Harvesting Watts at Ultra-High Frequencies

Harvesting higher levels of ambient RF energy emitted by existing infrastructure has the potential to enable new charging scenarios. However, current device limitations make harvesting at high frequencies and high power levels a challenging problem to solve. In this work we present a prototype energy harvester which delivers up to 2.9 W of DC power to a resistive load and 1.6 W to a battery load, many orders of magnitude more than has traditionally been provided by RF energy harvesters. Our solution uses an array of harvesters operating in parallel and in the ultra-high frequency (UHF) band at a local cellular carrier frequency of 749 MHz. This paper presents an overview of the design, implementation, and test results of a UHF harvester array prototype and introduces potential future applications.