Cecil Moore wrote:
. . .
Can the single-wire transmission line be modeled with EZNEC
if the height is greater than 0.2 wavelength?

Can it be modeled with NEC4? If so, could someone do it
and report the results?

I don't think either program can model it. Single wire transmission line
operation depends on an interaction among the field from the wire
current, the insulation, and the air, that NEC-2 and -4 don't model. The
wire insulation calculation provided by EZNEC and NEC-4 only calculates
the effect of insulation on wire impedance, not on how the field
launches from the wire. You might be able to do it with a 3D field
solving program (which, last I heard, were in the $20k+ category).

Roy Lewallen, W7EL