Nokia Recharge Without Mains

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Researchers at the Nokia Research Centre in Cambridge, UK, developed a prototype mobile phone charging system that harvests power from ambient radio waves given off by TV, radio and other mobile signals, aiming to keep a handset in standby mode indefinitely without ever needing mains electricity. Using a wide-band antenna tuned to frequencies between 500 megahertz and 10 gigahertz, the device had harvested up to 5 milliwatts of power at the time of reporting, with researcher Markku Rouvala targeting over 20 milliwatts to sustain standby mode and, eventually, up to 50 milliwatts to slowly recharge the battery, though outside experts cautioned that radio frequency power falls off sharply with distance and that the technology was intended to complement, not replace, other energy-harvesting approaches such as solar-cell handset casings.