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Microwave identification system

  • US 5,361,071 A
  • Filed: 08/06/1992
  • Issued: 11/01/1994
  • Est. Priority Date: 12/06/1990
  • Status: Expired due to Term
First Claim
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1. A microwave identification system comprising:

  • interrogation transmitter/receiver means and an interrogation antenna system for transmitting an interrogation electromagnetic field and receiving responsive electromagnetic waves;

    a plurality of responders each including a responder antenna system for communicating with the interrogation transmitter/receiver means, each of said responders being responsive to the interrogation electromagnetic field to generate responsive electromagnetic waves, the responder antenna system comprising an antenna array having at least first and second transmitting/receiving antenna elements and modulation means interconnecting the first and second transmitting/receiving antenna elements, the first and second transmitting/receiving antenna elements being responsive to the interrogation electromagnetic field to generate at least first and second antenna output signals, respectively, the modulation means responsive to the first and second antenna output signals for generating at least first and second modulated output signals which are encoded with a responder code that is particular to the associated responder, and the modulation means applying the first and second modulated output signals to the second and first antenna elements, respectively.

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