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2012-02-13
PIER
Vol. 124, 511-525, 2012
download: 118
Frequency-Selective Nanostructured Plasmonic Absorber by Highly Lossy Interface Mode
Yongkang Gong Kang Li Jungang Huang N. J. Copner Antony Davies Leiran Wang Tao Duan
We report on an existence of a highly lossy interface mode (HLIM) in a designed plasmonic nanostructure for perfect absorption of the incident optical waves. Interactions between the single thin-metallic-layer ($TML$) and slits arrays for excitation of the HLIM in the proposed plasmonic absorber are investigated, and eigenfrequency formula for the HLIM is derived. Analytical and numerical results show that the HLIM is frequency-selective, opens a narrow and steep absorption band in photonic stopband of the slits arrays. Due to the HLIM lossy characteristic, surface plasmon polaritons are significantly trapped at the TML interface with absorption close to 100%.
FREQUENCY-SELECTIVE NANOSTRUCTURED PLASMONIC ABSORBER BY HIGHLY LOSSY INTERFACE MODE
2012-02-12
PIER
Vol. 124, 487-510, 2012
download: 128
Dosimetry and Temperature Evaluations of a 1800 MHz TEM Cell for in Vitro Exposure with Standing Waves
Jian Zhao Hongmin Lu Jun Deng
A 1800 MHz transverse electromagnetic wave (TEM) cell is introduced for experiments investigating effects on biological samples caused by the exposure from mobile communications. To characterize and quantify the exposure environment in the setup for standardized in vitro experiments, we evaluate the dosimetry and the exposure-induced temperature rise in cultured cells. The study is numerically based on the finite-difference time-domain (FDTD) formulation of the Maxwell equations and the finite-difference formulation of the bioheat transfer equation, with all algorithms and models strictly validated for accuracy. Two sample formations of cells are considered including the cell layer and the cell suspension cultured in the 35 mm Petri dish. The TEM cell is designed to establish standing waves with the maximum E field and the maximum H field, respectively, at the position of the Petri dish. The Petri dish is oriented to E, -E, H, k, and -k directions of the incident field, respectively, to receive the exposure. The specific absorption rate (SAR) is calculated in cells for 10 exposure arrangements combined from the maximum fields and Petri dish orientations. A comparison determines the best arrangement with the highest exposure efficiency and the lowest exposure heterogeneity. The dosimetry and the exposure-induced temperature rise in cells are evaluated for the selected arrangement. To avoid thermal reactions caused by overheating, the maximum temperature rises in cells are recorded during the exposure. Based on the records, the temperature control is performed by setting limits to the exposure duration. We introduce a method to further reduce the exposure heterogeneity and evaluate the influence of the Petri dish holder on the dosimetry and temperature rise. The study compares the TEM cell to the waveguide, as well as the standing wave exposure to the propagating wave exposure. The TEM cell and the selected arrangement of the standing wave exposure improve the exposure quality over the traditional methods, with increased efficiency and decreased heterogeneity of the exposure.
DOSIMETRY AND TEMPERATURE EVALUATIONS OF A 1800 MHz TEM CELL FOR IN VITRO EXPOSURE WITH STANDING WAVES
2012-02-08
PIER
Vol. 124, 473-486, 2012
download: 118
Improvement of Iterative Physical Optics Using Previous Information to Guide Initial Guess
Huicheol Chin Jae-Hyun Yeom Hyo-Tae Kim Kyung-Tae Kim
We propose an improved method of iterative physical optics (IPO) to analyze electromagnetic scattering by open-ended cavities. The traditional IPO method uses a fixed number of iterations; if this number is too small, the accuracy of the estimated monostatic radar cross section (RCS) of open-ended cavities degrades as the incident angle of the incident field increases. The recently-introduced adaptive iterative physical optics-change rate (AIPO-CR) method uses a variable number of iterations; compared to the IPO method, it predicts monostatic RCS more accurately, but requires more computation time. In this paper, a new algorithm is devised to improve both the monostatic RCS prediction accuracy of the IPO method, and the computational efficiency of the AIPO-CR method. The proposed method, iterative physical optics-retained previous solution (IPO-RPS), calculates the currents at one incident angle, then reuses them as the initial currents of iterations for the next incident angle. In simulations of the monostatic RCS for various open-ended cavities, the IPO-RPS method was more accurate than the traditional IPO method, and computationally more efficient than both the IPO and AIPO-CR methods.
