90度轉彎超材料表面之伊頓透鏡之改良

Abstract

這篇論文提供了利用超材料表面製作二維九十度轉彎之伊頓透鏡的設計方法。為了合成離散後九十度轉彎伊頓透鏡之公式，本篇論文使用不同週期的方形金屬貼片與蕈狀結構之週期性單元以取得合成透鏡時所需要的反射係數數值。另外，為了適應電磁波行走方向而在表面佈局與合成時將部分區域的金屬貼片做旋轉。利用近場電場圖、遠場圖與遠場之增益數據來特徵化透鏡之表現，以評估九十度轉彎伊頓透鏡之性能。為了能使得波源饋入的表現能更好，本篇也提供修改二維透鏡與波導饋入之間的設計。並在最後加入了透鏡的實作與量測而驗證本篇論文之設計。 在本篇論文中，也提到了許多會需要在開放空間中將電磁波轉彎的狀況，可以透過九十度轉彎伊頓透鏡來得到這些目的，也希望超材料表面之伊頓透鏡能在高頻通訊、車用電子、雷達與天線等領域能佔有一席之地。

In this thesis, we propose a method to design and produce the two dimensional 90° rotating Eaton lens. The required values of equivalent refractive indices are achieved by using two different kinds of period square patches and mushroom structure cells. Parts of these unit cells are rotated in adaptation with the bending wave to improve its performance. We characterized the performance of the 90° rotating Eaton lens with the E-field distribution, far-field pattern and realized gain. In order to get the better far-field gain, additional parts which converting the incident wave into a surface wave, combined with the lens, and get the improved result in the electromagnetic simulation software. Finally, a fabric prototype of the lens was being manufactured and measurement. The experimental results verified the design and simulations. It also mentioned many situations which people want to bend the electromagnetic wave about 90°. This work has providing the 90° bending function to the world. The lens will play an important role in the future.