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2012-09-03
PIER
Vol. 130, 601-617, 2012
download: 167
Determination of Dielectric Property of Construction Material Products Using a Novel RFID Sensor
Rattapong Suwalak Chuwong Phongcharoenpanich Danai Torrungrueng Monai Krairiksh
This paper presents a concept, by which radio frequency (RF) tags are employed as remotely read dielectric-property sensors to determine qualities of some construction material products (CMPs); e.g., light weight concrete (LWC), mortar specimens and concrete. Using the dependency of the read range of the passive RF identification (RFID) sensor system on the electromagnetic properties of CMPs near or in contact with RFID tags, the qualities of CMPs can be determined through their estimated dielectric properties. Theoretical formulation is provided, and numerical simulations are performed for optimal design of passive RFID tag antennas suitable for RFID sensors and for read-range calculations. In addition, a series of measurements is performed to measure read ranges of the passive RFID sensor system for an LWC as an example of CMPs, and these measured read ranges will be processed appropriately to inversely determine the dielectric constant of the LWC under test, which in turn provides information on its qualities. It is found that the novel RFID sensor can be employed to determine the dielectric properties of the LWC under test with reasonable accuracy.
DETERMINATION OF DIELECTRIC PROPERTY OF CONSTRUCTION MATERIAL PRODUCTS USING A NOVEL RFID SENSOR
2012-09-03
PIER
Vol. 130, 581-600, 2012
download: 157
Evaluation of Lightning Return Stroke Current Using Measured Electromagnetic Fields
Mahdi Izadi Mohd Zainal Abidin Ab Kadir Chandima Gomes Vernon Cooray
The lightning return stroke current is an important parameter for considering the effect of lightning on power lines. In this study, a numerical method is proposed to evaluate the return stroke current based on measured electromagnetic fields at an observation point in the time domain. The proposed method considers all field components and the full wave shape of the current without the use of a special current model as a basic assumption compared to previous methods. Furthermore, the proposed algorithm is validated using measured fields obtained from a triggered lightning experiment. The results show a good agreement between the simulated field based on the evaluated currents from the proposed method and the corresponding measured field at a remote observation point. The proposed method can determine current wave shapes related to a greater number of lightning occurrences compared to the direct measurement of the current.
EVALUATION OF LIGHTNING RETURN STROKE CURRENT USING MEASURED ELECTROMAGNETIC FIELDS
2012-08-30
PIER
Vol. 130, 563-579, 2012
download: 110
An Adaptive Method to Focusing in an Unknown Scenario
Lorenzo Crocco Loreto Di Donato Domenica A. M. Iero Tommaso Isernia
The problem of field focusing radiated onto a target location in an unknown scenario is considered. In particular, we devise an adaptive procedure in which first an image of the unknown region where the target point is located is formed via LSM. Then, the LSM result is used also to define the excitations coefficients for the array elements needed to focus the field. This novel approach to focusing is described and tested with numerical examples.
AN ADAPTIVE METHOD TO FOCUSING IN AN UNKNOWN SCENARIO
2012-08-23
PIER
Vol. 130, 541-561, 2012
download: 112
Robust Lcmp Beamformer with Negative Loading
Congfeng Liu Jie Yang
The adaptive linearly constrained minimum power (LCMP) beamformer can improve the robustness of the Capon beamformer. And quadratic constraints on the weighting vector of the LCMP beamformer can improve the robustness to pointing errors and to random perturbations in sensor parameters. But how to solve it and how to select the constraint parameters are its key problems. In this paper, the Lagrange multiplier method is proposed to solve the LCMP beamformer under quadratic inequality constraint (QIC). The problem of finding the optimal weight vector is solved, and the choice of the quadratic constraint parameter is analyzed and the selected bound is also given. Since the quadratic equality constraint (QEC) is stronger than the quadratic inequality constraint (QIC), the performance of the QECLCMP beamformer is more robust than that of the QICLCMP beamformer. Therefore, the QECLCMP beamformer is proposed and is solved effectively. Numerical examples attest the correctness and the efficiency of the proposed algorithms. And the results show that the QECLCMP beamformer has the advantage of overcoming the steering vector mismatch, namely the optimal negative loading has the preferable robustness.
