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DEVICE FOR MEASURING PERMITTIVITY OF MATERIALS

  • US 3,694,742 A
  • Filed: 07/15/1970
  • Issued: 09/26/1972
  • Est. Priority Date: 07/15/1970
  • Status: Expired due to Term
First Claim
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1. A device for measuring permittivity of a material, comprising first and second electrodes to be applied to said material to measure a capacitance formed thereby;

  • a measuring oscillator coupled to said first and second electrodes to measure the capacitance formed thereby;

    a third electrode to be applied to said materials, said third electrode being identical with and additional to said first and second electrodes;

    a changeover switch means operable between first and second positions to respectively connect said additional electrode electrically in parallel with said first and second electrodes during measurement; and

    means connected to the oscillator output to measure the difference between a first value of capacitance measured in said first position of said changeover switch means, said first value of capacitance being that existing between the electrically paralleled first and third electrodes, and said second electrode, and a second value of capacitance measured in said second position of said changeover switch means between the first electrode and electrically paralleled second and third electrodes, whereby the permittivity of the material to be measured is computed from the difference between the first and second measured values of capacitance to eliminate any errors due to improper contact of the electrodes with the material.

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