A novel passive UHF RFID transponder with space division Anti-collision Algorithm

This paper presents a novel space division transponder anti-collision algorithm for RFID system, which has been implemented in a passive transponder. Working at 915 MHz carrier frequency with 4W effective isotropic radiated power (EIRP) from a reader, the tags can be distinguished by their diverse distances to the reader if the distance difference is larger than 0.11 m with communication range from 1 m to 2.5 m. Compared with a space division method using a multi-antenna reader, our approach only needs simple modifications of the transponder and reader circuits, which leads to negligible increments of circuit area and power consumption. Furthermore the proposed anti-collision algorithm can be implemented with any other tag anti-collision algorithms to achieve higher identification speed.