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Microwave spectrometers

  • US 5,548,217 A
  • Filed: 05/15/1995
  • Issued: 08/20/1996
  • Est. Priority Date: 11/10/1984
  • Status: Expired due to Fees
First Claim
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1. Apparatus for detecting at least a concentration of a fluid, comprising:

  • a chamber into which the fluid is introduced;

    propagation means for propagating microwave radiation into said chamber;

    microwave modulation means for applying a relatively high frequency modulation to the frequency of said microwave radiation;

    further modulation means for applying an independent relatively low frequency modulation to a frequency of a selected absorption peak in the absorption coefficient vs. frequency characteristic of said fluid;

    detector means for detecting the microwave radiation reflected from said chamber;

    means for selecting a frequency band around said relatively high modulation frequency;

    demodulating means for demodulating the output of said detector means within said frequency band with said relatively high modulation frequency; and

    processor means responsive to the output of said demodulating means and to the variations in said parameters to determine at least said concentration of said fluid.

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