Indoor 2.45 GHz Wi-Fi Energy Harvester With Bridgeless Converter

Abstract

This paper presents a new approach to designing an indoor Wi-Fi energy harvester with a bridgeless converter that operates at low incident power. The design approach started with the analysis of the incident power available at a point of the harvester with certain harvesting distance, dimension, position, and height from the ground plane. Then, a simple single-plane antenna was proposed. Finally, a bridgeless converter circuit was proposed to boost the voltage at very low input power. The analysis showed typical calculated incident power at the antenna on the pathway of the transmitter is approximately $15\; \mu \text{W}/\text{m}^{2}$ and in the case of non-line-of-sight, the values dropped down to about $2\; \mu\text{W}/\text{m}^{2}$ . The proposed system has been tested in an indoor environment where the measured signal strength is between $-60\;\text{dBm}$ to $-50\;\text{dBm}$ ; and the output voltage and power at the output of the converter were measured as 3.86 mV and 0.15 nW, respectively, a 100 ${\text k}\Omega$ resistive load is connected for testing. An additional boost-buffer module was connected to the converter circuit for further voltage boost. It was found that the energy harvester stabilizes after 38 hours of operation and 1.8 V was measured at the output supercapacitor (1000 uF), meaning 1.67 J of energy has been stored for driving external low power devices.