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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/6969

Title: 使用時域有限差分法探討擇頻表面之有限與無限尺寸之週期性結構散射問題
Analysis of the frequency selective surface of finite and infinite periodic structure using the FDTD Method
Authors: Cheng-Nung Liao
廖正農
Contributors: NTOU:Department of Electrical Engineering
國立臺灣海洋大學:電機工程學系
Keywords: 時域有限差分法;週期性邊界條件
FDTD;periodic boundary condition
Date: 2009
Issue Date: 2011-06-22T09:03:17Z
Abstract: 時域有限差分法時域有限差分法(finite-difference time-domain method, FDTD)能夠計算許多種類的結構所產生的電磁輻射與散射問題。一般使用FDTD的方法是將模擬物體置放在模擬空間中,並且利用吸收邊界條件置放在立體模擬空間中六個表面的邊界處,但也表示將所要探討的物體經離散化後,離散化的網格數量需要龐大的記憶體使用量和長時間的計算。   由於許多具有電磁相關問題的物體有一維或二維方向週期性結構的特性。當週期性邊界條件(Periodic Boundary Condition, PBC)應用於FDTD的方法被提出和實現後,具有週期性結構如天線、散射體等物體的計算可以透過假設該週期性結構為無限大陣列型態,簡化對此種物體的計算過程。   在本篇論文中,我們將使用FDTD法建構有限尺寸的模擬空間,以及使用PBC的FDTD法建構無限尺寸的模擬空間,探討有限尺寸與無限尺寸的擇頻表面散射的問題。有限尺寸的模擬空間中將會置放有限尺寸的擇頻表面,並於模擬空間外層以完美吸收層(Perfect Matched Layer, PML)為吸收邊界條件。無限尺寸的模擬空間則對擇頻表面中一個單元的尺寸進行離散化,於該單元離散化後的外圍邊緣置放週期性邊界條件。
The finite-difference time-domain method is a useful computational technique for many problems in electromagnetic scattering and radiation. A well-known application of the FDTD is to enclose the entire structure and to place the perfect matched layer (PML) around the boundary to truncate all of the directions of the space, which leads to an approach of dividing the problem volume into small cells and requiring large memory requirements and long simulation time. Many structures in electromagnetics are periodic in one or two dimensions, and this periodicity can be used to simplify the analysis by considering an infinite array. Because of the periodicity, the periodic boundary condition (PBC) was employed in FDTD to deal with infinite-periodic arrays or scatterers. The FDTD needs only gridding a single-unit cell of the periodic structure, which makes the computation more efficient. In this thesis, we report the analysis results of the frequency selective surface (FSS) of the finite and infinite periodic structure. The finite periodic structure will consist of finite units and the solution space will be delimited by PML. On the other hand, the infinite periodic structure will be analysed within a single-unit cell of the structure and the solution space will be surrounded by PBC.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M96530086
http://ntour.ntou.edu.tw/ir/handle/987654321/6969
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