Richard Fry wrote:
"Roy Lewallen" wrote
A head-on reflection to a flat surface results in the polarization sense
reversal you mention. But reflection at a shallow angle doesn't. (etc)
__________

Thanks for the reply. I was recalling the experimental results that RCA
gathered in fixed and mobile tests in the Chicago loop when Ch 7 (ABC)
installed an RCA c-pol transmit antenna on Sears Tower there in the 1970s.
The ghost-reduction for same-sense c-pol tx and rx antennas was clearly
evident, and quite remarkable.

The link below leads to a scan of several graphs showing why this was true
for those near-in tests. RCA published a paper about it, which I will try
to find and provide a link.

http://i62.photobucket.com/albums/h8...eflections.jpg

Sorry, I can't get enough out of these graphs to come to any
conclusions. But the equations for reflection coefficient as a function
of polarization and ground conductivity and permittivity are well known
(cf. Kraus, _Antennas_) and are used by NEC-2 and EZNEC. So conclusions
based on reflection coefficients should be the same. Perhaps the
multipath reflections involved in TV broadcasting are primarily from
surfaces more or less normal to the radiated signal.

Roy Lewallen, W7EL