"hasan schiers" wrote ...
Do 26 radials 5 metres long perform substantially as well as
26 radials 16 metres long at 3.62 mhz with the two soil
constants = 25 (in my case), with radial wire size #14 and
antenna wire size #10 (I think I used 2mm and 4mm in my calculations.)

Some insight into this is provided by the following.

Figure 37 in the BL&E paper shows about 77.5% of the theoretical maximum
inverse field for a 77 degree vertical used with 30 radials of
0.137-wavelength each.

Figure 36 shows 90.6% of the theoretical maximum inverse field for the same
vertical with 30 radials of 0.411-wavelength.

For 30 each 0.137-wavelength radials and a 77 degree vertical, Reg's program
radial_3 calculates an efficiency corresponding to 87.2% of the theoretical
maximum inverse field. (Other parameters for radial_3 were as shown in the
plots I posted earlier.) This is significant when considering that the
inverse field varies by the square root of this power difference.

NEC-4 should be able to tell us how much current is in a radial
and how that current is distributed along the length of the wire. If it
disappears into inconsequential levels within the first 5 metres,
then it confirms Reg's assertion. If it does not, i.e., it remains at
substantive levels well beyond 5 metres, then it contradicts Reg's
program, and agrees with BL&E, as well as W8JI.

BL&E data show that if few radials are used they may as well be "short,"
because system performance isn't improved greatly by making them much
longer. Quoting the BL&E paper (p.760), "These diagrams show that the
ground system consisting of only 15 radial wires need not be more than 0.1
wave length long, while the system consisting of 113 radials is still
effective out to 0.5 wave length.

But there was no experimental evidence from BL&E showing that radiation
efficiency ever _improved_ with shorter radials, as apparently calculated by
radials_3..

RF