RADIO TAG DEVICE, ANTENNA FOR RADIO TAG, POWER RECEPTION CIRCUIT, AND RADIO TAG READING METHOD

摘要

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 λ/40 from L1-L6 and directivity is tilted from a front direction to the direction of L4-L6; a power reception circuit which obtains a boosted rectification DC power supply voltage and an RF signal at a node D of a capacitor C1 and a rectifying element D3 from an RF input signal supplied from an antenna feeding point C and obtains a boosted RF signal at a node E of the rectifying element D3 and a short stab L7; a microprocessor U3; and a circuit for performing data input and power supply control of U3. Bias voltages of variable impedance elements D1 and D2 are efficiently changed according to an output from a data output terminal Dout of the microprocessor U3, thereby redirecting information outputted from the microprocessor U3 to a reader while placing it on radio waves.

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