使用H型諧振腔之奇偶模雙頻帶通濾波器

Abstract

本篇論文提出一個四埠平衡式帶通濾波器之數值解析方法，藉由在輸入端激發模態的不同，產生不同中心頻的通帶，此兩模態分別為奇模以及偶模。共振腔結構為一工字型共振腔，利用偶模與奇模訊號送入時，等效電路之差異產生不同的頻帶，以達到雙頻帶的效果，此架構不僅具有尺寸較小的優勢，且兩頻帶之隔絕度高。並以耦合矩陣的合成方式為基礎，用數值解析方法得到此種架構之理想電路的數值解，此分析方法可有效提供一個設計濾波器的參考依據，並提出兩個例子證明此分析方法的正確性。使用的板材為RO-4003，厚度20mil、介電常數3.58的基板，並選擇微帶線做為電路合成方式。

In this thesis, a novel analytical approach for a four-port balanced bandpass filter is proposed. The proposed bandpass filter could operate at different passbands while exciting even or odd-mode signal respectively. The filter based on H-shaped resonator would be different equivalent circuit when excited with even- or odd-mode signals. The proposed filters have the advantage of compact size and good isolation between two passbands. Based on the corresponding coupling matrices, the dimensions of the filter configuration are extracted via even- and odd-mode analysis. To verify the proposed method, two filters are implemented by microstrip lines on the Rogers RO-4003 substrate with a thickness of 20 mils and a dielectric constant of 3.58.