Hybrid Power Harvesting From Ambient Radiofrequency and Solar Energy

In this letter, a power harvester with a Schottky diode and a photodiode has been designed to harvest ambient radiofrequency (RF) and solar power in a cooperative way. The RF power is collected by a coplanar waveguide-fed circularly polarized antenna operating in wifi band and converted into the dc one by a rectifying circuit composed of the Schottky diode, and meanwhile the solar energy is harvested by the photodiode to bias the Schottky diode in the rectifying circuit. With the RF and solar power simultaneously injecting into the rectifying circuit, the resulting power conversion efficiency is greatly increased for the same RF and solar power levels in a range from −20 to 0 dBm. The prototype of the proposed harvester is fabricated, and the measured results demonstrate a maximal total PCE of 73% and a maximal output power of 1450 μW.