On Tue, 05 Apr 2005 15:33:42 GMT, Jim - NN7K
wrote:

|Thanks, Wes-- when originally considered it was looking at the moon
|in terms of approaching a point source (the surface of the moon
|being relatively small TIME-WISE- but the surface to the edges
|being relatvly HUGE in distance , per Wavelength would allow a
|distortion of a reflection. As I said , its dangerous to get me
|thinking too hard (I tend to fall asleep)! Tho, hadn't considered
|the (Cheezy) effect! makes me wonder if linear circular would be
|the way to go, or would it distort as bad as other signals
|(do to Faraday Rotation- the skewing of the signal's polarization)?
|Just curious. The linear circular refers to circular yagi construction
|rather than as a Helix? Or is this tilting at windmills? Jim - NN7K

Linear circular is an oxymoron. When you phase two crossed Yagis to
generate circular polarization, it is just as "circular" as a helix.

It's been 20 years (how time flies) since I was operating EME but I
remain interested. There is a current school of thought that
switchable polarization has an operational advantage. I remain
unconvinced when the complexity and degradation of performance is
factored in. I don't know of anyone who is using true circular
polarization (at VHF) even though their antennas are capable of
generating it.

The reason to have switching capability is speed up the QSO. With
fixed linear polarization, at any given time, there can be spatial and
Faraday rotation caused polarization mismatch between two stations
located on different parts of the Earth. Switching polarization at
one end can overcome all or part of this mismatch. Usually, if one
waits long enough the always changing Faraday rotation will bring the
mismatch to zero or near zero without any switching.

So there is a trade of complexity for speed. In the modeling I've
done, I have yet to see a case of high gain, crossed-element Yagis
that were not degraded by the presence of the stacking hardware.