A Novel Carrier Leakage Cancellation Circuit for RFID System

This paper proposed a novel high isolation leaking carrier cancelled system used in the UHF RFID reader. The circulator of conventional RFID system is replaced by the deformed microstrip rat-race circuit (RRC), furthermore, the leaking carrier extracted circuit is connected in the receiver. The amplitude and phase of leaking carrier varying need not be real-time tracking. Results showed that the TX-to-RX isolation improved 48~70 dB higher than other cancellation circuits. The proposed leaking carrier cancelled system cutting down the cost and improved obviously the isolation of Tx-Rx.