Tom, W8JI wrote:
"You didn`t read something correctly."

OK, here is the arithmetic.

Radiation Resistance of a Short Electric Dipole:

RR = 80 pi squared (L/lambda)squared

Constant = 80 (8.97) = 790

But a short monopole has 1/2 the resistance of a short dipole.

790 / 2 = 395

All Reg asked for was the constant.

Best regards, Richard Harrison, KB5WZI