A feasibility study of plug-in type RF tag localization system for handheld UHF RFID reader/writers

This paper proposes a plug-in type RF tag localization system, using an Angle of Arrival principle, in UHF RFID, particularly targeting handheld reader/writers. Being a plug-in type, the RF tag localization system is receive-only, incurring no radio license requirement, small in size and can be built at low cost. Our fundamental idea is to employ a newly developed short-range mono-pulse method for the RF tag direction detection enabled with affordable software defined radio device and an analog front end. In this paper, we report an experimental evaluation with a functional prototype primarily on the detecting accuracy. It is shown that we can achieve about 3 degree accuracy for RF tags at 7.3 m distance from a 4 W EIRP reader/writer. Because the measurement in the direction of boresight is more stable than the other directions, the direction accuracy can be improved when we feed back the direction detection to the orientation of handheld reader/writer. We also confirm this feature experimentally.