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ABSTRACT: The effects of the uniaxial anisotropy and chirality of the superstrate on the resonant frequency and bandwidth of rectangular microstrip patch in a substrate-superstrate configuration are investigated. The theoretical study is rigorously formulated via the integral equation and solved using Galerkin-s moment method. The complex resonant frequency for the TM<sub>01</sub> mode is studied using sinusoidal basis functions. The effects of the uniaxial anisotropic permittivity on the resonant frequency of a monolayer have been studied by many authors. Recently the same resonator antenna with a uniaxial permeability and chiral substrate has been studied by the authors, and it was found that these elements enhance the antenna characteristics. Some researchers have suggested the use of an anisotropic superstrate to improve the characteristics of the antenna. Therefore the aim of this work is focused on the effects of a superstrate having uniaxial electric, uniaxial magnetic anisotropies, and chirality elements on the resonant frequency and the bandwidth of the rectangular microstrip antenna.
IET Microwaves Antennas & Propagation 02/2011; · 0.68 Impact Factor
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ABSTRACT: The effect of a chiral bi-anisotropic substrate on the complex resonant frequency of a rectangular microstrip resonator has been studied on the basis of the integral equation formulation. The analysis is based on the numerical solution of the integral equation by using the Galerkin procedure for the moment method in the spectral domain. This work aims to study first the effect of the chirality of a bi-anisotropic substrate upon the resonant frequency and the half-power bandwidth, and then the effect of magnetic anisotropy via an asymptotic approach for very weak substrate upon the resonant frequency and the half-power bandwidth. The computed results are found to be in good agreement with the previously published work.
IET Microwaves Antennas & Propagation 05/2010; · 0.68 Impact Factor
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ABSTRACT: Horn Antenna for millimeter-wave application has been analyzed by two methods, the first one is an asymptotic one which is the aperture integration based on the geometrical optics (GO), the second one is a numerical method based on the well known moment method and improved by wavelets. The aim of this work is first to introduce the application of wavelet in electromagnetic scattering, secondly a comparison of the two method of analysis is presented to show the limit of use of the asymptotic method an to emphasize on the fact that moment method is an exact method which is improved by the introduction of wavelet by reduction of both memory space and processing time, this is illustrated in this work.
Electrical and Electronics Engineering, 2009. ELECO 2009. International Conference on; 12/2009
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ABSTRACT: This work consists in characterizing a rectangular microstrip antenna while emphasizing the possibilities of various types of current expansion functions. A detailed calculation of the spectral Green's dyad, and conduction current calculated by the integral equation method via the moment's method was treated. The numerical method consists in simulating the various types of basic functions by testing convergence and by considering the effect of the parameters of the dielectric substrate such as thickness and permittivity on resonance frequency. An application of the air gap structure was also taken into account.
Control, Communications and Signal Processing, 2004. First International Symposium on; 02/2004
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ABSTRACT: Closed-form expressions for two kinds of Hankel transform integrals, which are encountered in the spectral moment method solution of a circular patch, are obtained. Application of the newly obtained formulas alleviates dramatically the algebraic work for determining the Hankel transforms of the current basis functions involving Chebyshev polynomials and edge condition. Computed moment method results using these expressions are presented. The effects of both uniaxial anisotropy in the substrate on the resonant frequency and bandwidth are investigated.
Control, Communications and Signal Processing, 2004. First International Symposium on; 02/2004
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ABSTRACT: In this paper, the effects of both uniaxial anisotropy in the substrate and isotropic superstrate loading on the resonant frequency and bandwidth of a rectangular microstrip patch in a substrate–superstrate configuration are investigated. The problem is rigorously formulated using an integral equation, the kernel of which is the full-wave spectral domain dyadic Green's function for multilayer dielectric substrates. The proposed method for determining the Green's function leads to a concise form of this, diagonalized in the (TM,TE) representation. Using Galerkin's moment method to solve the integral equation, the complex resonance frequencies for the TM01 mode are studied with sinusoidal basis functions. The improper double integrals of the moment method matrix are efficiently calculated by means of a proper choice of the path of integration in the complex wavenumber plane, the upper bound of truncation, and the method of quadrature. For an isotropic substrate, it is demonstrated that the bandwidth decreases with increasing ratio of superstrate-to-substrate thickness for high permittivity and low thickness of superstrate. Also, we show that the resonant frequency and bandwidth are highly dependent on the permittivity variations along the optical axis. Simple approximate formula for the resonant frequency is derived. Other theoretical results obtained show that the resonant frequency decreases monotonically with increasing superstrate thickness, the decrease being greater for high permittivity loading and negative uniaxial anisotropy of the substrate. Thin superstrate with high permittivity together with negative uniaxial anisotropy of the substrate are shown to be the favourable conditions for severe degradation of the half-power bandwidth of the antenna. Copyright © 2000 John Wiley & Sons, Ltd.
Communications in Numerical Methods in Engineering 06/2000; 16(7):459 - 473. · 1.75 Impact Factor
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ABSTRACT: Closed-form expressions for two kinds of Hankel transform
integrals, which are encountered in the spectral moment method solution
of a circular patch, are obtained. Application of the newly obtained
formulas alleviates dramatically the algebraic work for determining the
Hankel transforms of the current basis functions involving Chebysbev
polynomials and edge condition. Computed moment method results using
these expressions are presented
Electronics Letters 06/2000; · 0.96 Impact Factor
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ABSTRACT: The influence of uniaxial anisotropy in the substrate on the
resonant frequency of a rectangular microstrip patch is investigated.
Computations shown that changes in ε<sub>z</sub> can drastically
shift the resonant frequency; moreover, a small shift is observed when
ε<sub>x</sub> changes. Other result also indicate that the effect
of ε<sub>x</sub> tends to be insignificant for low substrate
thicknesses
Electronics Letters 03/1999; · 0.96 Impact Factor
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ABSTRACT: The aim of this work is to introduce the application of wavelet in electromagnetic scattering, and making improvement in Moment Method development. The conventional Moment Method basis and testing functions are used to digitalize the integral equations resulting in dense matrix impedance. By using the wavelets expansions, wavelet as basis functions and testing functions, a sparse matrix is generated from the previous Moment Method dense impedance matrix. Results are compared to the previous work done and published, [Su C. And T.K. Sarkar 1998]. Excellent results are obtained for the two types of shapes circular and square contour antennas.
