Two-dimension localization of passive RFID tags using AOA estimation

RFID is widely used in electronic identification and tracking. Both identity and location information are important in object tracking applications. Recent techniques in RFID localization generally use active tags and pay attention to RSS (received signal strength). As the signal processing of passive RFID is more complicated, RSS based localization of passive tags has a high error. Note that phase characteristics play an important role in signal propagation. This paper presents a method to locate passive RFID tags by estimating AOA (angle of arrival) using the phase difference. Modelling and experimental results show that AOA estimation by phase difference can be used to locate RFID tags accurately.