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2011-12-08
PIER
Vol. 122, 557-575, 2012
download: 125
A Time-Domain Approach to the Synthesis of UWB Antenna Systems
Leonardo Lizzi Giacomo Oliveri Andrea Massa
In this paper, an approach for the synthesis of Ultra-Wideband (UWB) antenna systems in the time domain is proposed. Starting from the definition of suitable time-domain performance indexes, the design process is based on a spline representation of the antenna shape and a Particle Swarm Optimization (PSO) aimed at matching optimal radiation and electrical conditions. The effectiveness of the proposed time-domain technique is assessed by means of both numerical and experimental results.
A TIME-DOMAIN APPROACH TO THE SYNTHESIS OF UWB ANTENNA SYSTEMS
2011-12-08
PIER
Vol. 122, 537-555, 2012
download: 116
Point-Point Fixed Wireless and Broadcasting Services Coexistence with IMT-Advanced System
Zaid Ahmed Shamsan Tharek Bin Abdul Rahman Abdulaziz Mohammed Al-Hetar
Spectrum sharing analysis is remarkably important in investigating the possibility for coexistence between IMT-Advanced system and existing wireless services when operating in the same or adjacent frequency channel. The frequency band, 470-862 MHz, is currently allocating to TV broadcasting services (TVBS) and sub-bands within it are also allocated to fixed wireless access (FWA) service. Recently, international telecommunication union-radio (ITU-R) sector has allocated sub-bands within 470-862 MHz for IMT-Advanced systems. This concurrent operation causes destructive interference that influences the coexisting feasibility between IMT-Advanced and these existing services, FWA and broadcasting. This paper addresses a timely and topical problem dealing with spectrum sharing and coexistence between IMT-Advanced systems and both FWA and TVBS within 790-862 MHz. Co-channel and adjacent channel with an overlapping band and with or without guard band are intersystem interference scenarios investigated. The deterministic analysis is carried out by spectral emission mask (SEM) technique as well as interference to noise ratio graph. Various significant factors such as channel width, propagation path lengths, environments losses, and additional losses due to antenna discrimination which influence the feasibility of coexistence are evaluated. Feasible coexistence coordination procedures in terms of carrier frequency offset, separation distance, coverage cell size and required additional isolation are suggested.
POINT-POINT FIXED WIRELESS AND BROADCASTING SERVICES COEXISTENCE WITH IMT-ADVANCED SYSTEM
2011-12-08
PIER
Vol. 122, 519-535, 2012
download: 141
Suspended Substrate Stripline Bandpass Filters with Source-Load Coupling Structure Using Lumped and Full-Wave Mixed Approach
Min-Hua Ho Po-Fan Chen
This paper presents the design of two suspended substrate stripline (SSS) bandpass filters (BPFs), both with a source-load coupling structure embedded to create a transmission zero (TZ) near each side of the passband edges. For the first BPF, the physical circuit layout is proposed first and followed by the establishment of an equivalent LC circuit. The optimization of element values of the LC circuit using a circuit-level simulator leads to quick adjustment of the structural parameters of the physical circuit layout with the aid of a full-wave simulator. For the second BPF, the ingenious equivalent LC circuit modified from that of the first one is proposed for bandwidth enhancement, which is achieved by exciting two extra loaded resonances in the passband. With the element values of the LC circuit optimized, proper reshaping the physical circuit layout from that of the first BPF is easily accomplished. The presented lumped and full-wave mixed approach is very efficient in that the circuit-level simulator is used to the largest extent and the time-consuming full-wave simulator is employed only at the later stage of the design. Experiments are conducted to verify the design of the two SSS BPFs and agreements are observed between the measured and simulated data.
SUSPENDED SUBSTRATE STRIPLINE BANDPASS FILTERS WITH SOURCE-LOAD COUPLING STRUCTURE USING LUMPED AND FULL-WAVE MIXED APPROACH
2011-12-08
PIER
Vol. 122, 497-518, 2012
download: 172
Improving the Reliability of Frequency Domain Simulators in the Presence of Homogeneous Metamaterials - a Preliminary Numerical Assessment
Giacomo Oliveri
The accuracy of the finite difference frequency domain (FDFD) method in the solution of canonical waveguide discontinuity problems involving complementary or nearly complementary metamaterials (MTMs) is analytically discussed. It is shown that the good accuracy of the method (in comparison with other frequency-domain techniques) is due to the intrinsic approximation which it introduces in the finite-difference discretization of sharp dielectric interfaces. By exploiting such a result, a perturbation algorithm is proposed for the reliable modeling of MTMs devices when other frequency domain numerical methods are at disposal. A preliminary numerical analysis is carried out to assess the reliability and accuracy of the proposed modeling approach when canonical scattering problems are at hand.
