Radio tag

Patent Pending PROBLEM TO BE SOLVED: To provide a technology for reading, from a remote site, a radio tag device installed around a running path such as a road. ; SOLUTION: The present invention relates to the radio tag device including: an antenna for radio tags which is a rectenna including a reflector L1 of a microstrip structure, bisected power feeding elements L2 and L3 and waveguides L4-L6 and in which GND plates are disposed at intervals of about [lambda]/40 from L1-L6 and directivity is tilted from a front direction to the direction of L4-L6.