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2009-07-06
PIER
Vol. 93, 385-401, 2009
download: 442
A New Look at Numerical Analysis of Uniform Fiber Bragg Gratings Using Coupled Mode Theory
Jiun-Jie Liau Nai-Hsiang Sun Shih-Chiang Lin Ru-Yen Ro Jung-Sheng Chiang Chung-Long Pan Hung-Wen Chang
The coupled mode theory (CMT) is used to analyze uniform Fiber Bragg gratings. The multi-mode CMT is expressed as the first-order vector ordinary differential equations (ODEs) with coefficients depending on the propagation distance. We show in this paper that by changing variables, the original couple mode equations (CMEs) can be re-casted as constant coefficient ODEs. The eigenvalue and eigenvector technique (EVVT), the analytic method for solving constant coefficient ODEs, is then applied to solve the coupled mode equations. Furthermore, we also investigate the application of Runge-Kutta method (RKM) to the calculation of the global transfer-function matrix for CMEs. We compare the transmission and the reflection spectra obtained by EVVT with those by RKM. Both results agree within machine accuracy. Numerical simulations conclude that solving constant coefficient ODEs improves the speed and accuracy of solutions to the original CMEs.
A NEW LOOK AT NUMERICAL ANALYSIS OF UNIFORM FIBER BRAGG GRATINGS USING COUPLED MODE THEORY
2009-07-01
PIER
Vol. 93, 369-384, 2009
download: 121
An Efficient Twofold Iterative Algorithm of FE-BI-MLFMA Using Multilevel Inverse-Based Ilu Preconditioning
Zhen Peng Xin-Qing Sheng Fei Yin
It is known that the conventional algorithm (CA) of hybrid finite element-boundary integral-multilevel fast multipole algorithm (FE-BI-MLFMA) usually suffers the problem of slow convergence, and the decomposition algorithm (DA) is limited by large memory requirement. An efficient twofold iterative algorithm (TIA) of FE-BI-MLFMA is presented using the multilevel inverse-based incomplete LU (MIB-ILU) preconditioning in this paper. It is shown that this TIA can offer a good balance of efficiency between CPU time and memory requirement. The tree-cotree splitting technique is then employed in the TIA to further improve its efficiency and robustness. A variety of numerical experiments are performed in this paper, demonstrating that the TIA exhibits superior efficiency in memory and CPU time to DA and CA, and greatly improves the computing capability of FE-BI-MLFMA.
AN EFFICIENT TWOFOLD ITERATIVE ALGORITHM OF FE-BI-MLFMA USING MULTILEVEL INVERSE-BASED ILU PRECONDITIONING
2009-06-29
PIER
Vol. 93, 355-367, 2009
download: 222
A Reconfigurable U-Koch Microstrip Antenna for Wireless Applications
Ali H. Ramadan Karim Youssef Kabalan Ali El-Hajj Shahwan Khoury Mohammed Al-Husseini
In this paper, a low-cost multiband printed-circuit-board (PCB) antenna that employs Koch fractal geometry and tunability is demonstrated. The antenna is fabricated on a 1.6 mm-thick FR4-epoxy substrate with dimensions 4 cm × 4.5 cm, is microstrip-line fed and has a partial ground plane flushed with the feed line. The proposed antenna is simulated using the Finite-Element Method for three different switching cases and the return loss is measured for each case. It is shown that the antenna can cover the bands of several applications including 3G, WiFi, WiMAX as well as a portion of the UWB range. The radiation patterns are satisfactorily omnidirectional across the antenna's operation bands.
A RECONFIGURABLE U-KOCH MICROSTRIP ANTENNA FOR WIRELESS APPLICATIONS
2009-06-24
PIER
Vol. 93, 339-354, 2009
download: 151
Numerical Solution of Scattering from Thin Dielectric-Coated Conductors Based on Tds Approximation and EM Boundary Conditions
Shiquan He Zai-Ping Nie Jun Hu
Thin dielectric sheet (TDS) approximation and electromagnetic (EM) boundary conditions are considered together to derive out a set of integral equations as an alternative to the impedance boundary condition (IBC) method to solve the electromagnetic scattering from thin dielectric-coated conductors. Only with discretizing the induce current on the conductor surfaces and solving an integral equation similar to that for a PEC, the scattering fields from the whole coating system (electric or magnetic material coating) are computed. Both the electric field integral equation (EFIE), magnetic field integral equation (MFIE) and their combination form are presented. These equations are converted to a matrix equation by Galerkin's method and then solved with multilevel fast multipole algorithm (MLFMA) to obtain the far fields scattering from these coated objects.
