梯度人造磁導體的反射特性

Abstract

我們研究了下方有著接地金屬的介質平版所組成二維正方形貼片陣列的電磁反射特性。藉著改變金屬貼片的大小，兩兩相鄰的貼片會有一個相等的反射相位差角。利用這個在陣列單元中等差遞增的反射相位特性，當一個垂直入射的平面波打到這個結構時，他的反射波會被散射到我們所設計的方向。在這篇論文中，我們根據陣列天線理論建立了一個簡單的公式來計算反射波的遠場場形。再者我們使用一個時域全波模擬套裝軟體(CST)來精準地計算在結構中的電磁場分布以及遠場場形。此外我們將這個結構實作出來並且在電磁無反射實驗室中量測他的散射場型。經由這個實驗，我們量測到了很好的數據結果來驗證我們所提出的設計原理和步驟。這樣的一個結構可以被用來應用在波束控制(beam steering)以及減少雷達橫截面(radar cross section reduction)。

We studied the electromagnetic reflection of a two-dimensional square patches array backed with a grounded dielectric slab. By tuning the size of the metal patch, the adjacent two patches may have an equal reflected-phase angle. Using this property of progressively reflected-phase angle in the array elements, for a normal incident wave we can steer the reflected wave into a desired direction. In this thesis, we have established a simple formula based on the array antenna theory to figure out the reflected wave pattern. Moreover, a time-domain full-wave simulation package (CST) was employed to rigorously calculate the electromagnetic fields in the structure as well as the far-field pattern. Besides, we have fabricated the structure and measured its scattering pattern in an electromagnetic anechoic chamber. The excellent measured results confirm the design principle and procedures in this research. Such a planar structure may have potential applications in beam-tilting and radar cross section reduction.