Practical Implementation of an RF Energy Harvesting Module with Optimized Storage Capacitors for Low-Power Wireless Sensors

The proliferation of IoT devices and wireless sensors demands battery-free, long-term power solutions. This letter presents a practical RF energy harvesting (RFEH) module using the commercial Powercast P2110B (915 MHz), focusing on optimized storage capacitor selection for system-level efficiency. Experimental results with a 3 W dedicated transmitter show reliable energy delivery up to 2.2 m. A 47 mF Murata supercapacitor achieved an efficiency ratio of 0.065, outperforming a commercial 50 mF module (0.055). Lower-quality local supercapacitors exhibited high ripple and unstable output, highlighting the critical role of component quality. These results provide a compact, cost-effective solution for battery-free sensors in industrial environments.