Hi Steve,
> two) they usually don't help much or at all. However, as an rx
> antenna for people who have a lack of space and a predominantly
> vertically polarised tx antenna, they are a very useful antenna for
> discriminating against general atmospheric noise.
Atmospheric noise is just like skywave signals. It is random in
polarization. It can only be reliably discriminated against with
antenna directivity in azimuth or elevation response without regard
to polarization.
If you see a clear increase in noise level at night on nights without
local QRN (assuming nothing locally is turning on at night) you
almost certainly have propagated noise or atmospheric and
polarization generally won't help reduce it, so the best DX antenna
for transmitting will be the best for receiving.
Most of this is explained at w8ji.com under the "Receiving Antenna
Design Basics" article heading.
73, Tom W8JI
W8JI@contesting.com
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