Compact radio frequency transmitting and receiving antenna and control device employing same

• US 20050280598A1
• Filed: 06/21/2004
• Published: 12/22/2005
• Est. Priority Date: 06/21/2004
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Felegy, Edward M. Jr., Webb, Spencer L., DeJonge, Stuart, Altonen, Gregory S., Sinha, Siddharth P., Thompson, Stephen S.
• Granted Patent: US 7,362,285 B2
• Time in Patent Office: Days
• US Class Current: 343/867
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 7/005 with variable reactance for tuning the antenna

Abstract

A compact antenna for use in a device for controlling the power delivered to an electric load and operable to transmit or receive radio frequency signals at a specified frequency is presented. The antenna comprises a first loop of conductive material having a capacitance and an inductance forming a circuit being resonant at the specified frequency, and a second loop of conductive material having two ends adapted to be electrically coupled to an electronic circuit. The second loop is substantially only magnetically coupled to the first loop and is electrically isolated from the first loop. In a first embodiment of the antenna, the first and second loops are formed on respective first and second printed circuit boards, which allow for a small, low-cost antenna that is easy to manufacture and maximizes efficiency. When the antenna is installed in a load control device, such as a dimmer, the first loop of the antenna is mounted on an outer surface of the device. The second loop of the antenna may be at a high-voltage potential such as line voltage.

Claims

1. An antenna operable to transmit or receive radio frequency signals at a specified frequency, the antenna comprising:

a first loop of conductive material having a capacitance and an inductance, the capacitance and the inductance forming a circuit being resonant at the specified frequency; and

a second loop of conductive material having two ends adapted to be electrically coupled to an electronic circuit, the second loop being substantially only magnetically coupled to the first loop and electrically insulated from the first loop;

said first and second loops each having a loop axis, the loop axes of the first and second loops being substantially parallel or coincident;

said antenna for use with a device for controlling the power delivered to an electrical load.

2. The antenna of claim 1, wherein the first loop of conductive material comprises a break and the capacitance includes a capacitor bridging the break.

3. The antenna of claim 1, wherein the second loop is substantially at line voltage potential.

4. The antenna of claim 1, wherein the first and second loops are formed on respective first and second printed circuit boards.

5. The antenna of claim 1, wherein the first loop is formed on a first printed circuit board, and wherein the first printed circuit board is disposed in a plane parallel to a mounting yoke of an electrical control device, the yoke adapted to mount the electrical control device in an electrical box.

6. The antenna of claim 5, wherein the loop axis of the main loop is substantially parallel to the plane in which the yoke is disposed.

7. The antenna of claim 4, wherein the first printed circuit board of the first loop has a slot therein, and the second printed circuit board of the second loop is disposed in a plane perpendicular to a plane in which the first printed circuit board is disposed, the slot being sized to receive a dimension of the second printed circuit board, the second printed circuit board being received in the slot.

8. The antenna of claim 2, wherein the first loop includes a first conductive member disposed a defined distance above a mounting yoke of an electrical control device and substantially parallel to a plane in which the mounting yoke is disposed, the first conductive member being separated from the yoke at a portion thereof by said break, a dielectric member being disposed across the break forming said capacitor whereby an electrical current can be induced in said first loop comprising said first conductive member, said capacitor and areas of said yoke adjacent the first conductive member.

9. The antenna of claim 8, wherein the first conductive member comprises a metal member electrically coupled to said yoke at one end and said capacitor is disposed at an opposite end of said metal member between the metal member and the yoke.

10. The antenna of claim 9, wherein the metal member is mechanically fastened to the yoke at one end.

11. The antenna of claim 9, wherein the metal member is integrally formed with the yoke at said one end.

12. The antenna of claim 11, wherein the metal member is stamped from said yoke.

13. The antenna of claim 8, wherein the capacitor is clamped between said first conductive member and said yoke by a clamping device.

14. The antenna of claim 8, wherein said capacitor comprises a printed circuit board dielectric.

15. The antenna of claim 14, wherein the capacitor comprises a printed circuit board having a metal layer on at least one side of the printed circuit board.

