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2010-01-17
PIER
Vol. 100, 397-415, 2010
download: 195
Homogeneous and Heterogeneous Breast Phantoms for Ultra-Wideband Microwave Imaging Applications
Joshua Chong Yue Lai Cheong Boon Soh Erry Gunawan Kay Soon Low
The paper discusses fabrication of homogenous and heterogeneous breast phantoms to simulate the dielectric properties of human breast over the microwave frequency range from 0.5 GHz to 13.5 GHz. The breast phantoms have stable mechanical configuration and dielectric properties suitable for microwave imaging experiments particularly ultra-wideband microwave imaging for breast cancer detection.
HOMOGENEOUS AND HETEROGENEOUS BREAST PHANTOMS FOR ULTRA-WIDEBAND MICROWAVE IMAGING APPLICATIONS
2010-01-15
PIER
Vol. 100, 381-396, 2010
download: 100
The Anisotropic Cell Model in the Colloidal Plasmas
Qizheng Ye Fei Lu
The anisotropic spherical Wigner-Seitz (WS) cell model --- introduced to describe colloidal plasmas --- is investigated using the linearized Poisson-Boltzmann (PB) equation. As an approximation, the surface potential of the spherical macroparicle expanded in terms of the monopole (q) and the dipole (p) is considered as an anisotropic boundary condition of the linear PB equation. Here, the "apparent" moments q and p are the moments 'seen' in the microion cloud, respectively. Based on a new physical concept, the momentneutrality, the potential around the macroparticle can be solvable analytically if the relationship between the actual moment and the "apparent" moment can be obtained according to the momentneutrality condition in addition to the usual electroneutrality. The calculated results of the potential show that there is an attractive region in the vicinity of macroparticle when the corresponding dipole part of the potential dominates over the monopole part, and there is an attractive region and a repulsive region at the same time, i.e., a potential well, when the corresponding dipole part of the potential just comes into play. It provides the possibility and the conditions of the appearance of periodic structure of the colloidal plasmas, although it is a result of a simple theoretical model.
THE ANISOTROPIC CELL MODEL IN THE COLLOIDAL PLASMAS
2010-01-12
PIER
Vol. 100, 351-379, 2010
download: 158
Exposure to 2.45 GHz Microwave Radiation Provokes Cerebral Changes in Induction of Hsp-90 α/β Heat Shock Protein in Rat.
T. Jorge-Mora Marcos Alvarez Folgueiras Jose Manuel Leiro-Vidal F. J. Jorge-Barreiro Francisco Ares-Pena Maria Elena Lopez-Martin
Physical agents such as non-ionizing continuous-wave 2.45 GHz radiation may cause damage that alters cellular homeostasis and may trigger activation of the genes that encode heat shock proteins (HSP). We used Enzyme-Linked ImmunoSorbent Assay (ELI-SA) and immunohistochemistry to analyze the changes in levels of HSP-90 and its distribution in the brain of Sprague-Dawley rats, ninety minutes and twenty-four hours after acute (30 min) continuous exposure to 2.45 GHz radiation in a the Gigahertz Transverse Electromagnetic (GTEM cell). In addition, we studied further indicators of neuronal insult: dark neurons, chromatin condensation and nucleus fragmentation, which were observed under optical conventional or fluorescence microscopy after DAPI staining. The cellular distribution of protein HSP-90 in the brain increased with each corresponding (0.034 ± 3.10-3, 0.069 ± 5.10-3, 0.27 ± 21.10-3 W/kg), in hypothalamic nuclei, limbic cortex and somatosensorial cortex after exposure to the radiation. At twenty-four hours post-irradiation, levels of HSP-90 protein remained high in all hypothalamic nuclei for all SARs, and in the parietal cortex, except the limbic system, HSP-90 levels were lower than in non-irradiated rats, almost half the levels in rats exposed to the highest power radiation. Non-apoptotic cellular nuclei and a some dark neurons were found ninety minutes and twenty-four hours after maximal SAR exposure. The results suggest that acute exposure to electromagnetic fields triggered an imbalance in anatomical HSP-90 levels but the anti-apoptotic mechanism is probably sufficient to compensate the non-ionizing stimulus. Further studies are required to determine the regional effects of chronic electromagnetic pollution on heat shock proteins and their involvement in neurological processes and neuronal damage.
