Vol. 94
Latest Volume
All Volumes
PIER 179 [2024] PIER 178 [2023] PIER 177 [2023] PIER 176 [2023] PIER 175 [2022] PIER 174 [2022] PIER 173 [2022] PIER 172 [2021] PIER 171 [2021] PIER 170 [2021] PIER 169 [2020] PIER 168 [2020] PIER 167 [2020] PIER 166 [2019] PIER 165 [2019] PIER 164 [2019] PIER 163 [2018] PIER 162 [2018] PIER 161 [2018] PIER 160 [2017] PIER 159 [2017] PIER 158 [2017] PIER 157 [2016] PIER 156 [2016] PIER 155 [2016] PIER 154 [2015] PIER 153 [2015] PIER 152 [2015] PIER 151 [2015] PIER 150 [2015] PIER 149 [2014] PIER 148 [2014] PIER 147 [2014] PIER 146 [2014] PIER 145 [2014] PIER 144 [2014] PIER 143 [2013] PIER 142 [2013] PIER 141 [2013] PIER 140 [2013] PIER 139 [2013] PIER 138 [2013] PIER 137 [2013] PIER 136 [2013] PIER 135 [2013] PIER 134 [2013] PIER 133 [2013] PIER 132 [2012] PIER 131 [2012] PIER 130 [2012] PIER 129 [2012] PIER 128 [2012] PIER 127 [2012] PIER 126 [2012] PIER 125 [2012] PIER 124 [2012] PIER 123 [2012] PIER 122 [2012] PIER 121 [2011] PIER 120 [2011] PIER 119 [2011] PIER 118 [2011] PIER 117 [2011] PIER 116 [2011] PIER 115 [2011] PIER 114 [2011] PIER 113 [2011] PIER 112 [2011] PIER 111 [2011] PIER 110 [2010] PIER 109 [2010] PIER 108 [2010] PIER 107 [2010] PIER 106 [2010] PIER 105 [2010] PIER 104 [2010] PIER 103 [2010] PIER 102 [2010] PIER 101 [2010] PIER 100 [2010] PIER 99 [2009] PIER 98 [2009] PIER 97 [2009] PIER 96 [2009] PIER 95 [2009] PIER 94 [2009] PIER 93 [2009] PIER 92 [2009] PIER 91 [2009] PIER 90 [2009] PIER 89 [2009] PIER 88 [2008] PIER 87 [2008] PIER 86 [2008] PIER 85 [2008] PIER 84 [2008] PIER 83 [2008] PIER 82 [2008] PIER 81 [2008] PIER 80 [2008] PIER 79 [2008] PIER 78 [2008] PIER 77 [2007] PIER 76 [2007] PIER 75 [2007] PIER 74 [2007] PIER 73 [2007] PIER 72 [2007] PIER 71 [2007] PIER 70 [2007] PIER 69 [2007] PIER 68 [2007] PIER 67 [2007] PIER 66 [2006] PIER 65 [2006] PIER 64 [2006] PIER 63 [2006] PIER 62 [2006] PIER 61 [2006] PIER 60 [2006] PIER 59 [2006] PIER 58 [2006] PIER 57 [2006] PIER 56 [2006] PIER 55 [2005] PIER 54 [2005] PIER 53 [2005] PIER 52 [2005] PIER 51 [2005] PIER 50 [2005] PIER 49 [2004] PIER 48 [2004] PIER 47 [2004] PIER 46 [2004] PIER 45 [2004] PIER 44 [2004] PIER 43 [2003] PIER 42 [2003] PIER 41 [2003] PIER 40 [2003] PIER 39 [2003] PIER 38 [2002] PIER 37 [2002] PIER 36 [2002] PIER 35 [2002] PIER 34 [2001] PIER 33 [2001] PIER 32 [2001] PIER 31 [2001] PIER 30 [2001] PIER 29 [2000] PIER 28 [2000] PIER 27 [2000] PIER 26 [2000] PIER 25 [2000] PIER 24 [1999] PIER 23 [1999] PIER 22 [1999] PIER 21 [1999] PIER 20 [1998] PIER 19 [1998] PIER 18 [1998] PIER 17 [1997] PIER 16 [1997] PIER 15 [1997] PIER 14 [1996] PIER 13 [1996] PIER 12 [1996] PIER 11 [1995] PIER 10 [1995] PIER 09 [1994] PIER 08 [1994] PIER 07 [1993] PIER 06 [1992] PIER 05 [1991] PIER 04 [1991] PIER 03 [1990] PIER 02 [1990] PIER 01 [1989]
2009-07-30
PIER
Vol. 94, 419-433, 2009
download: 218
Lower Frequency Limit of Carbon Nanotube Antenna
Ahmed Attiya
Carbon nanotubes are characterized by slow wave propagation and high characteristic impedance due to the additional kinetic inductive effect. This slow wave property can be used to introduce resonant dipole antennas with dimensions much smaller than traditional half-wavelength dipole in Terahertz band. However, this property has less effect at lower frequency bands. This paper introduces the physical interpretation of this property based on the relation between the resonance frequency and the surface wave propagation constant on a carbon nanotube. This surface wave propagation is found to be characterized by high attenuation coefficient at low frequency bands which limits using carbon nanotube as an antenna structure at these frequencies.
