Correction:

Roy Lewallen wrote:
. . .
Both NEC and EZNEC provide simple ways of generating a helical model.
. . .

NEC-4 has a built-in method for generating a helix (the GH 'card'), but
NEC-2 doesn't. I wouldn't be surprised, though, if the feature hasn't
been added to some versions of NEC-2 floating around, since the basic
programming for that function isn't difficult to do.

Roy Lewallen, W7EL