This device “mines” energy from the environment, more precisely, uses the energy of the radio waves used to transmit the Wi-Fi wireless networks signal. Knowing how popular wireless networks are, it is easy to imagine that the electromagnetic field created by the Wi-Fi transmitters has a fairly high tension, especially in central quarters with high offices of offices. However, a simple calculation shows that this field is enough to cause a headache in easily suggestible individuals, but not enough for charging batteries of modern mobile devices for any acceptable time. To intercept a noticeable amount of energy, Airnergy Charger should be located directly near the antenna. One way or another, the obtained energy stored in the built -in battery, from which you can charge the battery of a cell phone or PDA. The expected price of an unusual charger is $ 40.