Engineers at the Nokia Research Centre have been using the electromagnetic radiation emitted from wifi transmitters, mobile phone antennas, TV masts and the like to harvest 3-5 milliwatts using current prototypes test circuits in the lab.
The target is to hit 50 milliwatts, which would be enough to eventually re-charge a phone that has run its battery flat.
Nokia has said that the concept is based on the idea behind an RFID tag - converting electromagnetic waves into an electrical signal. Nokia is working on increasing the range of frequencies from which power can be harvested from the ambient radio waves.
