New Formula for Conversion Efficiency of RF EH and Its Wireless Applications

Existing works on energy harvesting (EH) wireless systems often assume constant conversion efficiency for the energy harvester. In practice, conversion efficiency often varies with input power. In this paper, based on a review of existing energy harvesters in the literature, a heuristic expression for the conversion efficiency as a function of the input power is derived by curve fitting. Using this function, two example energy harvesters are used to analyze the realistic performances of wireless relaying and wireless energy transfer. Numerical results show that the realistic performances of the wireless systems could be considerably different from the performances predicted by the existing analysis.