Topband: Modeling "Ground" and losses

[Richard Fry]

Previously, from two different posters...

> ... it defies logic that radials would NOT exhibit the same current and 
> voltage distribution of any other conductor carrying RF current.

> The ground sucks up the current at such a rate that there is not enough 
> current left to increase.

Quote from page 757 of the BL&E paper:

"Where there are radial ground wires present,
the earth consists of two components, part
of which flows in the earth itself and the
remainder of which flows in the buried wires.
As the current flows in toward the antenna,
it is continually added to by more displacement
currents flowing into the earth. It is not
necessarily true that the earth currents will
increase because of this additional displacement
current, since all the various components differ
in phase."

Note the last sentence in the quote above, in particular.

The physical conditions that determine the r-f current distribution along 
buried radial wires used with a monopole are different than those for wires 
in free space.

The current distribution along a buried radial wire is a function of the 
current amplitudes and phases present in the earth adjacent to the entire 
physical length of that radial wire.  Those earth currents are produced by 
the EM fields radiated into the earth by the monopole, within a 
1/2-wavelength radius of the base of the monopole.

The current on elevated radial wires used as a counterpoise is produced 
mainly by a direct, metallic (low-loss) connection to the transmitter. 
Current distribution along such wires is based mostly on their electrical 
lengths, and the physical configuration of the counterpoise.

R. Fry