IMPROVING THE RELIABILITY OF FREQUENCY DOMAIN SIMULATORS IN THE PRESENCE OF HOMOGENEOUS METAMATERIALS - A PRELIMINARY NUMERICAL ASSESSMENT
2011-12-08
PIER
Vol. 122, 467-496, 2012
download: 2374
Axial-Flux Permanent-Magnet Motor Design for Electric Vehicle Direct Drive Using Sizing Equation and Finite Element Analysis
Amin Mahmoudi Nasrudin Abd Rahim Hew Wooi Ping
The design process of a double-sided slotted TORUS axial-flux permanent-magnet (AFPM) motor suitable for direct drive of electric vehicle (EV) is presented. It used sizing equation and Finite Element Analysis (FEA). AFPM motor is a high-torque-density motor easily mounted compactly onto a vehicle wheel, fitting the wheel rim perfectly. A preliminary design is a double-sided slotted AFPM motor with 6 rotor poles for high torque-density and stable rotation. In determining the design requirements, a simple vehicle-dynamics model that evaluates vehicle performance through the typical cruising trip of an automobile was considered. To obtain, with the highest possible torque, the initial design parameters of the motor, AFPM's fundamental theory and sizing equation were applied. Vector Field Opera-3D 14.0 commercial software ran the FEA of the motor design, evaluating and enhancing accuracy of the design parameters. Results of the FEA simulation were compared with those obtained from the sizing equation; at no-load condition, the flux density at every part of the motor agreed. The motor's design meets all the requirements and limits of EV, and fits the shape and size of a classical-vehicle wheel rim. The design process is comprehensive and can be used for an arbitrary EV with an arbitrary cruising scenario.
AXIAL-FLUX PERMANENT-MAGNET MOTOR DESIGN FOR ELECTRIC VEHICLE DIRECT DRIVE USING SIZING EQUATION AND FINITE ELEMENT ANALYSIS
2011-12-06
PIER
Vol. 122, 453-465, 2012
download: 144
A Compact Multilayer Dual-Mode Substrate Integrated Circular Cavity (SICC) Filter for X-Band Application
Zhi Gang Zhang Yong Fan Yu Jian Cheng Yong-Hong Zhang
A high-performance multilayer dual-mode filter is developed based on the substrate integrated waveguide circular cavity (SICC) in this paper. The filter is constructed with two circular cavities and each cavity supports two degeneration modes, which can be generated and controlled by the coupling aperture and slot located between layers. Detailed design process is introduced to synthesize an X-band dual-mode dual-layer filter. It not only has the good performances, but also reduces the circuit size much more. Moreover, it can be found that the upper side response of the filter is very steep. Good agreement is obtained between the simulated and measured results of the proposed structure.
A COMPACT MULTILAYER DUAL-MODE SUBSTRATE INTEGRATED CIRCULAR CAVITY (SICC) FILTER FOR X-BAND APPLICATION
2011-12-06
PIER
Vol. 122, 437-452, 2012
download: 219
Electromagnetic Optimal Design for Dual-Band Radome Wall with Alternating Layers of Staggered Composite and Kagome Lattice Structure
Yongmao Pei Anmin Zeng Licheng Zhou Rubing Zhang Kuixue Xu
In this paper, electromagnetic optimal design is carried out for dual-band radome wall with alternating layers of staggered composite and Kagome lattice structure. The novel wall structure provides broadband transmission capability, along with excellent thermal-elastic properties and mechanical performances for high temperature applications. By optimizing the layer number (n) and the thickness of the whole wall (d), the power transmission efficiency of the novel structure in the frequency range of 1-100 GHz is calculated via boundary value method (BVM) based on electromagnetic theory. The calculation results suggest that if the wall thickness is dimensioned to be 6 mm and the wall structure is designed as 5 layers, the novel structure demonstrates excellent transmission performance. The optimal design results show that the power transmission efficiency is higher than 80% from 1 to 31 GHz in the centimeter wave range and from 59 to 100 GHz in the millimeter wave range, and the average transmission efficiency over the pass band reaches as high as 91%.
