Energy Harvesting from Environment RF for IoT Applications

Energy harvesting power supply is essential for realizing IoT in the era of Trillion Sensor Universe. RF energy harvesting is a promising energy harvesting technology in which we can harvest energy anytime and anywhere if rectifier antenna (Rectenna) can harvest the energy from small power environmental RF signals. The research team of The University of Electro-Communications and Kanazawa Institute of Technology has investigated RF energy harvesting as a national project of JST/CREST to achieve high power conversion efficiency at input power range from -40 to -20dBm at various frequencies. We have investigated a super-steep transistor as a rectifier device, a meta-material antenna, and Rectenna design methodology, as well as high communication rate back scatter RF TAG as a new application. We have achieved 40% efficiency at -30dBm input power from environment AM radio signal, 72% efficiency at -30dBm and 900MHz CW RF signal, and 78% efficiency at -30dBm and 2.4GHz RF signal. We also have been successful to harvest 2.77uW power from -20dBm and 950MHz environment cell phone signal from a base station.