Hello Dick & group,
AO computes the feedpoint impedance as 0.042 - j16189 ohm.
Because efficiency is 26.4% the radiation resistance is 0.264 * 0.042 = 11
milli-ohm.
Using the simple formula for a short vertical :
Rs = 40*(Pi*L/W)^2 where L = annena length and W = wavelength
the radiation resistance for a 180m high vertical at 9kHz is 11.5 milliOhm
And taking a antenna capacitance of 6pF/m the total capacitance is 1080pF
or 16374 Ohm at 9kHz.
So the simple formulas seem to work quite well, even at VLF.
Another thing : I like Andy's idea about ground-loops. Maybe we can put out
some signal without handing many 100kV. I believe that others have tested
some kind of ground dipoles too (VK2ZTO ?).
73, Rik ON7YD
|