EXPOSURE TO 2.45 GHz MICROWAVE RADIATION PROVOKES CEREBRAL CHANGES IN INDUCTION OF HSP-90 α/β HEAT SHOCK PROTEIN IN RAT.
2010-01-11
PIER
Vol. 100, 327-349, 2010
download: 113
Investigation into Time- and Frequency-Domain EMI-Induced Noise in Bistable Multivibrator
Han-Chang Tsai
Electromagnetic interference (EMI) has a negative effect upon the performance of circuit communication systems. The present study considers the case of EMI induced in a conducting wire, and derives equations to establish the effect of the EMI on a bistable multivibrator. The validity of the equations is verified experimentally. The results indicate that the degree of influence of the EMI on the bistable oscillator depends on the interference power, the interference frequency, the induced power, the output resistance of the circuit, and the parasitic capacitance. Moreover, it is shown that the harmonic noise increases with an increasing interference amplitude and frequency. The theoretical results are found to be in good agreement with the experimental data.
INVESTIGATION INTO TIME- AND FREQUENCY-DOMAIN EMI-INDUCED NOISE IN BISTABLE MULTIVIBRATOR
2010-01-11
PIER
Vol. 100, 309-325, 2010
download: 96
Sensitivity Analysis of 3-D Composite Structures through Linear Embedding via Green's Operators
Vito Lancellotti Bastiaan P. de Hon Antonius G. Tijhuis
We propose a methodology --- based on linear embedding via Green's operators (LEGO) and the eigencurrent expansion method (EEM) --- for solving electromagnetic problems involving large 3-D structures comprised of ND ≥ 1 bodies. In particular, we address the circumstance when the electromagnetic properties or the shape of one body differ from those of the others. In real-life structures such a situation may be either the result of a thoughtful design process or the unwanted outcome of fabrication tolerances. In order to assess the sensitivity of physical observables to localized deviations from the "ideal" structure, we follow a deterministic approach, i.e., we allow for a finite number of different realizations of one of the bodies. Then, for each realization we formulate the problem with LEGO and we employ the EEM to determine the contribution of the ND - 1 "fixed" bodies. Since the latter has to be computed only once, the overall procedure is indeed efficient. As an example of application, we investigate the sensitivity of a 2-layer array of split-ring resonators with respect to the shape and the offset of one element in the array.
SENSITIVITY ANALYSIS OF 3-D COMPOSITE STRUCTURES THROUGH LINEAR EMBEDDING VIA GREEN'S OPERATORS
2010-01-11
PIER
Vol. 100, 299-308, 2010
download: 155
A High Band Isolation and Wide Stopband Diplexer Using Dual-Mode Stepped-Impedance Resonators
Chun-Yueh Huang Min-Hang Weng Chang-Sin Ye Yong-Xiang Xu
In this paper, a high performance diplexer is designed and fabricated for Global Positioning System (GPS) and wireless local area network (WLAN) applications simultaneously. The diplexer mainly comprises two dual-mode ring bandpass filters (BPFs), operated at 1.575 GHz and 2.4 GHz, respectively. By using the stepped-impedance resonator (SIR) in the BPFs, the size reduction and wide stopband from 2.8 GHz to 6 GHz are obtained. Moreover, several transmission zeros are located at the passband edges, thus improving the passband selectivity. Due to impedance matching between two BPFs, a high isolation greater than 40 dB between two channels is obtained. The diplexer is investigated numerically and experimentally. The simulated and measured results have a good agreement with the proposed design concept.