LOWER FREQUENCY LIMIT OF CARBON NANOTUBE ANTENNA
2009-07-29
PIER
Vol. 94, 403-418, 2009
download: 159
A New Method for Evaluation of Thickness and Monitoring Its Variation of Medium- and Low-Loss Materials
Ugur Cem Hasar
In this research paper, we propose an amplitude-only method for unique thickness evaluation of medium- and low-loss materials. The method is based on using amplitude-only measurements at different frequencies to evaluate the unique thickness. Main advantages of the method are a) it eliminates the necessity of repetitive measurements of different-length materials to evaluate the unknown thickness of the same type material and b) it determines the thickness at any desired frequency in the band. Because the method uses amplitude-only measurements and enables the thickness evaluation at any frequency, it can be a good candidate for thickness evaluation of materials in industrial-based applications.
A NEW METHOD FOR EVALUATION OF THICKNESS AND MONITORING ITS VARIATION OF MEDIUM- AND LOW-LOSS MATERIALS
2009-07-29
PIER
Vol. 94, 383-402, 2009
download: 174
Application of Two-Step Spectral Preconditioning Technique for Electromagnetic Scattering in a Half Space
Da-Zhi Ding , Ru-Shan Chen and Zhenhong Fan
To efficiently solve large dense complex linear system arising from electric field integral equations (EFIE) formulation of half-space electromagnetic scattering problems, the multilevel fast multipole algorithm (MLFMA) is used to accelerate the matrix-vector product operations. The two-step spectral preconditioning is developed for the generalized minimal residual iterative method (GMRES). The two-step spectral preconditioner is constructed by combining the spectral preconditioner and sparse approximate inverse (SAI) preconditioner to speed up the convergence rate of iterative methods. Numerical experiments for scattering from conducting objects above or embeded in a lossy half-space are given to demonstrate the efficiency of the proposed method.
APPLICATION OF TWO-STEP SPECTRAL PRECONDITIONING TECHNIQUE FOR ELECTROMAGNETIC SCATTERING IN A HALF SPACE
2009-07-28
PIER
Vol. 94, 367-382, 2009
download: 253
Accurate and Efficient Evaluation of MoM Matrix Based on a Generalized Analytical Approach
Kye See , Eng Kee Chua and Zhihong Liu
Based on an analytical expression for the integration of the free-space Green's function involving any combination of basis and test functions, an accurate and highly efficient method to determine the Method of Moments matrix has been developed. A full analytical expression is obtained through direct integration of the Taylor's series expansion of the free-space Green's function. Based on the distance between the source and observation points, a criterion is established to reduce the full expression to a much-simplified expression, which speeds up the computational efficiency to fill up the Method of Moments matrix without compromising the solution accuracy.
