車用前視防撞雷達之可切換波束天線陣列

Abstract

本論文進行有關77GHz FMCW (Frequency Modulation Continuous Wave)車載前視防撞雷達系統中天線陣列的設計。發展一平面印刷式微帶天線(microstrip antenna)陣列。此天線陣列由印刷電路形式之Rotman Lens饋入，利用不同輸入點在陣列輸入面上造成對應的相位差以提供數個可供選擇切換的主輻射波束方向。此天線陣列係由數個雙排天線次陣列組成，饋入功率經由一功率分配器平均分配至下層兩排子陣列。每一排子陣列由數十個串聯饋入(series fed)之微帶天線組成串接微帶天線次陣列，設計時在寬度上漸次變化以限制其旁波大小，使其在電場平面方向波束寬約5度，旁波較主波小15dB，在磁場平面方向可由Rotman Lens之不同輸入點在0度與正負7.5度選擇不同的主輻射波束。

A planner printed antenna array for 77GHz FMCW mobile forward-looking collision avoidance system is presented in this thesis. This antenna array is fed with a printed Rotman lens which provides different output beam directions respect to different input ports. The antenna array includes several antenna sub-arrays; each sub-array comprises a power divider and two antenna rows. The antenna row contains tens of series fed tapered microstrip antennas, to keep the main beam of E-plane within 5°and the side lobe level bellow then 15dB. Due to Rotman Lens, the direction of main beam of the integral antenna array can be switched between 0°,7.5°,-7.5°.