[TowerTalk] Impact of high water table levels on antennas

[GARY HUBER]

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 at 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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