ROBUST LCMP BEAMFORMER WITH NEGATIVE LOADING
2012-08-23
PIER
Vol. 130, 525-540, 2012
download: 110
A Novel 3-D Weakly Conditionally Stable FDTD Algorithm
Jian-Bao Wang Bi-Hua Zhou Li-Hua Shi Cheng Gao Bin Chen
For analyzing the electromagnetic problems with the fine structures in one or two directions, a novel weakly conditionally stable finite-difference time-domain (WCS-FDTD) algorithm is proposed. By dividing the 3-D Maxwell's equations into two parts, and applying the Crank-Nicolson (CN) scheme to each part, a four sub-step implicit procedures can be obtained. Then by adjusting the operational order of four sub-steps, a novel 3-D WCS-FDTD algorithm is derived. The proposed method only needs to solve four implicit equations, and the Courant-Friedrich-Levy (CFL) stability condition of the proposed algorithm is more relaxed and only determined by one space discretisation. In addition, numerical dispersion analysis demonstrates the numerical phase velocity error of the weakly conditionally stable scheme is less than that of the 3-D ADI-FDTD scheme.
A NOVEL 3-D WEAKLY CONDITIONALLY STABLE FDTD ALGORITHM
2012-08-23
PIER
Vol. 130, 513-524, 2012
download: 120
Controlling the Electromagnetic Field by Indefinite Media with Extremely Strong Anisotropy
Jingbo Sun Tieyu Sun Bo Li Helen Lai Wa Chan Ji Zhou Yu Wang
In this work, we show how to manipulate the electromagnetic wave at will by using an indefinite medium with extremely strong anisotropy. The negative element in the indefinite permittivity tensor goes to the negative infinity while the positive element is equal to 1, which stretches the hyperbolic equifrequency contour into a straight line type. The direction of the Poynting vector and the wave vector is aligned by the straight line type equifrequency contour along the orientation of the extremely negative permittivity, thus control the wave propagation. The other permittivity of 1 makes the indefinite medium matched with the air. Moreover, because of the hyperbolic equifrequency contour, evanescent wave can also transmit in the indefinite medium under the propagation mode, implying the possibility of controlling an evanescent wave by this special indefinite medium. Simulations are performed to demonstrate the controlling performance and a potential design to realize such a medium by metamaterial with multilayered metal/dielectric structure. This work may supply a shortcut for those former devices based on the Transformation optics.
CONTROLLING THE ELECTROMAGNETIC FIELD BY INDEFINITE MEDIA WITH EXTREMELY STRONG ANISOTROPY
2012-08-22
PIER
Vol. 130, 493-512, 2012
download: 132
Ground Moving Train Imaging by Ku-Band Radar with Two Receiving Channels
Yunhua Zhang Wenshuai Zhai Xiangkun Zhang Xiaojin Shi Xiang Gu Yuan Deng
Radar imaging experiment of ground moving target --- a light rail-way train by Ku-band radar with two receiving channel is introduced. Both coherent and incoherent imaging as well as co-pol and cross-pol interferometric imaging were conducted with SAR amplitude images as well as interferometric --- phase images obtained. In the obtained SAR images, there are 24 stronger scattering centers which correspond to 24 bigger doors of the train. Along-track interferometric --- phase images indicate that the train travels at an increasing speed in one direction and at a decreasing speed in the opposite direction. Short Time Fourier Transform (STFT) is applied to the azimuthal signals to get the instant Doppler frequencies (IDFs), from which one can judge acceleration or deceleration status of the moving train. Electromagnetic scattering characteristics of the train are analyzed according to the SAR images. The estimated speed and length of the train are very well agreed with real situation.
GROUND MOVING TRAIN IMAGING BY KU-BAND RADAR WITH TWO RECEIVING CHANNELS
2012-08-22
PIER
Vol. 130, 473-492, 2012
download: 183
Evaluation of Lightning Current and Velocity Profiles Along Lightning Channel Using Measured Magnetic Flux Density
Mahdi Izadi Mohd Zainal Abidin Ab Kadir Chandima Gomes Vernon Cooray Jens Schoene
In this paper, an inverse procedure algorithm is proposed in the time domain to evaluate lightning return stroke currents along a lightning channel using measured magnetic flux density at an observation point while the current velocity along a lightning channel is assumed to be a height dependent variable. The proposed method considers all field components and it can evaluate the full shape of currents and the current velocity at different heights along a lightning channel. Moreover, a sample of measured magnetic flux density from a triggered lightning experiment is applied to the proposed algorithm and the evaluated currents and current velocities are validated using a measured channel base current and magnetic flux density at another observation point.