NUMERICAL SOLUTION OF SCATTERING FROM THIN DIELECTRIC-COATED CONDUCTORS BASED ON TDS APPROXIMATION AND EM BOUNDARY CONDITIONS
2009-06-22
PIER
Vol. 93, 323-337, 2009
download: 147
Linearization Error in Electrical Impedance Tomography
Nick Polydorides
In electromagnetic tomography and resistivity survey a linearized model approximation is often used, in the context of regularized regression, to image the conductivity distribution in a domain of interest. Due to the error introduced by the simplified model, quantitative image reconstruction becomes challenging unless the conductivity is sufficiently close to a constant. We derive a closed form expression of the linearization error in electrical impedance tomography based on the complete electrode model. The error term is expressed in an integral form involving the gradient of the perturbed electric potential and renders itself readily available for analytical or numerical computation. For real isotropic conductivity changes with piecewise uniform characteristic functions the perturbed potential field can be shown to satisfy Poisson's equation with Robin boundary conditions and interior point sources positioned at the interfaces of the inhomogeneities. Simulation experiments using a finite element method have been performed to validate these results.
LINEARIZATION ERROR IN ELECTRICAL IMPEDANCE TOMOGRAPHY
2009-06-22
PIER
Vol. 93, 307-322, 2009
download: 435
A Heterodyne Six-Port FMCW Radar Sensor Architecture Based on Beat Signal Phase Slope Techniques
Bouraima Boukari Emilia Moldovan Sofiene Affes Ke Wu Renato G. Bosisio Serioja Ovidiu Tatu
A Heterodyne six-port FMCW collision avoidance radar sensor configuration based on beat signal phase slope techniques is presented in this paper. Digital IF circuitry has been used in order to avoid problems related to DC offset and amplitude and phase imbalance. Simulations show that the velocity and range to the target is obtained simultaneously, with very good accuracy. Results are compared to other techniques and system architectures.
A HETERODYNE SIX-PORT FMCW RADAR SENSOR ARCHITECTURE BASED ON BEAT SIGNAL PHASE SLOPE TECHNIQUES
2009-06-22
PIER
Vol. 93, 291-306, 2009
download: 325
Vector Hopkins Model Research Based on off -Axis Illumination in Nanoscale Lithography
Pengfei Cao Lin Cheng Xiaoping Zhang
Based on vector electromagnetic theory and the Waveguide Model, the vector Hopkins model is deduced. The model contains the vector Hopkins formula and the resist profile model of fast Optical Proximity Correction. The vector Hopkins formula considers incidence angles and azimuth angles of off-axis illumination, which differs from the traditional scalar Hopkins formula. The resist profile model is employed to analyze the effect of the photoresist diffusion under off-axis illumination by using self-adaptive Gaussian filter with scale adjustable, and a new transmission cross coefficient is obtained. The projection system parameters are introduced simultaneously, such as incidence angles, azimuth angles of off-axis illumination and diffusion parameters of photoresist. By simulating the aerial image of 3D mask in the actual lithography process, the optimal angular range of oblique incidence is studied; the image quality by impact with the oblique incidence angle is discussed as well.
VECTOR HOPKINS MODEL RESEARCH BASED ON OFF-AXIS ILLUMINATION IN NANOSCALE LITHOGRAPHY
2009-06-19
PIER
Vol. 93, 275-289, 2009
download: 162
A Metamaterial-Based E-Plane Horn Antenna
Ruey-Bing Hwang Hung-Wang Liu Cheng-Yuan Chin
In this paper, we reported an E-plane horn antenna incorporating a metamaterial. Such a metamaterial is made up of metallic cylinders organized in a two-dimensional square lattice. After properly designing the lattice constant and unit cell pattern, we synthesized a medium with the effective refractive index smaller than unity. Therefore, once the waves were excited within the metamaterial, the refractive waves tend to be perpendicular to the interface between the metamaterial and uniform medium. Based on this concept, a 4-way beam splitter was designed to equally distribute the input power into 4 different directions. We then guide each of the power into individual E-plane flared opening to radiate a directional beam pattern in each sector. We have fabricated this antenna and measured its radiation characteristics including the return loss and far-field pattern. The excellent agreement between the measured and simulated results was obtained. Due to the properties of robust, low-loss, and low-cost, this antenna may have promising application in a point-to-multiple-point downlink system.
