一种改进型微带线定向耦合器及其应用  

Improved microstrip directional coupler and its application

作　　者：魏峰[1] 史小卫[1] 陈蕾[2] 黄丘林[1] 

机构地区：[1]西安电子科技大学天线与微波技术重点实验室,陕西西安710071 [2]西安工业大学,陕西西安710032

出　　处：《西安电子科技大学学报》2009年第2期281-284,共4页Journal of Xidian University

基　　金：陕西省重大科技创新专项资金项目资助(2007ZKC(一)01-03)

摘　　要：在传统的微带线定向耦合器设计中,奇偶模之间不同的相位速度导致了较低的隔离度.针对此问题提出双枝节功率相消技术,在微带线定向耦合器的匹配端口添加两个枝节引入失配,通过调节两个枝节的参数改变匹配端口的反射信号,使其在接收端口处的幅度和相位产生变化,从而有效抵消发射端口在接收端口的泄漏信号.采用这种技术设计了一种工作频带为902-928 MHz的微带线定向耦合器,并将其应用于超高频射频识别阅读器中.该定向耦合器工作在920 MHz时隔离度可以达到-65 dB,耦合度约-10 dB,有效地改善了超高频射频识别阅读器的收发隔离,同时将微带线定向耦合器的尺寸减小了20%,在实际应用中取得了良好的效果.A conventional microstrip directional coupler has an inherent drawback of poor isolation due to an unequal phase velocity between even and odd mode.To solve this problem,the technology based power canceller with the dual-stub is presented.Mismatch is induced by the dual-stub added at the Match Port of the microstrip directional coupler.Parameters adjustment of the dual-stub can change the magnitude and phase of the reflected signal from the Match Port at the RX Port,which can effectively cancel the leaked signal from the TX Port at the RX Port.A microstrip directional coupler for the UHF RFID reader with the operating frequency band of the range of 902-928 MHz is proposed.The proposed directional coupler can obtain excellent isolation of-65 dB and coupling of-10 dB at 920 MHz,effectively improve the isolation between TX and RX and decrease the size by 20%.It is successfully used in a practical UHF RFID reader.

关 键 词：射频识别 定向耦合器 隔离度 方向性 微带线 

分 类 号：TN622[电子电信—电路与系统]