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Title: ACES Journal December 2015 Cover
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: ACES Journal December 2015 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: ACES Journal December 2015 Full
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Efficient, Accurate and Scalable Reflectarray Phase-Only Synthesis Based on the Levenberg-Marquardt Algorithm
Abstract: The Levenberg-Marquardt algorithm is used to perform an efficient phase-only synthesis for shapedbeam reflectarray antennas. A thorough analysis of the problem and algorithm allows to improve greatly its performance and its results with regard to those in the literature. Specifically, several optimizations in the Jacobian matrix computation are detailed, including its fully parallelization thanks to the fact that each column of the Jacobian can be independently computed. A Cholesky factorization based solver is used to obtain the updating vector at each iteration of the algorithm, which is the fastest exact solver for linear equation systems. Finally, some guidelines to choose proper values for the algorithm parameters are presented. Due to the high dimensionality of the problem, a good control in the algorithm evolution is important to guarantee good convergence and avoid non-desired local minima. The synthesis of a LMDS shaped beam for a dual-polarized reflectarray is proposed to test the developed algorithm and the results are compared with others in the literature, showing improvements in accuracy and time efficiency. The framework established for the phase-only synthesis can be used in a broader problem to directly optimize the geometry of the reflectarray through full wave analysis of the unit cell.
Author(s): D. R. Prado, J. Alvarez, M. Arrebola, M. R. Pino, R. G. Ayestaran, F. Las-Heras
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Modeling of Anisotropic Magnetic Objects by Volume Integral Equation Methods
Abstract: This paper presents the modeling of electromagnetic scattering from objects with magnetic anisotropy. We study the solutions of both the volume integral equation (VIE) method and augmented volume integral equation (A-VIE) method. For the VIE method, it is built from the 3D vector wave equation for electric field only. For the A-VIE method, it is built from 3D vector wave equation for both electric and magnetic fields. Numerical results show that the A-VIE method has better accuracy and convergence for magnetic objects compared to the VIE method.
Author(s): L. E. Sun, W. C. Chew
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: The Computational Performance and Power Consumption of the Parallel FDTD on a Smartphone Platform
Abstract: The use of the FDTD in Android applications heralds the use of mobile phone platforms for performing electromagnetic modeling tasks. The Samsung S4 and Alpha smartphones computations are powered by a pair of multi-core Advanced RISC Machines (ARM) processors, supported by the Android operating system, which comprises a self-contained platform, which can be exploited for numerical simulation applications. In this paper, the parallelized two dimensional FDTD is implemented on the Samsung Smartphone using threading and SIMD techniques. The computational efficiency and power consumption of the parallelized FDTD on this platform are compared to that for other systems, such as Intel’s i5 processor, and Nvidia’s GTX 480 GPU. A comparison is made of the power consumption of the different techniques that can be used to parallelize the FDTD on a conventional multicore processor. In addition to parallelizing the FDTD using threading, the feasibility of accelerating the FDTD with the SIMD registers inherent in the phone’s ARM processor is also examined.
Author(s): R. G. Ilgner, D. B. Davidson
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Mode Conversion Caused by Bending in Photonic Subwavelength Waveguides
Abstract: We study the propagation of light in a subwavelength planar waveguide with an angular bend. We observe the mode conversion of a guided wave with a symmetric beam profile impinging into the bending of a waveguide. The guided wave outgoing from the bend is a mixed set of symmetric and asymmetric modes. The amount of mode conversion through the bend is quantified by calculating the Fourier transform of the electric field profile. It is found that the conversion rate is a function of the bending angle.