ELECTROMAGNETIC OPTIMAL DESIGN FOR DUAL-BAND RADOME WALL WITH ALTERNATING LAYERS OF STAGGERED COMPOSITE AND KAGOME LATTICE STRUCTURE
2011-12-05
PIER
Vol. 122, 413-435, 2012
download: 174
Target Detection in Pulse-Train MIMO Radars Applying Ica Algorithms
Majid Hatam Abbas Sheikhi Mohammad Ali Masnadi-Shirazi
In this paper, the problem of target detection in co-located ``multi-input multi-output" (MIMO) radars is considered. A pulse-train signaling is assumed to be used in this system. As the doppler effect should be considered for the pulse-train signaling, we are confronted by a compound hypothesis testing problem, so in this paper a Generalized Likelihood Ratio (GLR) detector is derived. The high complexity of this detector makes us derive a new detector based on the theory of Independent Component Analysis (ICA). It is shown that the computational load of the ICA-based detector is much less than the GLR detector. It is also shown that the sensitivity of the ICA-based detector to the doppler effect is very low. According to this approach, an appropriate signal design method is presented, based on the separation performance of the ICA algorithms. It is shown that independent random sequences are proper signals in the sense of detection performance.
TARGET DETECTION IN PULSE-TRAIN MIMO RADARS APPLYING ICA ALGORITHMS
2011-12-05
PIER
Vol. 122, 389-411, 2012
download: 120
Optimized Local Superposition in Wireless Sensor Networks with T-Average-Mutual-Coherence
Di Guo Xiaobo Qu Lianfen Huang Yan Yao
Compressed sensing (CS) is a new technology for recovering sparse data from undersampled measurements. It shows great potential to reduce energy for sensor networks. First, a basic global superposition model is proposed to obtain the measurements of sensor data, where a sampling matrix is modeled as the channel impulse response (CIR) matrix while the sparsifying matrix is expressed as the distributed wavelet transform (DWT). However, both the sampling and sparsifying matrixes depend on the location of sensors, so this model is highly coherent. This violates the assumption of CS and easily produces high data recovery error. In this paper, in order to reduce the coherence, we propose to control the transmit power of some nodes with the help of t-average-mutual-coherence, and recovery quality are greatly improved. Finally, to make the approach more realistic and energy-efficient, the CIR superposition is restricted in local clusters. Two key parameters, the radius of power control region and the radius of local clusters, are optimized based on the coherence and resource consideration in sensor networks. Simulation results demonstrate that the proposed scheme provides a high recovery quality for networked data and verify that t-average-mutual-coherence is a good criterion for optimizing the performance of CS in our scenario.
OPTIMIZED LOCAL SUPERPOSITION IN WIRELESS SENSOR NETWORKS WITH T-AVERAGE-MUTUAL-COHERENCE
2011-11-29
PIER
Vol. 122, 361-387, 2012
download: 117
A Mixing Vector Based an Affine Combination of Two Adaptive Filters for Sensor Array Beamforming
Songtao Lu Jinping Sun Guohua Wang Yi-Long Lu
In this paper, a novel beamformer for adaptive combination of two adaptive filters is proposed for interference mitigation of sensor array. The proposed approach adaptively combines two individual filters by coefficient weights vector instead of one scale parameter and takes the constraint of affine combination into consideration rather than previous studies. Due to the more degrees of freedom offered by the mixing vector, the proposed beamformer significantly improves the convergence and tracking performances of the combined filter under both stationary and non-stationary environments, respectively. Based on the generalized sidelobe canceller (GSC) structure, the optimal mixing vector is derived by Lagrange method, and then several new effective iterative algorithms are developed for its updating in practical implementation. Furthermore, theoretical discussions of the convergent performances and complexities of the proposed iterative algorithms are also investigated to verify the feasibility of the proposed beamformer. Moreover, the proposed methods in application of beamforming for interference mitigation of antenna array are simulated based space-time processing technique. When compared to existing methods, the proposed approach exhibits faster convergence rate and higher output signal to interference plus noise ratio (SINR). Its good behavior is illustrated through simulation results.
