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RFID system with multiple reader transmit frequencies

  • US 8,692,654 B2
  • Filed: 06/26/2012
  • Issued: 04/08/2014
  • Est. Priority Date: 06/26/2012
  • Status: Active Grant
First Claim
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1. An RFID system, comprising:

  • a) an RF-blocking enclosure having a port with a selected shortest dimension;

    b) an active RFID tag including a controller and an interior antenna coupled to the controller and located in the enclosure, the tag responsive to a selected RF downlink frequency range; and

    c) an RFID reader located outside the enclosure, the RFID reader adapted to simultaneously transmit directional RF signals on a plurality of frequencies corresponding to respective wavelengths smaller than the selected shortest dimension, the plurality of frequencies including a carrier frequency and an interference frequency, so that a beat frequency is defined between the carrier frequency and the interference frequency and the beat frequency is within the selected RF downlink frequency range,so that the transmitted signals pass through the port and the tag responds to the beat frequency.

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