EVALUATION OF LIGHTNING CURRENT AND VELOCITY PROFILES ALONG LIGHTNING CHANNEL USING MEASURED MAGNETIC FLUX DENSITY
2012-08-21
PIER
Vol. 130, 447-472, 2012
download: 140
Image Sequence Measures for Automatic Target Tracking
Wei-He Diao Xia Mao Hai-Chao Zheng Yu-Li Xue Vasile Gui
In the field of automatic target recognition and tracking, traditional image metrics focus on single images, ignoring the sequence information of multiple images. We show that measures extracted from image sequences are highly relevant concerning the performances of automatic target tracking algorithms. To compensate the current lack of image sequence characterization systems from the perspective of the target tracking difficulties, this paper proposes three new metrics for measuring image sequences: inter-frame change degree of texture, inter-frame change degree of target size and inter-frame change degree of target location. All are based on the fact that inter-frame change is the main cause interfering with target tracking in an image sequence. As image sequences are an important type of data in the field of automatic target recognition and tracking, it can be concluded that the work in this paper is a necessary supplement for the existing image measurement systems. Experimental results reported show that the proposed metrics are valid and useful.
IMAGE SEQUENCE MEASURES FOR AUTOMATIC TARGET TRACKING
2012-08-21
PIER
Vol. 130, 429-446, 2012
download: 117
A Resonance Tunable and Durable Lspr Nano-Particle Sensor: Al2O3 Capped Silver Nano-Disks
Daryoush Mortazavi Abbas Z. Kouzani Kristy C. Vernon
Localized surface plasmon resonance (LSPR) biosensors are employed to detect target biomolecules which have particular resonance wavelengths. Accordingly, tunability of the LSPR wavelength is essential in designing LSPR devices. LSPR devices employing silver nano-particles present better efficiencies than those using other noble metals such as gold; however, silver nano-particles are easily oxidized when they come in contact with liquids, which is inevitable in biosensing applications. To attain both durability and tunabilty in a LSPR biosensor, this paper proposes alumina (AL2O3) capped silver nano-disks. It is shown that through controlling the thickness of the cap, the LSPR resonance frequency can be finely tuned over a wide range; and moreover, the cap protects silver nano-particles from oxidation and high temperature.
A RESONANCE TUNABLE AND DURABLE LSPR NANO-PARTICLE SENSOR: AL<sub>2</sub>O<sub>3</sub> CAPPED SILVER NANO-DISKS
2012-08-20
PIER
Vol. 130, 411-428, 2012
download: 159
Mixed-Mode Impedance and Reflection Coefficient of Two-Port Devices
Carrillo Tomas Carrasco Cordoba Javier Sieiro José Mª Lopez-Villegas Neus Vidal Reinier Gonzalez-Echevarría Moreno Elisenda Roca
From the point of view of mixed-mode scattering parameters, Smm, a two-port device can be excited using different driving conditions. Each condition leads to a particular set of input reflection and input impedance coefficient definitions that should be carefully applied depending on the type of excitation and symmetry of the two-port device. Therefore, the aim of this paper is to explain the general analytic procedure for the evaluation of such reflection and impedance coefficients in terms of mixed-mode scattering parameters. Moreover, the driving of a two-port device as a one-port device is explained as a particular case of a two-port mixed-mode excitation using a given set of mixed-mode loads. The theory is applied to the evaluation of the quality factor, Q, of symmetrical and non-symmetrical inductors.
