FDTD是以中央差分趨近將馬克斯威爾方程式離散化，配合空間網格之電磁場配置，以一個有限體積之計算空間，在時域上分析各種電磁問題之數值方法。在FDTD數值模擬時激發源利用全場/散射場公式處理來模擬均勻平面波的波源，在金屬盒上有一槽孔暴露在均勻平面波下，觀察經由槽孔的偶合在金屬盒內所感應的電場。並跟激發源利用附加源處理而且在不同激發面空間所得結果做一比較，激發源利用全場/散射場公式處理與激發源利用附加源處理其激發面空間越大所得結果越接近。
當屏蔽金屬盒上槽孔為長條型的槽孔而且跟干擾源極化方向垂直時經長條型槽孔偶合到金屬盒內的電場會很大。在不知干擾源極化方向下一般在金屬盒上的槽孔都是小槽孔避免是長條型槽孔。

The finite-difference time domain(FDTD) method is formulated by discretizing Maxwell’s equation over a finite volume and approximating the derivatives with centered difference approximation.
The total-field/scattered-field formulation use for simulating the uniform plane wave and the added -source formulation use for simulating the plane wave,compare the result of the electric field within metallic enclosures through aperture excited by uniform plane wave with plane wave,The larger of the exciting plane of the plane wave the more approximate to the result of the uniform plane wave .It must be very large for the induced electrical field within enclosure with a slot which vertical to interference source polarization .
Generally speaking, the aperture on the enclosures not the slot but small holes on the condition of don’t know interference source polarization.

目錄
謝辭............................................I
論文提要…………………………………………… … II
目錄……………………………………………….… ..III
圖表目錄……………………………………… …...IV
第一章 緒論…………………………………………..1
1.1 研究背景……………………………………...1
1.2 研究目的……………………………………...2
1.3 論文大綱……………………………………...3
第二章 FDTD演算法……………………………………...4
2.1 FDTD公式………………..……………………….4
2.2激發源……………………………………….……9
2.3穩定準則………………………………………...11
2.4 吸收邊界………………………………………… 12
第三章全場/散射場的公式 ....................20
3.1全場/散射場概念…………………………………20
3.2一維全場/散射場的公式……………………… 21
3.3二維全場/散射場的公式……………………… 24
3.4入射場的計算………..………………….… 27
3.5均勻平面波的模擬.………….……………… 31
第四章金屬盒內電場經由槽孔的偶合…………….. 40
4.1屏蔽問題………………………………………. 40
4.2均勻平面波經由金屬盒槽孔偶合的模擬…… 41
第五章 結論…………………………………… 53
附錄一 COM2吸收邊界之離散化……………………. 54
附錄二 三維全場/散射場的公式…………………… 56
參考文獻………………………………………………………………. 62

參考文獻
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