16. The antenna of claim 8, wherein the second loop comprises a conductive sheet metal material formed in a loop.

17. The antenna of claim 8, wherein the second loop comprises a metal trace formed on a printed circuit board.

18. The antenna of claim 8, wherein the second loop is surrounded by an insulation material.

19. An antenna operable to transmit or receive radio frequency signals at a specified frequency, the antenna comprising:

a first printed circuit board comprising a first loop of conductive material having a capacitance and an inductance, the capacitance and the inductance forming a circuit being resonant at the specified frequency; and

a second printed circuit board comprising a second loop of conductive material having two ends adapted to be electrically coupled to an electronic circuit, the second loop being substantially only magnetically coupled to said first loop and electrically insulated from the first loop;

said antenna for use with a device for controlling the power delivered to an electrical load.

20. The antenna of claim 19, wherein the first loop of conductive material comprises a break and the capacitance includes a capacitor bridging the break.

21. The antenna of claim 19, wherein the second loop is substantially at line voltage potential.

22. The antenna of claim 20, wherein the first loop comprises a first metal layer on a first side of the first printed circuit board and a second metal layer on a second, opposite side of the first printed circuit board, the first and second layers being electrically connected to each other and wherein the break is provided in one of said layers.

23. The antenna of claim 22, wherein said capacitor is trimmable to adjust said given frequency.

24. The antenna of claim 22, wherein the first and second layers are electrically coupled by via holes through the first printed circuit board provided at opposite ends of the printed circuit board.

25. The antenna of claim 19, wherein the first printed circuit board is disposed in a first plane, and the first loop is disposed in a plane perpendicular to the first plane whereby electrical current flows in the first loop in a plane perpendicular to the first plane.

26. The antenna of claim 25, wherein the first printed circuit board is fixed to a mounting yoke of a lighting control device, the yoke adapted to mount the lighting control device in an electrical box, and wherein the first printed circuit board is disposed parallel to a plane of the yoke.

27. The antenna of claim 25, wherein the second printed circuit board is disposed in a plane perpendicular to the plane of the first printed circuit board.

28. The antenna of claim 27, wherein the first printed circuit board has a slot therein, sized to receive a dimension of the second printed circuit board, the second printed circuit board being received in the slot.

29. The antenna of claim 26, wherein the first printed circuit board is attached to the yoke by at least one fastener disposed along an edge portion of the first printed circuit board.

30. The antenna of claim 26, wherein the first printed circuit board has a slot therein, sized to receive a dimension of the second printed circuit board, the second printed circuit board being received in the slot, and wherein the first printed circuit board is attached to the yoke by at least one fastener disposed adjacent the slot.

31. The antenna of claim 26, wherein the first printed circuit board is attached to the yoke by at least one fastener disposed in a portion of the loop having a minimal current density.

32. The antenna of claim 26, wherein the first loop has a main loop axis that is parallel to the plane of the yoke.

33. The antenna of claim 19, wherein an electrical current flows in said first loop in a plane perpendicular to the plane of the first printed circuit board.

34. The antenna of claim 19, wherein electrical current flows in said first loop along a main loop axis of the first printed circuit board.

35. The antenna of claim 19, wherein electrical current flows in said first loop along a main loop axis of the first printed circuit board through each of the metal layers of the first printed circuit board and through the via holes of the first printed circuit board.

36. The antenna of claim 22, further comprising an inductance trimmer provided on said first printed circuit board for adjusting the specified frequency.

37. The antenna of claim 36, wherein the inductance trimmer comprises at least one cut made in at least one of said metal layers.

38. The antenna of claim 22, wherein partially trimming away part of one of said first and second metal layers changes the inductance of the first printed circuit board thereby to adjust said given frequency.

39. The antenna of claim 22, further comprising interdigitated fingers in at least one of the metal layers for trimming the capacitance of the first printed circuit board thereby adjusting the specified frequency.