ACCURATE AND EFFICIENT EVALUATION OF MOM MATRIX BASED ON A GENERALIZED ANALYTICAL APPROACH
2009-07-26
PIER
Vol. 94, 351-366, 2009
download: 181
Focal Region Field of a Paraboloidal Reflector Coated with Isotropic Chiral Medium
Tariq Rahim , Muhammad Junaid Mughal , Qaisar Naqvi and Muhammad Faryad
Maslov's method is used to derive the expressions for high frequency fields around the focal region of a paraboloidal reflector coated with isotropic and homogeneous chiral medium. The field expressions thus calculated are solved numerically, and the results are presented in the paper. Moreover, the dependency of the electric field on the thickness of the coated chiral medium and its properties is also studied. The results of this study are presented in the paper, and the conclusions are drawn accordingly.
FOCAL REGION FIELD OF A PARABOLOIDAL REFLECTOR COATED WITH ISOTROPIC CHIRAL MEDIUM
2009-07-25
PIER
Vol. 94, 343-349, 2009
download: 308
A Novel Compact Ultra-Wideband (UWB) Wide Slot Antenna with via Holes
Dong Chen and Chong-Hu Cheng
A novel compact ultra-wideband (UWB) wide slot antenna with via holes is presented for UWB applications. The antenna is composed of a trapezoidal slot on the ground plane, a rectangular patch in the center of the slot and three via holes connecting the rectangular patch and the microstrip feed-line. The antenna is successfully designed, implemented, and measured. The measured results show that the proposed antenna with compact size of 27.0 mm×29.0 mm×1.0 mm achieves good performance, such as an impedance matching bandwidth of 111.7% (|S11|≤-10 dB), constant gain and stable radiation patterns over its whole frequency range.
A NOVEL COMPACT ULTRA-WIDEBAND (UWB) WIDE SLOT ANTENNA WITH VIA HOLES
2009-07-25
PIER
Vol. 94, 327-341, 2009
download: 168
Magnetic Field in MRI Yokeless Devices: Analytical Approach
Romain Ravaud and Guy Lemarquand
This paper presents a three-dimensional analytical expressions for studying the static magnetic field produced by Magnetic Resonance Imaging structures. This medical imaging technique uses a very high and uniform magnetic field produced by ring permanent magnets with rotating polarizations. However, the manufacturing of such ring permanent magnets is difficult to realize. Consequently, such ring permanent magnets are replaced by assemblies of tile permanent magnets uniformly magnetized. Unfortunately, the magnetic field produced by these tile permanent magnets uniformly magnetized is both less important and less uniform than the one produced by an idealized ring permanent magnet. We propose in this paper to study the influence of the number of tile permanent magnets used on the magnetic field properties.
MAGNETIC FIELD IN MRI YOKELESS DEVICES: ANALYTICAL APPROACH
2009-07-25
PIER
Vol. 94, 311-325, 2009
download: 227
Water-to-Cement Ratio Prediction Using Anns from Non-Destructive and Contactless Microwave Measurements
Ugur Cem Hasar , Gokay Akkaya , Mehmet Aktan , Cuneyt Gozu and Abdulkadir Cuneyt Aydin
In concrete industry, there is a need for water-to-cement ratio (w/c) estimation of cement-based materials since the w/c ratio of cement mixtures is typically given at the batch plant, and this ratio, sometimes, is deliberately changed to have a more workable cement mixture. To meet the requirements of accurate w/c ratio determination of cement-based materials, in this research paper, we propose an artificial neural network approach for w/c ratio estimation of these materials using free-space non-contact reflection and transmission measurements of mortar specimens with w/c ratios of 0.40, 0.45, 0.50, 0.55 and 0.60. We have tested the network and observed less than 5 percent difference between the estimated and known values of w/c = 0.50.
