以間隙波導實現羅特曼透鏡多波束成形網絡之共形陣列天線設計

Abstract

本論文提出一套整合電子式與機械式波束掃描機制的架構，達到二維訊號覆蓋(coverage)。其中電子式掃描的波束成型網絡(beam forming network)是透過共形(conformal)配置的羅特曼透鏡(Rotman lens)實現；並透過共形曲折的間隙波導(gap waveguide)空氣介質層的特性，分離天線單元與波束成型網絡，當內側的波束成型網絡環向(circumferential)旋轉時，可維持天線陣列的靜止，同時達到二維覆蓋的機械式波束掃描。本原型設計經過數值電磁模擬與實作量測之驗證，證實此概念的有效性。 本論文的架構如下，第1章將回顧羅特曼透鏡與間隙波導的理論，並平面間隙波導的邊界條件在共形配置下的散射係數驗證；第2章則聚焦在共形槽狀陣列天線之設計、共形羅特曼透鏡多波束掃描網絡的設計，並其與曲面間隙波導之整合，亦進行數值電磁模擬驗證；第3章以3D積層製造(additive manufacturing)與水浴電鍍實現陣列天線，呈現實作驗證、場型量測結果與誤差分析，其中的誤差分析涵蓋了製作之形變造成非共形陣列排列，與空氣間隙偏差造成之相位偏離；第4章則提出結論。

The paper is going to propose a framework to integrate electronic and mechanical beam scanning mechanisms to achieve two-dimensional coverage. The electronic scanning beamforming network is implemented through a conformally configured Rotman lens. By the nature of air substrate in conformally bent gap waveguides, the antenna elements are separated from the beamforming network. When the inner beamforming network rotates circumferentially, the antenna array can remain stationary, meanwhile achieving two-dimensional mechanical beam scanning. The thesis is organized as follows: Chapter 1 reviews the theory foundation of Rotman lenses and gap waveguides. Also, we verify the S parameters performance of gap waveguides in conformal configurations. Chapter 2 focuses on the design of conformal slot array antenna, the design of conformal Rotman lens beam scanning network, along with the integration of the previous with curved gap waveguides. In the meanwhile, numerical electromagnetic simulations are used to testify our design. Chapter 3 shows experimental verification implemented via 3D additive manufacturing and electroplating, field pattern measurement and error analyses. The error analyses cover main beam deviations from fabrication-induced deformed non-conformal array, and phase deviations caused by the thickness discrepancies of the airgap. Finally, chapter 4 shall conclude this paper.