Smart RF lensing: efficient, dynamic and mobile wireless power transfer

• US 10,367,380 B2
• Filed: 11/12/2013
• Issued: 07/30/2019
• Est. Priority Date: 11/09/2012
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Sengupta, Kaushik, Hajimiri, Seyed Ali
• Primary Examiner(s): Barnie, Rexford N
• Assistant Examiner(s): Ortiz, Elim
• Application Number:
  US14/078,489
• Publication Number:
  US 20140175893A1
• Time in Patent Office: 2,086 Days
• CPC Class Codes: H01Q 21/225 Finite focus antenna arrays
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/23 characterised by the type of transmitting antennas, e.g. directional array antennas or Yagi antennas
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment

Abstract

An RF lens includes a multitude of radiators adapted to transmit radio frequency electromagnetic EM waves whose phases are modulated so as to concentrate the radiated power in a small volume of space in order to power an electronic device positioned in that space. Accordingly, the waves emitted by the radiators are caused to interfere constructively at that space. The multitude of radiators are optionally formed in a one-dimensional or two-dimensional array. The electromagnetic waves radiated by the radiators have the same frequency but variable amplitudes.

Claims

1. An RF lens comprising:

a first plurality of radiators adapted to radiate electromagnetic waves to power a device positioned away from the RF lens, wherein the plurality of radiators operate at a first frequency; and

a plurality of locked loop circuits adapted to control phases of the electromagnetic waves radiated by the first plurality of radiators such that the phase of the electromagnetic wave radiated by each of the plurality of radiators is set in accordance with a distance between the radiator and the device, wherein said plurality of locked loop circuits are further adapted to lock a phase or a frequency of the electromagnetic wave radiated by each of the first plurality of radiators to a phase or frequency of a reference signal, wherein said reference signal is not generated by a target receiving the electromagnetic waves radiated by the plurality of radiators.

2. The RF lens of claim 1 wherein said first plurality of radiators are formed in an array.

3. The RF lens of claim 2 wherein said array is a one-dimensional array.

4. The RF lens of claim 2 wherein said array is a two-dimensional array.

5. The RF lens of claim 1 wherein an amplitude of an electromagnetic wave radiated by each of the first plurality of radiators is variable.

6. The RF lens of claim 1 wherein each of the first plurality of radiators comprises:

a variable delay element; and

an antenna.

7. The RF lens of claim 1 wherein said first plurality of radiators are formed in a first radiator tile adapted to receive a second radiator tile having disposed therein a second plurality of radiators.

8. The RF lens of claim 1 wherein said RF lens is further adapted to track a position of the device.

9. The RF lens of claim 1 wherein each of at least a first subset of the first plurality of radiators comprises a circuit for receiving an electromagnetic wave transmitted by the device thereby enabling the RF lens to determine a position of the device in accordance with a phase of the electromagnetic wave received by each of the at least first subset of the first plurality of radiators.

10. The RF lens of claim 1 wherein each of at least a first subset of the plurality of radiators comprises a circuit for receiving an electromagnetic wave transmitted by the device thereby enabling the RF lens to determine a position of the device in accordance with a travel time of the electromagnetic wave from the device to each of the at least first subset of the first plurality of radiators and a travel time of a response electromagnetic wave transmitted from the RF lens to the device.

11. The RF lens of claim 1 wherein said RF lens is formed in a semiconductor substrate.

12. The RF lens of claim 1 wherein said RF lens is formed in a flexible substrate.

13. The RF lens of claim 1 wherein the amplitude/phase of the first plurality of radiators are further selected to enable electromagnetic waves scattered off objects to power the device.

14. The RF lens of claim 1 wherein said RF lens further comprises:

a second plurality of radiators adapted to radiate electromagnetic waves to power a second device, wherein each of the second plurality of radiators operates at a second frequency different than the first frequency, wherein a phase of an electromagnetic wave radiated by each of the second plurality of radiators is selected to be determined by a distance between the radiator and the second device.