WATER-TO-CEMENT RATIO PREDICTION USING ANNS FROM NON-DESTRUCTIVE AND CONTACTLESS MICROWAVE MEASUREMENTS
2009-07-25
PIER
Vol. 94, 297-309, 2009
download: 359
A Millimeter-Wave Ultra-Wideband Four-Way Switch Filter Module Based on Novel Three-Line Microstrip Structure Band-Pass Filters
Zhigang Wang , Qiuliang Lai , Rui-Min Xu , Bo Yan , Weigan Lin and Yunnchuan Guo
This paper presents a millimeter-wave ultra-wideband four-way switch filter module integrating six building blocks including four band-pass filters and two switches. The switch filter module works at whole Ka-band (26-40 GHz) and consists of four wideband band-pass filters and two monolithic microwave integrated circuit (MMIC) single pole four throw (SP4T) switches. The four wideband band-pass filters are realized by a novel three-line microstrip structure band-pass filter. Compared with the traditional three-line filter, the proposed three-line filter not only retains virtues of traditional three-line filter, but also resolves drawbacks of it which include discontinuities between adjacent sections, many parameters of design, and no effective matching circuits at input/output ports. The proposed three-line filter is validated by electromagnetic simulation. The developed switch filter module is fabricated using hybrid integrated technology, which has a size of 64 mm×44 mm×7.5 mm. The fabricated switch filter module exhibits good performances: for four different states, the measured insertion loss and return loss are all better than 8.5 dB and 10 dB in each pass-band, respectively.
A MILLIMETER-WAVE ULTRA-WIDEBAND FOUR-WAY SWITCH FILTER MODULE BASED ON NOVEL THREE-LINE MICROSTRIP STRUCTURE BAND-PASS FILTERS
2009-07-22
PIER
Vol. 94, 281-296, 2009
download: 173
Reduction of Peak SAR in Human Head for Handset Applications with Resistive Sheets (R-Cards)
H.-H. Chou , Heng-Tung Hsu , Hsi-Tseng Chou , Kun-Han Liu and Fang-Yao Kuo
In this paper, reduction of peak specific absorption rate (SAR) for handsets with monopole type antenna through R-cards is investigated. While the numerical analysis was performed using finite integration in time domain (FIT), real measurement has been made to validate the simulation results. Both the simulation and measurement results revealed that a minimum SAR Reduction Factor (SRF) of 60% was achieved. The good agreement between the simulation and measurement results has evidenced the effectiveness of the proposed approach for SAR reduction in human head for handset applications.
REDUCTION OF PEAK SAR IN HUMAN HEAD FOR HANDSET APPLICATIONS WITH RESISTIVE SHEETS (R-CARDS)
2009-07-21
PIER
Vol. 94, 263-280, 2009
download: 269
Simulated and Experimental Investigation of Microwave Imaging Using UWB
Antonio Lazaro , David Girbau and Ramon Villarino
Microwave breast tumour detection is a non-invasive technique that uses non ionizing radiation. Microwave imaging has the potential to achieve early detection of breast cancer due to the high specificity and the large difference in electrical properties of the malignant tissue when compared to normal breast tissue. This paper studies the feasibility of using UWB signals for breast imaging. Simulated results using Finite-Difference Time-Domain (FDTD) Method will be presented. A sensibility study of the variations in the breast relative dielectric permittivity and of the variations of the skin-surface contour is also provided. A working prototype for microwave imaging is developed using a conventional Vector Network Analyzer (VNA) with the time processing capability.
