On 12/3/2022 10:20 AM, Chuck Dietz wrote:
Thanks for the info. I think I am going with 60 radials on the ground. I
want to use the 160 vertical tower to support an 80 meter array around it.
Elevated radials might make adjustments way more complicated.
It's worth studying N6LF's work on elevated radials. He stresses that
keeping radial currents equal reduces loss, that making them slightly
shorter than resonant helps that, and so does having MORE elevated
radials -- for example, 8 is better than four. From N6BT, I learned that
elevated radials for 160M should be at least 16-20 ft high; I learned
that when I asked him why my 4 ft high radials weren't working well.
I have a
tractor and a good welder guy to weld a bracket and tube to a single plow
shear to make a radial plow.
Remember that the only virtue of burying radials is to protect them from
damage, or from being a trip hazard. We are NOT trying to couple the
antenna to the earth. The function of radials is to SHIELD the field
produced by the antenna from the lossy earth, and to provide a low
resistance path for the antenna's return current IN PLACE OF THE LOSSY
EARTH.
Radials DO couple to the earth, and the ground loss shows up as series
resistance. But radial current divides by the number of radials, power
loss is I-squared R, so gets smaller in each radial twice as fast as the
number of radials is increased, so more radials reduces loss.
73, Jim K9YC
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