因應近年來被動雷達概念的出現與實現，在本論文中將以實測與模擬的方法研究空中目標物的雙向雷達反射截面積。吾人在UHF頻段，設計目標物散射量量測實驗，透過改變目標物的距離和角度等實驗參數，討論量測散射量大小的變化及訊號散射機制。我們亦使用模擬的方式，比較實際量測和模擬的雷達反射截面積差異，驗證實驗的準確性，以及分析實際量測會遭遇的問題。
本研究亦為配合被動雷達接收機開發兩件射頻電路。其一為驗證接收機目標物測向演算法的雙訊號源入射模擬板，模擬訊號入射時因天線擺設所產生的相位差，便於測試被動雷達接收機是否可準確判讀訊號源的方向。另一件射頻電路是因應射頻調諧器在使用過程中，其相位無法長期維持同步，需要將射頻調諧器的輸入由天線端切換至校正用訊號源進行重新校正的需求，故設計了一個射頻接收機同步校準器，透過搭配被動接收機的GPIO埠，切換射頻調諧器的天線端和校正端的連結。
配合被動雷達的表現我們提出一款電子式波束切換的超高頻陣列天線。該天線透過一個射頻開關切換器，在16支微帶天線切換中，切換選擇相鄰的4支天線，產生指向性波束。此天線可涵蓋360度的水平方向與垂直面25度的範圍，可當作被動雷達的接收天線。在未來的應用上可以搭配軟體無線電組成的被動雷達接收機，以分時多工的方式，產生可電子式旋轉的掃瞄波束，涵蓋較大的範圍。

In this thesis, measurements and simulation were conducted to study the bistatic radar cross section of airborne targets, which is critical to the realization of passive radar. The scattering measurements were performed in the UHF band. By altering parameters such as the target range and incident angle, we studied the changes in the amount of scattering to identify the scattering mechanism. Simulations were also performed to compare with measurement results. The differences were used to identify problems in the current measurement setup.
This research also developed two RF circuit devices to help facilitating the passive radar receiver. One is a simulation board useful to the development of direction-of-arrival algorithm on receiver. The board emulates the phase differences received by 4 RF tuners due to 2 sources from different angles. The other device is used to switch the tuner inputs from antennas to the same controlled RF sources, so that the clocks of individual receivers can be synchronized.
In this thesis, we also propose a electronically controlled beam switching antenna array in UHF band. By employing RF switches, 4 adjacent antenna elements are selected among 16 patch antennas to produce a directive beam. The antenna can be used as the receiving antenna of a passive radar. By employing time division method, the array system can therefore cover the azimuth plane via the switching beam.

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