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The Journal of The Korea Institute of Intelligent Transport Systems Vol.7 No.2 pp.43-49
UHF 대역 RFID를 위한 송수신 분리 방향성 결합기 설계
Design of Directional Coupler for TX/RX Isolation in UHF Band RFID Application
Abstract
In this paper, new directional couplers for T/R switch of UHF RFID applications are proposed to overcome TX-to-RX leakage problem. The proposed method can remove TX-to-RX leakage caused by both imperfect isolation characteristic of the conventional directional coupler and the mismatch of antenna impedance. Two directional couplers are implemented using distributed elements and lumped elements respectively for the verification. The varactor tuneable circuits for compensation of the antenna mismatch is also proposed. The measurement result shows excellent TX-to-RX leakage suppression, more than 45dB in 910MHz.
