A 5.8 GHz Low-Power Energy Harvester for RF Wireless Power Transfer Systems

This paper presents the design and implementation of an RF energy harvester system at 5.8 GHz for low-power wireless transmission applications. The potential application of the proposed system is to wirelessly power sensor nodes. First, a design methodology of the rectifier based on a theoretical approach is presented. The simulation results show an excellent correlation with the theoretical ones, proving the accuracy of the proposed design methodology. A prototype is fabricated and the simulation results are validated by the measurements. Then, the rectenna is combined to a commercial power management circuit and a load which emulates the behavior of a sensor. The power management circuit boosts and regulates the output DC voltage as well as stores the collected energy into a capacitor. Finally, the complete system is experimentally tested and excellent performances are demonstrated. The efficiency of the RF energy harvester is 24% at -10 dBm input power and 47% at -5 dBm input power which are the highest reported measured efficiencies at this frequency and at those power levels. The complete rectenna system is able to harvest 4.62 mJ in 40 s and 192 s for -6 dBm and -10 dBm input power, respectively allowing us to power wirelessly low-power electronic devices.