以非對稱直交分合波器設計跨接耦合器及其雙頻設計

Abstract

本論文研究串接兩個任意功率輸出比例的非對稱分波直交耦合器，設計跨接耦合器。每一個耦合器兩個對角端埠可具有不一樣的負載阻抗。由於電路有數個設計自由度，本文以區塊ABCD矩陣分析，以預測跨接耦合器的頻寬。 為了讓跨接耦合器具有雙頻功能，本文引用一個基本雙埠單元，取代直交分波耦合器中的四分之一波長傳輸線。此雙埠基本單元包含一段步階式阻抗線段及其末端的兩個並聯傳輸線殘段。利用傳輸線理論，列出解析方程式並求電路參數解。本文實作一個0.9/1.8 GHz 的跨接耦合器電路，並加以量測以驗證本文所提之設計。

Two asymmetric branch-line hybrids with arbitrary power divisions are cascaded for design of a crossover coupler. The two pairs of the diagonal ports are allowed to have different characteristic impedances. Block ABCD matrices are applied to estimate the bandwidth of the crossover coupler. To achieve the dual-band operation, an elementary two-port is employed to replace the □/4-section of each hybrid. The two-port consists of a stepped-impedance section with two open stubs shunt at both of its ends. By means of the transmission-line theory, analytical equations are formulated to solve the circuit parameters. A circuit designed at 0.9/1.8 GHz is realized and measured to validate the idea.