A mid-range wireless power transfer system for portable electronic devices using beam forming

This work presents the design, fabrication, and testing of a wireless power transfer system with a range of 3 m operating at 2.4 GHz. The system comprises custom-designed transmitter (TX), and receiver (RX) blocks to establish the power-link and data-link using ESP-32 module to perform a handshaking between TX and RX for efficient beam steering. The TX employs a 1-Dimensional (1D) 4-element microstrip patch antenna array for beam steering in azimuth and achieves the elevation coverage using multiple TX's. Each element in the TX antenna array is fed by a dedicated commerical of-the-shelf (COTS) channel consisting of Power Amplifiers, Phase Shifter ICs, a passive power divider, and a single oscillator. The RX patch antenna is followed by an efficient multi-stage charge-pump rectifier which generates buffered 5 V at 2.5Watts for the backend mobile device charging. The RX device activates the data link, enabling the TX to perform a smart segmented beam steering to determine the optimal beam directivity depending on the mobile device location. The system achieves a beam steering of ± 30 degrees in azimuth and a beam width of 10 degrees at 3 m while exhibiting TX and RX antenna gains of 4.4 dBi and 4 dBi, respectively. At a transmitted power of + 30dBm, the received power at 10 inches is − 5dBm, and the charge pump generates 5 V at its fourth stage, demonstrating the feasibility of a safe and efficient wireless power transfer for indoor settings.