John wrote:

I didn't know I could model loops in EZNEC. But now I see that it has
problems only with small loops. I guess a 1/4-wave loop is not considered
small. I'll go back and try it.
. . .

Because EZNEC uses NEC-2 for calculations, it has the same problems with
small loops that NEC-2 does. It's able to model any kind of antenna that
NEC-2 can, within its segment limitation.

Roy Lewallen, W7EL