SIMULATED AND EXPERIMENTAL INVESTIGATION OF MICROWAVE IMAGING USING UWB
2009-07-18
PIER
Vol. 94, 243-262, 2009
download: 175
A Novel Source Localization Scheme Based on Unitary ESPRIT and City Electronic Maps in Urban Environments
Hong Bing Song , Hao-Gang Wang , Kan Hong and Li Wang
In this paper, a novel source localization scheme is proposed based on the unitary ESPRIT algorithm with back ray tracing technique and the city electronic maps. Our scheme can be summarized into two steps. First, the unitary ESPRIT algorithm is employed to estimate the angles and delays of the arrival rays radiated from the source. Second, based on the obtained information we devise a back ray tracing technique to recover the signal propagation paths according to the Geometrical Theory of Reflections and the city electronic map. After these two steps the source position can be obtained by averaging all the estimated positions. In order to minimize estimated errors caused by the Unitary ESPRIT, a valid-range selection criterion for the judgment of the validity of the estimated position data is proposed. On the other hand, we introduce a path length weighting factor to reduce the estimated errors caused by the terrain data inaccuracy. This position method can locate both the line of sight (LOS) and non-line of sight (NLOS) sources efficiently and it also can locate multi-sources simultaneously. Six simulations are carried out in three terrain scenarios. The numerical results demonstrate that our model can be applied to estimate the positions for both 2D and 3D cases. The accuracy of our model for a cell of 80 m × 45 m can reach 10 m when SNR is greater than 10 dB.
A NOVEL SOURCE LOCALIZATION SCHEME BASED ON UNITARY ESPRIT AND CITY ELECTRONIC MAPS IN URBAN ENVIRONMENTS
2009-07-17
PIER
Vol. 94, 213-242, 2009
download: 224
Microwave Tomography Employing an Adjoint Network Based Sensitivity Matrix
Dimitrios G. Drogoudis , George Kyriacou and John Sahalos
A reconstruction algorithm for two- and three- dimen-sional microwave imaging is proposed. The present effort is focused on the reconstruction of conductivity (σ) and permittivity (εr) distri-butions aiming at a technique serving medical imaging, while perme-ability imaging can be easily incorporated to serve geophysical geophysical prospecting as well. This work constitutes the most recent one within the effort of extending our Modified Perturbation Method (MPM) from static to high and now microwave frequencies. MPM is an approximate method based on an exact Sensitivity or Jacobian matrix for an iterative update of an initial (σ, εr) guess until convergence. This method is proved almost immune of the problem inherent ill-posedness, but its robustness is actually gained by paying a penalty of compromised accuracy in the final achieved image. However, this image can be fine tuned by formulating and solving an exact inverse problem. Regarding the involved Jacobian matrix, this is evaluated through closed form expressions obtained through an Adjoint Network Theorem in conjuction with the electromagnetics reciprocity theorem. The field distributions required for its evaluation are readily available from the always required forward problem solutions on the assumed (σ, εr) distributions. Herein, the finite element method along with absorbing boundary conditions are employed for the forward problem electromagnetic simulation.
MICROWAVE TOMOGRAPHY EMPLOYING AN ADJOINT NETWORK BASED SENSITIVITY MATRIX
2009-07-16
PIER
Vol. 94, 197-212, 2009
download: 198
Efficient Approach for Sensitivity Analysis of Lossy and Leaky Structures Using FDTD
Mohamed A. Swillam , Ramy H. Gohary , Mohamed H. Bakr and Xun Li
An efficient approach is utilized for extracting the modal parameters of high frequency structures and their sensitivities with respect to all the design parameters. Using one FDTD simulation, the modal parameters of all the guided and leaky modes are extracted over the frequency band of interest. An adapted version of the matrix pencil method is utilized for efficient extraction of the modal parameters. In addition, using no extra simulations, the sensitivities of the propagation constants with respect to all the design parameters of the structure are extracted regardless of their number. The computational time is a small fraction of the cost of similar approaches.
