Stealth Threat

WEB EXCLUSIVE



The small British research institute Roke Manor made headlines earlier this year when engineers there announced the invention of a new radar system capable of detecting stealth aircraft. Called bistatic radar, the system uses separate antennas to transmit and receive radio signals. (Conventional radar relies on a single antenna.)

The U.S. Air Force may already be deploying a bistatic radar system. In April, one of our sources spotted the warty nose of an airplane in Air Force markings sticking out of a shop at Goodyear airport in suburban Phoenix. Experts speculate that the strange-looking plane contains an experimental bistatic radar system aimed at detecting stealth aircraft.




Known as the Radar Test Bed (RTB), the plane is a T-43, the Air Force version of the Boeing 737. The prime contractor is Denmar, a company specializing in stealth technology. The "Den" stands for President Denys Overholser, the former Skunk Works engineer credited with devising the shape of the first stealth aircraft.




RTB seems to be more than just a flying laboratory. In a purely experimental program, there would usually be no need to provide a radar system with a full 360-degree field of view, but the shape and size of the nose and tail radomes-6.5 feet in diameter-suggest they contain moving antennas.




The Air Force's center for airborne surveillance radar, Rome Laboratory in New York, has worked closely with MIT's Lincoln Laboratory on bistatic radar for many years. Technical papers from Rome Lab refer to a bistatic Advanced Airborne Surveillance system-originally due to be demonstrated in 2000-and a graphic in a Lincoln Lab briefing paper shows a bistatic radar with its transmitter mounted on a 737.

The Lincoln paper describes a radar operating in the UHF television band, which is seldom used for airborne radar because the long wavelength requires a big antenna. Lincoln Labs has also worked on laser radars to detect airborne targets, possibly explaining the optical domes above each radar housing.




In action, the 737 would orbit safely to the rear of a battlefield, sending out UHF signals. Unmanned planes would fly above the battle area, fitted with receivers to pick up target echoes. These receivers would require less power than a radar-transmitting system, so they could be carried on small, cheap planes that would be "attritable." That is, nobody gets killed or fired if one is shot down.