A METAMATERIAL-BASED E-PLANE HORN ANTENNA
2009-06-18
PIER
Vol. 93, 255-274, 2009
download: 303
Retrieving the Green's Function from Cross Correlation in a Bianisotropic Medium
Evert C. Slob Kees Wapenaar
Development of theory and experiments to retrieve Green's functions from cross correlations of recorded wave fields between two receivers has grown rapidly in the last seven years. The theory includes situations with flow, mechanical and electromagnetic disturbances and their mutual coupling. Here an electromagnetic theory is presented for Green's function retrieval from cross correlations that incorporates general bianisotropic media, which is the most general class of linear media. In the presence of dispersive non-reciprocal media, the Green's function is obtained by cross correlating the recordings at two locations of fields generated by sources on a boundary. The only condition for this relation to be valid is that the medium is non-dissipative. The principle of bianisotropic Green's function retrieval by cross correlation is illustrated with a numerical example.
RETRIEVING THE GREEN'S FUNCTION FROM CROSS CORRELATION IN A BIANISOTROPIC MEDIUM
2009-06-15
PIER
Vol. 93, 237-254, 2009
download: 83
Grey Prediction Based Particle Filter for Maneuvering Target Tracking
Jun-Feng Chen Zhi-Guo Shi Shao-Hua Hong Kang Chen
For maneuvering target tracking, we propose a novel grey prediction based particle filter (GP-PF), which incorporates the grey prediction algorithm into the standard particle filter (SPF). The basic idea of the GP-PF is that new particles are sampled by both the state transition prior and the grey prediction algorithm. Since the grey prediction algorithm is a kind of model-free method and is able to predict the system state based on historical measurements other than establishing a priori dynamic model, the GP-PF can significantly alleviate the sample degeneracy problem which is common in SPF, especially when it is used for maneuvering target tracking. Simulations are conducted in the context of two typical maneuvering motion scenarios and the results indicate that the overall performance of the proposed GP-PF is better than the SPF and the multiple model particle filter (MMPF) when the tracking accuracy, computational complexity and tracking lost probability are considered. The performance improvements can be attributed to that the GP-PF has both model-based and model-free features.
GREY PREDICTION BASED PARTICLE FILTER FOR MANEUVERING TARGET TRACKING
2009-06-13
PIER
Vol. 93, 221-236, 2009
download: 205
Composite Compact Triple-Band Microstrip Antennas
Majeed Alkanhal
Two new triple band small size composite-resonator microstrip antenna configurations for wireless communications are presented in this paper. The proposed antennas, each is built of three resonant elements. Two types of compact short-circuited resonators are used; stepped impedance and quarter-wave resonators. The design procedure based on composing the antenna resonators is straightforward and can be applied to design any triple band antenna at three pre-specified bands using simple relations and design curves. The resonator integration has been performed to maintain single feed, reduce the overall antenna size, and preserve the quality-performance at each band. The two designed antennas are simulated, optimized, and realized on RT-Duroid substrate to verify the concept. Simulation and experimental results are in good agreement and demonstrate the performance of both triple band compact antennas.
COMPOSITE COMPACT TRIPLE-BAND MICROSTRIP ANTENNAS
2009-06-13
PIER
Vol. 93, 205-219, 2009
download: 137
Quasi-Optical Bessel Resonator
Yan-Zhong Yu Wen-Bin Dou
In this paper, a quasi-optical Bessel resonator (QOBR) for generating approximations to Bessel-type modes at millimeter wavelengths have been designed and analyzed. A design approach is based on the quasi-optical techniques. In order to analyze the designed QOBR rigorously, a new method based on iterative Stratton-Chu formula (ISCF) is developed from the classical Fox-Li algorithm. And its validity is demonstrated. Numerical results reveal that at the output plane the intensity distributions of the Bessel-type modes of the QOBR are modulated by a bell-shaped envelope, and their phase patterns have a block-shaped profile except slight distortion on the edges of the element due to aperture diffraction. The effect of varying the parameters of the designed QOBR on the relevant output characteristics is also examined in our study.
QUASI-OPTICAL BESSEL RESONATOR
2009-06-13
PIER
Vol. 93, 189-203, 2009
download: 113
Thickness-Independent Complex Permittivity Determination of Partially Filled Thin Dielectric Materials into Rectangular Waveguides
Ugur Cem Hasar
A microwave method has been proposed for accurate complex permittivity measurement of thin dielectric materials partially filling the waveguide. The method employs propagation constant measurements at two locations of the sample inside its holder. It increases the accuracy of permittivity measurements of similar methods in the literature since it utilizes the measurements of the distances between the inner waveguide walls and sample lateral surfaces instead of directly measuring the sample thickness. It has been validated by comparing the measured complex permittivity of a thin Plexiglas sample by the proposed method with that of the method in the literature.