Author(s): Y. J. Rodriguez-Viveros, D. Moctezuma-Enriquez, P. Castro-Garay, B. Manzanares-Martinez, C. I. Ham-Rodriguez, E. Urrutia-Banuelos, J. Manzanares-Martinez
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
Download Link:Click here to download PDF     File Size: 708 KB

Title: A Novel Frequency and Radiation Pattern Reconfigurable Antenna for Portable Device Applications
Abstract: In this paper, a dielectric embedded antenna with frequency and radiation pattern reconfigurable characteristic is proposed for portable terminal applications. The proposed reconfigurable antenna consists of one excitation element, two parasitic elements and eight radio frequency switches. The proposed reconfigurable functions are obtained by controlling the ON/OFF states of the radio frequency switches which are integrated into the excitation elements. As a result, the proposed reconfigurable antenna can operate at two frequencies, 1.9 GHz and 2.8 GHz for supporting DCS1800 (1.71-1.88 GHz) and UMTS (1.92-2.17 GHz), LTE2300 (2.305-2.4 GHz), LTE2500 (2.5-2.69 GHz), WIFI (2.4-2.484 GHz). The radiation pattern reconfigurable characteristic is achieved by controlling the state combination of six radio frequency switches installed on the parasitic elements, resulting in three modes in the radiation pattern at each frequency band. The experimental results demonstrated that the proposed antenna can achieve good frequency and radiation pattern reconfigurable characteristics.
Author(s): W. Li, L. Bao, Y. Li
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Design of an Efficient Triple Band RF Energy Harvester
Abstract: In this paper, a new triple band RF energy harvester, considering all the influential parameters, is designed by using Advanced Design System (ADS) simulation software. The most important problem in the RF energy harvesters is low system efficiency. Another problem is that these circuits work on narrow RF bands. The proposed design is found to be much efficient with its current form and provide broadband working frequencies. The output power values and efficiencies of each circuit have been obtained from the software by varying input RF power, load resistance and the number of stages in voltage multiplier at DTV 575 MHz, GSM 900 MHz and WiFi 2.45 GHz frequencies. Thereby a triple band RF energy harvester is proposed for higher efficiency. The system efficiencies for this input power level are obtained about 55% at 575 MHz, 45% at 900 MHz, 30% at 2.45 GHz. The average efficiency is found to be 43% for the individual systems. However, the system efficiency is 68% in the proposed triple band RF energy harvester. This corresponds to an increase rate of 58% for the efficiency. Furthermore, thanks to the proposed RF energy harvester, the efficiencies are increased significantly in cases which only one or two RF signals exist.
Author(s): Y. Uzun
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
Download Link:Click here to download PDF     File Size: 738 KB

Title: Analysis of Dual-Reflector Antenna for Radar Applications
Abstract: A dual-reflector antenna in millimeter wave frequency band is designed at center frequency of 35 GHz. The designed antenna has small size, low weight, fast beam scanning, high efficiency and high gain. Beam rotation of the proposed structure makes it useful for wide angle scanning in modern airborne radar systems. In the literature, beam rotation of similar structures used to be evaluated by two times of the twist-reflector rotation. For the first time, a nonlinear relationship is found between beam rotation and twist-reflector rotation. This nonlinear relation is theoretically extracted in this work. Furthermore, the designed antenna is simulated with a commercial full wave package. The results confirm that the designed goals are addressed. Moreover, the simulation results validate the extracted analytic relationship between beam rotation and twistreflector rotation. In addition, low VSWR, low crosspolarization and good radiation pattern are observed.
Author(s): A. Imani, M. Soleimani, S. Amiri
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Series Solution to the Radiation from Slotted Antenna on Elliptic Cylinder Coated by Biaxial Anisotropic Material
Abstract: Radiation characteristics of an axially slotted circular or elliptical antenna coated by biaxial anisotropic material are investigated using series solution. The fields inside and outside the coating regions are expressed in terms of appropriate Mathieu functions with unknown field coefficients. The boundary conditions at the conducting and dielectric coating surfaces are invoked to obtain the unknown field expansion coefficients. Numerical results are presented graphically for the radiation pattern with various geometries and electrical parameters.
Author(s): A.-K. Hamid
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
Download Link:Click here to download PDF     File Size: 402 KB

Title: UWB Monopole Antenna with Switchable Band-Notch Characteristic Using a Novel MEMS Afloat
Abstract: In this paper, a novel microelectro-mechanical system (MEMS) U-shaped afloat is designed and used instead of a simple slot to activate and deactivate the band notch characteristic of an ultra wideband (UWB) monopole antenna at the WLAN band (5.15-5.825 GHz) without extra DC bias lines. The novelty of this work is design of MEMS afloat that can stay in down state permanently. When the dc actuation voltage, about 20 volts, is applied to the microstrip center line, the ?/2 long U-shaped afloat moves down and creates a slot (resonating element) in its vacant place. Whereas no voltage is applied, the afloat remains in the up position and serves as a part of the antenna, which eliminates the resonance. The proposed design for MEMS afloat has least negative effect on gain, reflection coefficient, and pattern of the antenna. The gain of the antenna is about 3.2 dBi over the entire UWB frequency band (3.1-10.6 GHz), while it decreases sharply over 7 dB at the rejection band. More-over, the time-domain characteristics of the antenna is investigated, which shows 1 ns delay over the UWB frequency band for 20 cm. Due to a novel afloat design, the addition of the resonance element does not affect on the radiation performance, reflection coefficient, gain, and group delay of the antenna outside of notched band frequencies.