IMPROVEMENT OF ITERATIVE PHYSICAL OPTICS USING PREVIOUS INFORMATION TO GUIDE INITIAL GUESS
2012-02-08
PIER
Vol. 124, 457-471, 2012
download: 116
Coupling Issues Associated with Electromagnetic Vulnerability (Emv) Testing of Vehicles Over Ground
Thomas H. Shumpert Marsellas L. Waller Steven H. Wong Robert W. Scharstein
Electromagnetic Vulnerability (EMV) testing of ground vehicles and helicopters is (by necessity) performed in the immediate presence of ground surfaces (natural earth, asphalt, concrete, ship decks, and other finitely conducting grounds). The impact of the nature of these grounds on the EM coupling to the various vehicles being tested is the focus of this work. As one approach to addressing these issues quantitatively, personnel at Redstone Test Center Electromagnetic Environmental Effects (RTC/E3) Division have combined measurements on a semi-canonical physical structure along with EM modeling. In particular, a hollow 25 foot long, 4 foot diameter aluminum cylinder with a finite slot (~8 in wide) running along its entire length is positioned over (and near to) a finite conducting ground plane. Measurements of the electric fields produced both in the slot aperture and inside the hollow cylinder by an external log period dipole antenna (LPDA) positioned (broadside to the horizontal cylinder) approximately 5\,m away radiating both vertical and horizontal polarizations, respectively, are presented and discussed. The entire experimental setup (aluminum cylinder, finite aluminum ground plane, and radiating LPDA) are enclosed inside an RF anechoic chamber (inside dimensions between the respective tips of the anechoic pyramids of approximately 19 m х 9.0 m х 5.0 m). A moment method model (CARLOS) is also developed and the fields in the aperture and inside the cylinder are compared to the measured fields.
COUPLING ISSUES ASSOCIATED WITH ELECTROMAGNETIC VULNERABILITY (EMV) TESTING OF VEHICLES OVER GROUND
2012-02-08
PIER
Vol. 124, 441-455, 2012
download: 153
Synthesis of Microwave Resonator Diplexers Using Linear Frequency Transformation and Optimization
Rui Wang Jun Xu Mao-Yan Wang Yu-Liang Dong
This paper presents a method for synthesizing coupled resonator diplexers composed of TX and RX filters (two types of junctions connecting the TX and RX filters are considered). For the first junction type, the common port is directly coupled to the first resonator of the TX and RX filters, respectively. For the second junction type, common node is realized by adding an extra resonator besides those of the TX and RX filters. The method is based on the evaluation of the characteristic polynomials of the diplexer using the proposed linear frequency transformation and well-established method, and then the "N + 3" coupling matrix of overall diplexer can be obtained using hybrid optimization methods. Two diplexers have been designed and fabricated to validate the proposed method.
SYNTHESIS OF MICROWAVE RESONATOR DIPLEXERS USING LINEAR FREQUENCY TRANSFORMATION AND OPTIMIZATION
2012-02-06
PIER
Vol. 124, 425-440, 2012
download: 160
Design of an Ultra-Wideband Power Divider via the Coarse-Grained Parallel Micro-Genetic Algorithm
Lei Chang Cheng Liao Ling-Lu Chen Wenbin Lin Xuan Zheng Yan-Liang Wu
An ultra-wideband (UWB) power divider is designed in this paper. The UWB performance of this power divider is obtained by using a tapered microstrip line that consists of exponential and elliptic sections. The coarse grained parallel micro-genetic algorithm (PMGA) and CST Microwave Studio are combined to achieve an automated parallel design process. The method is applied to optimize the UWB power divider. The optimized power divider is fabricated and measured. The measured results show relatively low insertion loss, good return loss, and high isolation between the output ports across the whole UWB (3.1-10.6 GHz).
