I would like to know the input resistance, at resonance, of a
1/4-wavelength counterpoise, at a low height above a ground of known
conductivity.

It will require modelling on an NEC-type program which takes soil
conductivity and very low heights accurately into account. If there
is such a program!.

The counterpoise can be modelled as a low-height, Inverted-L antenna
with the vertical and horizontal sections totalling 1/4-wavelength.

Modelled at approximately -

2 MHz and 10 MHz.

With heights above ground approximately -

0.005, 0.1, 1.0 metres.

With wire diameter = 1.6 mm or 14 awg.

With ground resistivities -

50, 200, 1000 ohm-metres.
(20, 5, 1 milli-Siemens).

I am interested only in input resistance. Input reactance will be
small when near resonance. Input resistance will not change very much
in the vicinity of resonance. So obtaining exact resonance is not
necessary. I would be happy with resistance values accurate to within
15 or 20 percent.

If anyone has a suitable modelling program and the time to spare I
would be very grateful. Just one or two figures would be useful.
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Reg, G4FGQ.