Far-field wireless power transfer using localized field with multi-tone signals

A method of wirelessly transferring power, comprising:

• generating a first set of multiple copies of a multi-tone power waveform by a first wireless power transmitter;
• introducing, by the first wireless power transmitter, a first set of relative delays into the first set of copies of the multi-tone power waveform, wherein the first set of relative delays are configured to form a beam when the first set of copies of the multi-tone power waveform is transmitted from a first array of antennas;
• and
• transmitting the first set of copies of the multi-tone power waveform with the first set of relative delays from first array.

A wireless power transfer system, comprising

• a first wireless power transmitter comprising:
• a first signal generation and optimization circuit configured generate a first plurality of multi-tone beam forming waveforms;
• and
• a first antenna array connected to the first signal generation and optimization and configured to receive and transmit the first plurality of multi-tone beam forming waveforms;
• and
• a second wireless power transmitter comprising:
• a second signal generation and optimization circuit configured generate a second plurality of multi-tone beam forming waveforms;
• and
• a second antenna array connected to the second signal generation and optimization and configured to receive and transmit the second plurality of multi-tone beam forming waveforms,
• wherein first signal generation and optimization circuit and the second signal generation and optimization circuit are further configured to respectively generate the first plurality of multi-tone beam forming waveforms and the second plurality of multi-tone beam forming waveforms to constructively interfere at a region located between the first wireless power transmitter and the second wireless power transmitter.