A cell phone that never needs recharging might sound too good to be true, but Nokia says it’s developing technology that could draw enough power from ambient radio waves to keep a cell-phone handset topped up. Ambient electromagnetic radiation–emitted from Wi-Fi transmitters, cell-phone antennas, TV masts, and other sources–could be converted into enough electrical current to keep a battery topped up, says Markku Rouvala, a researcher from the Nokia Research Centre, in Cambridge, U.K.
In a way this is perfectly logical. It’s just a direct reversal of the way that radio and all other electromagnetic waves are produced in the first place, and it’s surprising that it took so long for someone to come up with it. We already convert electromagnetic waves into electrical signals every time we turn on a phone, radio or television. These electrical signals are then converted to sound, or picture by whatever we’re listening with or watchin and it seems to be a natural progressionto convert them back to electricity that can be stored in a battery. It’s not as if there isn’t enough wasted energy signals flying around the place with phone masts hidden everywhere.
Nikola Tesla first demonstrated this technology in the 18th century and demonstrated working wireless transmission way back in 1893. His attempts to build a transmitter to send electricity across the Atlantic are the stuff of legend, but Nokia have gone down a far simpler route.
The system involves a wide band antenna which will pick up signals from 500 megahertz to 10 gigahertz and two electrical circuits. One converts the electromagnetic waves into an electrical current, while the second circuit is designed to feed this current to the battery to recharge it. The trick is making these circuits use less energy than they receive to allow for the overflow to be used to charge a battery. The second trick is making it small enough to fit into a phone. Starting off it’s not going to charge your phone for you but it will generate a top-up charge which will make your phone last much much longer. Combine it with some photovoltaic cellphone covers and the thing is flying.
Interesting stuff, This is another real-time projec, and not one for the long finger, Nokia reckon they’ll have it in phones within three years.