Smartphones as a power source for radio frequency energy harvesting

Details

Supervisors

Flandre, Denis ; Oestges, Claude

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électromécanicien

Abstract

The rapid development of the Internet of Things (IoT) industry in the past years has led to a rising demand for autonomous sensors. Energy harvesting is seen as an ideal method to scale-up deployment at a reasonable cost by avoiding maintenance. Radio frequency (RF) harvesting provides a solution in some situations, offering certain advantages over solar, thermal and vibration-powered energy harvesters. Modern approaches use fixed transmitters such as WiFi routers and television, radio and cellphone Base Transmission Stations (BTS) as their RF source. This strongly restricts the deployment possibilities as the harvesters are limited to areas where sufficiently strong RF signals are available. A novel idea consisting of using nearby smartphones as a source of RF for energy harvesting as an alternative is proposed and explored in this work, in view of determining if it is feasible, and if it presents an interest for the industry by providing more deployment possibilities. An overview of the concepts of Radio Frequency Energy Harvesting (RFEH) are presented, and smartphone transmissions are analysed. LTE (4G) is chosen as the investigated transmission. The case of a simple RF-DC circuit, comprised of an antenna, a matching circuit and a voltage doubler is investigated. A method for replicating realistic LTE signals in Matlab is presented and used to simulate the circuit in LTspice, and the circuit is optimised accordingly. Finally, a proof of concept PCB is developed. Energy harvesting is achieved, reaching peaks up to 220mV with a single smartphone and single stage rectifier at 1m transmission distance, demonstrating feasibility