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Title: ACES Journal April 2014 Cover
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
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Title: ACES Journal April 2014 Front/Back Matter
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 110 KB

Title: ACES Journal April 2014 Full
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
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Title: Convergence Analysis in Deterministic 3D Ray Launching Radio Channel Estimation in Complex Environments
Abstract: In this paper, a convergence analysis to obtain the optimal calculation parameters in an inhouse 3D ray launching algorithm to model the radio wave propagation channel in complex indoor environments is presented. Results show that these parameters lead to accurate estimations with reduced computational time. In addition, simulation results of an indoor complex scenario in terms of received power and power delay profile are presented, showing significant influence of multipath propagation in an indoor radio channel. The adequate election of simulation parameters given by convergence conditions, can aid in optimizing required computational time.
Author(s): L. Azpilicueta, M. Rawat, K. Rawat, F. Ghannouchi, F. Falcone
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 1982 KB

Title: The Error Cross-Section Method for Quantifying the Error in Electromagnetic Scattering Problems
Abstract: The Error Cross-Section (ECS) is introduced to quantify the error associated with the numerical solution of electromagnetic scattering problems. The ECS accounts for different approximations and inaccuracies in the object discretization and numerical computations. The ECS definition is based on the power conservation principle and is visualized by comparing it to the radar cross-section of a thin wire for twodimensional (2-D) problems or a small sphere for three-dimensional (3-D) problems. The proposed ECS method is independent of the adopted numerical technique and therefore can be used to give confidence in the obtained solution using several methods, such as the Method of Moments (MoM) and the Finite-Difference FrequencyDomain (FDFD) method. Application of the ECS to the optimization of certain parameters for some numerical formulations, such as the CombinedField Integral Equation (CFIE) is also presented.
Author(s): A. M. Kord, I. A. Eshrah
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 348 KB

Title: FPO-Based Shooting and Bouncing Ray Method for Wide-Band RCS Prediction
Abstract: The fast physical optics (FPO) method for calculating the monostatic radar cross section (RCS) of an object over a range of frequencies is extended to the shooting and bouncing rays (SBR) method where the multi-bounce phenomena of the launched rays is considered. The FPO method is an improved version of the physical optics (PO) method, which is efficient when calculating the monostatic RCS over a wide range of frequencies or/and angles. The SBR method, based on the combination of geometrical optics (GO) and PO methods, can reach a higher accuracy compared with the PO method. However, due to different length of ray tube paths, it is difficult to implement the phase compensation and phase retrieval in the SBR as that in the FPO method. In this paper, a coordinate transformation is introduced in the integral equation, which transforms the original ray tubes model into a new one. The FPO technique can then be taken on the revised model without difficulty. The validity and efficiency of the proposed method are validated though a couple of numerical experiments.
Author(s): Y. An, Z. Fan, D. Ding, R. Chen
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 301 KB

Title: A Miniaturization Band-Pass Filter with Ultra-Narrow Multi-Notch-Band Characteristic for Ultra-Wideband Communication Applications
Abstract: In this paper, we present a novel approach for designing compact Ultra-Wideband (UWB) band-pass filters with desired multi-notchband characteristics. The multi-notch-band features are realized by using a ring-stub multimode resonator, while the equivalent model is also obtained by using the odd/even excitation resonance condition. The fabricated prototype of the band-pass multi-notch-band filter demonstrates a good behavior as expected. Simulated and experimental results show that the proposed filter with a compact size of 25◊10 mm2 , has an impedance bandwidth between 3.0 GHz and 10.6 GHz; while the multiple notch bands are achieved and their center frequencies are located at 3.9 GHz, 5.25 GHz, 5.9 GHz, 6.8 GHz and 8.0 GHz. The proposed filter is suitable for being integrated in UWB radio systems to efficiently enhance the interference immunity from unexpected signals, such as Worldwide Interoperability for Microwave Access (WiMAX), Wireless Local-Area Network (WLAN), 6.8 GHz Radio Rrequency Identification (RFID) communication and X-band satellite communications.
Author(s): Y. Li, W. Li, W. Yu, C. Liu
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 1205 KB

Title: A Hybrid MoM-PO Method Combining ACA Technique for Electromagnetic Scattering from Target above a Rough Surface
Abstract: In this paper, an efficient hybrid method of moments (MoM)-physical optics (PO) method combining adaptive cross approximation (ACA) technique is applied to calculate the electromagnetic scattering from three-dimensional (3-D) target and rough surface composite model. The current on the rough surface is obtained through the PO approximation, while the current on the target surface is obtained through the MoM. Furthermore, an ACA technique is used to accelerate the coupling interaction between the target and the rough surface. Numerical results demonstrate that the memory and time cost can be substantially reduced without losing precision by applying the hybrid method, and which can be used to analyze large scale target/rough surface scattering problems.
Author(s): J. Chen, M. Zhu, M. Wang, S. Li, X. Li
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 208 KB

