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Re: Solar measurements, and 3dB between CP and Linear???


Well you give me pause to think.  If we assume the sun is randomly
polarized {in other words equal intensity at all polarizations} I guess it
would not matter what polarization one chose.  And of course Faraday will
have no effect.  If on the other hand there is a component of linear or
circular polarization present in the radiation it would matter.  Likewise,
if the radiation were to pass thru media that imparts polarization to the

I guess its my difficulty shifting from thinking in terms of coherent
radiation to random noise.  I would sure like to get an opinion from a
radio astronomer...or a better explanation for myself.

But I guess it doesn't matter.  I stand corrected.

PS: I later read the reply from Tom Clark who agrees with you and
definitely qualifies as a radio astronomer!

At 05:20 PM 6/27/2001 +0100, you wrote:
>I am not sure I have understood your statement.  Are you saying that sun
>noise measured with a CP antenna will be 3dB higher than with a linear
>polarised antenna? If you are saying this, I do not agree.  They will
>measure the same.
>Perhaps you are referring to the 3dB difference you will certainly get (at
>least when the satellite squint is zero) when using a linear antenna with a
>CP source, such as AO-40.
>Also, Faraday rotation is an irrelevance as far as sun noise is concerned.
>Charlie G3WDG

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