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Dual resonant antenna circuit for RF tags

  • US 5,317,330 A
  • Filed: 10/07/1992
  • Issued: 05/31/1994
  • Est. Priority Date: 10/07/1992
  • Status: Expired due to Term
First Claim
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1. In a two-way communication system having a stationary member and a portable passive member, said portable passive member having circuitry for storing and transmitting coded information, said stationary member transmitting a signal at a first frequency via a magnetic field and said portable passive member transmitting coded information stored by said circuitry in said portable passive member at a second frequency via a magnetic field, the improvement comprising an antenna circuit provided in said portable passive member, said antenna circuit comprising:

  • (a) a parallel resonant circuit having a receive antenna for deriving operating power from said signal at a first frequency for use in said circuitry provided in said portable passive member; and

    (b) a series resonant circuit having a transmit antenna for transmitting at a second frequency said coded information stored by said circuitry in said portable passive member, said second frequency differing from said first frequency.

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