Auto hang tag with radio transponder

摘要: There is disclosed an automobile hang tag for use in parking control and the like with integral radio transponder, together interrogator apparatus associated therewith a system or other purposes. The detection range RFID transponder at least about six meters (20 feet) to enable rapid monitoring of facilities from moving vehicle through back window front windshield parked vehicles. Reliable trouble-free tags customary rear view mirror location facilitated by employing directional antennas tags, increasing antenna gain while suppressing false signals noise improving range-to-power ratio system. may be battery powered but are preferably unpowered transponders. Suitable employed include Yagi antennas, log periodic stacked dipole spiral slot monodirectional bidirectional those suitable selected frequencies within 1,000 megahertz 10,000 range.