平面式並接三對耦合線帶拒／帶通結構

A Planar Tri-Coupled-Line Band Reject/Band Pass Structures

本文探討三對並行耦合線形成 T 型之帶拒與帶通結構，並提供藉由結構微小變化使電路特性具有帶拒或帶通之方法，使後續在差異點連接開關以形成帶拒或帶通特性。文中所提三種濾波結構特性皆以耦合線阻抗矩陣進行分析，再依據求得之散射參數作為電路特性的探討與驗證。三種濾波結構之中心頻率均設計在2.45 GHz。為使電路易於分析，結構中所有耦合線之奇模與偶模阻抗皆設為一致，電氣長度同為90°。電路以電磁模擬軟體Microwave office 及IE3D進行模擬，並以RO4003 基板製作電路。結果顯示實際量測與模擬有良好的一致性。

This paper proposes band reject/band pass structures formed by usingthree sets of parallel-connected coupled-lines. The circuits could achieveband reject or band pass characteristics with slightly changes in the structure.All structures were analyzed by using a coupled-line impedance matrix.The scattering-parameters derived from the final two-port impedance matricescan be used to evaluate and verify electric characteristics of the structures.The design frequency was centered at 2.45 GHz, and full-wave electromagneticsimulators, known as the Microwave office and IE3D, were used forsimulating the filter structures. Further, the circuits were fabricated on aRO4003 substrate for carrying out laboratory evalutions. The measured resultsare the same as the simulation results indicating that the filter structuresproposed in this study function well as expected.