THICKNESS-INDEPENDENT COMPLEX PERMITTIVITY DETERMINATION OF PARTIALLY FILLED THIN DIELECTRIC MATERIALS INTO RECTANGULAR WAVEGUIDES
2009-06-13
PIER
Vol. 93, 177-188, 2009
download: 485
X-Band Miniaturized Wideband Bandpass Filter Utilizing Multilayered Microstrip Hairpin Resonator
Helmi Adam Alyani Ismail Mohd Adzir Mahdi Mohammad Shahrazel Razalli Adam Reda Hasan Alhawari Babak Kazemi Esfeh
This paper presents a new design of miniaturized wideband bandpass filter using microstrip hairpin in multilayer configuration for X-band application. The strong coupling required for wideband filter is realized by arranging five hairpin resonators in two layers on different dielectric substrates. Since adjacent resonator lines are placed at different levels, there are two possible ways to change coupling strength by varying the overlapping gap between two resonators; vertically and horizontally. In this paper, simulated and measured result for a wideband filter of 4.4 GHz bandwidth at 10.2 GHz center frequency with fifth order Chebyshev response is proposed. The filter is fabricated on 0.254 mm thickness R/T Duroid 6010 and R/T Duroid 5880 with dielectric constant 10.2 and 2.2 respectively using standard photolithography technique. Two filter configurations based on vertical (Type 1) and horizontal (Type 2) coupling variation to optimize the coupling strength are presented and compared. Both configurations produce very small and compact filter size, at 5.0 x 14.6 mm2 and 3.2 x 16.1 mm2 for the first and second proposed filter type respectively. The measured passband insertion losses for both filters are less than 2.3 dB and the passband return loss is better than -16 dB for filter Type 1 and -13 dB for filter Type 2. Very small and compact filter is achieved where measured results show good agreement with the simulated responses.
X-BAND MINIATURIZED WIDEBAND BANDPASS FILTER UTILIZING MULTILAYERED MICROSTRIP HAIRPIN RESONATOR
2009-06-13
PIER
Vol. 93, 161-176, 2009
download: 148
A New Microwave Method Based on Transmission Scattering Parameter Measurements for Simultaneous Broadband and Stable Permittivity and Permeability Determination
Ugur Cem Hasar
A new microwave method has been proposed for simultaneous broadband and stable complex permittivity and complex permeability determination of magnetic and nonmagnetic materials. The method utilizes complex transmission scattering measurements at different frequencies. For a change in constitutive parameters determination, we considered zero-order and higher-order approximations. We have verified the proposed method from measurements of two medium- and low-loss materials with another method and available reference data in the literature.
A NEW MICROWAVE METHOD BASED ON TRANSMISSION SCATTERING PARAMETER MEASUREMENTS FOR SIMULTANEOUS BROADBAND AND STABLE PERMITTIVITY AND PERMEABILITY DETERMINATION
2009-06-13
PIER
Vol. 93, 145-160, 2009
download: 102
Synthesis of Planar Arrays Using a Modified Particle Swarm Optimization Algorithm by Introducing a Selection Operator and Elitism
Marta Lanza Diego Jesus Ramon Perez Lopez Jose Basterrechea
A modified particle swarm optimization (PSO) algorithm applied to planar array synthesis considering complex weights and directive element patterns is presented in this paper. The modern heuristic classical PSO scheme with asynchronous updates of the swarm and a global topology has been modified by introducing tournament selection, one of the most effective selection strategies performing in genetic algorithms the equivalent role to natural selection, and elitism. The modified PSO proposed combines the abilities of the classical PSO to explore the search space and the pressure exerted by the selection operator to speed up convergence. Regarding the optimization problem, the synthesis of the feeds for rectangular planar arrays consisting of microstrip patches or subarrays of microstrip patches is considered. Results comparing the performance and limitations of classical and modified PSO-based schemes are included considering both test functions and planar array complex synthesis to best meet certain far-field radiation pattern restrictions given in terms of 3D-masks. Finally, representative synthesis results for sector antennas for worldwide interoperability for microwave access (WiMAX) applications are also included and discussed.
