臺灣博碩士論文加值系統

本論文針對有限時域差分法(FDTD)的硬式源和透明電流源的電磁特性作完整的研究。硬式源相關的電荷、電流以及準靜磁場的公式首度被完成證明。吾人發現在電源端，準靜磁場和時間的微分成正比。
透過相關的電荷和電流，透明電流源相關的準靜電場和準靜磁場的公式也是第一次被提出。透明電流源之電磁特性為，在電源端的準靜電場和驅動方程式的時間的積分成正比，且準靜磁場在電源端與時間的微分成正比。因為驅動方程式的作用準靜電荷可能在空間中累積並且形成準靜電場，造成脈波激發時FDTD演算法的直流偏移問題。本論文詳述了直流偏移在更新方程式為高斯脈波函數時行程的原因以及解釋了為何能夠使用雙極脈波來加以避免。
本論文更進一步的探討，所有FDTD電磁波源中，準靜電場與準靜磁場的時間微分成正比，此一關係將導致先所提出的電磁波源模型所提供的輻射能量為零。因此進一步的檢驗電磁源端電場和磁場的關係。吾人應用外加電流源所造成電場和磁場的完整時域公式分析FDTD透明源完整的電磁特性，其中包括了Hertzian電偶極和短電偶極兩種模型來分析此一特性。並且證明了，當利用一透明電流源來激發模擬空間時，電荷的分部型式為均勻分布成平面盤狀電荷，而不是體電荷的分配，當利用透明源激發FDTD問題空間時應被視為一Hertzian電偶極而非一短電偶極。
當應用一透明電場源激發 FDTD問題空間時必須透過兩階段的模擬過程。首先在第一階段紀錄FDTD格子系統的脈衝響應和相關的震盪電荷。接著扣除由格子系統響應所傳回的多餘電場，如此變能夠克服透明電流源的直流偏移問題。在本論文中，詳細探討了透明電場源的運作機制。最後，本論文提出一個新的高效率的雙極化透明場源。

CHAPTER 1 INTRODUCTION……………………………………………1
1.1 Introduction and Literature Survey………………………1
1.2 Chapter Outline…………………………………………..4
CHAPTER 2 FINITE DIFFERENCE TIME DOMAIN METHODS
(FDTD) & SIMULATION SETTINGS………………………7
2.1 Maxwell’s equations……………………………………...7
2.2 Discretization in Time and Space of
Maxwell’s Equations……………………………………..10
2.3 The Cell size and the Courant Stability Condition……….16
2.4 Absorbing Boundary Conditions (ABC)………………....17
2.5 Simulation Settings for this Thesis……………………….17
CHAPTER 3 ELECTROMAGNETIC CHARACTERISTICS
THE HARD FIELD SOURCES……………………………..20
3.1 The Electric Field and Associated Charges………………20
3.2 Formulations of the Magnetic Field at the Source Node…25
3.3 Summary………………………………………………….30
CHAPTER 4 ELECTROMAGNETIC CHARACTERISTICS
OF TRANSPARENT CURRENT SOURCES…………….....31
4.1 Static Charges and Static Fields Due to a
Current Source……………………………………………31
4.2 Magnetic Fields of an ICE near the Source Node………..39
4.3 Summary………………………………………………….45
CHAPTER 5 PHYSICAL MECHANISMS OF
TRANSPERNT FIELD SOURCES……………………………47
5.1 Physical Mechanisms of Transparent Field Source in
Time Domain………………………………………………..47
5.2 Bipolar Transparent Field Source (BTFS)……………….55
5.3 Summary…………………………………………………60
CHAPTER 6
ELECTRODYNAMICS FOR FDTD SOURCES………….……………61
6.1 Difference between the quasi-static formulation and
the FDTD…………………………………………………..61
6.2 E and H fields by a transparent current source of
FDTD methods………………………………………………66
6.3 EM energy from a transparent current source…………….84
6.4 Summary………………………………………………….87
CHAPTER 7 CONCLUSIONS……………………………….………….88

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