Evaluation of tag moving direction detection in a UHF RFID gate system

A UHF-band RFID system handling many RF tags has some advantages over a bar code system such as simultaneous multi-reading and long read range. Especially, it has been strongly desired by the logistics and the retail industries for efficiency of operation. Recently, user-friendly RFID systems are being studied. We focused on a gate system using RFID technologies. If the tag moving direction can be recognized at the RFID gate system, it will be very useful for the efficiency of inventory management and the checking of pilferage or shoplifting. In this paper, new methods of tag moving direction detection using the difference of passing time of two antennas without expensive external sensors is proposed and evaluated.