Armada
Cortex
Beholder
The Beholder is a tiny observation structure that can be built practically anywhere, even on the side of steep cliffs.
It has Cloak and Stealth and is hidden from radar AND line of sight when it's cloaked, making it impossible to detect.
It costs -3 energy while uncloaked, and -15 when it's cloaked.
It cannot see cloaked units, but likewise, spy bots/stealth tanks etc. cannot see the camera. If you set a staggered line of them in a gap, any cloaked units moving through it will be revealed when they unwittingly blunder into one.
Set cameras to watch over any contested ground to defeat radar jamming—especially useful vs. Sharpshooters paired with a Smuggler.
Beholders are instantly destroyed by a Juno missile.
Read more about Perimeter Cameras here