本文探討兩段耦合線以上下方式排列形成類似分裂環之結構，並利用耦合線段不同的連結方式，使結構具有帶拒與帶通濾波之特性，其等效電路以兩段耦合線段連結代表方形環狀之傳輸線段。電路分析以耦合線阻抗矩陣進行，求取整體電路散射參數以做為電路特性瞭解與運用之依據。文中介紹帶拒與帶通濾波結構之分析與設計，中心頻率均設計在0.915 GHz，以做為UHF頻段射頻標籤系統之用。實際電路量測與模擬結果顯示，模擬值與量測值相當吻合。

In this paper a double coupled line band reject/band pass filtering structure is proposed. The proposed circuit is analyzed by the coupled-line matrix method. The over-all two-port scattering-parameters derived from these matrices can e used to understand the electric characteristics of the proposed structures and as a guideline for circuit designs. A one band reject and one band pass filtering circuit are designed to verify the theory. The central frequency is 0.915 GHz for the use of UHF band RFID applications. The measurement results show a very good agreement with the simulation results.