Expert: Philip A. Stahl - 9/30/2011

Question
sir pls  tell why radio waves are non polarizing while light waves are

Answer
Hello,

I'm not sure where exactly you got the idea that radio waves are not polarized, but they are. For example, the planet Jupiter exhibits decametric radiation that's circularly polarized and near 20 MHz band it is predominantly right-handed. Recall the direction of the E-field defines the orientation of polarization. With circular polarization, the E-field rotates through 360 degrees with every cycle.  It is possible this is what has you confused, since some texts erroneously refer to circular polarized waves as "unpolarized".

In addition, I have answered earlier questions in this forum to do with radio wave applications and Stokes' parameters. See e.g.

http://en.allexperts.com/q/Astrophysics-3368/2008/2/Normalized-Stokes-parameters

Of course, one can also look at the response, say of a particular antenna (e.g. for a simple dipole radio telescope) to a radio wave that's arbitrarily polarized.

In this case, if an antenna dipole exhibits voltage V when when a polarized radio wave of field E is incident on it, then (if l is the effective length of the dipole):

V = El = El cos Θ

and Θ is the angle between E and l.

One can also, in such cases, express the voltage V for the dipole in terms of the polarization state of the antenna - call it P(a) and the polarization state of the wave, call it P(w). Then:

V = El cos [½ P(a)P(w)]

Thus, we see that not only are radio waves polarized, but also polarizing!

Hope this helps shed light!