Passive UHF RFID Tag With Backscatter Diversity

Performance degradation caused by multipath fading channel was investigated in a passive UHF RFID system. The fading channel problem is often mitigated using diversity combining techniques. In this letter, a novel dual-antenna passive UHF RFID tag with polarization-time coded backscatter diversity is proposed. An RFID system with such kind of tags can use polarization diversity combining technology to overcome the fading problem. The proposed polarization-time coding scheme not only lowers the corresponding RFID tag design complexity, but also effectively reduces detection errors of modulated backscatter signal. Empirical results of the dual-antenna tag emulator validate the feasibility of the proposed design.