EFFICIENT APPROACH FOR SENSITIVITY ANALYSIS OF LOSSY AND LEAKY STRUCTURES USING FDTD
2009-07-15
PIER
Vol. 94, 175-195, 2009
download: 205
Layer-Mode Transparent Boundary Condition for the Hybrid FD-FD Method
Hung-Wen Chang , Wei-Chi Cheng and Shih-Min Lu
We combine the analytic eigen mode expansion method with the finite-difference, frequency-domain (FD-FD) method to study two-dimensional (2-D) optical waveguide devices for both TE and TM polarizations. For this we develop a layer-mode based transparent boundary condition (LM-TBC) to assist launching of an arbitrary incident wave field and to direct the reflected and the transmitted scattered wave fields back and forward to the analytical regions. LM-TBC is capable of transmitting all modes including guiding modes, cladding modes and even evanescent waves leaving the FD domain. Both TE and TM results are compared and verified with exact free space Green's function and a semi-analytical solution.
LAYER-MODE TRANSPARENT BOUNDARY CONDITION FOR THE HYBRID FD-FD METHOD
2009-07-15
PIER
Vol. 94, 153-173, 2009
download: 180
The Origin of Electromagnetic Resonances in Three-Dimensional Photonic Fractals
Ushio Sangawa
After a report on strange electromagnetic resonances emerging in an isotropic paraelectric Menger sponge (MS) now known as a photonic fractal, vigorous studies began to reveal their properties. However, the mechanics of how the resonances occur is still unknown. This report focuses on the findings that the resonances can be perturbation-theoretically identified as those originally occurring in an isolated dielectric cube, and that they arise within band gaps and uncouple with Bloch modes for a certain multiperiodic lattice. This interpretation is justified by the fact that the MS can be considered as a cube embedded in the lattice rather than the outcome of conventional recursive fractal structuring operations. An experimental formula for resonance conditions already reported can be derived from this interpretation.
THE ORIGIN OF ELECTROMAGNETIC RESONANCES IN THREE-DIMENSIONAL PHOTONIC FRACTALS
2009-07-15
PIER
Vol. 94, 133-152, 2009
download: 215
A Reverberation Chamber to Investigate the Possible Effects of "in Vivo" Exposure of Rats to 1.8 GHz Electromagnetic Fields: a Preliminary Study
Pier Francesco Biagi , L. Castellana , Tommaso Maggipinto , G. Maggipinto , Teresa Ligonzo , Luigi Schiavulli , Domenico Loiacono , Anita Ermini , Maria Lasalvia , Giuseppe Perna and Vito Capozzi
A system generating 1.8 GHz electromagnetic fields for bio-medical and behavioral study on laboratory animals was designed and implemented. The system is based on a reverberation chamber. An input power up to 5 W can be sent to an indoor transmitting antenna and an electric field strength (E) more than 90 V/m can be reached inside the chamber. The system was characterized at different input powers measuring E in different points by means of a miniature sensor. Then, boxes with 300 cc of physiological liquid inside were realized as simple phantoms simulating laboratory animals (rats) and E inside the liquid was measured, performing several simulations by moving the phantoms (1,2) in the chamber and/or putting them still in different positions. On the basis of these measurements, the SAR (Specific Absorption Rate) and the Pe (power efficiency = SAR/input power) were determined at different powers. The actual system is characterized by a low power efficiency with respect to the "in vivo" exposition systems based on transversal electromagnetic (TEM) cells. Its advantage is to have inside the chamber a habitat similar to the usual one for the laboratory animals.
A REVERBERATION CHAMBER TO INVESTIGATE THE POSSIBLE EFFECTS OF
2009-07-14
PIER
Vol. 94, 119-132, 2009
download: 237
Low RCS Dipole Array Synthesis Based on MoM -PSO Hybrid Algorithm
Wen-Tao Wang , Shu-Xi Gong , Yu-Jie Zhang , Feng-Tao Zha , Jin Ling and Tingting Wan
In this paper, a hybrid algorithm combined method of moments (MoM) with particle swarm optimization (PSO) is used to realize low radar cross section (RCS) array synthesis. Both the scattering factor and the radiation factor are involved in the proposed objective function to achieve the promising dipole array with a reduced RCS and satisfied radiation performance. To improve the optimization efficiency, radiation constraint conditions are adopted to avoid unnecessary scattering calculation. The symmetric matrix and block treatment are also used to fill the MoM impedance matrix. The optimization results show that the proposed algorithm is able to achieve RCS reduction of 5.5 dB for dipole array.
