Safer and more efficient mobile phones the size of a credit card are on the horizon after a chance discovery by a Warwick University engineer.
Roger Green has come up with a revolutionary new antenna that will cut the amount of radiation given off and halve the size of the battery needed in mobile phones.
His invention has attracted interest from 16 mobile phone and antenna-making companies, who are discussing its commercial potential.
The success of his research has surprised Professor Green, a professor of electronic communications systems at Warwick's engineering department, who had originally been working on an optical antenna.
"I was looking at my mobile phone one day and thought it was a waste of power sending energy into your head. I threw this thing together and tried out some ideas, and the result was totally unexpected.
"I couldn't believe it to start with, as antenna design is not my specialism. What I usually do is more methodical research. When you have an off-the-cuff idea that turns out to have commercial value it is a bit of a surprise," Professor Green said.
He noticed that mobile antennas were based on traditional designs such as quarter wave structures that emit radiation in all directions including the user's head. His antenna combines a refraction antenna, a dielectric antenna and a contoured electric field structure. Together, they make a compact antenna that reduces radiation to the head by up to 100 times, while quadrupling radiation broadcast away from the head. This gives a stronger signal and means smaller batteries can be used.
Professor Green said mobile phone size was ultimately limited to the size of a human finger, but credit card size phones of about 5mm deep were on the horizon.
A team of three academics is working with him on the antenna. They have patented two other designs: a safe hands-free mobile phone set and technology for a flat loudspeaker 10mm thick.