DESIGN OF AN ULTRA-WIDEBAND POWER DIVIDER VIA THE COARSE-GRAINED PARALLEL MICRO-GENETIC ALGORITHM
2012-02-04
PIER
Vol. 124, 405-423, 2012
download: 172
Optimal Synthesis of Phase-Only Reconfigurable Linear Sparse Arrays Having Uniform-Amplitude Excitations
Andrea Francesco Morabito Tommaso Isernia Loreto Di Donato
In a large number of applications, including communications from satellites, an optimal exploitation of the available power is of the outmost importance. As a consequence, isophoric array architectures, i.e., arrays using the same power in all the different entry points and achieving the amplifiers' maximum efficiency, are of great interest. At the same time, the easy reconfigurability of the power patterns results fundamental in order to get a full exploitation of the payload. In this paper, an innovative and deterministic approach is proposed for the optimal synthesis of linear phase-only reconfigurable isophoric sparse arrays able to commute their pattern amongst an arbitrary number of radiation modalities. The introduced perspective leads to an effective solution procedure for the fast design of antennas with high performance, and does not recur to computationally expensive global-optimization techniques. Numerical results concerning applications of actual interest and employing realistic element patterns are provided in support of the given theory.
OPTIMAL SYNTHESIS OF PHASE-ONLY RECONFIGURABLE LINEAR SPARSE ARRAYS HAVING UNIFORM-AMPLITUDE EXCITATIONS
2012-02-04
PIER
Vol. 124, 383-404, 2012
download: 162
Improvement to Performance of Solid-Rotor-Ringed Line-Start Axial-Flux Permanent-Magnet Motor
Amin Mahmoudi Solmaz Kahourzade Nasrudin Abd Rahim Hew Wooi Ping
This paper presents two design-and-analysis cases of a line-start axial-flux permanent-magnet motor: with solid rotor and with composite rotor. For a novel structure of the motor, two concentric unilevel spaced raised rings are added to the inner and outer radii of its rotors to enable auto-start capability. The composite rotor was coated by a thin (0.05 mm) layer of copper. The basic equations for the solid rotor ring were extracted. The motor's lack of symmetry necessitated 3D time-stepping finite element analysis, conducted via Vector Field Opera 14.0, which evaluated the design parameters and predicted the motor's transient performance. Results of the FEA show the composite rotor significantly improving both starting torque and synchronization capability over solid rotor.
IMPROVEMENT TO PERFORMANCE OF SOLID-ROTOR-RINGED LINE-START AXIAL-FLUX PERMANENT-MAGNET MOTOR
2012-02-04
PIER
Vol. 124, 365-381, 2012
download: 136
A New Tri-Band Bandpass Filter for GSM, WiMAX and Ultra-Wideband Responses by Using Asymmetric Stepped Impedance Resonators
Wei-Yu Chen Min-Hang Weng Shoou-Jinn Chang Hon Kuan Yi-Hsin Su
In this paper, a design of new tri-band bandpass filter for the application of GSM (1.8 GHz), WiMAX (2.7 GHz) and UWB (3.3-4.8 GHz) is proposed. The first two narrow passbands are created, and the bandwidth of the third passband can be tuned by properly selecting the impedance ratio (R) and physical length ratio (u) of the asymmetric stepped-impedance resonator. To improve passband performance and form the UWB passband, a U-shape defected ground structure and extra extended coupling lines are integrated with the asymmetric SIR. Due to the three transmission zeros appearing near the passband edges, the band selectivity of the proposed filter is much improved. The filter was fabricated, and the measured results have a good agreement with the full-wave simulated ones.
