This is not part of the launch silo, but a separate silo-like structure located some distance away from the silo. This structure contains a hardened high frequency radio antenna. The antenna is normal kept safely underground to shield it from the effects of a nuclear detonation. When needed, the antenna telescopes out from its underground silo and can be raised as high as 117 feet (35 m).
Initial view: The mechanism that raises the antenna is ingenious. Rubber tires grip the antenna mast. When the tires rotate they pull the mast up. Mast sections lock together as they rise. The entire antenna and the machinery that raise it are suspended from springs.