The Bucks Harbor (J54 or QYA) Joint Surveillance System ARSR-4 radar is used for USAF air defense and Federal Aviation Administration (FAA) air traffic control. Also: http://en.wikipedia.org/wiki/ARSR
http://www.radomes.org/museum/recent/BucksHarborAFSME.html
http://www.radomes.org/museum/showsite.php?site=Bucks+Harbor+AFS,+ME