The US Missile Defense Agency's Sea-Based X-Band Radar (SBX) is the largest phased array X-band radar in the world - in other words, each of the radar's antennae are individually controlled by its own computer and operates within the X-ray band of the electromagnetic spectrum. Being designed to move around the Pacific Ocean, the actual radar is carried by a mobile, ocean-going semi-submersible oil platform, the entirety of which measures 73 m (240 ft) wide, 118 m (390 ft) long, 85 m(280 ft or 26 storeys) tall and displaces 45,360 tonnes (50,000 tons) of water. Built by Boeing (USA), the SBX cost US$900 million (£504 million) to develop and is powerful enough to distinguish between incoming and decoy missiles. It will be used with other radar installations as part of the American Missile Defense Agency's ground-based midcourse defense program (GMD). The SBX was due to arrive at its home port in Adak, Alaska, USA in late 2006.
The protective 'radome' alone measures 31 m (103 ft) high, 36.5 m (120 ft) in diameter and weighs 8,100 kg (18,000 lb). It is supported only by air pressure and can withstand winds speeds of over 209 km/h (130 mph).
According to the US Missile Defense Agency:
"The radar is so powerful that if it were off the east coast of the United States near Washington, D.C., it would be capable of detecting the motion and rotation of a baseball launched into outer space from the San Francisco area".