TL;DR
Add either a Tips & Tricks entry or, as standalone or in addition to it, a factoriopedia blurb/description blurb about this mechanic.What?
The radar has a very useful mechanic! It transmits signals across a surface, on a globally readable connection. And this is told to the player... absolutely nowhere, except an old FFF from 8 months ago. (https://factorio.com/blog/post/fff-402)A little blurb, such as "Can transmit signals from a circuit network across the entire surface." in factoriopedia/tips & tricks would likely do.