Near-Field Beamforming Loop Array for Selective Wireless Power Transfer

This letter presents near-field beamforming using a loop array for selective wireless power transfer. Near-field beamforming is achieved by controlling the loop current. The magnitude and phase of the loop currents are controlled by adjusting the loop capacitances. The appropriate capacitance value of the loop array can be found with a genetic algorithm for maximum efficiency. It is demonstrated that the power is selectively transferred when there are two receivers whose separation is 50 cm from the 1 x 4 loop array at the frequency of 6.78 MHz. The experimental results agree with the theoretical results. In addition, the loop array has an advantage of insensitiveness to misalignment of a receiver for power transfer.