各向異性單軸完美匹配層(UPML)原本只是全波模擬(Full-Wave Simulation)上的一種數值技巧;使用理想完美匹配損耗性介質,用以近似無窮開放空間藉此節省計算資源的虛擬吸收器。實際上因為製程技術與材料科學的進步透過利用各種次波長的高阻抗性超穎材料來組合出於設計波段(如微波、兆赫波)作用的吸收器之設計,也因此才能在物理上實踐出近似UPML存在的吸收器。在此篇論文裡我們不僅研究且利用數值分析呈獻出基於UPML的概念,一個對極化低敏感度、近乎全角度入射性、且極寬頻寬的超穎材料吸收器並用於解決傳統吸收器在厚度與相異極化斜向入射時穩定性的相衝突問題,而且也另外研究並展示出多個寬頻吸收器設計的相關應用,例: 無輻射的缺陷接地面結構吸收性共模濾波器,吸收性帶止濾波器。在上述濾波器設計裡引入並使用吸收概念來取代傳統反射概念,可同時地改善傳統反射濾波器缺點以及解決其他潛在電磁相容與相干擾問題。在此篇論文裡提到各式吸收器應用設計,其吸收的部分頻寬(fractional bandwidth)至少皆超過100%以上。我們提出的各式應用設計皆能透過全波模擬跟實驗量測結果驗證其效能跟理論設計方法正確性。本論文提出各式吸收元件都是具備寬頻、低敏感度、輕盈、且低成本特性具有潛力應用在各個領域與波段其中包括電磁相容性元件、匿蹤科技、兆赫波成像與偵測。
Uniaxial perfect matching layer (UPML) was originally a practical full-wave numerical technique. A practicable physically UPML can be actually practiced through combing multiple sub-wavelength structures with high-impedance metamaterial absorber in THz region. In this dissertation the author doesn’t only investigate and present a polarization-insensitive nearly omnidirectional wideband terahertz metamaterial (MM) absorber inspired from UPML by numerical study to resolve the confliction between thickness and stability of conventionally thin absorber, but also demonstrates several wideband absorbers applications, such as absorptive band-stop filter, and radiation-less absorptive common-mode filter. The concept of absorption rather than reflection is used to solve the potential problems of traditional reflective band-stop filters, while improving the original defects. The fractional bandwidth of absorption of each proposed designs all are exceeded to 100% at least in this dissertation. Both simulation and measurement results verify the performance and confirm the methodology for each proposed applied designs. These proposed absorptive devices which are wide-band, light-weighted and simplify low-cost have potential in various applications including EMC/EMI device, stealth technology, THz imaging and bolometric detector.