File:PAVE PAWS Radar Clear AFS Alaska.jpg

Summary
Phased array: Not all radar antennas must rotate to scan the sky. Courtesy of Alaska District, this 90-foot (27m) diameter radar installation monitors the northern sky. Its construction was part of the Clear Radar Upgrade to make all Ballistic Missile Early Warning System radars phased-array rather than mechanical. http://commons.wikimedia.org/wiki/File:PAVE_PAWS_Radar_Clear_AFS_Alaska.jpg