characteristic by selecting the proper dimensions of the MLS, USS and SL. The equivalent circuit model and its simulations are presented to evaluate the designed triple stop-band filter. Simulated and measured results are given to demonstrate that the proposed triple stop-band filter has controllable center frequencies and compact size.
Author(s): Y. Li, S. Luo, W. Yu
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Mutual Coupling Reduction of a MIMO Antenna Array Using 3-D Novel Meta-material Structures
Abstract: A 3-D metamaterial structure (3DMMS) is proposed and is used to reduce mutual coupling of a twoelement patch antenna array. The 3DMMS consists of an upper M-shaped patch and two lower U-shaped patches, which are connected by two shorted pins. The proposed 3DMMS has a negative permeability at 2.35-2.45 GHz band, which covers the operation band of the patch antenna array with an edge-to-edge array-element distance of 0.13 lambda 0. Five designed 3DMMS cells are embedded into the substrate between two antenna elements, which has a 0.1mm vertical distance to the patch antennas. The proposed antenna is optimized, fabricated and measured. The results show that about 18 dB mutual coupling reduction is achieved by using the 3DMMS without affecting the operating bandwidth and radiation characteristics.
Author(s): K. Yu, Y. Li, X. Liu
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Wideband Multi-Port Network Integrated by 3-dB Branch-Line Couplers
Abstract: The design of a multi-port network integrated by symmetrical alignment of four 3-dB branch-line couplers (BLCs) for wideband communication applications is presented. The BLC is designed with the implementation of stub impedance at each port’s transmission line and defect ground structure (DGS) underneath the shunt branches of BLC to improve bandwidth. The designs of the BLC and the multi-port network are performed by using CST Microwave Studio, a three-dimensional (3D) electromagnetic wave simulator. The designed wideband BLC and multi-port are fabricated, and their wideband performances of 2.3 to 5.3 GHz are verified.
Author(s): N. A. M. Shukor, N. Seman, T. A. Rahman
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Efficient Design of Metamaterial Absorbers using Parametric Macromodels
Abstract: Metamaterial absorbers have recently attracted a lot of interest for applications spanning from microwave to terahertz, near infrared and optical frequencies, such as electromagnetic compatibility, thermal emitters, solar cells and micro- bolometers. In this paper, a procedure for the efficient design of metamaterial absorbers based on parametric macromodels is presented. These models are used to describe the frequency-domain behaviour of complex systems as a function of frequency and design parameters (e.g., layout features). Parametric macromodels are very efficient and can be used to speed up the design fow in comparison with using electromagnetic simulators for design tasks. The use of quasi-random sequences for the sampling of the design space and of radial basis functions and polynomial functions for the model construction is proposed. Numerical results validate the efficiency and accuracy of the proposed technique for multiple optimizations.
Author(s): G. Antonini, M. D. Astorino, F. Ferranti, F. Frezza, N. Tedeschi
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Optimization of T-shaped Suspension Magnetic Ring for Vertical Axis Wind Turbine
Abstract: Aiming at realizing breeze startup, light wind power generation, a novel T-shaped group of passive magnetic bearing (PMB) with three rings high suspension characteristics was proposed to increase the utilization of wind energy and improve the suspension characteristics of passive bearings. The inner magnetic ring of the T-shaped magnetic ring group adopts an oblique 45° polarization method, which can simultaneously balance radial force and axial force with high suspension characteristics. The static characteristics of the T-shaped magnetic ring group are compared with the traditional double rings which dynamic disturbance characteristics were analyzed in three degrees of freedom (DOF) and the parameters are optimized to achieve the optimal suspension characteristics through methods of Taguchi, response surface with mathematical model. The study shows that the capacity of T-shaped magnetic ring group is 2.5 times which can balance axial force and radial force simultaneously with 40% increase in volume than the double ring. The capacity of T-shaped magnetic ring group is increased by 33.6% and the stiffness is increased by 33.7% after optimized, which meets the requirements of suspension characteristics. When the bearing is disturbed in 3 DOF operation, the stable running state of the bearing can still be maintained due to its selfstabilizing system. It provides a reference for the suspension characteristics of the vertical axis wind turbine suspension system.
