Improved radiofrequency energy harvesting based on a rectenna array system and its feasibility evaluation in urban environments

Energy recycling has become very atractive due to the extended usage time of devices. Among several forms of recycling energy, radiofrequency (RF) harvesting is becoming popular due to its immense availability mainly in urban environments. The possible utilizations for such amount of energy is mainly applicable for sensors nodes and, depending on the quantity of antennas, charging low power consumption portable devices. In this paper, we evaluate the feasible application of RF waves for energy recycling as an energetic source for charging a cell phone and furnishing power to embeded sensors. To validate our analysis, we conducted an RF measurement campaign at four important locations in Brasília, Brazil. Considering the average incidence of -3 dBm, we have achieved the final value of 2.18 mWh per day per antenna. In such context, and from the energetic standpoint, the utilization concerning to powering sensors was suitable for sensor networks applications, due to its low power consumption. However, in order to apply the RF energy harvesting in higher power consumption devices, we propose a rectenna array system which increases considerably the amount of recycled power. In particular, for massive MIMO communication systems, our proposed solution would require very little additional hardware being, therefore, very attractive.