Microwave wireless charger with focusing of microwave field

A power transmitter for performing power transmission, the power transmitter comprising:

• at least one power transmitter antenna array configured to generate a microwave field;
• and
• a controller configured to determine angular coordinates of the power transmitter in relation to a position of at least one power receiver, determining a distance between the at least one power receiver and the power transmitter based on the determined angular coordinates by using a focused microwave field, determining the position of the at least one power receiver based on the determined angular coordinates and the determined distance, and wirelessly transmitting power by focusing a microwave field to the determined position of the at least one power receiver,
• wherein, if a number of at least one power receiver is at least two, the controller is configured to simultaneously charge the at least two power receivers by multi-focusing the microwave field to positions of the at least two power receivers.

A transmitter antenna array for generating a microwave field, the transmitter antenna array comprising:

• a first printed circuit board (PCB) and a second PCB, which are stacked without electric connection,
• wherein the first PCB carries microwave input, power dividing circuitry, phase shifters, microstrip or coplanar array element excitation circuitry on a first side, and couples with a slot aperture on a second side,
• wherein the second PCB carries a circularly polarized patch excited by the slot aperture coupled to microstrip or coplanar excitation circuitry, and
• wherein the first PCB comprises a double-sided, low-loss, high frequency PCB, and the second PCB comprises a single-sided PCB.