Reg Edwards wrote:
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.
(snip)

Does Radial_3 assume that each radial is independent of its neighbors,
regardless of how close or far?