Adaptive Receiver Orientation Intracavity Microwave Power Transfer Using Programmable Metasurfaces

In intracavity microwave power transfer (MPT) applications, receiver rotations cause fluctuations and a decrease in over-the-air (OTA) efficiency. To address this issue, we propose an intracavity MPT system incorporating metasurfaces that are programmable in both phase and polarization. Programmable metasurfaces (PMS) manipulate both the reflection phase and the polarization direction of microwaves within the cavity, thereby altering the electric field strength and polarization direction at the receiver. Subsequently, we develop an adaptive receiver orientation algorithm that integrates genetic algorithms with time reversal (TR) theory to optimize the PMS pattern. For experimental validation, an intracavity MPT system, incorporating 147 meta-atoms and operating at 2.4 GHz, was designed, fabricated, and tested. Experimental results indicate that our system achieved an improvement of at least 11 dB in the OTA efficiency, reaching an efficiency of 13% or more at the measurement orientation, compared to systems using a fixed PMS pattern. This improvement significantly enhances the robustness of the intracavity MPT system against variations in receiver orientation.