MIXED-MODE IMPEDANCE AND REFLECTION COEFFICIENT OF TWO-PORT DEVICES
2012-08-20
PIER
Vol. 130, 389-409, 2012
download: 152
A Novel Compact Split Ring Slotted Electromagnetic Bandgap Structure for Microstrip Patch Antenna Performance Enhancement
Md. Shahidul Alam Mohammad Tariqul Islam Norbahiah Misran
A novel design of an electromagnetic bandgap (EBG) structure based on the uniplanar compact EBG (UCEBG) concept is proposed in this paper. The structure is realized by inserting split-ring slots inside two reversely connected rectangular patches, which is known as a split-ring slotted electromagnetic bandgap (SRS-EBG) structure. The bandgap properties of the EBG structure are examined by the suspended microstrip line and finite element methods (FEM). The achieved bandgaps have widths of 4.3 (59.31%) and 5.16 GHz (38.88%), which are centered at 7 and 13 GHz, respectively. The SRS-EBG is applied to enhance the performance of a single-element microstrip patch antenna (at 7 GHz) and a two-element array (at 13 GHz) configuration. A wider bandwidth is obtained with a better reflection coefficient level for the single element antenna; a reduction in mutual coupling of more than 20.57 dB is obtained for the array design. In both cases, the gain and radiation characteristics are improved. The results are verified by measuring the fabricated lab prototype, and a comparison with the computed results showed good agreement.
A NOVEL COMPACT SPLIT RING SLOTTED ELECTROMAGNETIC BANDGAP STRUCTURE FOR MICROSTRIP PATCH ANTENNA PERFORMANCE ENHANCEMENT
2012-08-19
PIER
Vol. 130, 369-388, 2012
download: 309
An Mr Brain Images Classifier via Principal Component Analysis and Kernel Support Vector Machine
Yu-Dong Zhang Lenan Wu
Automated and accurate classification of MR brain images is extremely important for medical analysis and interpretation. Over the last decade numerous methods have already been proposed. In this paper, we presented a novel method to classify a given MR brain image as normal or abnormal. The proposed method first employed wavelet transform to extract features from images, followed by applying principle component analysis (PCA) to reduce the dimensions of features. The reduced features were submitted to a kernel support vector machine (KSVM). The strategy of K-fold stratified cross validation was used to enhance generalization of KSVM. We chose seven common brain diseases (glioma, meningioma, Alzheimer's disease, Alzheimer's disease plus visual agnosia, Pick's disease, sarcoma, and Huntington's disease) as abnormal brains, and collected 160 MR brain images (20 normal and 140 abnormal) from Harvard Medical School website. We performed our proposed methods with four different kernels, and found that the GRB kernel achieves the highest classification accuracy as 99.38%. The LIN, HPOL, and IPOL kernel achieves 95%, 96.88%, and 98.12%, respectively. We also compared our method to those from literatures in the last decade, and the results showed our DWT+PCA+KSVM with GRB kernel still achieved the best accurate classification results. The averaged processing time for a 256x256 size image on a laptop of P4 IBM with 3 GHz processor and 2 GB RAM is 0.0448 s. From the experimental data, our method was effective and rapid. It could be applied to the field of MR brain image classification and can assist the doctors to diagnose a patient normal or abnormal in some degree.
AN MR BRAIN IMAGES CLASSIFIER VIA PRINCIPAL COMPONENT ANALYSIS AND KERNEL SUPPORT VECTOR MACHINE
2012-08-17
PIER
Vol. 130, 347-368, 2012
download: 187
System-on-Chip 36.8 GHz Radiometer for Space-Based Observation of Solar Flares: Feasibility Study in 0.25 μm SiGe BiCMOS Technology
Luca Aluigi Luca Roselli Stephen M. White Federico Alimenti
This paper deals with a feasibility study for a System-on-Chip (SoC) mmwave radiometer devoted to space-based observation of solar flares and operating in the Ka-band. The radiometer has been designed in 250 nm SiGe BiCMOS process. The circuit integrates a three stages differential LNA with 37.2 dB gain and 4.8 dB noise figure at 36.8 GHz and a differential square-law detector based on HBTs, featuring a 96 mV/μW responsivity. The full radiometer achieves, potentially, a NETD of 0.1 K for 1 s integration time in Dicke mode. This work represents the first study of such an integrated instrument for Ka-band space-based observation of solar flares.
