| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a radio tag of a passive system (battery exchange unnecessary) with a detection distance of several meters (capable of remotely detecting a moving person or object) and weak radio wave use (without the need of legal utilization procedure and without influence upon human bodies and medial equipment). <P>SOLUTION: A radio tag 20 comprises a receiving antenna unit 21, an impedance conversion matching unit 22, a High-Q resonance circuit 23, a double wave rectifier circuit 24, an impedance adjusting unit 25, a smoothing circuit 26, an ID transmitting unit 27 and a transmitting antenna unit 28. In order to achieve the detection distance of 1m or longer, the transmitting antenna unit and the receiving antenna unit are separately structured and as regards the gain of the receiving antenna unit, by employing the receiving antenna unit of a type having a higher gain than that of the transmitting antenna unit, the detection distance can be made longer within the specific value of weak radio wave. <P>COPYRIGHT: (C)2008,JPO&INPIT |