LOW RCS DIPOLE ARRAY SYNTHESIS BASED ON MOM-PSO HYBRID ALGORITHM
2009-07-13
PIER
Vol. 94, 105-117, 2009
download: 169
Investigations of the Electromagnetic Properties of Three-Dimensional Arbitrarily-Shaped Cloaks
Qiang Cheng , Wei Xiang Jiang and Tie-Jun Cui
We investigate the electromagnetic properties of three-dimensional (3D) arbitrarily-shaped invisible cloaks based on the analytical field transformation theory instead of the complicated numerical simulations. Very simple closed-form expressions for fields and energy flows have been derived for arbitrarily-shaped 3D cloak, which could help us to investigate the electromagnetic properties of the 3D cloaks rapidly and efficiently. The difference between 2D and 3D cloaks have been compared in detail. Distributions of the fields, power flows and wave polarizations for the 3D case have been discussed inside the cloak. Numerical results have been presented at the cutplanes of cloaks to valid the theoretical analysis, which shows clearly how the incident waves are bent at the inner boundary. In order to further reveal the physical essence of the cloaks, both 3D spherical and ellipsoidal cloaks have been considered based on the analytical method. The common features and the differences for the two structures have been also illustrated in this paper.
INVESTIGATIONS OF THE ELECTROMAGNETIC PROPERTIES OF THREE-DIMENSIONAL ARBITRARILY-SHAPED CLOAKS
2009-07-13
PIER
Vol. 94, 83-104, 2009
download: 230
A New Classifier for Polarimetric SAR Images
Yudong Zhang , Lenan Wu and Geng Wei
This paper proposes a hybrid classifier for polarimetric SAR images. The feature sets consist of span image, the H/A/α decomposition, and the gray-level co-occurrence matrix (GLCM) based texture features. Then, the features are reduced by principle component analysis (PCA). A 3-layer neural network (NN) is constructed, trained by resilient back-propagation (RPROP) method to fasten the training and early stop (ES) method to prevent the overfitting. The results of San Francisco and Flevoland site compared to Wishart Maximum Likelihood and wavelet-based method demonstrate the validness of our method in terms of confusion matrix and overall accuracy. In addition, NNs with and without PCA are compared. Results show the NN with PCA is more accurate and faster.
A NEW CLASSIFIER FOR POLARIMETRIC SAR IMAGES
2009-07-10
PIER
Vol. 94, 69-81, 2009
download: 253
Prediction of the Interference Level from a Low-Power Radio Device Provoking the Intermodulation Interference to the Amps Receiver
Che-Young Kim and Dang-Oh Kim
In this article, the harmful radiation level of electric field strength from the hostile low-power radio devices causing the intermodulation interference to the AMPS receiver has been predicted. The predicted level becomes the upper limit to avoid the intermodulation interference on the victim device. Our findings show that the quantified upper limit was 79.13[dBμV/m] to mitigate the adverse influence from these low-power radio devices. Our results are based on the calculation, simulation, and measurement for the commercial AMPS chip. Resulting values are in a good agreement within less than 3[dB].