SYSTEM-ON-CHIP 36.8 GHZ RADIOMETER FOR SPACE-BASED OBSERVATION OF SOLAR FLARES: FEASIBILITY STUDY IN 0.25 μm SIGE BICMOS TECHNOLOGY
2012-08-17
PIER
Vol. 130, 319-346, 2012
download: 117
Short Range Propagation Model for a Very Wideband Directive Channel at 5.5 GHz Band
Bazil Taha-Ahmed David Fernandez Campillo Jose Luis Masa-Campos
In this work, the propagation loss of three short range directive channels at 5.5 GHz is measured using different directive antennas and a Vector Network Analyzer (VNA). Results are given for a channel bandwidth of 300 MHz which will be the future channel bandwidth of IEEE 802.11 ac system. It has been noted that the multipath induced fading tends to have Normal Distribution at low distance between the transmitting and the reception antennas. At higher distances, it tends to have Normal distribution plus Rayleigh one. Channel Impulse response (CIR) is also measured indicating that the main contribution is due to the direct ray and the one reflected from the floor. The human being obstruction causes an extra propagation loss of 2 to 10 dB depending on its distance from the transmitting antenna.
SHORT RANGE PROPAGATION MODEL FOR A VERY WIDEBAND DIRECTIVE CHANNEL AT 5.5 GHZ BAND
2012-08-17
PIER
Vol. 130, 281-317, 2012
download: 96
Finite Data Performance Analysis of Lcmv Antenna Array Beamformers with and Without Signal Blocking
Yen Lin Chen Ju-Hong Lee
A linearly constrained minimum variance (LCMV) antenna array beamformer using finite data samples suffers from slow convergence when the received array data contain the desired signal. It has been reported that signal blocking techniques speed up the convergence rate and increase the robustness of LCMV antenna array beamformers. However, the reason of this improvement has not been explored in the literature. Moreover, the existing formulas for the output signal-to-interference-plus-noise ratio (SINR) are too rough to realize the influence of signal blocking techniques on the performance. In this paper, we show that the correlation due to finite samples causes the redundant component (termed as the cross weight) embedded in the weight vector of a LCMV beamformer even if the signal sources and noise are independent. The cross power results from the cross weight degrades the performance when the sample size is small. In contrast, the cross weight and cross power can be fully eliminated when a signal blocking technique is used. The theoretical results presented in this paper provide a comprehensive description on the effectiveness and the price of using signal blocking for antenna array beamforming. Simulation results are also given for confirming the validity of the theoretical results.
FINITE DATA PERFORMANCE ANALYSIS OF LCMV ANTENNA ARRAY BEAMFORMERS WITH AND WITHOUT SIGNAL BLOCKING
2012-08-15
PIER
Vol. 130, 257-279, 2012
download: 113
Atmospheric Propagation at 100 and 300 GHz : Assessment of a Method to Identify Rainy Conditions During Radiosoundings
Gustavo Adolfo Siles Soria Jose M. Riera Pedro Garcia del Pino Jordi Romeu
The influence of atmospheric gases and tropospheric phenomena becomes more relevant at frequencies within the THz band (100 GHz to 10 THz), severely affecting the propagation conditions. The use of radiosoundings in propagation studies is a well established measurement technique in order to collect information about the vertical structure of the atmosphere, from which gaseous and cloud attenuation can be estimated with the use of propagation models. However, some of these prediction models are not suitable to be used under rainy conditions. In the present study, a method to identify the presence of rainy conditions during radiosoundings is introduced, with the aim of filtering out these events from yearly statistics of predicted atmospheric attenuation. The detection procedure is based on the analysis of a set of parameters, some of them extracted from synoptical observations of weather (SYNOP reports) and other derived from radiosonde observations (RAOBs). The performance of the method has been evaluated under different climatic conditions, corresponding to three locations in Spain, where colocated rain gauge data were available. Rain events detected by the method have been compared with those precipitations identified by the rain gauge. The pertinence of the method is discussed on the basis of an analysis of cumulative distributions of total attenuation at 100 and 300 GHz. This study demonstrates that the proposed method can be useful to identify events probably associated to rainy conditions. Hence, it can be considered as a suitable algorithm in order to filter out this kind of events from annual attenuation statistics.
