Intel ambient RF energy harvesting demonstration
The world is awash in RF energy, particularly in metropolitan areas. Intel recently demonstrated an experiment of ambient RF energy harvesting from a TV tower. Powercast did a similar demonstration several years ago from an AM radio station.
Intel Research Seattle harvested power at 4.1km from the KING-TV tower in Seattle which broadcasts 960KW at 674-680 MHz. The demonstration used a broadband log periodic antenna (5 dBi) designed for TV applications and
a 4-stage power harvesting circuit of the same design as the Intel WISP, with a front end tuned to the desired channel.
This ambient RF harvesting system was connected to the battery terminals of a commercially available indoor/outdoor temperature and humidity meter (“thermometer/hygrometer”) with an LCD display. The thermometer/hygrometer was measured to consume around 25uA at 1.5V from a laboratory power supply. About once per second, its current consumption briefly spiked up to around 50uA, presumably when sensor measurements were made.
The paper for this experiment is available from TechOnline.
We’ve been promoting the use of RF energy for battery-free wireless sensors. Although the antenna in this demonstration is a little large, it does show the concept of wireless power over distance and battery-free operation.
LinkedIn Group