雙極化寬頻單脈衝天線

Abstract

本研究中，將會實做雙極化寬頻單脈衝天線，將陣列天線設計成雙極化，可以避免因為訊號與陣列天線極化正交，導致接收的訊號能量過小，造成無法正確解調訊號的問題。此陣列天線應用於定向系統(direction finding system)，使用單脈衝偵測來波角度，所以本研究將會模擬與量測此陣列天線的單脈衝特性，在量測單脈衝的sum和difference遠場時，需要使用波束成形器(beam-former)來產生A+B+C+D、(A+B)-(C+D)和(A+C)-(B+D)的場形，此研究使用的波束成形器為威爾京森功率分配器(Wilkinson power divider)和鼠競環耦合器(rat-race coupler)，將會量測4GHz、7GHz和11GHz三個頻率點的場形，在本文的最後會附上4~18GHz的模擬場形圖，驗證此陣列天線在4~18GHz都能有良好的單脈衝特性。

In this thesis, the monopulse antenna is applied to direction finding system. A dual polarization wideband monopulse antenna is presented. We can prevent the wave polarization and antenna polarization are orthogonal by a dual polarization antenna. To verify the monopulse performance, we measured the sum and difference radiation patterns. The beam-former is used to get the sum and difference patterns and the beam-former includes both Wilkinson power divider and rat-race coupler in this thesis. Finally, we attached to the 4-18GHz simulation pattern explaining the monopulse performance.