Frank,

The input impedance of 26 radials is NOT equal to all 26 connected in
parallel. There is a non-linear relationship between the number N and
input impedance because they share the same volume of soil at least
when they are short.

For 26 radials the resonant effects have disappeared which I cannot
explain. Yet attenuation is the same, Zo converges on Zin at
approximately 8 or 10 metres as before.

You appear to have automated the results. Can you do a large number
of radials, say around 100, from 0.4 to 8.0 metres?

And can you do a small number of radials such as 6 or 8, from 0.4 to
8.0 metres?

Reg,

I suspected as much concerning the input impedance of a number or
radials. Note that my model was 36 radials, not 26. 26 was simply a
typo.

Believe me there is no automation involved in running NEC, although
the work is trivial. The 36 radial model was taking 13 minutes per
run as I approached 8 m length radials. I can certainly model the
small number of radials, which should not take too long.

As for 100 radials; this exceeds the maximum number of junctions
limit in NEC. This does not mean it cannot be done, there are
work-arounds. Due to excessive computer time I will have to
develop a model with a more realistic run time. I am interested
in doing this for my own benefit, but it will take some time. I
will be very busy for the next few weeks, but will be able
to squeeze some time in occasionally.

Frank