Title: Null Broadening and Sidelobe Control Algorithm via Multi-Parametric Quadratic Programming for Robust Adaptive Beamforming
Abstract: Adaptive beamforming algorithm can automatically optimize the array pattern by adjusting the elemental control weights until a prescribed objective function is satisfied. Unfortunately, it is possible that the mismatch occurs between adaptive weights and data, due to the perturbation of the interference location when the antenna platform vibrates or interference moves quickly. Besides, the traditional beamformers may have unacceptably high sidelobes when few samples are available. To solve these problems, an effective robust adaptive beamforming method is presented. In the proposed method, firstly, a tapered covariance matrix is constructed to broaden the width of nulls for interference signal sources. Secondly, multiple additional quadratic inequality constraints outside the mainlobe beampattern area are used to guarantee that the sidelobe level is strictly lower than the prescribed threshold value. Finally, the beamforming optimization problem is formulated as a multi-parametric quadratic programming problem, such that the optimal weight vector can be easily obtained by real-valued computation. Simulation results are shown to demonstrate the efficiency of the proposed approach.
Author(s): F. Liu, G. Sun, J. Wang, R. Du
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 467 KB

Title: Optimal Design of Electromagnetic Absorbers
Abstract: A procedure for the optimal design of compact and light-weight electromagnetic absorbers is presented. The absorbers are designed to damp resonances inside metallic enclosures on the basis of Jaumannís theory; several layers of lossy artificial dielectrics are separated by two high/low impedance frequency selective surfaces and one resistive sheet. The constitutive parameters of the absorbing layers are optimized by means of the Particle Swarm Optimization method in order to maximize bandwidth and absorption rate of the structure in the GHz frequency range, where typically the first resonances of small enclosures occur. Ind
Author(s): R. Araneo, S. Celozzi
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 930 KB

Title: Bandwidth Improvement of Omni-Directional Monopole Antenna with a Modified Ground Plane
Abstract: This study introduces a new design of low profile, multi-resonance and omni-directional monopole antenna for Ultra-Wideband (UWB) applications. The proposed antenna configuration consists of an ordinary square radiating patch and a ground plane with pairs of inverted fork-shaped slits and inverted ?-shaped parasitic structures, which provides a wide usable fractional bandwidth of more than 135%. By cutting a pair of inverted fork-shaped slits in the ground plane and also by inserting a pair of inverted / -shaped conductorbacked plane in the feed gap distance, additional resonances are excited and hence much wider impedance bandwidth can be produced; especially at the higher band. By obtaining the third and fourth resonances, the usable lower frequency is decreased from 3.12 GHz to 2.83 GHz and also the usable upper frequency of the presented monopole antenna is extended from 10.3 GHz to 14.87 GHz. The proposed antenna has symmetrical structure with an ordinary square radiating patch; therefore, displays a good omni-directional radiation patterns, even at the higher frequencies. The antenna radiation efficiency is greater than 87% across the entire radiating band. The measured results show that the proposed antenna can achieve the Voltage Standing Wave Ratio (VSWR) requirement of less than 2.0 GHz in frequency range from 2.83 GHz to 14.87 GHz, which is suitable for UWB systems.
Author(s): N. Ojaroudi, N. Ghadimi, Y. Ojaroudi
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 731 KB

Title: Compact Microstrip Lowpass Filter with Ultra-Wide Stopband using Stepped-Impedance Trapezoid Resonators
Abstract: A new microstrip lowpass filter with compact size and ultra-wide stopband is presented. The resonance properties of a microstrip main transmission line parallel loaded with the steppedimpedance trapezoid resonator are studied. Analysis results reveal that a compact size and ultra-wide stopband lowpass filter can be realized by properly introducing multiple steppedimpedance trapezoid resonators in the design. A demonstration filter with 3 dB cutoff frequency at 0.8 GHz has been designed, fabricated, and measured. Results indicate that the proposed filter is able to suppress the 17th harmonic response by 15 dB, together with a small size of 0.057 g ◊0.077 g, where g is the guided wavelength at 0.8 GHz.
Author(s): G. Zhang, J. Wang, Y. Dou, H. Cui
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 225 KB

Title: Optimization of Interior Permanent Magnet Motor on Electric Vehicles to Reduce Vibration Caused by the Radial Force
Abstract: The vibration and noise level of a driven motor on electric vehicles has a great influence on the overall comfort of the whole vehicle. In this paper, the main vibrational harmonic waves with high amplitudes of Interior Permanent Magnet (IPM) motor were investigated via an experiment. In order to lower the amplitudes of these harmonic waves, the paper carries out the optimization of radial force of the IPM motor based on the parameter sensitivity analysis and also implemented the structural optimization, according to the dynamic response of the stator. The final dynamic simulation of the optimized model excited by the optimized radial force, show that the optimization results in a better performance of the vibration behaviors. This study could provide some guidelines for the optimal design of the interior permanent magnet motor to reduce vibration.
Author(s): L. Y. Xiang, S. G. Zuo, L. C. He, M. H. Zhang, J. J. Hu, G. Long
File Type: Journal Paper
Issue:Volume: 29      Number: 4      Year: 2014
Download Link:Click here to download PDF     File Size: 550 KB