No, there's no upper or lower frequency limit.

However, EZNEC results are only as good as the model. As frequency
increases it's increasingly difficult to make a model which adequately
imitates the real antenna.

Roy Lewallen, W7EL

Scott wrote:
Is there an upper frequency limit that EZNEC can calculate with? If so,
how high can one go? Will it do reasonably well up to say 902 MHz?

Scott
N0EDV