English: Buildings housing the AN/FPS-85 phased array radar at Eglin Air Force Base Site C-6 in Eglin, Florida. The AN/FPS-85, which became operational in 1969, was the world's first large phased array radar, used for tracking of spacecraft and orbiting objects as part of the Space Surveillance Network operated by the US Air Force Space Command. With a peak output power of 32 megawatts the Air Force claims it to be the most powerful radar in the world. It consists of a transmitting building (white, bottom center) facing south, with the radar antennas mounted on its sloping 45° face. The transmitting antenna (left) consists of a rectangular 72x72 array of 5,184 crossed dipole antennas spaced 37 cm apart. It transmits at 442 MHz with each transmitter module having an output power of 10 kW. The receiving antenna (right) consists of an octangular array 58 m in diameter consisting of 19,500 crossed dipole antenna elements feeding 4,660 receiver modules. It can reportedly track an object the size of a basketball at a distance of 22,000 nautical miles.