威爾金森式濾波功率分配器之隔絕度分析

Abstract

本論文將提出對於濾波威爾金森式功率分配器的隔絕度計算方式，透過ABCD矩陣及奇偶模分析法萃取出方程組，進而設計各電阻值。首先，從多節威爾金森式功率分配器討論隔絕度，然後，透過近似合成法設計短路端平行耦合濾波器，並延伸到短路端平行耦合濾波等功率分配器。相對於窄頻的耦合濾波器設計，利用S平面合成法設計寬頻濾波器，透過相同的設計原理套用在寬頻濾波等功率分配器上。由於等功率分配器和巴倫在輸出埠只相差一個相位反轉器，因此透過等效電路轉換，設計出濾波式巴倫。將四種電路模擬與製造後，對於隔絕度分析，以反射損耗的零點為基準，使隔絕度的零點與之重疊，將提供一套完整的數學系統說明。

A method to find the isolation resistances of a filtering power divider is proposed. By introducing the ABCD matrix and even-odd-mode analysis, a nonlinear simultaneous function for calculating of the resistors values for an equi-ripple isolation response is obtained. First, for simplicity, a conventional multi-stage Wilkinson power divider is studied. Then, for narrowband filtering power divider, a short-end parallel coupled filter is proposed and designed by the approximation designing method. In comparison with narrow band filtering power divider, a broadband filtering power divider is proposed and designed by the S-plane synthesis method. Finally, due to the equivalent circuit of a short-end coupling section inherently involving an ideal phase inverter, a filtering balun can be easily adopted from the proposed broadband filtering power divider. The proposed method to obtain the isolation resistors values will be used in all of the four cases.