ATMOSPHERIC PROPAGATION AT 100 AND 300 GHZ: ASSESSMENT OF A METHOD TO IDENTIFY RAINY CONDITIONS DURING RADIOSOUNDINGS
2012-08-14
PIER
Vol. 130, 241-256, 2012
download: 555
Design and Fabrication of Wideband Archimedean Spiral Antenna Based Ultra-Low Cost ``Green'' Modules for RFID Sensing and Wireless Applications
Yasar Amin Qiang Chen Li-Rong Zheng Hannu Tenhunen
A parametric analysis is performed for a wideband Archimedean spiral antenna in recognition of an emerging concept to integrate RFID along with several applications by using a single antenna. The antenna is fabricated using state-of-the-art inkjet printing technology on various commercially available paper substrates to provide the low-cost, flexible RF modules for the next generation of "green" electronics. The effects on electromagnetic characteristics of the planar Archimedean spiral antenna, due to the use of paper are investigated besides other parameters. The proposed antenna is evaluated and optimized for operational range from 0.8-3.0 GHz. It exhibits exceptional coverage throughout numerous RFID ISM bands so do for other wireless applications.
DESIGN AND FABRICATION OF WIDEBAND ARCHIMEDEAN SPIRAL ANTENNA BASED ULTRA-LOW COST ``GREEN'' MODULES FOR RFID SENSING AND WIRELESS APPLICATIONS
2012-08-14
PIER
Vol. 130, 225-240, 2012
download: 104
Reconstruction of Microwave Absorption Properties in Heterogeneous Tissue for Microwave-Induced Thermo-Acoustic Tomography
Jinguo Wang Zhiqin Zhao Jian Song Xiaozhang Zhu Zai-Ping Nie Qing Huo Liu
Aiming to efficiently overcome the acoustic refraction and accurately reconstruct the microwave absorption properties in heterogeneous tissue, an iterative reconstruction method is proposed for microwave-induced thermo-acoustic tomography (MITAT) system. Most current imaging methods in MITAT assume that the heterogeneous sound velocity (SV) distribution obeys a simple Gaussian distribution. In real problem, the biological tissue may have several different inclusions with different SV distribution. In this case, the acoustic refraction must be taken into account. The proposed iterative method is consisted of an iterative engine with time reversal mirror (TRM), fast marching method (FMM) and simultaneous algebraic reconstruction technique (SART). This method utilizes TRM, FMM and SART to estimate the SV distribution of tissue to solve the phase distortion problem caused by the acoustic refraction effect and needs little prior knowledge of the tissue. The proposed method has great advantages in both spatial resolution and contrast for imaging tumors in acoustically heterogeneous medium. Some numerical simulation results are given to demonstrate the excellent performance of the proposed method.
RECONSTRUCTION OF MICROWAVE ABSORPTION PROPERTIES IN HETEROGENEOUS TISSUE FOR MICROWAVE-INDUCED THERMO-ACOUSTIC TOMOGRAPHY
2012-08-13
PIER
Vol. 130, 207-224, 2012
download: 112
Sierpinskized Koch-Like Sided Multifractal Dipole Antenna
Daotie Li Jun-Fa Mao
Koch-like fractal curve and Sierpinski Gasket are syncretized into a novel Sierpinskized Koch-like sided bow-tie (SKLB) multifractal in superior-inferior way. A K4S4 SKLB multifractal dipole fed by a linearly tapered microstrip Balun is designed, simulated, fabricated and measured. The well consistent results from measurement and experiment corroborate validity of design and the multifractal antenna's superiority and advantages over its monofractal counterparts in impedance, bandwidth, directivity, efficiency, and dimension. Six good matched bands(S11 ≤ -10 dB) with moderate gain (2.12 dBi-9.55 dBi) and high efficiency (87%-97%) are obtained within band 1.5 GHz-14.5 GHz, of which f1 = 1.92 GHz, f2 = 3.94 GHz, and f3 = 5.09 GHz are generally useful. The multibands are all almost omnidirectional or quasi-omnidirectional in H-plane (Phi=0°, XOZ) and doughnut-shaped or dented doughnut-shaped in E-plane (Phi = 90°, YOZ). So it is an attractive candidate for applications like PCS, IMT2000, UMTS, WLAN, WiFi, WiMAX and other fixed or mobile wireless multiband communication systems.
SIERPINSKIZED KOCH-LIKE SIDED MULTIFRACTAL DIPOLE ANTENNA