Frank,

After correcting the resonant lengths for the change in frequency from
7 to 8.07 MHz there is almost exact agreement between NEC4 and
Radial_3.

Keep a record of length, Rin, jXin for each incremental increase in
length. They could be useful.

When using Radial_3 set the number of radials to 1. The input
impedance of the radial system will then be same as the input to the
single radial and will be displayed with a greater number of
significant figures.

When you compare results between the two programs set the frequency on
Radial_3 also to 8.07 MHz. The resonant frequency of the Radial_3
antenna is slightly higher - it's something to do with the end-effect
and the fact that a vertical antenna needs pruning by a few percent to
make it resonate at the theoretical value of 75/Height MHz. Since at
present we are concerned only with the radials it is better to use the
same frequency for both programs.

I think that will complete all I have in mind. It may involve you
with a tedious amount of work. If you find it interesting you could
do something similar at 28 MHz. The 20dB limit may be reached with an
even shorter length of radial. Radial resonances ( which BL&E never
dreamed of ) will be much more pronounced especially with high ground
resistivity.

Has anybody ever generated an input table for 120 radials?

It's all in the cause of Science. Thanking you in advance.
----
Reg.