40. The antenna of claim 39, wherein the at least one capacitor is coupled across said break on the first metal layer on the first side of said first printed circuit board and the interdigitated fingers are disposed on the second side of the first printed circuit board.

41. The antenna of claim 40, wherein the interdigitated fingers comprise first and second sets of fingers, the first set of fingers being coupled to the first metal layer of the first side of the first printed circuit board and the second set of fingers being coupled to the second metal layer on the second side of the first printed circuit board.

42. The antenna of claim 41 wherein the first set of fingers are coupled to the first metal layer on the first side of the first printed circuit board by a via hole.

43. The antenna of claim 22, further comprising at least one conductive region on one of said first and second sides of the first printed circuit board separated from said one of said first and second metal layers by a gap surrounding the at least one conductive region, the at least one conductive region being electrically coupled to the other of said first and second metal layers thereby forming a capacitance, said capacitance being trimmable by adjusting at least one dimension of said at least one conductive region.

44. The antenna of claim 43, wherein said at least one conductive region is coupled to the other of said first and second metal layers by a via hole.

45. The antenna of claim 43, further comprising a plurality of said electrically conductive regions.

46. The antenna of claim 22, further comprising a plurality of capacitors connected across the break on one of the first and second sides of the first printed circuit board, each capacitor being coupled by a via hole to the metal layer on the other of the first and second sides, there being provided a respective trace coupled to each capacitor connecting the capacitor to the metal layers on the other of the first and second sides, at least one of the traces being capable of being cut to trim the capacitance thereby to adjust said given frequency.

47. The antenna of claim 46, wherein the traces are on at least one of said first and second sides of the printed circuit board.

48. The antenna of claim 47, wherein the plurality of capacitors are on the first side of the first printed circuit board and respective via holes connect the capacitors to the second side of the first printed circuit board, and further wherein the traces for each capacitor are disposed on one or both sides of the first printed circuit board and connect the via holes to at least one of the first and second metal layers.

49. The antenna of claim 22, further comprising via holes connecting the first and second metal layers, and wherein respective traces on at least one side of the first printed circuit board connect the via holes to at least one of the metal layers, the traces being capable of being cut to trim the inductance of the first loop, thereby to adjust the given frequency.

50. The antenna of claim 19, wherein said second printed circuit board comprises two layers of insulating material with said second loop sandwiched between said two layers.

51. The antenna of claim 19, wherein one of said two ends of said second loop is coupled to said electronic circuit by a DC blocking capacitor.

52. The antenna of claim 26, further comprising shielding material covering a portion of said second loop below the plane of said yoke.

53. The antenna of claim 19, further comprising a plurality of second loops connected in parallel.

54. The antenna of claim 53, wherein the plurality of second loops are sandwiched between layers of insulating material.

55. The antenna of claim 26, wherein the first loop is insulated from said yoke.

56. The antenna of claim 26, wherein the first loop is electrically connected to said yoke.

57. The antenna of claim 19, wherein the first loop radiates an RF signal at the specified frequency that is substantially isotropic.

58. A compact antenna for transmitting or receiving radio frequency signals at a specified frequency comprising a first loop of conductive material having at least one break in said loop and a capacitance including a capacitor bridging the break, the loop having an inductance and forming a circuit with the capacitance, the circuit comprising the loop and the capacitance being resonant at the specified frequency, and a second loop of conductive material having two ends adapted to be electrically coupled to an electronic circuit, the second loop being substantially only magnetically coupled to the first loop, the antenna comprising a part of an electrical control device, the electrical control device having a mounting yoke disposed in a plane, the first loop having a loop axis that is substantially parallel to or coincidental with the plane of the yoke

