奇偶模雙頻帶通濾波器

Abstract

本篇論文提出一個新的雙頻濾波器架構，此濾波器的兩個通帶分別呈現在兩種不同的輸入訊號下，一種是奇模訊號，另一種是偶模訊號。其中，主要利用耦合微帶線在針對此兩種訊號輸入時，會有不同波速與特性阻抗的特點，將分別以步階阻抗諧振器或均勻阻抗諧振器架構設計的兩個帶通濾波器加以組合。並且，適當的控制微帶線的耦合強度能有效調整兩個通帶的距離。更進一步，利用步階阻抗的諧振特性，將原本二倍頻的諧振頻率推遠。

In this thesis, a new filter structure has two passbands while exciting differential or common signals is proposed. In microstrip coupled lines, there are different characteristic impedances and phase velocities for even- and odd- mode signals. Using the characteristics, the filters can be realized with both stepped-impedance and uniform impedance resonators. By controlling the coupling strength of the coupled lines, the two passbands can be separated effectively. Based on the resonant characteristics of a stepped-impedance resonator, the first spurious harmonic can be higher than 2fo.