Mobile phones may foil stealth bombers By Robert Uhlig in London America's multi-billion-dollar stealth bombers could be rendered obsolete by a British invention that uses existing mobile telephone masts to detect and track aircraft that were previously invisible to radar. US stealth fighters and bombers such as the F117, B1 and B2 played key roles in the Gulf and Kosovan wars as they are almost impossible to detect using conventional radar. However, the ease with which the mobile telephone mast system - developed at a laboratory in Hampshire - can be used to detect the aircraft has greatly concerned the military. Mr Peter Lloyd, the head of projects at Roke Manor Research, said: "I cannot comment in detail because it is a classified matter, but let's say the US military is very interested." Stealth aircraft, each of which costs at least $A3.6 billion, are shaped to confuse radar. A special paint absorbs radio waves, reducing the radar signature to the equivalent of a gull in flight. The Roke Manor scientists discovered that telephone calls sent between mobile phone masts detected the precise position of stealth aircraft with ease. "We use just the normal phone calls that are flying about in the ether," Mr Lloyd said. "The front of the stealth plane cannot be detected by conventional radar, but its bottom surface reflects very well." Mobile telephone calls bouncing between base stations produce a screen of radiation. When the aircraft fly through this screen they disrupt the phase pattern of the signals. The Roke Manor system uses receivers, shaped like television aerials, to detect distortions in the signals. A network of aerials large enough to cover a battlefield can be packed in a Land Rover. Using a laptop connected to the receiver network, soldiers on the ground can calculate the position of stealth aircraft with an accuracy of 10 metres with the aid of the GPS satellite navigation system. "It's remarkable that a stealth system that cost £60 billion [$158 billion] to develop is beaten by £100,000 mobile phone technology," Mr Lloyd said. "It's almost impossible to disable a mobile phone network without bombing an entire country, whereas radar installations are often knocked out of action with a single bomb or missile." http://www.smh.com.au/news/0106/12/world/world2.html