When someone asks me what's the optimal radial ground screen, I mostly
answer: "120 radials with a length of 0.4 lambda".

This answer is somehow fixed in my mind, based on a study and
experiments undertaken long time ago by ...?

Does anybody have a pointer/link/url to this study or can someone
deliver me more details ?

I already did some Googling, but could not find the article I once
red.

Thanks in advance,
Arie Voors.