KS8S/AD8P had a contest station in Deshler, Ohio in the mid 80's (about
1 hour South of Toledo). With just a ~100' shunt-fed tower they seemed
to have a stand out signal on 160 meters compared to others in the area
with similar setups. Dean KS8S mentioned they had a very high water
table in that area. Also, I remember noticing that there was a region of
higher than average conductivity on the FCC soil conductivity map in
that part of Ohio. Not enough for a firm scientific conclusion, but it
sure seemed like Dean had some sort of magic dirt under his low-band
antennas.
73, Mike W4EF.......................
On 11/3/2013 11:42 AM, GARY HUBER wrote:
Rudy,
I have a similar situation. My QTH is on a glacial moraine about a
tenth of a mile from the crest. There is water bearing clay less than
thirty inches down and the soil is the black muck left by the glacial
ponding. To top it off, I've mounted my HV-2 w/160m mod and umbrella
capacitance hat over two dozen 66 foot radials all over the septic
leach field. A friend who has operated from ZF2 and C6 numerous times
says I am very strong using the HV-2 on 40..... I've worked a lot of
DX with the HV-2 over the septic field over the past 27 years
including ZL9CI, KH1, KH6, etc.
I believe the high water table helps me and will help you.... but the
advantage works also for the 4SQ or any antenna. Probably about 3 dB
from the Fresnel reflection.
-----Original Message----- From: Rudy Bakalov
Sent: Sunday, November 03, 2013 1:02 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Impact of high water table levels on antennas
Ever since I have put up two inv-Vs, one for 80m and one for 160m,
with their apexes at roughly 90', I have been puzzled by their
exceptional performance. Ditto for my vertical on 40m. I have done
tons of comparisons using skimmer data and my signal seems to be
pretty darn close to the big stations I am using as my benchmark. The
performance is so good that I have been wondering if I should bother
with building 4SQs. I have read tons of books on antennas and the
performance of these two antennas simply does not match what the books
describe.
I shared my thoughts with a friend of mine (a WRTC2014 participant)
and he shared a similar experience with his station. He recently
relocated to a new place, about 30 miles from his old place, and his
antennas at the new place perform significantly better than the old
location. Same antennas, tower, feed line, and FLAT terrain. His only
explanation is that the new place had a very high water table that
somehow impacted antenna performance.
This is when I realized that I also have a very high water table. Even
in the driest months of summer, the area around my tower is damp and
the grass is very green, growing like crazy. This was the obvious
common element between his and my situations.
I have not seen anything on high water tables in my antenna books.
The soil itself is mostly sandy. The impact I believe I am seeing is
mostly on the lower bands, but I am not sure if this is also the case
on the upper bands as at 105' my antennas are a bit too high.
Is there any rationale in our thinking? Can high water table explain
better than expected performance from low band antennas? If so, what
is the theory behind it and how do I take advantage of it? If not, any
other suggestions for why the antennas work so well?
Rudy N2WQ
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