Byron,
How has the 3db bandwidth been affected?
Have you noticed any difference in antenna performance?
Going from an inefficient ground system, to a more-efficient ground/radial one,
raises SWR, and also narrows bandwidth. This is because you're going from a
resistive load, to a tuned (reactive) one. You say that you have observed a
change in feedpoint impedance/matching, but nothing else.
Herb pointed out that FRESH water can act as an insulator, which I had never
considered. If your radial system is insulated from earth, you have a lesser
ground, I guess. I have seen articles advising use of INSULATED wire, to
reduce corrosion. They used to dump bags of Copper Sulphate at the ground
stakes in the past, but I don't think that is PC these days. Did you plan on
planting a garden there? Personally, I am an advocate of elevated radial
systems, but realize this is often simply not an option. (Even "turkey-wing"
radials are more efficient than buried ones, unless you do a lot of burying.)
How about adding some chickenwire? That's the secret of an efficient buried
radial system ...."adding."
Allen - N2KW
---------- Original Message ----------
From: BRYON PAUL n0ah VEAL <bryonveal@msn.com>
To: "topband@contesting.com" <topband@contesting.com>
Subject: Topband: water saturated ground effect
Date: Mon, 18 Jul 2011 18:31:55 -0600
On my Cushcraft MA160V, the resonant SWR point has lowered from almost 5:1 to
1:1 without the Amidon unUn in line. All 26 of the buried radials are
attached. The main difference is that the normally dry ground is saturated
from 6 inches of rain in the past two weeks. Can the water saturated soil
really make this much of a difference? The last time this antenna showed this
good of an SWR, was when I had no radials attached, in dry dirt, as expected-
Of course attaching radials only began to show the true impedance mismatch,
thus the need for the Amidon UnUn to match the coax to the antenna- Bottom
line, the antenna is acting like I disconnected the radials, which are very
much intact- My guess is that as the soil drys out, my SWR at sresonance will
once again rise, and i will need the UnUn again for matching reasons- does this
sound right>?
73 Paul N0AH
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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