A NEW TRI-BAND BANDPASS FILTER FOR GSM, WIMAX AND ULTRA-WIDEBAND RESPONSES BY USING ASYMMETRIC STEPPED IMPEDANCE RESONATORS
2012-02-02
PIER
Vol. 124, 347-364, 2012
download: 146
Analysis of Electromagnetic Behavior in Switched Reluctance Motor for the Application of Integrated Air Conditioner on-Board Charger System
Jianing Liang Linni Jian Guo Xu Ziyun Shao
In order to achieve low cost and compact design, it becomes more and more popular to integrate the circuit of the on-board charger into other power electronic circuits existing in EVs. In this paper an integrated air conditioner on-board charger system based on switched reluctance motor (SRM) was proposed, and the electromagnetic behavior occurring in the SRM when working in the charging mode was investigated. Three charging patterns, viz. single-phase charging, double-phase charging and triple-phase charging were analyzed. The specific rotor positions for which the rotor can be kept still when injecting charging currents to the armature windings were identified. The optimal design for maximizing the keeping-still capability was conducted. The power losses occurring in the SRM when working in charging mode were estimated.
ANALYSIS OF ELECTROMAGNETIC BEHAVIOR IN SWITCHED RELUCTANCE MOTOR FOR THE APPLICATION OF INTEGRATED AIR CONDITIONER ON-BOARD CHARGER SYSTEM
2012-01-30
PIER
Vol. 124, 331-345, 2012
download: 182
Characteristics of Guided Modes in Uniaxial Chiral Circular Waveguides
Jian-Feng Dong Jie Li
The characteristics of guided modes in the circular waveguide consist of uniaxial chiral medium have been investigated. The characteristic equation of guided modes is derived. The dispersion curves and energy flux of guided modes for three kinds of uniaxial chiral media are presented. Unusual dispersion characteristics and negative energy flux are found, i.e., backward wave is supported in the uniaxial chiral waveguide.
CHARACTERISTICS OF GUIDED MODES IN UNIAXIAL CHIRAL CIRCULAR WAVEGUIDES
2012-01-30
PIER
Vol. 124, 315-329, 2012
download: 132
Hydrostatic Pressure Sensor Based on a Gold-Coated Fiber Modal Interferometer Using Lateral Offset Splicing of Single Mode Fiber
Daru Chen Xin Cheng
A novel hydrostatic pressure sensor based on a gold-coated fiber modal interferometer (FMI) is proposed and demonstrated. Two single mode fibers (SMFs) are spliced with a lateral offset which forms a single-end FMI. The single-end FMI is gold-coated to enhance the reflectivity and to avoid the influence of any unwanted light from getting into the sensor. Relative reflection spectra of the proposed FMIs with different sensing SMF lengths or different lateral offsets are experimentally investigated. A high hydrostatic pressure sensor test system is proposed for the testing of the proposed FMI pressure sensor. The performance of a gold-coated FMI pressure sensor based on a 12-mm sensing SMF has been experimentally investigated. The proposed pressure sensor has a sensing range from 0 to 42 MPa and a sensitivity of 53 pm/MPa.
HYDROSTATIC PRESSURE SENSOR BASED ON A GOLD-COATED FIBER MODAL INTERFEROMETER USING LATERAL OFFSET SPLICING OF SINGLE MODE FIBER
2012-01-27
PIER
Vol. 124, 301-314, 2012
download: 151
Design of a Terahertz Polarization Rotator Based on a Periodic Sequence of Chiral-Metamaterial and Dielectric Slabs
Cumali Sabah Hartmut G. Roskos
The lack of wave-plates for the terahertz region opens the way for novel components/devices enabling polarization control at these frequencies. With the aid of chiral metamaterials - a new class of metamaterials - novel possibilities for the fabrication of multilayer structures for the realization of polarization rotators emerge. In this study, we present design and analysis of a polarization rotator for the terahertz frequency regime based on a multilayer structure consisting of an alternating sequence of chiral-metamaterial- and dielectric-plates. The combination of chiral constituents with dielectrics permits optimization of the spectral-filter and polarization-rotation features. We can generate either polarization-rotation combs or narrow rotation bands with very good and broad sideband suppression, of interest for example for data transmission or sensing purposes.
