現代科技發展至今，資料傳輸量的需求也越來越龐大，產品的電磁干擾分析更顯得重要。以電腦機殼為例，使用傳統FDTD法在分析機殼內元件或PCB結構之電磁干擾與屏蔽有效度時，因為頻率的增加，導致金屬機殼變成電性大尺寸結構(Electrically large structures)，考量散熱孔的存在及金屬機殼所造成的影響，且為了得到有效之分析數據，在分析時必須全面性地將網格比例縮小，導致耗費大量運算時間與記憶體。
FDTD次網格法能夠針對部分區域的結構，縮減網格比例進行運算，提升計算的效率。次網格法對於穩定性與準確性上的探討，也是許多研究者的重點。本文提出網格比可調之次網格法，在直角坐標系統中次網格的三個分量均可個別調整做精確模擬，方法架構採用分離時間與空間界面的做法，以非均勻網格法計算位於次網格界面上切線方向之電場，並以適應性調整時間步階技術實現時間同步計，提供一個嵌入式的架構。
最後使用上述提出之方法，分析具有多個散熱孔的金屬機殼之屏蔽有效度與電磁干擾。方法將和單純網格全細切的FDTD法比較，探討本方法的穩定性與計算效率。

As the development of modern technology grows rapidly, the demand of data transmission is higher than before; therefore, product electromagnetic interference analysis is even more important. Take computer cases for example, traditional FDTD method can be applied to analyze components inside the enclosure or electromagnetic interference and shielding effectiveness of PCB. With the frequency increases, the metallic enclosure turns into an electrically large structure. Considering the heat dissipation holes and the impact of the metallic enclosure, also in order to get effective analysis data, the grid must be scaled down comprehensively during the analysis, which consumes a lot of calculation time and memory.
FDTD subgridding is able to be applied to the part of the structure by reducing grid proportion, which successfully enhances the efficiency of the calculation. Subgridding algorithm for discussion of stability and accuracy is also the focus of the researcher. In this thesis, we propose a grid method which is capable of adjusting grid ratio. In the Cartesian coordinate system, the three components of the subgridding algorithm can be adjusted individually to make precise simulation. In the proposed FDTD framework, separate temporal and spatial interfaces are adopted. The concept of the non-uniform grid method is employed to calculate the tangential electric components on the spatial interface, and the adaptively adjusted time-steps to achieve time synchronization calculation, employing an embedded architecture.

論文審定書 i
誌謝 ii
中文摘要 iii
英文摘要 iv
目錄 v
圖表目錄 viii
第一章 序論 1
1.1 研究目的與方法 1
1.2 論文大綱 3
第二章 FDTD演算法 5
2.1 FDTD介紹 5
2.1.1 FDTD公式推導 5
2.1.2 Courant 穩定條件 8
2.2 吸收邊界 9
2.3 FDTD演算法模擬 11
第三章 非均勻網格法 13
3.1 非均勻網格法介紹 13
3.2 非均勻網格法推導 14
3.5 非均勻網格法的誤差 18
第四章 次網格法 20
4.1 傳統次網格介紹 20
4.1.1 傳統次網格演算法 20
4.1.2 數值不穩定現象 22
4.2 適應性調整時間步階程序 24
4.3 FDTD次網格法 27
4.3.1 使用非均勻網格的FDTD次網格法 32
4.3.2 FDTD次網格法穩定性測試 33
4.4 網格比可調之FDTD次網格法 36
第五章 金屬機殼模型之屏蔽有效度測試 43
5.1 屏蔽有效度介紹 43
5.2 屏蔽有效度分析 44
5.3 改變孔徑對方法的影響 48
5.4 具有多個散熱孔的金屬機殼屏蔽有效度分析 52
第六章 結論 55

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