"Walter Maxwell" wrote:
When reviewing these data, please keep in mind that as the field strength
approaches 194.5 mv/meter the effective ground is approaching perfect
ground, which means that the conductivity of the ground in which the
radials are planted is irrelevant, only the ground external to the radial
system is relevant with respect to conductivity.

BL&E measured the groundwave field strength generated by a 200 milliwatt
carrier 0.3 miles from a vertical radiator. This value was converted to
equivalent field for 1 kW of radiated power at a distance of 1 mile. With
this technique, and with 113 each 0.412-wave radials, they found that their
measured/converted field was less than 0.1124 dB below the theoretical value
for it over a perfect ground plane. These results demonstrate that the
consideration of ground conductivity during this study over this short path
was unnecessary (REG, please note).

It should also be kept in mind that the energy in the EM fields
surrounding the vertical radiator diminishes with distance from the
radiator. Thus the displacement currents entering the ground diminish
proportionately with distance. Consequently, there is a distance from the
radiator after which the currents become too small to be significant to
the conservation of power radiated. This fact determines the maximum
length of the radials necessary to reach the point where the law of
diminishing returns prevails. The measurements reported in the BLE paper
show this distance to be between 0.4 and 0.5 wavelengths.

And that was for 113 radials. If only a few radials are used, BL&E report
that it is pointless to extend them that far.

RF