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Micropower RF material proximity sensor

  • US 5,832,772 A
  • Filed: 01/27/1995
  • Issued: 11/10/1998
  • Est. Priority Date: 01/27/1995
  • Status: Expired due to Term
First Claim
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1. An apparatus for detecting a proximity of a material, comprising:

  • an oscillator which oscillates at a nominal frequency and produces an oscillator signal;

    an antenna coupled to the oscillator which is resonant at the nominal frequency of the oscillator and which has a characteristic impedance which depends on materials in proximity to the antenna; and

    a detector coupled to the oscillator which detects changes in the oscillator signal as a result of changes in the characteristic impedance of the antenna caused by changes in materials in proximity to the antenna.

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