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A Dielectric constant of air with temperature change

  1. May 6, 2018 #1
    I'm looking to see how much the dielectric constant of air will change mostly as a function or air temperature.

    Is there a formula that outputs air dielectric as a function of temperature or atmospheric pressure?
  2. jcsd
  3. May 6, 2018 #2
    If using a capacitor you might be able to use C=Ae/d but I really don’t understand your question fully
  4. May 6, 2018 #3
    Let's pretend I have a source antenna outputting a 1 GHz. I have two receive antennas on the main lobe. One is 10 meters away and the other is 11 meters away. I do my measurement at 25 C. I'm going to get some phase delta between these two antennas.

    Now if the temp is 15 C when I make the measurement, what will the phase delta be? I'm ignoring everything else at the moment and only care about the effect of air. If I knew the dielectric I can compute the velocity factor and know the magnitude of change.
  5. May 8, 2018 #4
    Intuitively, I would expect permittivity to increase with an increase in temperature. The relative permittivity is directly related to electric susceptibility, and I believe there are a number of publications that exist discussing the subject of the dependence on electric susceptibility of air with temperature. I haven't done a lot of research on the subject, but I would start there.
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