Active power summation for efficient multiband RF energy harvesting

Radio frequency scavenging power supplies targeting ambient and/or intentional sources of energy present a reliability challenge when faced with single-source fading (both geographic and small scale), and this is an impediment to their practical adoption. Recent work has described simultaneous harvesting of power from multiple spectrally separated bands as a method to mitigate single-source fading. The method used for summation of DC output power from each band rectifier is critical in determining efficiency of the multiband harvester. Existing work explores a diode network topology for summation of power, but this network doesn't always provide a benefit over a naive implementation of power summation. This paper characterizes the costs and benefits of existing power summation topologies, and introduces a new intelligent switching method for summation which generally exceeds the performance of prior methods.