在本論文中我們將探討有限時域差分法(FDTD)的透明源在近場時的電磁特性，包括準靜電磁場和近場的輻射特性。由於對所有FDTD的模擬而言，能量都必須藉由內部源(Internal Source) 或外部源(External Source)來適當的將能量耦合到網格之中，從先前的研究中我們知道對於驅動方程式來說，透明源伴演著電流源的角色，透過驅動方程式建立的準靜電荷(Quasi-static Charges)，我們可以得到所需要的靜電場，而且我們也將針對透明源的電磁輻射特性做一番探討，包括電場與磁場在源點上相關的電磁特性，還有源點附近的電磁特性均有所探究。另外我們也推導了電場還有磁場的準靜場公式以及輻射項的公式，透過這些公式我們可以非常容易的得到FDTD模擬空間中每一個網格的電磁特性。 另外，在應用方面我們也利用了驅動方程式會建立準靜電荷的特性來研究平行電容板的結構，並用準靜電荷穩定後的電場值來計算出平行金屬板間的電壓，然後再將電荷總量除以電壓即可獲得電容值，如此一來不使用傳統的動差法，而是利用FDTD法即可模擬電容結構，所得到的結果與其他論文相比，兩者之間的誤差少於4%。 In this thesis, the electromagnetic (EM) characteristics and the application of the transparent source by the finite-difference time-domain (FDTD) method are investigated. The concerned electromagnetic characteristics include the quasi-static E field and H field and the near-zone radiation fields. The formulations for the E and H fields at the source node are derived by using Gauss’s law and Ampere’s law, respectively, and shown to be quasi-static. The derived quasi-static E field and H field are very close to the simulated results by the FDTD method, but they may lead to null energy radiated from the transparent source. That terms representing the very small radiated energy for such a high Q system are identified via the decompositions of the impulse response at the source node for the E field and the step response for the H field. In the application, the FDTD method is employed to calculate the static capacitance of a parallel-plate structure. Through the use of the transparent current source, the parallel-plates are charged such that the transient and static E fields are simulated using the FDTD update equation. The static E field is used to calculate the voltage across the parallel-plates. The capacitance is obtained directly by dividing the charge over the voltage without using the traditional MOM method. The results calvulated very well with the literatures with difference less than 4%.