Author(s): A. Nemati, B. A. Ganji
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Analysis of TM and TE Modes in Eccentric Coaxial Lines Based on Bipolar Coordinate System
Abstract: The cutoff wavenumbers, cutoff frequencies, field distributions and dispersive characteristics of TM and TE modes (higher order modes) in eccentric coaxial lines are carefully calculated by a new method directly based on the finite difference method (FDM) in bipolar coordinate system (BCS). Detailed comparisons with the previous results in the literature demonstrate the accuracy of the proposed method. Several characteristic features of the field distributions and the dispersion relations are also indicated. This method and its variations are very suitable and efficient for the computation of electromagnetic field problems in transmission lines with eccentric parallel cylinders.
Author(s): J. Zhou, M. Chen, R. Zhong, S. Liu
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Microstrip Dielectric Substrate Material Characterization with Temperature Effect
Abstract: This paper describes a dielectric substrate materials electromagnetic (EM) characterization method in the ultra-wideband (UWB) frequencies from DC to 5 GHz by taking into account the temperature influence. The proposed method theoretical principle is described and fundamentally built with the analytical formulation from the microstrip transmission line (TL) theory. From this basic concept, the analytical equations enabling to determine the dielectric material relative permittivity and loss tangent from the given S-parameters are established. The characterization method is validated with numerical and experimental tests. As proof of concept, a prototype of microstrip TL printed on FR4 epoxy substrate was designed, fabricated and experimented. The relative permittivity and loss tangent were extracted in the UWB frequency from DC to 5 GHz in the range of temperature varied from 40°C to 140°C. This innovative characterization method is useful for the investigation on the frequency dependent and especially by taking into account the temperature influence on the substrate materials; for example, during the microstrip circuits design phase.
Author(s): B. Ravelo, A. Thakur, A. Saini, P. Thakur
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: A Novel Printed Antenna with Square Spiral Structure for WiMAX and WLAN Applications
Abstract: ? A new printed antenna with multiband characteristic suitable for WiMAX and WLAN operating frequency bands is presented. For this purpose, two square spiral arms as radiating elements and partial ground plane are considered in the antenna structure. By adding the square spirals and adjusting the number of turns of the square spirals, new resonances are excited and desired resonant frequencies at 2.56, 3.94, 5.20, 5.80, and 10.18 GHz can be achieved to cover WLAN and WiMAX systems. Parametric simulation of the main parameters affecting the antenna performance are presented and discussed. The designed antenna with full size of 20×20 mm2 is fabricated and tested. The radiation pattern is approximately omnidirectional in operating bands. The simulated and the experimental results are in acceptive agreement and confirm good performance for the offered antenna.
