Radio Frequency Energy Harvesting Characterization: An Experimental Study

This paper presents the outcomes of experiments performed to acquire data and to evaluate various parameters to: (1) assess the feasibility of harvesting the energy from the ambient RF power to energize wireless sensor nodes, and, (2) characterize commercially available PowerCastTM energy harvester. The parameters of interest are: (1) Ambient RF power along several bands, (2) Time, Tc, taken by PowerCastTM energy harvester for charging, and (3), The received signal strength indicator (RSSI) captured by PowerCast™ energy harvester. The former measurements are taken at different locations inside King Fahd University campus. The latter two quantities were computed from data acquired at various coordinates of the harvester relative to the transmitter and the source of energy. The data is acquired in indoor and outdoor scenarios. The acquired data was processed in MATLAB and it was concluded that: (1) The ambient RF power in not sufficient to energize the commercially available PowerCast™ RF power harvester which has a specified requirement of at least -10dBm power to successfully harvest RF energy. (2) The outdoor experiments suggested that Tc is directly, while RSSI is inversely proportional to the radial distance from the power transmitter. The two quantities are also significantly affected by the variation of azimuth and elevation of harvester w.r.t. the transmitter. (3) It is observed in the indoor experiments that trends of Tc and RSSI are not as regular as those in the case of outdoor experiments. Experimental procedure and all of the analyses are documented in detail so that it can be a useful reference for researchers working in this area.