Auto-Tracking Time Reversal Wireless Power Transfer System With a Low-Profile Planar RF-Channel Cascaded Transmitter

In order to continuously power movable sensors, we present an autotracking continuous-wave time reversal (TR) wireless power transfer (ACTR-WPT) system of a novel low-profile planar transmitter. The new transmitter is designed with a radio-frequency (RF)–channel cascaded structure, which couples only a little energy of the amplified feeding signal of each radiating element to the following cascaded one. Such RF-channel cascaded transmitter makes the decrease or increase of the number of the radiating elements quite flexible. The transmitting circuits are highly integrated with a microstrip antenna for every radiating element, which benefits the planar transmitter with the profile of less than 3 mm and the weight of each radiating element of less than 40g. Meanwhile, we develop an autotracking algorithm for the ACTR-WPT system, which inherently depends on the adaptive focusing mechanism of the TR technique. With the newly developed autotracking algorithm, we successfully demonstrate the experiments of powering the devices arbitrarily moving within a range from 1m to 7 m and the angle from -45° to +45°. The received dc power ranges from 1mW to 250 mW. The demonstration results are exciting for applications in charging or powering the movable sensors of low power consumption within a mid-range region.