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Surveillance and identification system antennas

  • US 5,280,286 A
  • Filed: 06/12/1992
  • Issued: 01/18/1994
  • Est. Priority Date: 06/12/1992
  • Status: Expired due to Fees
First Claim
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1. In a system for article surveillance and identification, an antenna system comprising:

  • interrogating transmitting antenna means for radiating an electromagnetic interrogation signal at a center frequency and having an elliptical polarization in a first-handed direction;

    transponder antenna means for receiving said electromagnetic interrogation signal and reradiating a modified electromagnetic interrogation signal having a linear polarization; and

    ,interrogating receiving antenna means for receiving said modified electromagnetic interrogation signal at substantially said center frequency and having an elliptical polarization in a direction opposite to that of said first-handed direction.

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