Author(s): Z. Jun, S. Dandan, H. Qiaoli, W. Jinmei, G. Li, L. Shaolong
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Advanced Imaging for Down-Looking Contactless GPR Systems
Abstract: This paper investigates the performance of an advanced imaging procedure for ground penetrating radar (GPR) operating in contactless configuration, i.e., when data are collected at variable distances from the air-soil interface. A data processing procedure is presented, based on an advanced implementation of a microwave tomographic approach. This improved version, recently proposed by the authors, is able of accounting for the near-field distribution generated by a directional transmitting antenna. The effectiveness of the procedure is shown by processing numerical data, which are obtained by suitably implementing a realistic system on a full-wave commercial simulator. Metallic canonical objects are considered to compare the reconstruction capabilities of the proposed algorithm with respect to more conventional procedures, as well as to assess the role of the antenna distance from the air-soil interface.
Author(s): D. Comite, F. Murgia, I. Catapano, F. Soldovieri, A. Galli
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: A High Resolution Algorithm for Null Broadening Beamforming Based on Subspace Projection and Virtual Antenna Array
Abstract: In this paper, we proposed a high resolution algorithm for null broadening beamforming. The algorithm is based on the property of subspace orthogonal principle between signal and noise, and on virtual antenna array. By utilizing Capon spectrum estimator, we construct the correlation matrix to obtain projection transformation matrix, the width of null increases when original covariance matrix is processed by projection transformation matrix. In order to improve the depth of null and increase array resolution, virtual antenna technique is introduced. Also diagonal loading technique is used to form robust beam pattern. With the theoretical analysis and computer simulation, it’s demonstrated that the superiority of proposed algorithm corresponding other null broadening beamforming methods.
Author(s): W. Li, H. Yang, Y. Mao
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: On the Design and Simulation of Antennas on Ultra-thin Flexible Substrates
Abstract: Flexible wireless systems are rapidly evolving in a wide spectrum of applications such as medical, entertainment and sport facilities. The aim of this paper is to investigate whether the ultra-thin substrates along with their permittivity are essential for the initial design stage of a flexible antenna, which is a key element of any wireless system, or it is merely a supporting structure. Three state-of-the-art simulation tools are used to evaluate the scattering parameter, S11 which are then compared against precise measurements conducted inside an anechoic chamber. These methods are the Finite Integration Technique (FIT) based Time Domain Solver (TDS) and the Finite-Element Method (FEM) based Frequency Domain Solver (FDS) of CST Microwave Technology and the (FEM) based HFSS of ANSYS. This paper attempts to provide an answer as to whether the substrate and other geometrically small features such as the feeding structure should be sufficiently discretized or else conventional default adaptive meshing should be enough. Three different flexible antennas with two fabrication techniques and feed lines have been used in the simulations and measurements.
Author(s): A. Kashkool, S. Yahya, H. Al-Rizzo, A. Al-Wahhamy, A. A. Issac
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Modelling of Electromagnetic Scattering from Large and General Intakes on Complex Platforms
Abstract: In the framework of the design of low observable aircraft, one of the most difficult problem is the numerical modelling of aeronautical air intakes with an – usually complex – arbitrary shape. Also the presence of radio absorbing material demands for accurate methods in evaluating the low level scattering for real life problems. This paper addresses the use of a full wave approach, based on the Multilevel Fast Multipole Approach (MLFMA), for a high fidelity modelling both of the whole (real life) aircraft, and of the intake scattering contribution, useful in the design and optimization stage of the intake itself.
