Energy Harvesting and Optimisation from Ambient RF Sources: A Review

Abstract

Energy harvesting from ambient sources has attracted a lot of research recently due to the high demand for cheaper and greener energy. Energy harvesting from RF sources involves three major stages, the first stage is the reception of the RF signal using an antenna, secondly the signal is conditioned using the appropriate circuits. Finally the signal is either used directly by a load or is stored in a battery or a capacitor. Several researchers have investigated the possibility of harvesting energy from ambient RF energy sources such as Wi-Fi, GSM, microwaves, CDMA, UHF and even AM signals. But in most of these researches, the harvested energy is too low, especially when the energy harvester is far from the transmitting station.This paper reviews the techniques used in RF energy harvesting and optimization of the harvested energy. The aim is to review past and present developments and approaches employed in harvesting energy from RF sources. The areas that require attention will also be presented. This paper will contribute positively towards research and development in the field of energy harvesting from ambient RF sources such as cell phone radiations, FM and AM radio signals, Wi-Fi signals and cellular networks signals.

Keywords: Energy harvesting, Optimisation, RF signals