印刷偶級天線組合Ka-頻帶檢波器之設計與量測

Abstract

本篇論文主在以線性偶極天線結合檢波器，設計製做量測一Ka-Band的映 像接收器(Video Rectenna)。因為在往更高頻的領域發展時，信號源和接 收器具有同樣重要的地步。此接收器是將Ka-Band的RF信號能量轉換為直 流的信號能量，它主要可應用於衛星的微波發電站及間諜衛星偵查。首先 ，全波分析的數值方法被應用來模擬印刷線型偶極天線的特性,以便在可 控制的變數中求取最佳幅射效率。我們將線性耦極天線視為一赫茲偶極( Hertzian Dipole)，由影像定理可求其頻域格林函數 (Green's Function)分佈，代入帕格林頓方程式 (Pocklington Equation)後化成積 分運算子方程式，利用動差法(Moment Method)化成矩陣型型式，最後得 到天線上電流分佈。由電流分佈可算出輸入阻抗和介電板的 介電常數和 厚度對幅射效率的影響。利用此設計的Ka-Band偶極天線加上整流器，我 們製做了一類光接收器(Quasi-optical Receiver)。但基於實際可獲得最 大功率源的限制，我們採用將電路放入波導管的量測方法，整系統當有18 dBm的RF能量強度落在天線上時，轉換效率最佳可達27%。當我們把10mA偏 壓電流加於二極體時,接收器的敏感度為82mV/mW，在輸入能量-7dBm時。 最後，許多改進此印刷天線的方法及未來研究方向被加以討論。 The main target of this thesis is to make a Ka-band video rectenna by printed wire antenna associate with a rectifier. When we want use to a higher frequency band, the importance of power source is the same as the receiver. This receiver change the RF signal energy into DC output power. At first, a full- wave numerical analysis method is used to simulate the characteristics of a wire printed dipole antenna, a best radiation efficiency was obtained under controlled factors. we treat a wire printed dipole antenna as a Hertzian dipole on the substrate. The Green's function is obtained by image theory, then put it into Pocklington's equation, it becomes an integral- solving problem. Method of moment is used to obtain an integral- solving solution by a matrix form. Finally, we can get the current distribution of the antenna, and calculated the input impedance, and the effect of substrate on the radiation efficiency. Using this Ka-band dipole antenna with a rectifier, we design an quasi-optical receiver. Due to the limitation of the power, we put the rectenna in a waveguide, in order to measure the rectenna efficiency. The best transfer efficiency reach 27% when there is 18dBm energy incident on to the printed dipole. When a 10mA current bias on the diode, the sensitivity of the detector is 82mV/mW at -7dBm input power level. Finally, many improve methods and the directions of future study are given.