RF Energy Harvesting System Integrating a Passive UHF RFID Tag as a Charge Storage Indicator

This paper presents a radio frequency (RF) energy harvesting unit integrating a passive UHF RFID tag as a charge storage indicator. In this system, an energy harvesting unit converts the RF signal to DC and charges a storage capacitor. The RF switch, consists of a pin diode and UHF RFID tag, monitors the capacitor voltage and transmits signal to RFID reader if voltage at the capacitor terminals approaches 0.633 V. The proposed RF energy harvesting system operates at European UHF RFID spectrum from 865.7 MHz to 867.7 MHz. The experimental results indicate that 0.633 V at the capacitor terminals can be achieved with -5.5 dBm RF input power to the energy harvesting unit.