A HIGH BAND ISOLATION AND WIDE STOPBAND DIPLEXER USING DUAL-MODE STEPPED-IMPEDANCE RESONATORS
2010-01-11
PIER
Vol. 100, 285-298, 2010
download: 113
Cloaking a Perfectly Conducting Sphere with Rotationally Uniaxial Nihility Media in Monostatic Radar System
Xiangxiang Cheng Hongsheng Chen Xian-Min Zhang Baile Zhang Bae-Ian Wu
In this paper, the backscattering properties of a perfect electric conducting sphere coated with layered anisotropic media whose constitutive parameters are close to nihility are investigated. We show that the backscattering is more sensitive to the radial constitutive parameters than to the tangential ones. Compared with isotropic case, the anisotropic media with small axial parameters have the potential to yield more reduction of backscattering magnitude on coated perfectly conducting spheres.
CLOAKING A PERFECTLY CONDUCTING SPHERE WITH ROTATIONALLY UNIAXIAL NIHILITY MEDIA IN MONOSTATIC RADAR SYSTEM
2010-01-06
PIER
Vol. 100, 265-284, 2010
download: 562
Analysis of Vital Signs Monitoring Using an IR-UWB Radar
Antonio Lazaro David Girbau Ramon Villarino
Ultra-Wide Band (UWB) technology is a new, useful and safe technology in the field of wireless body networks. This paper focuses on the feasibility of estimating vital signs --- specifically breathing rate and heartbeat frequency --- from the spectrum of recorded waveforms, using an impulse-radio (IR) UWB radar. To this end, an analytical model is developed to perform and interpret the spectral analysis. Both the harmonics and the intermodulation between respiration and heart signals are addressed. Simulations have been performed to demonstrate how they affect the detection of vital signs and also to analyze the influence of the pulse waveform. A filter to cancel out breathing harmonics is also proposed to improve heart rate detection. The results of the experiments are presented under different scenarios which demonstrate the accuracy of the proposed technique for determining respiration and heartbeat rates. It has been shown that an IR-UWB radar can meet the requirements of typical biomedical applications such as non-invasive heart and respiration rate monitoring.
ANALYSIS OF VITAL SIGNS MONITORING USING AN IR-UWB RADAR
2010-01-05
PIER
Vol. 100, 245-263, 2010
download: 116
Application of the Improved Matrix Type FDTD Method for Active Antenna Analysis
Shao-Qiu Xiao Zhenghai Shao Bing-Zhong Wang
An improved finite-difference time-domain (FDTD) method has been extended to analyze the antennas with complicated lumped/active networks in this paper. The improved FDTD method is based on a novel integral transform and the matrix theory. Combing the novel integral transform with Kirchhoff's circuit laws, the hybrid networks comprised of high order linear and nonlinear elements with arbitrary connection can be modeled by a stable matrix equation. An effective model is built for the linear lumped networks including the internal independent sources. A wire antenna loaded with wideband match network and a two-element active patch antenna loaded with Gunn diodes are analyzed by the developed techniques. The analysis results indicate that the improved matrix-type FDTD method is not only stable and accurate, but also time-saving in simulating the complicated hybrid networks.
APPLICATION OF THE IMPROVED MATRIX TYPE FDTD METHOD FOR ACTIVE ANTENNA ANALYSIS
2010-01-04
PIER
Vol. 100, 235-243, 2010
download: 168
Novel Miniaturized Bandpass Filters Using Spiral-Shaped Resonators and Window Feed Structures
Gao-Le Dai Mingyao Xia
In this paper, we present a new class of miniaturized microstrip bandpass filters with low-insertion loss, sharp-rejection and narrow-band performance. The proposed filters are composed of two spiral-shaped resonators and rectangle window feed structures. Both back-to-back and interdigital combinations of the resonators are adopted to obtain the miniaturized filter size. Compared to the traditional square loop bandpass filter, the sizes are reduced by 82% and 80%. It is also found that there is a pair of transmission zeros located on each side of the passbands, resulting in high selectivity. To validate the proposed idea, two demonstration filters with back-to-back and interdigital spiral-shaped resonators are implemented. The measured results exhibit good agreement with the full-wave simulation results.
