I noticed, I did not read the link I supplied well enough. There also
seems to be an online course. I presume it's based on the same book and
model-files.

Concerning the frequency-limit, I know there are a number of 2.4 ghz
wlan Nec2 models published on the internet and for myself I once
modeled a 11 ghz satellite dish using both surface patches and a
wire-grid. However I can not say very much about how well these models
agree with the real world counterparts.

Arie.