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A Drop in power in a directed microwave beam?

  1. Sep 1, 2016 #1
    Would it be a drop in power as the square of the distance in a directed microwave beam? Thanks!
     
  2. jcsd
  3. Sep 1, 2016 #2

    mfb

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    For small distances: probably not.
    For very large distances: yes.

    The typical length scale is (antenna diameter)^2 / (wavelength), focusing something over a longer distance does not work.
     
  4. Sep 1, 2016 #3
    Thanks! What would be a short / large distance in this context?
     
  5. Sep 1, 2016 #4

    mfb

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    Did you see my comment about the length scale? If you are at 5+ times this length scale the inverse squared distance is a good scaling law. If you are below that length, it does not have to be a good approximation. It might be, but that depends on the beam then. In between, things are in between those two cases.
     
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