NOVEL MINIATURIZED BANDPASS FILTERS USING SPIRAL-SHAPED RESONATORS AND WINDOW FEED STRUCTURES
2010-01-04
PIER
Vol. 100, 219-234, 2010
download: 152
Three-Dimensional Nonlinear Inversion of Electrical Capacitance Tomography Data Using a Complete Sensor Model
Robert Banasiak Radoslaw Wajman Dominik Sankowski Manuchehr Soleimani
Electrical Capacitance Tomography (ECT) is a non-invasive and non-destructive imaging technique that uses electrical capacitance measurements at the periphery of an object to generate map of dielectric permittivity of the object. This visualization method is a relatively mature industrial process tomography technique, especially in 2D imaging mode. Volumetric ECT is a new method that poses major computational challenges in image reconstruction and new challenges in sensor design. This paper shows a nonlinear image reconstruction method for 3D ECT based on a validated forward model. The method is based on the finite element approximation for the complete sensor model and the solution of the inverse problem with nonlinear iterative reconstruction. The nonlinear algorithm has been tested against some complicated experimental test cases, and it has been demonstrated that by using an improved forward model and nonlinear inversion method, very complex shaped samples can be reconstructed. The reconstruction of very complex geometry with objects in the shape of letters H, A, L and T is extremely promising for the applications of 3D ECT.
THREE-DIMENSIONAL NONLINEAR INVERSION OF ELECTRICAL CAPACITANCE TOMOGRAPHY DATA USING A COMPLETE SENSOR MODEL
2010-01-04
PIER
Vol. 100, 201-218, 2010
download: 507
Log Periodic Fractal Koch Antenna for UHF Band Applications
Mohd Nazri A Karim Mohamad Kamal Abd Rahim Huda Abdul Majid Osman Ayop Maisarah Abu Farid Zubir
In this paper, the design of Log Periodic Fractal Koch Antennas (LPFKA) is proposed for Ultra High Frequency (UHF) band applications. The procedure to design the LPFKA with three different numbers of iterations in order to reduce the antenna size is discussed. The Computer Simulation Technology (CST) software has been used to analyze the performances of the designed antennas such as return loss, radiation patterns, current distribution and gain. The antennas have been fabricated using FR4 laminate board with wet etching technique. Using fractal Koch technique, the size of the antenna can be reduced up to 27% when the series iteration is applied to the antennas without degrading the overall performances. Both simulated and measured results are compared, analyzed and presented in this paper.
LOG PERIODIC FRACTAL KOCH ANTENNA FOR UHF BAND APPLICATIONS
2009-12-17
PIER
Vol. 100, 189-200, 2010
download: 153
A Dual-Polarized Wide-Band Patch Antenna for Indoor Mobile Communication Applications
Mustafa Secmen Altunkan Hizal
This paper proposes the configuration of a novel dual-polarized wide-band patch antenna system suitable for indoor mobile communication applications. This configuration consists of two compact patch antennas, which have different feed structures from classical patch antenna configuration. These antennas, which are separated by a thin absorber to have a good isolation, are fed independently to obtain dual polarization. The antenna structure is designed, simulated, manufactured and measured. The operation bandwidth spans 1900-2700 MHz covering Bluetooth, Wireless Local Area Networks (WLAN) and Universal Mobile Telecommunications System (UMTS) bands. The simulations show good agreement with the measurement results that the antennas have return losses higher 15 dB, and the coupling between two antennas is below -20 dB within the operation band.
A DUAL-POLARIZED WIDE-BAND PATCH ANTENNA FOR INDOOR MOBILE COMMUNICATION APPLICATIONS
2009-12-16
PIER
Vol. 100, 175-187, 2010
download: 387
Modified Two-Element Yagi-Uda Antenna with Tunable Beams
Bao-Hua Sun Shi-Gang Zhou Yun-Fei Wei Qi-Zhong Liu
A modified two-element Yagi-Uda antenna with tunable beams in the H-plane (including four significant beams: forward, backward, omni-directional, and bi-directional beams) is presented. These tunable beams are achieved by simply adjusting the short-circuit position of the transmission line connected to the parasitic element. The principle of operation is investigated by examining the current relations between the driven and parasitic elements. Measured results of a fabricated prototype are presented and discussed.
