Numerical Study of Frequency Selective Surface by Spectral Galerkin Method
Date Issued
2005
Date
2005
Author(s)
hung, Shih-Che
DOI
zh-TW
Abstract
Frequency Selective Surfaces (FSSs) are a kind of periodically two-dimensional structures. Since it exhibits total reflection (patch FSSs) and total transmission (aperture FSSs) in certain frequency, there are a lot of researches in recent years. In addition to researches, there are many applications, like radomes and antennas system in microwave region or polarizers and beam splitters in the infrared and submillimeter region, and so on.
In this thesis, spectral Galerkin method is used to solve the scattering problem of FSSs. We will divide the physical problems into problems of incident-propagating and induced current scattering. On the problem of scattering, Floquet’s Theorem is used to express induced surface current density in Fourier series, and reduce computation domain into a unit cell. After applying the boundary condition at the location of conduction screen, we can calculate out the unknown induced surface current density distribution by using known incident and spectral Green’s function. And then, we can use that to analyze reflection and transmission. In order to decouple TE (transverse-electric) and TM (transverse-magnetic) waves, we use vector potential approach to suppose incident. In addition, spectral domain immitance approach is used to obtain spectral Green’s function.
In computation, in order to let our shapes free, subdomain basis functions are used to be basis of expansion of induced surface current. In addition, in the cases of big unknown matrices, conjugate gradient method is used. And we also use Fast Fourier Transform (FFT) to speed up our computation.
We stress on thin-screen frequency selective surfaces in this thesis. Many arguments affect its frequency responses. We are going to discuss several different kinds of numerical cases, including different shapes, different scales of conducting screen, patch and aperture, and different incident angles. Further, the FSSs with impedance and dielectrics, and multilayered-FSSs are considered. At the same time, we present some reference to verify the accuracy of our computations.
Subjects
表面擇頻元件
頻率撰擇表面
週期性陣列
頻域動差法
頻域阻抗法
Frequency selective surface
periodic array
spectral moment method
spectral immitance approach
Type
thesis
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