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Title: ACES Journal March 2013
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 604 KB

Title: ACES Journal March 2013 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 3959 KB

Title: RCS2D: A 2D Scattering Simulator for MoM vs. FDTD Comparisons
Abstract: A Java-based, two dimensional (2D) electromagnetic wave scattering and Radar Cross- Section (RCS) simulation software, RCS2D Virtual Tool, is developed. Both Method of Moments (MoM) and Finite-Difference Time- Domain (FDTD) methods are used to simulate the Transverse Magnetic (TM) and Transverse Electric (TE) polarized scattering waves for arbitrary geometries and materials under the plane wave illumination.
Author(s): G. Toroglu, M. A. Uslu, L. Sevgi
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 723 KB

Title: MoM Analysis of an Axisymmetric Chiral Radome
Abstract: An axisymmetric chiral radome has been analyzed numerically by using the method of moments. The chiral body is illuminated by a plane wave and the surface equivalence principle is used to replace the body by equivalent electric and magnetic surface currents. The effect of adding chirality to a dielectric radome of revolution is investigated throughout numerical results obtained for bodies of different shapes and material parameters. Chiral materials can be used to design anti-reflective structures to control scattering cross section patterns of bodies. A computer program is developed for the chiral radome of revolution and examples of numerical calculations are given for a chiral spherical radome, a chiral cylindrical radome, and a chiral Von Karman radome. Numerical results for the chiral spherical radome are in excellent agreement with the exact ones obtained by the eigenfunction solution. Moreover, the numerical results of the chiral Von Karman radome are in excellent agreement with the published results.
Author(s): H. Mustacoglu, J. R. Mautz, E. Arvas
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 453 KB

Title: Broadband Miniaturized Efficient Array Antennas
Abstract: This paper introduces a new array architecture, in which antenna elements are arranged in a spiral curve. The spiral array enhances ultra-wideband (UWB) pattern characteristics compared to alternative array geometries of similar elements, without requiring a complex feed network for frequency change compensation. A number of examples are illustrated to demonstrate the array capability in broadband array designs. It is revealed that for the same number of elements and curvature lengths, a spiral array has a wider radiation bandwidth than the corresponding circular and linear array antennas. In addition, it is also demonstrated that the spiral architecture discussed here can be best suited for small antenna array applications. Simulations show that different spiral parameters lead to different size reduction, which vary from 30% to 90% with regards to a conventional circular array antenna.
Author(s): A. Jafargholi
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 330 KB

Title: Unsplit-Field Implementation of the Higher-Order PML using Z-Transform Method and D-B Formulation for Arbitrary Media
Abstract: On the basis of the stretched coordinate perfectly matched layer (SC-PML) formulations, the Z-transform method, and D-B formulation, an efficient and unsplit-field implementation of the higher-order PML scheme with more than one pole is proposed to truncate the finite-difference time-domain (FDTD) lattices. This method is completely independent of the material properties of the FDTD computational domain and hence can be applied to the modeling of arbitrary media without any modification. The higher-order PML has the advantages of both the conventional PML and the complex frequency shifted PML (CFS-PML) in terms of absorbing performances. The proposed algorithm is validated through two numerical tests carried out in three dimensional and two dimensional domains. It is shown in the numerical tests that the proposed PML formulations with the higher-order scheme are efficient in terms of attenuating both the low-frequency propagating waves and evanescent waves and reducing late-time reflections, and also hold much better absorbing performances than the conventional SC-PML and the convolutional PML (CPML) with the CFS scheme.
Author(s): N. Feng, J. Li, X. Zhao
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 288 KB

Title: Radiation from a Dielectric Coated Conducting Circular Cylinder Buried in a Conducting Corner (TM Case)
Abstract: The paper presented a new design of a corner reflector antenna, fed through a dielectric coated slotted cylinder. An exact solution to a two dimensional problem is developed using the modal expansion solution for TM case. Computer program was developed to evaluate the radiation pattern, aperture conductance, and antenna gain. This antenna structure finds many applications on ships and airplanes in which the antenna is buried at corners of horizontal and vertical conducting planes. The radiation from this antenna showed many new features, which could not be achieved by the conventional corner reflector antenna.
Author(s): H. A. Ragheb
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 369 KB

Title: A Novel Compact High-Gain Printed Quasi-Yagi Antenna and its Harmonic-Suppression Array
Abstract: In this paper, a novel compact printed quasi-Yagi antenna with a high gain of 8.39 dB is presented, and its binary antenna array with harmonic suppression is explored. The proposed antenna fed by a 100 Ohm coplanar stripline (CPS) achieves a 14.32 % relative bandwidth for a -10 dB reflection coefficient. The stepped impedance resonator (SIR) structure is adopted to suppress the harmonic radiations in the binary array, which is fed by a 50 Ohm coplanar waveguide (CPW). Due to its single-sided structure, this high gain antenna element and the binary array have many advantages, such as easy fabrication, compactness, low profile, and low cost. The antenna and array can be widely applied in wireless communication systems, especially in wireless power transmission (WPT) system.
Author(s): L. Zhong, J. S. Hong, H. C. Zhou
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 450 KB