MODIFIED TWO-ELEMENT YAGI-UDA ANTENNA WITH TUNABLE BEAMS
2009-12-16
PIER
Vol. 100, 153-173, 2010
download: 484
Design of the Compact Parallel-Coupled Lines Wideband Bandpass Filters Using Image Parameter Method
Chang-Sin Ye Yan-Kuin Su Min-Hang Weng Cheng-Yuan Hung Ru-Yuan Yang
In this paper, the design of compact and high performance parallel coupled line wideband bandpass filter using image parameter method are proposed. The filter mainly comprising one-stage parallel coupled line and two open stubs are designed and implemented on commercial RT/Duroid 5880 substrate. The equivalent circuit of the proposed structure is initially derived by using the image parameter method. It is found that, the normalized bandwidth (NBW) of image impedance for the one-stage parallel coupled line has a relation to the electromagnetic (EM) simulated bandwidth. To further improve the selectivity, two open stubs are connected near the input/output (I/O) ports. The design procedures and their limitations are discussed in detail. The proposed filters are fabricated, measured and showing good characteristics of 87% fractional bandwidth as well as good insertion/return loss, flat group delay varies between 0.3-1.5 ns. High passband selectivity and wide stopband from 8-14 GHz are obseved. The measured results are also having a good agreement with the simulated results.
DESIGN OF THE COMPACT PARALLEL-COUPLED LINES WIDEBAND BANDPASS FILTERS USING IMAGE PARAMETER METHOD
2009-12-16
PIER
Vol. 100, 129-152, 2010
download: 118
Critical Analysis of Microwave Specular Scattering Response on Roughness Parameter and Moisture Content for Bare Periodic Rough Surfaces and Its Retrieval
Gunjan Mittal Dharmendra Singh
The main aim of this paper is to accentuate the sensitivity of correlation length 'l' as an important roughness parameter in quantifying the moisture content of bare soil surfaces with specular scattering. For this purpose, an indigenously designed bistatic scatterometer has been used to generate co-polarized specular data at X-band (10 GHz) with incidence angle varied from 30°-- 70°in steps of 10 degrees. The moisture and roughness conditions of the bare soil surface were changed under controlled conditions. Twenty seven experimental fields specified on the ground of different roughness and moisture conditions have been analyzed. Higher level of moisture content with larger correlation lengths was found to be more suitable for observing the effect of increasing rms height on specular scattering. Kirchhoff approach (KA) considered under the stationary phase approximation (SPA) has been used as an inversion algorithm with the application of genetic algorithm for the retrieval of soil parameters. A good agreement was observed between the experimental and retrieved values of soil moisture content (mν) and roughness parameters (s and l).
CRITICAL ANALYSIS OF MICROWAVE SPECULAR SCATTERING RESPONSE ON ROUGHNESS PARAMETER AND MOISTURE CONTENT FOR BARE PERIODIC ROUGH SURFACES AND ITS RETRIEVAL
2009-12-16
PIER
Vol. 100, 119-128, 2010
download: 102
Subspace-Based Optimization Method for Reconstructing Perfectly Electric Conductors
Xiuzhu Ye Xudong Chen Yu Zhong Krishna Agarwal
Reconstruction of perfectly electric conductors (PEC) with transverse magnetic (TM) illumination by a subspace-based optimization method (SOM) is presented. Apart from the information that the unknown object is PEC, no other prior information such as the number of the objects, the approximate locations or the centers is needed. The whole domain is discretized into segments of current lines. Scatterers of arbitrary number and arbitrary shapes are represented by a binary vector, and the descent method is used to solve the discrete optimization problem. Several numerical simulations are chosen to validate the proposed method. In particular, a combination of a line type object and a rectangular shape object is successfully reconstructed. The subspace-based optimization method for PEC scatterers is found to be more complex than its counterpart for dielectric scatterers.
