A Survey of RF Energy Harvesting Techniques for Powering 5G Mobile Devices

Abstract

Radio frequency (RF) energy harvesting has been established as a viable alternative for powering mobile devices without increasing greenhouse gas (GHG) emission, which is a threat to the environment. However, there are challenges facing effective harvesting of appreciable energy for these devices. Low RF power harvestable from various sources and low radio frequency-direct current (RF-DC) conversion efficiency has made it a very difficult task to harvest sufficient power to operate mobile devices such as smartphones. Lower frequency RF sources could yield appreciable harvestable energy but this comes with the challenge of portable antennas that could match these frequencies. This paper presents a review of various RF energy harvesting techniques in literature and exposes some of the challenges currently being faced by researchers in the design of RF energy harvesting circuits. The importance of using alternative renewable sources to power mobile devices in the face of the looming global energy crisis while avoiding global warming were highlighted. Suggestions for future work aimed at harvesting sufficient power for the operation of smartphones and other mobile devices were also made.