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Polarization change upon Reflection

  1. Jul 2, 2015 #1

    I am trying to determine how an electromagnetic wave changes polarization upon reflection off of an arbitrary object. Here are my confusions in particular.

    1. My assumption is that the change in polarization is very much dependent on the geometry of the object, but I don't know the exact mathematical formalism behind it.

    2. If the object is a PEC, will polarization be preserved upon reflection independent of geometry?

    Thanks in advance.
  2. jcsd
  3. Jul 2, 2015 #2


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    I have only a simple view of it which might help slightly, and I have two examples (assume transmitting Horizontal linear polarisation (HP) for illustration):-
    1. If we have a rod at an angle to horizontal, then it will have a current induced in it by the component of the field lying along its axis. This current causes radiation polarised in the plane of the rod, and has a vertically polarised field component. The polarisation has been rotated. Complex objects might be studied using antenna analysis techniques.
    2. Assume we have a transmitter, plane mirror and receiver all located on a flat table with a wave passing between them. No rotation of polarisation. But if the mirror is raised up so it is not in the plane of the table, and is tilted appropriately, geometry indicates that the reflected wave is now not truly H or V but is rotated. You can also see that an object viewed in the mirror is rotated. This is just geometry, "no physics" involved.
  4. Jul 2, 2015 #3


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    Yes. That's the bottom line. There is no hint of any violation of any physical conservation law here. In fact it is not at all surprising - except possibly at first sight.
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