Author(s): P. Beigi, J. Nourinia
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: A 340-400 GHz Zero-Biased Waveguide Detector Using a Self-Consistent Method to Extract the Parameters of Schottky Barrier Diode
Abstract: A type of low-barrier Schottky barrier diode (SBD), based on InGaAs/InP, is designed and fabricated, and then a 340-400 GHz zero-biased waveguide detector utilizing this diode is proposed. To predict the performance of the SBD, firstly we present a self-consistent analytical method to find the accurate values of the parameters of the SBD by using the on-wafer measured S-parameter under different bias conditions up to 40 GHz and an auxiliary de-embedding structure. The extracted values show a very good agreement with the theoretical values. Then a concept called effective capacitance is proposed to model the high frequency (340-400 GHz) properties of the SBD. This concept has greatly improved the consistency of the simulated and measured results of the detector. The measured maximum voltage responsivity and the minimum noise effective power (NEP) of the detector are 800 mV/mW and 3.46×10-11 W/Hz0.5 at 382 GHz, respectively
Author(s): T. Ren, Y. Zhang, R. Xu, J. Zhou, C. Yang, Z. Jin
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Optimization of Electromagnetics Problems Using an Improved Teaching-Learning-Based-Optimization Technique
Abstract: Teaching-learning-based optimization (TLBO) is a rising star technique among metaheuristic techniques with highly competitive performance. This technique, which has been recently introduced, is based on the effect of influence of a teacher on learners and learners on their colleagues. This paper intends to apply an improved version of TLBO in the field of electromagnetics. To demonstrate its effectiveness in this area, the proposed technique is applied to two benchmarks related to brushless direct current wheel motor problem and testing electromagnetic analysis methods problem number 22. The quality of the results presented shows that the proposed technique is very competitive with other well-known optimization techniques; hence, it is a promising alternative technique for optimization in the field of electromagnetics.
Author(s): H. R. E. H. Bouchekara, M. Nahas
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Frequency and Time Domain Investigation of Compact UWB Slot Antenna with Triple Band Notched Characteristics
Abstract: In this paper, a simple compact ultrawideband (UWB) microstrip slot antenna with triple band notched characteristics is presented. In the proposed antenna, a good impedance matching over a very wide frequency range is achieved by adding two rectangular stubs to the bottom section of the simple rectangular patch. Moreover, by employing an inverted T-shaped stub connected to the ground plane and two U-shaped and ?-shaped slots in the modified patch, triple band notched properties are obtained. This proposed triple band notched antenna with dimensions of 26×26 mm2 has a very wide bandwidth from 2.5 GHz up to 19 GHz, which is about 150% fractional bandwidth of the center frequency. Unlike the most previous works reported in the literature, the triple band notched feature applied in the proposed antenna does not deteriorate the impedance bandwidth at higher frequencies. The radiation results such as gain, efficiency and radiation patterns as well as time domain properties of the proposed antenna show that it can be a good candidate for new super wideband applications.
Author(s): S. R. Emadian, J. Ahmadi-Shokouh, A. Raessi, A. Askani, J. Nazari
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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Title: Numerical Evaluation of the Radar Cross Section of Human Breathing Models
Abstract: In this paper, anatomical models of the human body are used to evaluate the radar cross section (RCS) of breathing subjects. The study is performed by using a self-developed finite difference time domain (FDTD) code implemented in the message passing interface environment (MPI). The realized models represent three different phases of the breathing activity taking into account the respiration physiology and the pulmonary mechanics. In particular, the end expiration phase (resting state), the end of a normal inspiration phase (tidal), and the end of a deep inspiration phase (deep) were considered. Computed results show RCS values of the resting state model in agreement with literature data, and appreciable variations of the RCS determined by the breathing activity. Simulations performed with homogeneous body models suggest that these differences depend both on the model anatomy and on the tissue dielectric properties.
Author(s): M. Cavagnaro, E. Pittella, S. Pisa
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
Download Link:Click here to download PDF     File Size: 307 KB

Title: Bandwidth Enhancement of Small Square Monopole Antenna Using Self-Complementary Structure for Microwave Imaging System Applications
Abstract: A novel printed monopole antenna for ultrawideband (UWB) applications is designed based on self-complementary structure as a matching network. The proposed antenna consists of a square radiating patch and a self-complementary structure located next to feed line, which provides a wide usable fractional bandwidth of more than 100% (3.04-11.43 GHz). Selfcomplementary matching network is created, by cutting two rectangular ring slots on the ground plane and by inserting two rectangular rings coupled elements in the top layer; hence, additional resonances are excited and much wider impedance bandwidth can be produced. The designed antenna has a small size of 14×22 mm2 , about 0.15?×0.25? at 4.3 GHz. It is shown that simulated and measured results agree well with each other and demonstrate the usefulness of the proposed antenna for UWB applications. The proposed antenna exhibits almost omni-directional radiation patterns with low crosspolarization levels and provides an acceptable gain over whole band.
Author(s): M. Ojaroudi, O. A. Civi
File Type: Journal Paper
Issue:Volume: 30      Number: 12      Year: 2015
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