A MIXING VECTOR BASED AN AFFINE COMBINATION OF TWO ADAPTIVE FILTERS FOR SENSOR ARRAY BEAMFORMING
2011-11-24
PIER
Vol. 122, 341-360, 2012
download: 124
A 3D Target Imaging Algorithm Based on Two-Pass Circular SAR Observations
Lingjuan Yu Yunhua Zhang
In circular synthetic aperture radar (CSAR), the radar collects data over a circular not a linear trajectory. The two-dimensional (2D) CSAR image also contains three-dimensional (3D) information about the target. In this paper, we propose an imaging algorithm for 3D target reconstruction with two-pass CSAR observations so as to overcome the problem of limited azimuthal persistence for real anisotropic targets, and avoid the assumption that target falls into the same resolution cell for each elevation pass when multi-pass observations are used. In the algorithm, the first step is to divide both of the two full-aperture CSAR data into subapertures in the same way; the second step is to obtain, for each subaperture, the height of target according to the established relationship between the pixel displacements in the image pair of two observations on the same focal plane and the pixel displacements in the image pair of one observation on two different focal planes; the third step is to obtain the 3D target coordinates based on the retrieved height information and the 2D image coordinates; the last step is to get the final 3D image by combining the obtained 3D images of all subapertures. The results of point target simulation indicate that the 3D information (both amplitudes and positions) are well reconstructed. At the same time, the processing results of backhoe data simulated by the Xpatch software show that the outline of the 3D structure is also well reconstructed although the available data corresponding to the depressing angles are not as good as expected.
A 3D TARGET IMAGING ALGORITHM BASED ON TWO-PASS CIRCULAR SAR OBSERVATIONS
2011-11-22
PIER
Vol. 122, 327-339, 2012
download: 160
Design and Optimization of Low RCS Patch Antennas Based on a Genetic Algorithm
Xinyue Zhu Wei Shao Jia-Lin Li Yu-Liang Dong
In this article, a genetic algorithm (GA) is employed to the design of low radar cross section (RCS) patch antennas. Combined with the high frequency simulation software (HFSS) for antenna simulations, the GA performs the optimization of geometric parameters. In order to reduce the RCS while holding the satisfying radiation performance of antennas, the radiation model and scattering model are respectively calculated. The combination of proportionate selection and elitist model for the selection strategy is used to speed up the convergence of the GA. Two-point crossover is adopted to accelerate the converging speed and results in more fit individuals. Moreover, the whole design procedure is auto-controlled by programming the VBScript in the HFSS. Two examples of low RCS slot antennas are provided to verify the accuracy and efficiency of the proposed method.
DESIGN AND OPTIMIZATION OF LOW RCS PATCH ANTENNAS BASED ON A GENETIC ALGORITHM
2011-11-22
PIER
Vol. 122, 311-325, 2012
download: 106
Analysis of Topological Derivative Function for a Fast Electromagnetic Imaging of Perfectly Conducing Cracks
Y.-K. Ma Pok-Son Kin Won-Kwang Park
We consider a topological derivative based imaging technique for non-iterative imaging of small and extended perfectly conducting cracks with Dirichlet boundary condition. For this purpose, we introduce topological derivative imaging function based on the asymptotic formula in the existence of narrow crack. We then mathematically analyze its structure in order to investigate why it yields the shape of crack(s). Analyzed structure gives us an optimal condition to get a better image of them. Various numerical experiments support our analysis.
ANALYSIS OF TOPOLOGICAL DERIVATIVE FUNCTION FOR A FAST ELECTROMAGNETIC IMAGING OF PERFECTLY CONDUCING CRACKS
2011-11-21
PIER
Vol. 122, 293-309, 2012
download: 107
Electrically Tunable Fabry-Perot Resonator Based on Microstructured Si Containing Liquid Crystal
Vladimir A. Tolmachev Vasily A. Melnikov Аnna V. Baldycheva Kevin Berwick Tatiana S. Perova
We have built Fabry-Pérot resonators based on microstructured silicon and a liquid crystal. The devices exhibit tuning of the resonance peaks over a wide range, with relative spectral shifts of up to Δλ/λ = 10%. In order to achieve this substantial spectral shift, cavity peaks of high order were used. Under applied voltages of up to 15 V, a variation in the refractive index of the nematic liquid crystal E7 from ΔnLC = 0.12 to ΔnLC = 0.17 was observed. These results may have practical applications in the near-, mid and far-infrared range.