DESIGN OF A TERAHERTZ POLARIZATION ROTATOR BASED ON A PERIODIC SEQUENCE OF CHIRAL-METAMATERIAL AND DIELECTRIC SLABS
2012-01-25
PIER
Vol. 124, 285-299, 2012
download: 453
A Multi-Beam and Multi-Range Radar with FMCW and Digital Beam Forming for Automotive Applications
Seong-Hee Jeong Han-Yeol Yu Jae-Eun Lee Jun-Nam Oh Kwae-Hi Lee
In this paper, we propose a multi-beam and multi-range (MBMR) radar with frequency modulated continuous wave (FMCW) waveform and digital beam forming (DBF) algorithm to cover a detection area of long range and narrow angle (150 m, ±10°) as well as short range and wide angle (60 m, ±30°) as a single 24 GHz sensor. The developed radar is highly integrated with multiple phased-array antennas, a two-channel transmitter and a four-channel receiver using K-band GaAs RF ICs, and back-end processing board with subspace-based DBF algorithm. The proposed 24 GHz MBMR radar can be used for an adaptive cruise control (ACC) stop-and-go system which typically consists of three radars, such as two 24 GHz short-range radars for object detection in an adjacent lane and one 77 GHz long-range radar for object detection in the center lane.
A MULTI-BEAM AND MULTI-RANGE RADAR WITH FMCW AND DIGITAL BEAM FORMING FOR AUTOMOTIVE APPLICATIONS
2012-01-22
PIER
Vol. 124, 265-283, 2012
download: 206
Detuning Study of Implantable Antennas Inside the Human Body
Neus Vidal Sergio Curto José Mª Lopez-Villegas Javier Sieiro Francisco Manuel Ramos
This study quantifies the detuning and impedance mismatch of antennas implanted inside the human body. Maximum frequency shifts caused by variations in the electrical properties of body tissues and different anatomical distributions were derived. The results are relevant to the design of implantable antennas. They indicate the bandwidth enhancement and initial tuning necessary for correct functioning. The study was carried out using electromagnetic modeling based on the finite-difference time-domain method and high-resolution anatomical models. Four anatomical computer models of two adults and two children were used. The implanted antennas operated in the Medical Implant Communication Service band. The most important detuning and impedance mismatch was found for subcutaneous locations and in areas where a layer of fat tissue was present. The maximum frequency shift towards higher frequencies was 70 MHz. The frequency shift did not occur symmetrically around 403 MHz, but was shifted towards higher frequencies.
DETUNING STUDY OF IMPLANTABLE ANTENNAS INSIDE THE HUMAN BODY
2012-01-21
PIER
Vol. 124, 249-263, 2012
download: 101
Improved CRLH-TL with Arbitrary Characteristic Impedance and Its Application in Hybrid Ring Design
Xianqi Lin Peng Su Yong Fan Zhong Bo Zhu
An improved designable composite right/left-handed transmission line (CRLH-TL) is presented in this paper, whose operating frequency-band and transmission characteristics can be tuned, respectively, by three structure variables. The equivalent characteristic impedance is studied carefully, and CRLH-TLs with arbitrary characteristic impedances are obtained. Some useful empirical formulae are derived for engineering application. Then, a sample of 50-Ω CRLH-TL, which can be used directly as a wide-band filter, is fabricated with the center frequency of 2.8 GHz. The measured results show that a relative 3-dB bandwidth of 74.6% is achieved, in good agreement with the simulated results. Moreover, the phase-frequency responses of our proposed CRLH-TLs are discussed in detail. A novel hybrid ring is then proposed, where 70-Ω CRLH-TL is used. At the center frequency of 5.8 GHz, equal power dividing is achieved with return loss and isolation more than 20 dB and 30 dB, respectively. The sample is finally fabricated and good agreements among theoretical analysis, simulated results, and measured results are obtained.
IMPROVED CRLH-TL WITH ARBITRARY CHARACTERISTIC IMPEDANCE AND ITS APPLICATION IN HYBRID RING DESIGN
2012-01-20
PIER
Vol. 124, 233-247, 2012
download: 147
Coupling Effect of Split Ring Resonator and Its Mirror Image
Fuli Zhang Qian Zhao Jingbo Sun Ji Zhou Didier Lippens
We report on experimental and numerical studies on the coupling effect of a single split ring resonator (SRR) and its mirror image inside an X-band hollow waveguide. It is shown that, for single SRR with gap bearing side perpendicular to $E$ field, the magnetic resonance exhibits red/blue shift as SRR moves to the gap facing/backing waveguide edge, due to the capacitance and magnetic dipoles coupling effect between original SRR and its mirror image, respectively. Furthermore, electric dipole interplay dominates the coupling effect between SRR and its image when SRR has the gap bearing side parallel to the E field, although SRR is excited by E and H field simultaneously.
