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Re: (meteorobs) radio meteor polarisation diversity

  Dear All,

A late reaction.

The University of Ghent did study to contribution of the vertical component
of forward scattered meteor signals in the FM band. The conclusion was that
it is not worth doing. 

When you browse the RMOB observations, you will notice that only one
observer, Maurice De Meyere, is currently using a crossed Yagi setup, only
because he made his setup this way several years ago. 



	Kind regards,

	 Chris


Date: Fri, 22 Sep 2000 14:56:03 +0000
From: "Shelby Ennis, W8WN" <w8wn@arrldot net>
Subject: Re: (meteorobs) radio meteor polarisation diversity

At 12:08 2000-09-22 +1000, you wrote:
>In one email he brought up the issue of loss of sensitivity due the 
>probable change in polarization of the radio signal after reflection 
>not matching your antenna. He then speculated on the use of helical 
>antennas.

I agree with the comments by Phil Gebhardt.  But, as he indicated, I'm not
aware of much work either vertical or crossed polarization.  I've used
meteor scatter for communications since 1955.  Just about all work that I'm
aware of has been horizontal.  This is primarily because everybody was
already horizontally polarized, as tests many years ago indicated that
horizontal was slightly better for weak-signal VHF work.

I am aware of only a very few vert-to-vert tries, and they were generally
unsuccessful.  However, the attempts were too few to really draw any
conclusions.

With circular, you of course lose 3 dB on a linear-polarized signal.  I am
not aware of any cross-polarized tests, as few would be willing to atempt
them.  Some years ago I did run circular polarization for a few schedules.
They were rather successful - but it's unknown how they would have compared
with my running horizontal for the same schedules.  And all of these were
*not* direct forward scatter, but were side scatter (necessitated becaue of
the short distance between us).  This means that the geometry of the
reflection may have caused a polarization shift, which might have favored
circular on my end.

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