Wireless Power Range Increase Using Parasitic Antennas

• US 20090134712A1
• Filed: 11/26/2008
• Published: 05/28/2009
• Est. Priority Date: 11/28/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Nigel Power LLC (Qualcomm, Inc.)
• Inventors: Sieber, Lukas, Widmer, Hanspeter, Cook, Nigel P.
• Granted Patent: US 8,766,483 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/50 using additional energy repeaters between transmitting devices and receiving devices

Abstract

Wireless power transfer is created using a first antenna that is part of a magnetic resonator, to create a magnetic field in an area of the first antenna. One or more parasitic antennas repeats that power to create local areas where the power is more efficiently received.

Claims

1. A system, comprising:

a first system including a transmitting antenna of a first size, transmitting wireless power in a magnetic field; and

a parasitic antenna, of a second size smaller than said first size, repeating said wireless power in an area.

2. A system as in claim 1, wherein said parasitic antenna is a formed of an inductive loop and a capacitance.

3. A system as in claim 2, wherein said inductive loop is formed of stranded wire with strands that are electrically isolated from one another.

4. A system as in claim 2, wherein said inductive loop is formed of a material that increases the effective cross sectional area of a wire used for the antenna without increasing an actual cross sectional area of the wire.

5. A system as in claim 1, wherein said transmitting antenna surrounds a perimeter of a room.

6. A system as in claim 5, wherein said transmitting antenna is at different levels in the room.

7. A system as in claim 1, wherein said first system includes a frequency generator, and a matching system, said matching system including a coupling transformer, and a capacitor on a primary side of said transformer.

8. A system as in claim 2, wherein said parasitic antenna includes a tuning part that is adjustable to change a resonant frequency of said parasitic antenna.

9. A system as in claim 8, wherein said tuning part includes a variable capacitance.

10. A system as in claim 8, wherein said part only adjusts said resonant frequency in a downward direction.

11. A system as in claim 8, wherein said tuning part includes a portion that short circuits a portion of said inductive loop.

12. A system as in claim 11, wherein said part has a variable size to change an area of the inductive loop that it short circuits.

13. A system as in claim 12, wherein said part is triangular.

14. A system as in claim 9, wherein said variable capacitance is a switched capacitance.

15. A system, comprising:

a parasitic antenna, tuned to receive and repeat magnetically-generated wireless power in an area of said parasitic antenna.

16. A system as in claim 15, wherein said parasitic antenna is a formed of an inductive loop and a capacitance.

17. A system as in claim 16, wherein said inductive loop is formed of a material that increases the effective cross sectional area of a wire used for the parasitic antenna without increasing an actual cross sectional area of the wire.

18. A system as in claim 17, wherein said inductive loop is formed of stranded wire with strands that are electrically isolated from one another.

19. A system as in claim 15, further comprising a transmitting antenna that transmits magnetic energy.

20. A system as in claim 16, wherein said parasitic antenna includes a tuning part that is adjustable to change a resonant frequency of said parasitic antenna.

21. A system as in claim 20, wherein said tuning part includes a variable capacitance.

22. A system as in claim 20, wherein said tuning part only adjusts said resonant frequency in a downward direction.

23. A system as in claim 20, wherein said tuning part includes a portion that short circuits a portion of said inductive loop.

24. A system as in claim 23, wherein said tuning part has a variable size to change an area of the inductive loop that it short circuits.

25. A system as in claim 24, wherein said part is triangular in its outer shape.

26. A system as in claim 22, wherein said variable capacitance is a switched capacitance.

27. A system, comprising:

a parasitic antenna, formed of an inductive loop in series with a capacitance, said inductive loop is formed of a material that increases an effective cross sectional area of a wire used for the parasitic antenna without increasing an actual cross sectional area of the wire, an LC value of the inductive loop and capacitance defining a resonant frequency at a specified frequency, to receive and repeat said specified frequency of magnetically-generated wireless power in an area of said parasitic antenna.

28. A system as in claim 27, wherein said inductive loop is formed of stranded wire with multiple strands of wire that are electrically isolated from one another.

29. A system as in claim 28, wherein said stranded wire is Litz wire.

30. A system as in claim 27, further comprising a transmitting antenna that transmits magnetic energy at said specified frequency.

31. A system as in claim 27, wherein said parasitic antenna includes a tuning part that is adjustable to change a resonant frequency of said parasitic antenna.

32. A system as in claim 31, wherein said tuning part includes a variable capacitance.

33. A system as in claim 31, wherein said tuning part only adjusts said resonant frequency in a downward direction.

34. A system as in claim 31, wherein said tuning part includes a portion that short circuits a portion of said inductive loop.

35. A system as in claim 34, wherein said tuning part has a variable size to change an area of the inductive loop that it short circuits.

36. A system as in claim 32, wherein said variable capacitance is a switched capacitance.

37. A system, comprising:

a parasitic antenna, formed of an inductive loop in series with a capacitance, an LC value of the inductive loop and capacitance tuned to a resonant frequency at a specified frequency, to receive and repeat said specified frequency of magnetically-generated wireless power in an area of said parasitic antenna, said parasitic antenna including a tuning part that is adjustable to change a resonant frequency of said parasitic antenna by short circuiting across a portion of said inductive loop.

38. A system as in claim 37, wherein said inductive loop is formed of a material that increases the effective cross sectional area of a wire used for the antenna without increasing an actual cross sectional area of the wire.

39. A system as in claim 37, further comprising a transmitting antenna which transmits magnetic power at said specified frequency.

40. A system as in claim 37, wherein said part has a variable size to change an area of the inductive loop that it short circuits.

41. A system as in claim 40, wherein said part is triangular.

42. A system, comprising:

a wireless power transmitter, including a magnetic field generator, that generates a magnetic field at a specified frequency, and a transmitting antenna that transmits wireless power by producing a magnetic field that has said specified frequency, said transmitting antenna having an inductance, and having a capacitance, forming an LC value that is substantially resonant with said specified frequency, said inductance formed by an antenna loop that extends around a loop, and the area forming the loop has at least two different planar sections, with a first of the planar sections being above the second planar section.

43. A system as in claim 42, further comprising a parasitic antenna, smaller than said loop of said transmitting antenna, and repeating said wireless power in an area.

44. A system as in claim 42, wherein said antenna has a first area in a first plane, and a second area in a second plane that is horizontally above said first plane.

45. A system as in claim 44, further comprising a third portion which extends between said first and second planes.

46. A method, comprising:

producing wireless power from a first antenna that forms a first part of a magnetic resonator and which produces wireless power as a magnetic field;

using a parasitic antenna, within a range of said first antenna, to repeat said wireless power; and

receiving said magnetic power that has been repeated by said parasitic antenna wirelessly into a portable device and using said power to power said device.

47. A method as in claim 46, wherein said first antenna has a larger outer size than said second antenna.

48. A method as in claim 46, further comprising using a material that increases an effective cross sectional area of a wire used for the antenna without increasing an actual cross sectional area of the wire.

49. A method as in claim 46, wherein said producing uses a transmitting antenna that surrounds a perimeter of a room.

50. A method as in claim 49, wherein said transmitting antenna is at different height levels in the room.

51. A method as in claim 46, further comprising tuning a resonant frequency of said parasitic antenna.

52. A method as in claim 51, wherein said tuning comprises changing a value of a variable capacitance.

53. A method as in claim 51, wherein said tuning comprises short circuiting a portion of said inductive loop.