ELECTRICALLY TUNABLE FABRY-PEROT RESONATOR BASED ON MICROSTRUCTURED SI CONTAINING LIQUID CRYSTAL
2011-11-19
PIER
Vol. 122, 269-292, 2012
download: 211
A Circular Synthetic Aperture Radar for on-the-Ground Object Detection
Mojtaba Mohammadpoor Raja Syamsul Azmir Raja Abdullah Alyani Ismail Ahmad Fauzi Abas
Detecting an on-the-ground object is a subject of interest for use in some applications. Foreign Object Detection (FOD), which is an important issue in aviation safety, is a possible application. In this way, radar imaging, has several inherent advantages over other on-the-ground object detection techniques. This paper will introduce a ground-based Circular Synthetic Aperture Radar, which detects and localizes various objects, based on their reflection properties of microwaves. Here, wideband Linear Frequency Modulated (LFM) chirp pulses are employed for the transmission and reception of reflection pulses, both to and from the object under test. Once the pulses are received by the radar, a processing algorithm (proposed later in this paper) is executed to confirm detection. In order to verify the validity of the model, a prototype was developed and a series of field experiments was carried out. The results show that the proposed system has the ability to detect and localize on-the-ground objects with dimensions as small as 2 cm high and 1 cm diameter, located several metres away. Furthermore, the resolution of the system was analysed and results indicate that the system is capable of distinguishing multiple objects in close proximity to each other, which therefore, makes it suitable for FOD applications by some small modifications.
A CIRCULAR SYNTHETIC APERTURE RADAR FOR ON-THE-GROUND OBJECT DETECTION
2011-11-18
PIER
Vol. 122, 245-268, 2012
download: 601
A New Unmanned Aerial Vehicle Synthetic Aperture Radar for Environmental Monitoring
Voon Koo Yee Kit Chan Gobi Vetharatnam Chua Ming Yam Chot Hun Lim Chee Siong Lim C. C. Thum Tien Sze Lim Zahid bin Ahmad Khairul Annuar Mahmood Mohd Hamadi Bin Shahid Chin Yang Ang Wei Qiang Tan Poi Ngee Tan Kuo Shen Yee W. G. Cheaw Huey Shen Boey A. L. Choo Bee Cheng Sew
A new Unmanned Aerial Vehicle (UAV) Synthetic Aperture Radar (SAR) has been developed at Multimedia University, in collaboration with Agency of Remote Sensing Malaysia. The SAR operates at C-band, single $VV$-polarization, with 5 m x 5 m spatial resolution. Its unique features include compact in size, light weight, low power and capable of performing real-time imaging. A series of field measurements and flight tests has been conducted and good quality SAR images have been obtained. The system will be used for monitoring and management of earth resources such as paddy fields, oil palm plantation and soil surface. This paper reports the system design and development, as well as some preliminary results of the UAVSAR.
A NEW UNMANNED AERIAL VEHICLE SYNTHETIC APERTURE RADAR FOR ENVIRONMENTAL MONITORING
2011-11-17
PIER
Vol. 122, 223-244, 2012
download: 133
Numerical and Experimental Analysis of EMI-Induced Noise in RC Phase Shift Oscillator
Han-Chang Tsai
Electromagnetic interference (EMI) has an adverse effect on the performance of electronic circuit communication systems. This study derives a series of equations to analyze the effects of the EMI induced in a conducting wire on the noise spectrum of a RC Phase Shift Oscillator (RCPSO). It is shown that the extent to which EMI affects the RCPSO depends on the interference power, interference frequency, induced power, output resistance of the oscillator circuit, and parasitic capacitance. Specifically, higher EMI frequencies and amplitudes have a greater effect on the RCPSO output. The results presented in this study are in good agreement with those predicted from general EMI theory.
