Mon 26 Jul 2004
Ring tones silenced by wallpaper
THE trill of a mobile phone in a cinema at a key moment in a film could soon be a thing of the past, thanks to a revolutionary new screening method.
British scientists have developed a hi-tech "wallpaper" that will block radio waves to prevent phones ringing when they should be turned off.
Researchers have found a way to mass-produce frequency-selective screens (FFS) which filter out radio signals while allowing others through.
The screens, an intricate pattern of fine metal grids, can be hidden within wallpaper so they will not be noticed when they are installed.
The breakthrough was made by experts at QinetiQ, a technology development company, who say the wallpaper will be useful in areas that require a "quiet zone", such as cinemas, airports, hospitals and schools.
The company, which, before it was privatised, was part of the Ministry of Defence, believes the innovation will also be a valuable weapon in the fight against terrorism.
Areas that could be screened within an airport include the arrival halls and the explosive containment areas, where suspicious packages are held while under investigation, because the radiowaves emitted by a mobile phone could not be used to detonate a bomb.
Michael Burns, the director of aviation markets at QinetiQ, confirmed that the company has now developed a way to produce the screens on a large scale.
He said: "Phones can not only be disruptive but, on occasions, can pose a real security threat as they could be used to set off a device.
"The wallpaper allows certain wavelengths to pass through them while preventing others, so that some mobile phone signals are effectively wiped out."
"Until now, it’s only been practical to manufacture small areas of frequency selective screens, so they have been predominantly used as the protective screening for microwave doors or in various radar applications.
"It’s now both practical and economical to produce large sheets of material."
The wallpaper is produced by printing the grid pattern on to the surface to be screened. Metal is then "grown" in the desired pattern when the wallpaper is immersed in a chemical bath.
However, the experts admit that the technology, whose origins lie in stealth aircraft and boats, does have a flaw. Radiowaves can flood a screened room when a door is opened.