本論文提出以可重組式微波元件所實現之測速雷達系統，目標為利用簡單的電路架構整合雷達測速與偵測結果傳送兩個子系統，提供一個低成本的短距離速度監測方案。首先，本研究提出一個具有三種功能的可重組式微波元件，中心頻率設計於 2.45 GHz，藉由控制二極體開關改變微帶線的連接方式，可切換成分支線耦合器、帶通濾波器與帶拒濾波器三種不同電路功能，並實作於印刷電路板上。其整體電路面積為 31.1 mm × 34.6 mm，電氣尺寸在中心頻率 2.45 GHz 下為 0.4785 λg × 0.5324 λg。而後，據以發展成一簡易都卜勒測速雷達系統，當此 2.45 GHz 可重組式微波元件操作在分支線耦合器模式下，具有測速雷達的功能，有15 dBm的發射功率，20 dBi的發射天線增益，在 200 cm 的偵測距離內提供 100 mm/s 至 270 mm/s 的速度監控，且誤差低於 7 %。而當可重組式微波元件操作於帶通與帶拒濾波器模式下，則具有調變發射機的功能，得以開關鍵控將速度資訊通過天線發送，再以一簡易接收模組進行速度的解調。論文中包含此一基於可重組式微波元件之測速雷達系統的工作原理與設計流程，並以實測驗證系統效能。;In this study, a compact radar system for speed measurement based on a novel reconfigurable microwave circuit is proposed. Specifically, to provide a low-cost solution for short-range speed monitoring, a Doppler radar and a transmission module for the detected speed are integrated in a simple circuit architecture. First, a 2.45-GHz reconfigurable microwave circuit with three circuit functions is proposed. By using p-i-n diode switches to change the connections of microstrip lines, the proposed reconfigurable microwave circuit can be switched between three different circuit function including branch-line coupler, bandpass filter and bandstop filter. It is implemented on a printed circuit broad with a circuit size of 31.1 mm × 34.6 mm, and the corresponding electrical size is around 0.4785 λg × 0.5324 λg at 2.45 GHz. It is then developed into a Doppler radar for speed-measurement. When the reconfigurable microwave circuit is operated in the branch-line coupler mode, it has the function of a Doppler radar with 15-dBm transmitting power and 20-dBi antenna gain. It can provide speed monitoring from 100 mm/s to 270 mm/s within the range of 200 cm, and the error is less than 7 %. When the reconfigurable microwave circuit is switched between the bandpass and bandstop filter mode, the system becomes a wireless transmitter and send the detected speed information through the on-off keying modulation scheme. A simple wireless receiver module will then demodulate the speed information. This thesis includes the operation principle and design flow of this compact radar system, and the system performance are carefully verified by measurement.
