24-GHz車輛前視防撞警示雷達之單脈衝透鏡天線系統設計與驗證

Abstract

本論文中設計一個應用於24-GHz前視防撞雷達之單脈衝透鏡天線系統。本論文之架構為使用數個串聯饋入之微帶天線組成串接微帶天線陣列作為號角天線的饋入，相同的設計應用於接收與發射端天線。另外在接收端天線部分，設計一個焦距與接收號角天線高度相等的透鏡覆蓋於號角天線上，並驗證此尺寸與焦距僅數波長之透鏡仍有其效果。此架構的優點是使用號角天線能壓抑串接微帶天線陣列的旁波束以及降低波束寬，同時可作為透鏡的支架，另外，接收與發射天線的號角天線金屬牆也可大幅提升接收與發射端的隔離度。 最後為了驗證此單脈衝天線在實際應用上的效果，搭配上射頻模組與數位訊號處理模組，實際測量金屬圓柱與小型車輛等目標物之回波頻率與回波量的多寡，據以判斷目標物距離，並且與天線之 和 場型比值做比較與分析。

In this thesis, a Monopulse lens antenna system for 24-GHz forward-looking collision warning radar system has been developed. We use horn antenna which fed with a series-fed microstrip patch antenna array as transmitting and receiving antenna. In additional, we design a lens which focus length equals the height of horn to cover the horn of the receiving antenna, and verified that lens with dimension and focal length in several wavelength is working. Horn could suppress side lobe level and decrease the beamwidth of microstrip patch antenna array. Horn could also be strut of the lens of receiving antenna. Another advantage of horn antenna is the metal wall of horn could enhance the isolation between transmitting and receiving port. In the end, we combine the Monopulse lens antenna system with RF-module and DSP-module as a radar system. We measure the frequency of echo-wave to determine the distance between target and radar senor. At the same time, we measure and analysis the power level of echo-wave to compare with the sum and difference pattern of the receiving antenna we introduce.