NUMERICAL AND EXPERIMENTAL ANALYSIS OF EMI-INDUCED NOISE IN RC PHASE SHIFT OSCILLATOR
2011-11-17
PIER
Vol. 122, 197-221, 2012
download: 106
Extraction of Internal Spatial Features of Inhomogeneous Dielectric Objects Using Near-Field Reflection Data
Douglas J. Kurrant Elise C. Fear
Ultra-wideband (UWB) microwave radar imaging techniques provide a non-invasive means to extract information related to an object's internal structure. For these applications, a short-duration electromagnetic wave is transmitted into an object of interest and the backscattered fields that arise due to dielectric contrasts at interfaces are measured. In this paper, we present a method that may be used to estimate the time-of-arrival (TOA) parameter associated with each reflection that arises due to a dielectric property discontinuity (or dielectric interface). A second method uses this information to identify the locations of points on these interfaces. When data are collected at a number of sensor locations surrounding the object, the collection of points may be used to estimate the shape of contours that segregate and enclose dissimilar regions within the object. The algorithm is tested with data generated when a cylindrical wave is applied to a number of numerical 2D models of increasing complexity. Moreover, the algorithm's feasibility is evaluated using data generated from breast models constructed from magnetic resonance (MR) breast scans. Results show that this is a promising approach to identifying regions and the internal structure within the breast.
EXTRACTION OF INTERNAL SPATIAL FEATURES OF INHOMOGENEOUS DIELECTRIC OBJECTS USING NEAR-FIELD REFLECTION DATA
2011-11-17
PIER
Vol. 122, 175-196, 2012
download: 119
Reduction of Numerical Dispersion of the Six-Stages Split-Step Unconditionally-Stable FDTD Method with Controlling Parameters
Yong-Dan Kong Qing-Xin Chu
A new approach to reduce the numerical dispersion of the six-stages split-step unconditionally-stable finite-difference time-domain (FDTD) method is presented, which is based on the split-step scheme and Crank-Nicolson scheme. Firstly, based on the matrix elements related to spatial derivatives along the x, y, and z coordinate directions, the matrix derived from the classical Maxwell's equations is split into six sub-matrices. Simultaneously, three controlling parameters are introduced to decrease the numerical dispersion error. Accordingly, the time step is divided into six sub-steps. Secondly, the analysis shows that the proposed method is unconditionally stable. Moreover, the dispersion relation of the proposed method is carried out. Thirdly, the processes of determination of the controlling parameters are shown. Furthermore, the dispersion characteristics of the proposed method are also investigated, and the maximum dispersion error of the proposed method can be decreased significantly. Finally, numerical experiments are presented to substantiate the efficiency of the proposed method.
REDUCTION OF NUMERICAL DISPERSION OF THE SIX-STAGES SPLIT-STEP UNCONDITIONALLY-STABLE FDTD METHOD WITH CONTROLLING PARAMETERS
2011-11-17
PIER
Vol. 122, 155-173, 2012
download: 109
A Novel Non-Interpolation Polar Format Algorithm Using Non-Lineal Flight Trajectories and Auto-Adaptive Prf Technique
Yan Wang Jingwen Li Jie Chen Huaping Xu Bing Sun
The classical interpolation-based Polar Format Algorithm (PFA) for spotlight synthetic aperture radar (SAR) results in numerous computation load, which, reduces processing speed and increase system complexity. To decrease computation load, this paper proposes a novel non-interpolation PFA algorithm for sensor flying along non-lineal flight trajectories, which are specially designed curves in conical surface. Then an innovative auto-adaptive Pulse Repetition Frequency (PRF) technique is put forward to uniformly sample signal in azimuth direction. The computation load of the new PFA is merely left to azimuth chirp z-transforms (CZTs) and range fast Fourier transforms (FFTs) after dechirp processing and residual video phase (RVP) compensation. Two flight modes (ellipse trajectory mode and hyperbola trajectory mode) are analyzed. A lineal approximation method is proposed to simplify non-lineal sensor trajectory analysis. Computer simulation results for multiple point targets validate the presented approach. Comparison of computation load between this PFA and traditional PFA is represented in Appendix B.
A NOVEL NON-INTERPOLATION POLAR FORMAT ALGORITHM USING NON-LINEAL FLIGHT TRAJECTORIES AND AUTO-ADAPTIVE PRF TECHNIQUE