Title: Harmonics Amplitude Measurement in UHF Band by Multi Harmonic Multiplication
Abstract: Analysis of a system to measure the amplitude of harmonics of a signal in UHF band is presented. First, analytical considerations are proposed, in which multi harmonic signal is used as local oscillator signal. The results are used to obtain optimal implementation by which conversion loss of mixer becomes minimal. The proposed method is implemented by single diode mixer. In mixer, harmonics of the desired signal to be measured are fed into RF port and a comb signal is synthesized to be fed into LO port to down convert the desired signal. Bottle neck is the amplitude of each harmonic in comb signal fed in LO port of mixer. The proposed design is validated and optimized by ADS (a full wave electromagnetic simulator). Optimization of conversion loss of the mixer boots the system bandwidth.
Author(s): A. Naserialiabadi, Gh. Moradi, A. Kheirdoost, R. S. Shirazi
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 235 KB

Title: Miniaturized Wilkinson Power Divider with nth Harmonic Suppression using Front Coupled Tapered CMRC
Abstract: In this paper, a novel microstrip power divider with a new technique for nth harmonic suppression is presented. This technique is based on using front coupled tapered compact microstrip resonant cell (FCTCMRC) that inserted into a quarter-wavelength transmission line of the conventional Wilkinson power divider. This cell is used to obtain high harmonic suppression. The proposed power divider not only impressively improves harmonic suppression, but also reduces the length of a quarter-wave line over 29.3 % as compared with the conventional power divider. From the measured results, the proposed structure achieved ultra wide stop-band bandwidth (6 GHz – 12 GHz) with a minimum attenuation level of 24 dB, while maintaining the characteristics of the conventional Wilkinson power divider. The input and output return losses at 2 GHz are 48 and 44 dB, respectively. The insertion loss is about 3.1 dB and better than 45 dB isolation is obtained.
Author(s): M. Hayati, S. Roshani
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 406 KB

Title: Design of Compact SITLs Low Pass Filter by Using Invasive Weed Optimization (IWO) Technique
Abstract: Step impedance transmission line (SITL) is optimized by Invasive Weed Optimization (IWO) technique to compact a low pass microstrip filter (LPF). In the proposed method, the uniform microstrip lines in the LPF structure are replaced by optimized SITLs. The equality of SITL and uniform transmission line gives two additional design parameters, which are optimized by IWO method to achieve the most compact SITLs. Finally, a compact high degree LPF is designed and fabricated with the area reduction of more than 70%. The measurement results of the fabricated LPF are in good agreement with the simulation ones.
Author(s): H. R. Khakzad, S. H. Sedighy, M. K. Amirhosseini
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 361 KB

Title: Study and Applications of an Unconditionally Stable Multi-Resolution Time-Domain Scheme
Abstract: An unconditionally stable locally one-dimensional multi-resolution time-domain (LOD-MRTD) algorithm is studied, which is free of the Courant-Friedrich-Levy (CFL) stability condition. The LOD-MRTD method is reformulated to get more efficient and simple formulations. The unconditional stability and dispersion equations of the LOD-MRTD in two dimension (2D) case are analyzed, and a 2D example is calculated to demonstrate these characteristics.
Author(s): Q. Cao
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 223 KB

Title: Electromagnetic Device Optimization Based on Electromagnetism-Like Mechanism
Abstract: The algorithm based on the Electromagnetism-Like mechanism results from the Coulomb’s law of electromagnetics. In this paper, a novel stochastic approach based on the Electromagnetism-Like mechanism is applied to the optimization of electromagnetic devices. In order to show the effectiveness of the proposed method, it has been demonstrated on a magnetizer by optimizing its pole face to obtain the desired sinusoidal magnetic flux density distribution.
Author(s): H. R. E. H. Bouchekara
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 394 KB

Title: Performance Improvement of the AOA Estimation Algorithm Using the Newton Iteration
Abstract: In this paper, a simple numerical method based on the Newton iteration for improving the accuracy of the Conventional beam forming algorithm, the Capon beam forming algorithm, and the MUSIC algorithm for AOA (Angle-of-Arrival) estimation is presented. Based on observation, the estimates of the AOA’s for a specific AOA algorithm can be obtained from the extrema of a cost function associated with the specific AOA algorithm employed. We derive explicit expressions of the iterations used for the recursive update of the estimates of the AOA’s for the conventional beam forming algorithm, the Capon beam forming algorithm, and the MUSIC algorithm. The formulation is only for the update of the azimuth angle, while the extension to the update of the elevation angle and the azimuth angle can be implemented by taking into account the dependence of the array manifold on the elevation angle as well as the azimuth angle. Note that, for estimation of the azimuth, both the UCA (uniform circular array) and the ULA (uniform linear array) can be employed, and that, for simultaneous estimation of the elevation and the azimuth angle, the UCA, not the ULA, should be adopted since ULA-based algorithm cannot uniquely estimate both the azimuth and the elevation due to the ambiguity pertinent to the ULA structure. We consider the array structure of the ULA and the UCA, but it is quite straightforward to extend the proposed scheme to an arbitrary array structure by simply modifying the array vector consistently with the specific array structure. Index Terms - AOA, accuracy improvement, conventional beam forming algorithm, Capon beam forming algorithm, MUSIC algorithm, Newton method, UCA, and ULA.
Author(s): J. H. Lee, S. W. Cho
File Type: Journal Paper
Issue:Volume: 28      Number: 3      Year: 2013
Download Link:Click here to download PDF     File Size: 1173 KB