A Survey of Radio Frequency Energy Harvesting Techniques: Towards Effective Powering of Mobile Devices

Abstract

The fundamental goal of energy harvesting systems is to reduce the need for a wired power supply or battery replacements. 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 the 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 have made it a very difficult task to harvest sufficient power to drive 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 various RF energy harvesting techniques in literature and discusses some of the difficulties encountered by researchers while designing RF energy harvesting circuits. The significance of adopting alternative renewable sources to power mobile devices in the face of the looming global energy crisis while avoiding global warming was highlighted. Additionally, suggestions for future work aimed at harvesting enough energy to power smartphones and other mobile devices were presented.