SUBSPACE-BASED OPTIMIZATION METHOD FOR RECONSTRUCTING PERFECTLY ELECTRIC CONDUCTORS
2009-12-15
PIER
Vol. 100, 105-117, 2010
download: 361
Design Optimization of a Bow-Tie Antenna for 2.45 GHz RFID Readers Using a Hybrid Bso-nm Algorithm
Korany Mahmoud
Recently the Bacterial foraging optimization algorithm (BFA) has attracted a lot of attention as a high-performance optimizer. This paper presents a hybrid approach involving Bacterial Swarm Optimization (BSO) and Nelder-Mead (NM) algorithm. The proposed algorithm is used to design a bow-tie antenna for 2.45 GHz Radio Frequency Identification (RFID) readers. The antenna is analyzed completely using Method of Moments (MoM), then the MoM code is coupled with the BSO-NM algorithm to optimize the antenna. The simulated antenna and the optimization algorithm programs were implemented using MATLAB version 7.4. To verify the validity of numerical simulations, the results are compared with those obtained using Feko Software Suite 5.3.
DESIGN OPTIMIZATION OF A BOW-TIE ANTENNA FOR 2.45 GHz RFID READERS USING A HYBRID BSO-NM ALGORITHM
2009-12-15
PIER
Vol. 100, 83-103, 2010
download: 394
Optimum Design of Lumped Filters Incorporating Impedance Matching by the Method of Least Squares
Homayoon Oraizi Mehdi Seyyedesfahlan
The method of least squares (MLS) is used to develop an algorithm for the optimum design of any type of filter under any design specifications for the realization of lowpass, bandpass, highpass and bandstop characteristics. The proposed filter design method can be used for any general filter network topology, which provides high flexibility for the selection of circuit configurations suitable for any desired application. The MLS filter design procedure also incorporates source and load impedance matching, which eventually leads to the simplicity of circuits. The proposed method of filter design may be used for lowpass prototype filters or directly for bandpass, highpass or bandpass filters. Several examples of MLS filter designs are given, which compare very well with the classical methods and indicate the advantages of the proposed method of filter design. The MLS filter design may realize any frequency response characteristics, such as spurious response elimination, multiband filter realization and enhancement of some desired behaviors.
OPTIMUM DESIGN OF LUMPED FILTERS INCORPORATING IMPEDANCE MATCHING BY THE METHOD OF LEAST SQUARES
2009-12-14
PIER
Vol. 100, 69-82, 2010
download: 96
A Wideband Wide-Strip Dipole Antenna for Circularly Polarized Wave Operations
Li-Pin Chi Sheau-Shong Bor Sheng-Ming Deng Ching-Long Tsai Peng-Hao Juan Kuo-Wei Liu
A thin dipole antenna is a well-known antenna with linearly polarized wave operation. In this work, a wide-strip dipole antenna is proposed for circularly polarized wave operations. To obtain circularly polarized (CP) wave operations, there are two conditions to be satisfied. One is that the antenna must have two degenerated orthogonal modes with different resonant frequencies. The other is that the phase difference of two orthogonal modes is 90 degrees. To match the first condition, the slab width W is tuned to generate current distributions directed in two different directions. In addition, the second condition is matched by asymmetric feeding point by adjusting the overlapped square width C. The parametric study is completed by the Ansoft HFSS simulator. Simulated results reveal that the CP wave is mainly influenced by the slab width W. The influences of the parameters C and d on the performances of the proposed antenna are also investigated in this paper. Taking -8 dB as reference, there are two working bands for this proposed antenna and the measured center frequencies are 0.66 GHz and 2.04 GHz, respectively, and the corresponding bandwidths are 0.27 GHz (40%) and 1.78 GHz (87%), respectively. In addition, the measured center frequencies and bandwidths of the axial ratio are 1.94 GHz and 0.53 GHz (27%), respectively.
A WIDEBAND WIDE-STRIP DIPOLE ANTENNA FOR CIRCULARLY POLARIZED WAVE OPERATIONS