A Novel Carrier Leakage Suppression Front-End for UHF RFID Reader

In this paper, a novel carrier leakage suppression (CLS) front-end for UHF RF identification (RFID) reader is presented. We demonstrated through experiment in the laboratory environment that the proposed CLS front-end has a significant improvement in the carrier-to-data ratio by more than 36 dBc in the UHF RFID frequency band. When inserted between the antenna and a Class-1 RFID reader, measurements show that the reader can successfully demodulate the generated tag signal for a power level of -80 dBm, which corresponds to the backscattered power at 20-m distance. The read range of the reader with the proposed CLS front-end is verified again in an indoor environment. The measured read range is found to be about 23 m for a commercial battery-assisted passive (BAP) tag. We showed that a Class-3 RFID system for a long read range of 20 m can be successfully established with BAP tags and the Class-1 reader with the proposed CLS front-end.