Stan
So many variables going to be hard to predict. Soil conductivity and
drainage will be a much bigger variable than the models can always predict.
Put it up, measure the impedance at the feed point with a decent VNA and
a calibrated ( to the VNA) feed line and keep good log book records.
During dry spells and the rainy season
Depending on how from the ocean you are even the tides may affect it at
certain critical heights
Dave
NR1DX
On 1/4/2021 9:10 AM, john@kk9a.com wrote:
I do not think that this will be easy to estimate plus your coral
ground is different than the ground in Arkansas. Usually I pull my
antennas up in the air, test them while it is hanging from the rope
and bring it back down to the ground to make any adjustments.
GL
John KK9A
Stan Stockton K5GO wrote:
If any of you have built a coil loaded 40m dipole and can remember
approximately how much higher in frequency it resonated when moved from
10-15 feet off the ground to a half wavelength or more, please let me
know.
Guess my memory isn't as good as I thought because I can't remember
exactly
what happened when I built one and put it up at home a couple years ago.
Whatever it was, as I recall, was not nearly the same as my model
indicated. I've got more work to do but want to put it up soon.
73...Stan, ZF9CW
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