Low cost and efficient rectifier design for microwave energy harvesting

In this article we present a low cost and efficient rectenna design at 2.485 GHz for microwave energy transfer. The antenna and the rectifying circuitry are designed and printed on a FR4 substrate. A single stage voltage doubler rectifier with harmonic terminations is studied and developed for conversion efficiency optimization. Experimental results of the rectifier show 60% RF to DC conversion efficiency for 17 dBm input power at 700 Ω DC load when the rectifier is matched to 50Ω. Free-space measurements of the rectenna demonstrate 2.25V DC output voltage at 2.485GHz for 11dBm received power at 1KΩ DC load. Good agreement between simulation and measurement results is obtained and guidelines for rectenna efficiency optimization are discussed.