Hi Dave.
Care to comment on how much benefit vertically polarized antennas might
gain from terrain sloping away from vertical?
For horizontally polarized antennas, where ground reflection gain is up
to 6 dB, the sloping terrain can lower the effective take off angle a
lot- 10's of degrees. There was a program called YTAD that estimated
this effect in one dimension. It's results were quite enlightening.
Vertical antennas have no ground reflection gain. Would one then expect
sloping terrain NOT to alter their already low take off angle much? On
the other hand, folklore seems to indicate a benefit of roof top
verticals with their "elevated" radials over ground mounted verticals
with elevated radials/or in ground radials.
73 de Brian/K3KO
On 7/13/2016 8:49 AM, David Gilbert wrote:
Agree on the coax losses, but totally disagree on both of your other
comments:
1. Elevated radials will ONLY help reduce near field ground losses ...
they will do nothing to help radiation pattern. The effects of ground
conductivity determine far field pattern (given a particular profile) no
matter what kind of radials he uses.
2. If there is any gain benefit from the terrain profile at all, it
will be much more than 1 db.
Dave AB7E
On 7/12/2016 3:49 PM, Craig Smith wrote:
Ted …
I think you are overstating the coax losses. Even stock RG-11 should
be perhaps 0.3 dB/100ft on 80 meters - around 1.5 dB for the 500 ft. run.
Even so, I would probably gravitate toward the closer location. With
the elevated radials, the effects of the ground conductivity should be
minimal. Not sure if ON4UNs data assume elevated radials or many
on-ground radials. It could be that his estimate of the sloping
ground advantage is for the later. With the closer location, you
will have perhaps 1 dB stronger signal in all directions because of
the lower feedline loss.
73 Craig AC0DS
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