Zero-Power Radio Receiver

There are several different types of wireless radio frequency identification (RFID) tags that are truly zero-power radios. Currently, most unpowered wireless RFID tags only have a range of a few meters. There are longrange, low-powered tags that draw energy either from a battery or some other form of localized power. A passive, or zero-power, radio receiver uses no direct electrical power, but makes sole use of the power available from a transmitter via the radio spectrum.