How the FCC tracks radio signals

Ringway Manchester does a great job of explaining how, since the dawn of broadcasting, the U.S. Federal Communications Commission has been tracking radio transmissions by using direction-finding installations in remote, rural areas.

Many employ a unique antenna known as a Wullenweber array that looks sort of like a wireframe Stonehenge. Viewed from above, some of these circular setups could pass for center-pivot irrigation systems.