[Hi-zreceivingarraydiscussions] Grounds for 4 square

[Paul Ferguson]

John,

I also have an AIM 4170C and am interesting in looking at my HI-Z verticals
ground resistances. Did you do the measurement by taking the analyzer to
each vertical and connecting it to the ground rod wire and vertical wire
with the vertical amplifier removed?

I also noted Frank, W3LPL, uses a TDR to check his verticals from his
shack. I assume you cannot get useful information about the HI-Z verticals
from the shack because of the vertical amplifiers, phasing controller, and
preamp being part of the system near the arrays. Is this correct?

73,
Paul
K5ESW


On Mon, Dec 12, 2016 at 8:13 PM, John Kaufmann <john.kaufmann at verizon.net>
wrote:

 > I have measured RF ground resistance for a short receiving vertical 
(about
 > 15 ft tall) with just a 4-foot ground rod.  I used the AIM-4170, 
which is a
 > pretty accurate instrument, although I won't claim it's perfect.  On 160m
 > the resistance is about 60 ohms.  As expected, the measurement also 
shows a
 > large amount of capacitive reactance, equivalent to a series capacitor of
 > about 50 pF.
 >
 >
 >
 > Actually I measured the resistance across a span of 1 to 10 MHz.  The 
trend
 > is for the resistance to decrease with increasing frequency, although it
 > reaches a floor of 25-30 ohms around 4 MHz and higher.  The equivalent
 > series capacitance is pretty constant across frequency.
 >
 >
 >
 > I would have expect the resistance to be higher with just a simple ground
 > rod and it's possible there is some measurement error here. On the other
 > hand the vertical is installed in an area that is surrounded by wetlands,
 > so
 > the soil conductivity is probably above average.
 >
 >
 >
 > 73, John W1FV
 >
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