59. An electrical control device for controlling the status of a controlled electrical device, the electrical control device comprising:

a controllably conductive device for controlling the status of the controlled electrical device;

a control circuit;

a transmitter and/or receiver in communication with the control circuit; and

an antenna coupled to the transmitter and/or receiver;

the antenna adapted to receive a first signal at a specified frequency from a remote control device and/or transmit a second signal at a specified frequency to a remote control device;

wherein the transmitter is operable to couple the first signal from the antenna to said control circuit for remotely controlling said controllably conductive device and/or couple the second signal from said control circuit for providing a status of said controlled electrical device,

the antenna comprising;

a first loop of conductive material having a capacitance and an inductance;

the capacitance and the inductance forming a circuit being resonant at the specified frequency;

a second loop of conductive material having two ends adapted to be electrically coupled to a control circuit, the second loop being substantially only magnetically coupled to said first loop;

said first and second loops each having a loop axis, the loop axes of the first and second loops being substantially parallel or coincident.

60. The device of claim 59, wherein the first loop of conductive material comprises a break and the capacitance includes a capacitor bridging the break.

61. The device of claim 59, further comprising:

an actuator coupled to the control circuit;

said control circuit responsive to the actuator.

62. The device of claim 59, wherein the first loop is electrically isolated from the second loop.

63. The device of claim 62, wherein the second loop is substantially at line voltage potential.

64. The device of claim 59, further comprising

a status indicator for indicating the status of the controlled electrical device;

the status indicator coupled to and responsive to the control.

65. The device of claim 59, further comprising:

a housing for the controllably conductive device, the control circuit, the transmitter and/or receiver, and the antenna; and

a support yoke coupled to the housing for fastening the electrical control device to an electrical wall box.

66. The device of claim 65, wherein said yoke comprises a metal plate substantially coextensive with said housing and having mounting ears extending therefrom for fastening the yoke to the electrical wall box, said antenna being disposed on an outwardly facing surface of said yoke.

67. The device of claim 66, wherein said yoke includes an opening therein for said second loop.

68. The device of claim 59, further comprising a manual actuator for controlling the controllably conductive device.

69. The device of claim 59, wherein said controlled electrical device comprises an electrical lamp and said control circuit further comprises a dimmer circuit for controlling the intensity of said lamp.

70. The device of claim 65,

wherein the antenna is disposed approximately in the center of the yoke.

71. The device of claim 65, wherein the first and second loops comprise printed circuit boards, the first loop being disposed on a printed circuit board disposed parallel to the plane of the yoke, and the second loop is disposed on a printed circuit board disposed perpendicular to the printed circuit board containing the first loop.

72. The device of claim 65, wherein the first loop is formed in part from a first conductive member disposed at a defined distance from the yoke parallel to a plane of the yoke, with the break formed between a portion of the first conductive member and the yoke.

73. A remote control device adapted to control without a wire connection, an electrical control device connected to a controlled electrical device, the remote control device comprising:

a control circuit;

a transmitter and/or receiver in communication with the control circuit;

an antenna coupled to the transmitter and/or receiver, the antenna adapted to transmit a first signal at a specified frequency to said electrical control device and/or receive a second signal at the specified frequency from said electrical control device;

wherein the transmitter is operable to couple said first signal from said control circuit to the antenna and/or the receiver is operable to couple said second signal from said antenna to said control circuit;

the antenna comprising;

a first loop of conductive material having a capacitance and an inductance;

the capacitance and inductance forming a circuit being resonant at the specified frequency;

a second loop of conductive material having two ends adapted to be electrically coupled to the control circuit, the second loop being substantially only magnetically coupled to said first loop; and

said first and second loops each having a loop axis, the loop axes of the first and second loops being substantially parallel or coincident.

74. The device of claim 73, further comprising:

an actuator coupled to the control circuit;

said control circuit responsive to the actuator;

wherein the first signal is transmitted to the electrical control device for remotely controlling the electrical control device thereby to control the status of the controlled electrical device.

75. The device of claim 73, further comprising:

a status indicator coupled to the control circuit and responsive to the control circuit;

wherein the second signal is received from the electrical control device for indicating a status of said controlled electrical device.

76. The device of claim 73, wherein the first loop of conductive material comprises a break and the capacitance includes a capacitor bridging the break.

