Removable Luneburg lens type radar reflectors are sometimes attached to military aircraft in order to make stealth aircraft visible during training operations, or to conceal their true radar signature.
The global spread of sophisticated air defense systems in the 1970s-1980s threatened the USAF’s ability to destroy an enemy’s most valued targets. To overcome this threat, the USAF incorporated the revolutionary low-observable, or “stealth,” technology into tactical aircraft (first in the F-117 and then in the F-22 and in the F-35, the latter jointly developed with the US Navy and the US Marine Corps) and into a long-range bomber (the B-2, and in the forthcoming years the B-21) capable of delivering large payloads of conventional or nuclear weapons.
Stealth aircraft destroyed key targets in conflicts in Iraq, both in the 1991 Desert Storm operation and in 2003 during Operation Iraqi Freedom; in Yugoslavia during Operation Allied Force in 1999; in Afghanistan during Operation Enduring Freedom in 2001; and in Libya in 2011.
But, is it possible to make stealth aircraft visible on radar screens?
‘Do you see these small objects bolted to the outside for the F-35?
‘Here is another good shot of the F-35 with them.
‘Here is one on the F-22.
‘And here on the F-117.
‘What are they? They are Luneburg lenses. They are bolt on radar reflectors,’ says Damien Leimbach, USAF avionics technician, on Quora.
Removable Luneburg lens type radar reflectors are sometimes attached to military aircraft in order to make stealth aircraft visible during training operations, or to conceal their true radar signature. Unlike other types of radar reflectors, their shape doesn’t affect the handling of the aircraft.
‘The planes are so stealthy that civilian air traffic control would not be able to see them on radar (obviously, that’s the point of a stealth plane).
‘Unlike what you may see in Hollywood, stealth mode is not a switch that you flip in the cockpit. The shape is stealthy all the time. You also have things like encoded altimeters that broadcast your altitude to ATC, but not your position, so it still helps if they can see you with radar. So sometimes, they add little radar reflectors to the planes when they don’t need to be “stealthy.”
‘Their entire purpose is to reflect radar energy back at the transmitter, so the plane can be “seen.”’
‘It would therefore be very easy to take a small cruise missile, like this ADM-160 MALD and put Luneburg lenses inside it, to give it the same radar signature of a fighter or a bomber.
‘So it can be done electronically with antennas and transmitters, or physically with reflectors.’
Photo credit: Master Sgt. John Gordinier / U.S. Air Force and Raytheon