A smart beam steering RFID interrogator for passive tags in item level tagging applications

Item level tagging is a challenge for low cost and passive RFID tags since these are closely packed in the operating environment. Passive tags suffers from poor reading rates using existing RFID interrogators with limited capability on tags and interrogator. In this paper, we have proposed a low cost electronic beamsteering method which enable existing RFID interrogator to be ldquosmarterrdquo by reconfiguring its RF beam adaptively and yet maintain high angular resolution. Little changes to existing transceiver is required to minimize costs since only its external reference clock is enable by direct digital synthesizer (DDS) as a variable reference time delay. The new RFID transceiver system is designed at ISO standards at UHF bands. Experimental results show that it is able to read at least twice as many passive tags, as compared to the conventional beam-switching system.