Hi all,
The tests done by Jim, and comments made are all very interesting. The
following is a further matter to consider:
For any counterpoise system that is elevated and insulated from ground,
there will be an "interface" situation at the outer ends of the counterpoise
and that could influence the strength of a ground wave lauched from the
antenna (assuming the antenna as such can be considered as a separate part
of the wider environment). There must be some degree of "mutual coupling"
between the elevated radials and the ground. However, despite whatever
occurs with ground coupling, amateur LF DX is mostly a result of sky wave
propagation.
The lower that losses can be made within the antenna, the higher the current
for a given applied power, so the better the DX result by sky wave mode.
Carrying out field strength readings a few km away would be more of an
investigation of the ground wave mode rather than the manner in which the
antenna actually launches "rays" that can then reflect off the ionosphere.
So it is not easy to investigate the impact of elevated radials with respect
to radiating energy that goes into sky wave mode.
Most text books are concerned with efficiently launching ground waves and
having reliable coverage. The matter of how the antenna launches energy
that supports sky wave mode of communication is not so easy to find. Any
comments on that?
73, Bob ZL2CA
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