利用週期性金屬貼片陣列操控表面波與倫伯格透鏡天線之設計

Abstract

首先，超穎介面有種強大的獨特性，可打造出傳統自然材料無法擁有的特性，使得廣泛的研究於各種不同領域，例如:光學、光子學、通訊天線、生物醫學感應…等。本論文探討點之一為應用週期性結構於倫柏格透鏡，我們使用的週期性金屬貼片陣列是一種表面超材料，可以用來合成倫伯格透鏡，使在其表面傳導的表面等離子極化激元達到應有功能表現，並且應用於傳導表面波式天線。 本論文提出兩種應用表面阻抗的方法，找出各級金屬貼片的表面阻抗並提供公式將其轉換成為透鏡的重要參數-折射率，也對兩種方式結果做比對，有了此參數之後就能將倫伯格透鏡的折射率分布離散化，並使用金屬貼片近似之，已達成預期的透鏡表現。 其次，本論文對於超穎介面的倫伯格透鏡天線，有著利用免費的空氣來達到有大範圍的天線輻射範圍，我們修改、精化其金屬貼片陣列所合成的天線，並計算出各種影響天線表現的因素，以數值化方式來看到結果。最重要的一點是，本論文建立了構造超穎介面的倫伯格透鏡天線的方法與量化數值。

Research on metasurfaces has been widespread recently because they have strong potential in several fields such as optics, photonics, antennas, sensing, imaging, and spectroscopy. The metasurface is able to exude unusual properties which natural materials or ordinary structures do not possess. In this thesis, we use a periodic array of square metallic patches etched on a grounded dielectric substrate to synthesize a flat 2D Luneburg lens which is used as a surface-wave antenna. No surface wave launcher is required by this meta-lens, which would otherwise add to space and weight. We calculate the various sub-efficiencies of aperture area that collectively characterize the quality of the radiating aperture, which is bounded only by one surface but exploits the exterior free-space above the metasurface to make up the rest of the boundaries, resulting in an essentially material-less aperture that is consequently light, low-profile, compact and also cheaper to manufacture. The design is validated by simulation results.