COUPLING EFFECT OF SPLIT RING RESONATOR AND ITS MIRROR IMAGE
2012-01-19
PIER
Vol. 124, 211-231, 2012
download: 183
HF-Band Wireless Power Transfer System: Concept, Issues, and Design
Byung-Jun Jang Seongjoo Lee Hyungoo Yoon
High-frequency (HF) band wireless power transfer systems offer the promise of cutting the last cord, allowing users to seamlessly recharge mobile devices as easily as wireless communication. Yet there are still many technical issues that need to be overcome. Among them, one of the most difficult problems is maintaining impedance match over a short range, where the distance between a transmitter and receiver could vary. In this paper, the effect of impedance mismatch of a HF-band wireless power transfer system is carefully investigated and two compensation methods are suggested to overcome this within a short range, where frequent impedance mismatch can occur. Each method has pros and cons. In order to verify the feasibility of the proposed methods, HF-band wireless power transfer systems, with a pair of rectangular loop resonators, were designed. The efficiency and input impedance variation were simulated and measured. From these results, proposed methods show enhanced efficiency performance than a typical wireless power transfer system without any compensation circuits.
HF-BAND WIRELESS POWER TRANSFER SYSTEM: CONCEPT, ISSUES, AND DESIGN
2012-01-19
PIER
Vol. 124, 187-210, 2012
download: 183
On Body Concealed Weapon Detection Using a Phased Antenna Array
Stuart William Harmer Shawn Edward Cole Nicholas John Bowring Nacer Ddine Rezgui David Andrews
The detection and identification of metal items and, in particular weapons, of linear size ≥10 cm, concealed upon the human body, is demonstrated as being entirely feasible by using a phased array of suitably ultra wide band transceivers. The complex natural resonances and especially the fundamental resonance, are excited by ultra wide band, stepped frequency continuous wave illumination of the target, using a phased array of antennae to focus the radiation. Broadband illumination of the target with microwave radiation of suitable frequency range (Typically 0.3-3 GHz for handgun sized objects) excites low order complex natural resonances and the late time response of the concealed item can be spatially located using phased array imaging techniques. Further processing of the late time response enables classification of the concealed object, based on the complex natural resonant frequencies of the object, so that threat items such as handguns and knives can be differentiated from benign items such as mobile phone handsets and cameras.
ON BODY CONCEALED WEAPON DETECTION USING A PHASED ANTENNA ARRAY
2012-01-19
PIER
Vol. 124, 163-186, 2012
download: 152
Nonlinear Modeling of Trapping and Thermal Effects on GaAs and GaN Mesfet/HEMT Devices
Mohamed Chaibi Tomas Fernandez Asmae Mimouni José Rodriguez-Tellez Antonio Tazón Angel Mediavilla Sanchez
A novel nonlinear model for MESFET/HEMT devices is presented. The model can be applied to low power (GaAs) and high power (GaN) devices with equal success. The model provides accurate simulation of the static (DC) and dynamic (Pulsed) I-V characteristics of the device over a wide bias and ambient temperature range (from -70ºC to +70ºC) without the need of an additional electro-thermal sub-circuit. This is an important issue in high power GaN HEMT devices where self-heating and current collapse due to traps is a more serious problem. The parameter extraction strategy of the new model is simple to implement. The robustness of the model when performing harmonic balance simulation makes it suitable for RF and microwave designers. Experimental results presented demonstrate the accuracy of the model when simulating both the small-signal and large-signal behavior of the device over a wide range of frequency, bias and ambient temperature operating points. The model described has been implemented in the Advanced Design System (ADS) simulator to validate the proposed approach without convergence problems.
NONLINEAR MODELING OF TRAPPING AND THERMAL EFFECTS ON GaAs AND GaN MESFET/HEMT DEVICES