RF Energy Harvesting for IoT Sensors: Effects of Inductor Quality Factor on Efficiency

This paper discusses key factors in the design of RF energy harvesters that have a significant impact on overall efficiency, and in particular the critical role of selecting a high-quality factor inductor in the matching network. The proposed rectenna is composed of an L-matching network and a half-wave rectifier, and the target frequency is 868 MHz. First, a circuit analysis is presented to highlight the critical parameters. Then, various types of inductors, including discrete and short-circuited transmission lines, with high-quality factors, are used and the rectenna performance is simulated. Finally, the rectennas are fabricated and their performance is experimentally measured, mainly agreeing with the simulation results. Remarkable power efficiencies of 19 %, 47.7 %, and 68 % are achieved for input powers of -30 dBm, -20 dBm, and -10 dBm, respectively, which are the highest among similar reported designs for all input power levels.