A 5.8-GHz 64-Channel Phased Array Microwave Power Transmission System Based on Space-Time Beamforming Algorithm for Multiple IoT Sensors

This paper reports a microwave power transmission system for charging multiple devices using a 64-channel phased array based on the space-time beamforming algorithm. The proposed algorithm switches multiple retrodirective beams in optimal time intervals based on DC receiving power information so that the required energies of all devices are satisfied in a minimum time. Measured results exhibit the advantages of the proposed method under practical hardware constraints: (i) 40-fold faster time than a max-min method to satisfy the requirements, and (ii) high total receiving power comparable with a max-sum method with 2.2 dB margin.