Wireless Ambient Radio Power
Radio frequency (RF) signals provide a near ubiquitous energy source due to the large number of TV, radio, cellular, and Wi-Fi transmitters throughout our urban environments. While the traditional use of RF signals is for data transfer, it is possible to harvest, convert, and store the energy in these signals for use in a variety of applications. In general, the energy harvesting process includes four stages: excitation of current in an antenna by an incident electromagnetic wave, recti?cation of the resulting power at the antenna output, conversion of this power to optimal voltage and current levels, and ?nally, energy storage in a capacitor or battery for later use. This chapter describes a sensor node that is powered by UHF television broadcast signals. The sensor node transmits the measured data wirelessly over a short distance using a IEEE 802.15.4 radio. Typically broadcast television signals are considered to be sources of information, but this chapter demonstrates that these ubiquitous ambient signals can be used as a power source to do non-trivial work.
KeywordsSensor Node Radio Frequency Capacitor Bank Wireless Sensor Node Transmission Tower
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