SYNTHESIS OF PLANAR ARRAYS USING A MODIFIED PARTICLE SWARM OPTIMIZATION ALGORITHM BY INTRODUCING A SELECTION OPERATOR AND ELITISM
2009-06-12
PIER
Vol. 93, 125-143, 2009
download: 110
Slot Antenna on a Conducting Elliptic Cylinder Coated by Nonconfocal Chiral Media
Biglar Najjar-Khatirkolaei Abdel Sebak
The characteristics of a slot antenna on a perfectly conducting elliptic cylinder coated by nonconfocal chiral media are investigated. The structure is fed with a line source or plane wave. The analysis is carried out by expressing the fields in and around the cylinder in terms of Mathieu and modified Mathieu functions using the separation of variable and exact boundary value technique. The unknown aperture field is expressed in terms of Fourier series with unknown expansion coefficients. The expansion coefficients are found by applying the boundary conditions on different surfaces and employing the addition theorem and orthogonality properties of the Mathieu functions. For TM and TE cases some numerical results of the antenna gain for co- and cross-polarized waves are presented and discussed.
SLOT ANTENNA ON A CONDUCTING ELLIPTIC CYLINDER COATED BY NONCONFOCAL CHIRAL MEDIA
2009-06-11
PIER
Vol. 93, 107-124, 2009
download: 851
Direct Radiating Arrays for Satellite Communications via Aperiodic Tilings
Andrea Francesco Morabito Tommaso Isernia Maria Grazia Labate Michele Durso Ovidio Mario Bucci
This paper presents an innovative Direct Radiating Array (DRA) architecture exploiting aperiodic tilings of the plane. In particular, a pinwheel tiling has been selected in order to fix positions of the different radiating sources, which are constituted by properly shaped elements. Such a choice allows to achieve a good aperture efficiency and very low pseudo-grating lobes while using only two different kinds of radiating elements. Preliminary results are shown and discussed with reference to both cases wherein the single tiles are not fully populated and wherein ad-hoc sub-array radiators are used. The very encouraging results achieved leave open the way for further interesting possibilities.
DIRECT RADIATING ARRAYS FOR SATELLITE COMMUNICATIONS VIA APERIODIC TILINGS
2009-06-10
PIER
Vol. 93, 91-105, 2009
download: 143
The Combination of Bcgstab with Multifrontal Algorithm to Solve Febi-MLFMA Linear Systems Arising from Inhomogeneous Electromagnetic Scattering Problems
Xue Wei Ping Tie-Jun Cui Wei Bing Lu
The hybrid finite-element/boundary-integral method (FEBI) combined with the multilevel fast multipole algorithm (MLFMA) has been applied to model the three-dimensional scattering problems of inhomogeneous media. The stabilized Bi-conjugate gradient (BCGATAB) iterative solver based on the inner-looking algorithm is proposed to solve the final FEBI linear system, and the multifrontal algorithm combined with the approximate minimal degree permutation (AMD) is used for the LU decomposition of the FEM matrix. The accuracy and efficiency of the combined algorithm has been validated in the final of the paper. Numerical results show that the proposed method can greatly improve the efficiency of FEBI for scattering problems of inhomogeneous media.
THE COMBINATION OF BCGSTAB WITH MULTIFRONTAL ALGORITHM TO SOLVE FEBI-MLFMA LINEAR SYSTEMS ARISING FROM INHOMOGENEOUS ELECTROMAGNETIC SCATTERING PROBLEMS
2009-06-04
PIER
Vol. 93, 71-90, 2009
download: 101
Filtering Lens Structure Based on Srrs in the Low THz Band
Belen Andres-Garcia Luis Enrique Garcia-Munoz Vicente Gonzalez-Posadas Francisco Javier Herraiz-Martinez Daniel Segovia-Vargas
A filtering lens for conical horns based on Metamaterials is presented. The paper focuses on a millimeter wave application. The metamaterial structure is composed of a printed layer of Split Ring Resonators (SRRs) on a substrate. The structure is used as a superstrate on the horn aperture. When the SRRs are excited, a filter performance arises preventing radiation in the desired frequency bands. Besides the filtering property, also a lens behavior is achieved. In this way larger gain can be achieved in both E and H planes, reducing the 3 dB beamwidth. A 6% -3 dB stop band is achieved from 73.3 GHz to 85.7 GHz. Symmetrisation of the radiation pattern up to 3 dB is accomplished and the focalization effect is achieved by emulating a hyperbolical-plane lens. Thus, a simplified system based on a conical horn can be designed by unifying the filter and lens in one electromagnetic element.
FILTERING LENS STRUCTURE BASED ON SRRS IN THE LOW THZ BAND