"Radar is to air-traffic control what eyes are to people. It allows ground controllers to guide planes around the skies without the risk of a mid-air collision. But air-traffic-control radars—which use up more than 25kW per pulse—have a hefty appetite for electricity. [...] Radar engineers believe that this thirst could be reduced by the use of so-called Active Electronically Scanned Arrays (AESAs). AESAs use thousands of individual radar-emitting blocks mounted on a single antenna." (Quoted from article)