15. The RF lens of claim 1 wherein each of the plurality of locked loop circuits is a phase locked loop circuit.

16. The RF lens of claim 1 wherein each of the plurality of locked loop circuits is a frequency locked loop circuit.

17. The RF lens of claim 1 wherein the first frequency is different from the frequency of the reference signal.

18. The RF lens of claim 1 wherein the frequency of the reference signal is a sub-harmonic of the first frequency.

19. The RF lens of claim 1 wherein said RF lens is further adapted to track and power a second device.

20. The RF lens of claim 1 wherein a distance between a first one of the first plurality of radiators and a second one of the first plurality of radiators is different from a distance between a third one of the first plurality of radiators and a fourth one of the first plurality of radiators.

21. A method of wirelessly powering a device, the method comprising:

transmitting a plurality of electromagnetic waves at a first frequency from a first plurality of radiators to the device;

varying phases of the first plurality of radiators by a plurality of locked loop circuits such that the phase of an electromagnetic wave radiated by each of the plurality of radiators is set in accordance with a distance between the radiator and the device;

locking a phase or a frequency of the electromagnetic wave radiated by each of the first plurality of radiators to a phase or frequency of a reference signal, wherein said reference signal is not generated by a target receiving the electromagnetic waves radiated by the plurality of radiators; and

providing power to the device using the plurality of electromagnetic waves received by the device.

22. The method of claim 21 further comprising:

forming the first plurality of radiators in an array.

23. The method of claim 22 further comprising:

forming the first plurality of radiators in a one-dimensional array.

24. The method of claim 22 further comprising:

forming the first plurality of radiators in a two-dimensional array.

25. The method of claim 21 further comprising:

varying an amplitude of an electromagnetic wave radiated by each of the first plurality of radiators.

26. The method of claim 21 wherein each of the plurality of radiators comprises:

a variable delay element; and

an antenna.

27. The method of claim 21 wherein said first plurality of radiators are formed in a first radiator tile adapted to receive a second radiator tile having disposed therein a second plurality of radiators.

28. The method of claim 21 further comprising:

tracking a position of the device.

29. The method of claim 21 further comprising:

determining a position of the device in accordance with relative phases of an electromagnetic wave transmitted by the device and received by each of a first subset of the first plurality of radiators.

30. The method of claim 21 further comprising:

determining a position of the device in accordance with a travel time of an electromagnetic wave transmitted by the device and received by each of a first subset of the first plurality of radiators, and further in accordance with a travel time of a response electromagnetic wave transmitted from the RF lens to the device.

31. The method of claim 21 further comprising:

forming the first plurality of radiators in a semiconductor substrate.

32. The method of claim 21 further comprising:

forming the first plurality of radiators in a flexible substrate.

33. The method of claim 21 further comprising:

selecting the amplitude/phase of the first plurality of radiators to enable the electromagnetic waves transmitted by the first plurality of radiators and scattered off objects to power the device.

34. The method of claim 21 further comprising:

transmitting a second plurality of electromagnetic waves having a second frequency from a second plurality of radiators to a second device and concurrently with the transmission of the electromagnetic waves from the first plurality of radiators;

selecting a phase of each of the second plurality of radiators in accordance with a distance between the radiator and the second device; and

providing power to the second device using the second plurality of electromagnetic waves.

35. The method of claim 21 further comprising:

tracking and powering a second device using the electromagnetic waves radiated by the first plurality of radiators.

36. The method of claim 21 wherein a distance between a first one of the first plurality of radiators and a second one of the first plurality of radiators is different from a distance between a third one of the first plurality of radiators and a fourth one of the first plurality of radiators.

37. The method of claim 21 wherein each of the plurality of locked loop circuits is a phase locked loop circuit.

38. The method of claim 21 wherein each of the plurality of locked loop circuits is a frequency locked loop circuits.

39. The method of claim 21 wherein the first frequency is different from the frequency of the reference signal.

40. The method of claim 21 wherein the frequency of the reference signal is a sub-harmonic of the first frequency.