本論文採用以 Z-轉換輔助的有限時域差分法 (Z-transform assisted finite-difference time-domain method 或 Z-transform assisted FDTD method) 來模擬電磁波包在細金屬線陣列 (Wire Array) 和裂環共振器陣列 (Split-Ring Resonator Array) 所構成的複合式人工構造 (Wire-SRR Array) 中的傳播行為。此種複合介質具有類似於 Drude 模型形式的色散型介電係數 (permittivity) 以及類似於 Lorentz 模型的色散型磁導率 (permeability)，並在某一段頻率範圍內具有負折射率 (negative refractive index)。本研究主要探討電磁波在負折射頻段於介質中的傳播行為，具體內容包括：波包在介質中的移動速度、群速度、能量速度在介質強吸收以及弱吸收的情況下的行為比較，以及波包在空氣與Wire-SRR介質介面處的能量穿透情形。最後探討波包在Wire-SRR進入介質中的折射行為，並將其結果和單頻的折射定率做比較。 In this thesis we adopt the Z-transform assisted Finite-difference time domain (FDTD) method to simulate the wave packet propagating behavior in the artificial structure which composed with periodically arranged thin metallic wires and spilt-ring resonators (SRRs). This artificial medium has dispersive permittivity like that of Drude model and dispersive permeability like that of Lorentz model, and has negative refractive index in a range of frequency. The main theme of our study is about the propagating behaviors of electromagnetic waves in this medium in the negative refraction frequency range. We study and discuss the differences among wave packet velocity, group velocity, and energy velocity in lossless and absorptive medium respectively. Finally, we compare the energy transmittance and refractive performance of wave packet with that of the monochromatic waves.
