Optimal Operation of RF Energy Rectifiers by Adaptive Number of Frequency Selection using Multisine Excitation

This paper is about optimal operation conditions of RF energy rectifiers that are used for wireless power transfer (WPT) with multisine (MS) excitation. We show by simulation that the optimal operation of MS signals can be achieved by properly choosing the number of frequencies N-f to transmit, which is variable with the input power, rectifier load, and topology. We found by adaptive N-f on the transmitter side, a significant power gain can be achieved only when input power is low and rectifier load is large, showing the significance of operational condition for MS to show superiority over conventional sinusoid signal. The simulation results show that by adapting N-f, the WPT is much more robust against load variation, which is a novel finding about MS's advantage. Moreover, we propose an analytical model for MS transmission with adaptive N-f based on empirical results with power and load feedback from the rectifier.