Radar dish

A radar dish was structure used in radar systems. The Fourth Doctor had Grierson redirect the radar dishes of the Space Defence Station on itself. When turned on, they would deactivate the Kraal androids that were attempting to release a virus and, as a side effect, jam radio and electronic equipment for miles. Grierson was shot by an android of the Doctor before he could activate the dishes. After fighting with the android, the Doctor was able to reach the switch and use it, freezing his duplicate, and the others, in place. (TV: The Android Invasion)