PREDICTION OF THE INTERFERENCE LEVEL FROM A LOW-POWER RADIO DEVICE PROVOKING THE INTERMODULATION INTERFERENCE TO THE AMPS RECEIVER
2009-07-08
PIER
Vol. 94, 49-67, 2009
download: 188
Parametric Study of Power Absorption Patterns Induced in Adult and Child Head Models by Small Helical Antennas
Maria Christopoulou , Stavros Koulouridis and Konstantina Nikita
ƒA comparative assessment of power absorption in adult and child heads exposed to a small helical antenna at 1710 MHz, is presented, emphasizing the effect of age related parameters. Finite Difference Time Domain simulations are employed to study the interaction between MRI-based head models and a mobile communication terminal equipped with a small helical monopole. A semi-analytical method, based on Green's function theory and the Method of Moments, is used to study the absorption in three-layer spherical head models exposed to a small helical dipole. SAR patterns in child head models derived by non-uniform scaling of adult ones were assessed against SAR patterns computed in child heads derived by uniform downscaling procedures. In both realistic and canonical exposure scenarios, comparable levels of absorbed power (maximum difference: 12%) in adult and child head models were observed. Dependence of SAR values upon separation distance and tissue dielectric properties was quantitatively assessed. In realistic exposure scenarios, the reduction in peak SAR values was 60-80% for a 1 cm increase in distance and up to 16% for a 110% to 90% decrease in dielectric properties values with reference to the nominal value of 100%. These trends were respectively less (55-65%) and more (up to 24%) emphasized in the corresponding canonical exposure scenarios.
PARAMETRIC STUDY OF POWER ABSORPTION PATTERNS INDUCED IN ADULT AND CHILD HEAD MODELS BY SMALL HELICAL ANTENNAS
2009-07-07
PIER
Vol. 94, 33-47, 2009
download: 263
Negative Group Velocity in a Split Ring Resonator-Coupled Microstrip Line
Giuseppina Monti and Luciano Tarricone
The dispersive behaviour of an artificial Transmission Line is investigated demonstrating the existence of a negative group velocity region. More specifically, the propagation of amplitude modulated signals in a microstrip line coupled with Split Ring Resonators is analyzed, investigating the influence of the propagating pulse shape on the possibility to observe a negative group delay.
NEGATIVE GROUP VELOCITY IN A SPLIT RING RESONATOR-COUPLED MICROSTRIP LINE
2009-07-06
PIER
Vol. 94, 19-32, 2009
download: 215
A Trust Region Subproblem for 3D Electrical Impedance Tomography Inverse Problem Using Experimental Data
Mehran Goharian , Manuchehr Soleimani and Gerald R. Moran
Image reconstruction in electrical impedance tomography (EIT) is an ill-posed nonlinear inverse problem. Regularization methods are needed to solve this problem. The results of the ill-posed EIT problem strongly depends on noise level in measured data as well as regularization parameter. In this paper we present trust region subproblem (TRS), with the use of Lcurve maximum curvature criteria to find a regularization parameter. Currently Krylov subspace methods especially conjugate gradient least squares (CGLS) are used for large scale 3D problem. CGLS is an efficient technique when the norm of measured noise is exactly known. This paper demonstrates that CGLS and TRS converge to the same point on the L-curve with the same noise level. TRS can be implemented efficiently for large scale inverse EIT problem as CGLS with no need a priori knowledge of the noise level.
A TRUST REGION SUBPROBLEM FOR 3D ELECTRICAL IMPEDANCE TOMOGRAPHY  INVERSE PROBLEM USING EXPERIMENTAL DATA
2009-07-06
PIER
Vol. 94, 1-18, 2009
download: 307
Design of a Reconfigurable Antenna for Ground Penetrating Radar Applications
Nicola Romano , Giancarlo Prisco and Francesco Soldovieri
This paper deals with the design and numerical analysis of a reconfigurable antenna implemented according to the total geometry morphing approach. The reconfigurable antenna is designed so to resemble a reference bowtie antenna, suitable for a stepped frequency Ground Penetrating Radar (GPR) applications, with geometry variable in order to work in different operative conditions. In particular, the good agreement between the reference antenna and the reconfigurable one is tested within the work frequency band 0.3-1 GHz for both the free-space and half-space geometry. Finally, a trial of the reconfigurability of the proposed solution is shown for operative conditions with antenna in contact with different dielectric media.
DESIGN OF A RECONFIGURABLE ANTENNA FOR GROUND PENETRATING RADAR APPLICATIONS