兩種微帶線慢波結構與短路端步階阻抗諧振腔雙頻濾波器之設計

Abstract

本論文含二部份，第一部份提出二種新的微帶線慢波結構，第一種慢波結構是在傳統的微帶線內部週期性地加入接地細帶，利用微帶線內部的接地細帶可提升其單位長度電容，並利用減少微帶線兩側的線寬增加單位長度電感，當單位長度的電容值與電感值都提升後，慢波因子因此增加，使得電路大幅縮小；第二種慢波結構是由曲折線與並聯的開路殘段所構成，單位長度電感主要由曲折線的線寬控制，而單位長度電容主要由並聯的開路殘段之線寬決定，此慢波結構的最大特色是具有可獨立控制的結構參數來分別達到所要的慢波因子和特性阻抗值，使電路設計相當方便，本文使用此二種慢波結構微帶線設計許多小型化微波電路。 本論文第二部分提出一種全為解析解的方法設計雙頻濾波器，首先是根據濾波器的規格來決定兩端接地的半波長步階阻抗諧振腔其結構參數，再利用K轉換器決定諧振腔間的耦合量，由於步階阻抗諧振腔與K轉換器均有完整的解析方程式，這種方式使得雙頻濾波器設計相當簡單迅速。

This dissertation consists of two parts. First, two types of microstrip slow-wave structure are proposed. The first one has the signal strips and the inserted ground strips periodically loaded in the internal part of the conventional microstrip line. The inserted ground strips increase the per-unit-length capacitance. The per-unit-length inductance is increased by decreasing the line widths on the two sides of the microstrip line. Therefore, the slow-wave factor increases so that the circuit size can be significantly reduced. The second type comprises a meander line and a shunt open-circuited stub. The per-unit-length inductance is mainly attributed to the meander line, and the per-unit-length capacitance is primarily controlled by the shunt open-circuited stub. The main property of this slow-wave line is that it has independently controlled structural parameters to realize the required slow-wave factor and characteristic impedance. This facilitates the circuit design. These two slow-wave structures are used in many miniaturized circuits. Second, a dual-band filter with the analytical design method is proposed. The structural parameters of the short-circuit terminated half-wavelength stepped-impedance resonator (SIR) are first determined by the filter specifications. Then, the K-inverter is used to control the coupling between resonators. Due to the completely analytical equations of the SIR and K-inverter, the dual-band filter design becomes easier and much more efficient.