利用三焦點羅特曼透鏡實現應用於車用雷達系統可切換三模態的平面相位陣列

Abstract

這篇論文介紹了一種多模式的相控陣天線設計，用於先進駕駛輔助系統 (ADAS) 雷達應用。這項創新設計用一個具有較大尺寸且能產生三種模式的天線陣列，取代了遠距離和短距離車輛偵測的三個獨立的發射 (TX) 天線陣列，從而在實現較大增益的同時保持較小的尺寸。透過使用兩種不同的波束模式，短距離檢測的視野 (FOV) 顯著擴展至超過100度，模擬結果顯示FOV達到110度。這種多模式的功能是由Rotman Lens Switchable Multi-Mode Beamforming Network (RL-SMMBFN)實現，使三模式切換成為可能。 研究中開發了數學模型並討論了多個參數。引入了一種埠口不連續的解耦方法。開發並模擬了一種漸縮式的串聯饋入微帶貼片天線傳輸線模型，應用了Dolph-Tschebyscheff分布來抑制旁瓣波束。設計並模擬了連接腔體和傳輸線的透鏡端口。根據數學模型構建了Rotman透鏡，並透過組裝透鏡端口和傳輸線實現。隨後，提取了Rotman透鏡的相位和振幅，並匯入設計的天線陣列。使用Woodward-Lawson方法解決了由耦合或透鏡端口發射波不完美特性引起的相位偏差。最後，組裝了天線-Rotman透鏡系統，模擬結果證明了該設計的可行性，並且天線的實驗測量驗證了這些概念。 然而，RL-SMMBFN目前在毫米波頻率的介質基板中面臨功率損耗挑戰。未來的研究將致力於使用空氣波導減少這些損耗，並將天線尺寸微型化以縮小體積與面積。

This dissertation introduces a multi-mode design of phased arrays of antennas for Advanced Driver Assistance Systems (ADAS) radar applications. The innovative design replaces three separate TX antenna arrays for long- and short-range vehicular detections with a single, larger-dimension antenna array capable of producing three operational modes for the TX ports, achieving larger gains while maintaining a compact size. By employing two different beam modes, the field of view (FOV) for short-range detection is significantly extended to over 100 degrees, with simulations indicating an FOV of 110 degrees. This multi-mode capability is facilitated by a Rotman Lens Switchable Multi-Mode Beamforming Network (RL-SMMBFN), enabling the creation of three-mode selection ports. A mathematical model has been developed, and multiple parameters have been discussed. The direct-end decoupling method has been introduced to address impedance matching issues. A tapered series-fed microstrip patch antenna transmission line model has been developed and simulated, applying the Dolph-Tschebyscheff taper to suppress sidelobe levels. The lens port has been designed and simulated to connect the cavity and transmission line. The Rotman lens was constructed based on the mathematical model and realized by assembling the lens port and transmission line. The resulting phase and amplitude of the Rotman lens were extracted and applied to the designed antenna array. The Woodward-Lawson method was used to resolve phase deviations caused by mutual coupling or imperfections in the lens ports. Finally, the antenna-Rotman lens system was assembled, with simulations demonstrating the feasibility of this design, and experimental measurements of the antenna prototype validating the concepts. However, the RL-SMMBFN currently faces power loss challenges in dielectric substrates at millimeter-wave frequencies. Future research will focus on reducing these losses using air-filled waveguide technologies and miniaturizing the antenna size for compactness and a low profile.