Author(s): A. Mori, S. Bertini, M. Bercigli, R. Scuderi, P. de Vita, S. Sensani
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: A Finite Difference Frequency Domain Based Full Vectorial Transverse Modesolver for Anisotropic Waveguides with Arbitrary Permittivity and Permeability Tensors
Abstract: In this work a Yee’s mesh based full vectorial transverse finite difference frequency (FDFD) modesolver has been derived from discretized Maxwell’s equations in Matrix form for anisotropic waveguides with arbitrary permittivity and permeability tensors. This work incorporates arbitrary permittivity and permeability simultaneously into matrix equations of Yee’s mesh based modesolver, which previous works have not done. For benchmarking the Python implementation of these matrix equations, cross section of Yittrium Iron Garnate (YIG) channel waveguide has been taken as first one of the three test structures. Numerical result from this work has been compared with that from previous work on YIG channel waveguide and is found to be in good agreement. Further, for benchmarking the effective index values of waveguides having both permittivity and permeability anisotropic simultaneously, a finite element based commercial software (COMSOL) has been used, the values of effective indexes from solver presented in this work and commercial software have been compared, and are also found to be in good agreement.
Author(s): V. Singh
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: Broadband Permittivity and Permeability Extraction of Ferrite Cores up to the GHz Range via Measurements and Simulations
Abstract: In this contribution a method is presented which allows for the characterization of the magnetic (mu’-j mu’’) as well as the dielectric (epsilon’-j epsilon’’) properties of ferrites in a broad frequency band (kHz to GHz). In order to determine the material properties at certain frequencies, the simulation model parameters of a particular test setup are tuned via optimization such that the simulated response of a sample to an electromagnetic excitation matches to the measured one. A loop and parallel plate setup support a low frequency parameter extraction of the sample while a coplanar line is used for high frequencies. The extracted material properties are fitted by a broadband causal fit in order to obtain a material model for the whole frequency range. The presented method is verified for a setup with a coil and a ferrite core. The results show that dielectric properties of the ferrite core cannot be neglected for microwave frequencies.
Author(s): C. Reinhold, P. Scholz, U. Jumar
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: An HSS-Matrix-Based Fast Direct Solver with Randomized Algorithm
Abstract: Discretization of the electric field integral equation (EFIE) generally leads to dense impedance matrix. The resulting matrix, however, can be compressed in sparsity based on hierarchical structure and low rank approximation. In this paper, we propose an HSS-matrix-based fast direct solver for surface integral equation (SIE) that has a compression complexity of O(rN2) to analysis the large-scale electromagnetic problems, where r is a modest integer. The proposed solver efficiently compresses the dense matrices using a randomized algorithm and requires modest memory. Efficiency and accuracy is validated by numerical simulations. In addition, being an algebraic method, the HSS-matrix-based fast solver employs Green’s kernels and hence is suitable for other integral equations in electromagnetism.
Author(s): W. Yu, H. Yang, S. Li, Y. Xu
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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Title: A Compact CPW-Fed MIMO Antenna with Band-Notched Characteristic for UWB System
Abstract: A compact coplanar waveguide (CPW)-fed multiple-input-multiple-output (MIMO) band-notched antenna with a small size of 20×36×0.8 mm3 for ultrawideband (UWB) system is proposed in this paper. The two rectangular monopole (RM) elements fed by CPW are printed on the FR4 substrate. To improve impedance bandwidth and the isolation, a T-shaped stub structure is positioned in the middle of two RM elements. The bandnotched characteristic is achieved by etching a U-shaped loop resonator slot on each RM element. The S11 reflection coefficients, S12 coupling isolation, radiation pattern, peak gain and radiation efficiency of the MIMO antenna are measured. The MIMO performance of the proposed MIMO antenna is analyzed and evaluated by the envelope correlation coefficient (ECC) and total active reflection coefficient (TARC).
Author(s): L.-Y. Chen, J.-S. Hong, M. Amin
File Type: Journal Paper
Issue:Volume: 33      Number: 7      Year: 2018
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