77. The device of claim 73, wherein the first loop is electrically isolated from the second loop.

78. The device of claim 77, wherein the second loop is substantially at line voltage potential.

79. The device of claim 73, further comprising a display for displaying the status of the controlled electrical device.

80. The device of claim 76, further comprising:

a housing for the controllably conductive device, the control circuit, the transmitter and/or receiver, and the antenna; and

a support yoke coupled to the housing for fastening the electrical control device to an electrical wall box.

81. The device of claim 80, wherein said yoke comprises a metal plate substantially coextensive with said housing and having mounting ears extending therefrom for fastening the yoke to the electrical wall box, said antenna being disposed on an outwardly facing surface of said yoke.

82. The device of claim 73, wherein the controlled electrical device comprises an electric lamp.

83. The device of claim 80, wherein the antenna is disposed approximately in the center of the yoke.

84. The device of claim 80, wherein the first and second loops comprise printed circuit boards, the first loop being disposed on a printed circuit board disposed parallel to the plane of the yoke, and the second loop is disposed on a printed circuit board disposed perpendicular to the printed circuit board containing the first loop.

85. The device of claim 80, wherein the first loop is formed in part from a first conductive member disposed at a defined distance from the yoke parallel to a plane of the yoke, with the break formed between a portion of the first conductive member and the yoke.

86. An electrical control device adapted to be mounted at least partly within an electrical wall box for controlling the status of a controlled electrical device, the electrical control device comprising:

a housing;

a support yoke coupled to the housing, the support yoke being disposed in a plane and having a fastening device for coupling the yoke to the electrical wall box;

a controllably conductive device contained within the housing for controlling the status of the controlled electrical device;

a control circuit contained in the housing;

a transmitter and/or receiver contained in the housing; and

an antenna adapted to receive a signal at a specified frequency from a remote control device and/or transmit a signal at a specified frequency to a remote control device, the antenna being coupled to the transmitter and/or receiver, the transmitter and/or receiver;

coupling a signal from the remote control device to said control circuit for remotely controlling said controllably conductive device; and

/or receiving a signal from said control circuit for providing a signal to said remote control device to indicate the status of said controlled electrical device,

the antenna comprising;

a first loop of conductive material having at least one break in said loop and a capacitance including a capacitor bridging the break, the loop having an inductance and forming a circuit with the capacitance, the circuit comprising the loop and the capacitance being resonant at the specified frequency;

a second loop of conductive material having two ends adapted to be electrically coupled to a control circuit, the second loop being substantially only magnetically coupled to said first loop;

said first loop having a main loop axis substantially parallel to the plane of the yoke.

87. The device of claim 86, wherein the first loop is electrically isolated from the second loop.

88. The device of claim 87, wherein the second loop is substantially at line voltage potential.

89. A remote control device adapted to be mounted at least partly within an electrical wall box, and adapted to control without a wire connection, an electrical control device connected to a controlled electrical device, the remote control device comprising:

a housing;

a support yoke coupled to the housing, the support yoke being disposed in a plane and having a fastening device for coupling the yoke to the electrical wall box;

a control circuit contained in the housing;

a transmitter and/or receiver contained in the housing;

an antenna;

said antenna adapted to;

transmit a signal at a specified frequency from the control circuit to said electrical control device; and

/or receive a signal at the specified frequency from said electrical control device;

the antenna being coupled to a transmitter and/or receiver, the transmitter and/or receiver;

coupling said signal from said control circuit to the antenna for remotely controlling the electrical control device thereby to control the status of the controlled electrical device; and

/or receiving said signal from said antenna from the electrical control device for providing a signal to said control circuit to indicate the status of said controlled electrical device;

the antenna comprising;

a first loop of conductive material having at least one break in said loop and a capacitance including a capacitor bridging the break, the loop having an inductance and forming a circuit with the capacitance, the circuit comprising the loop and the capacitance being resonant at the specified frequency;

a second loop of conductive material having two ends adapted to be electrically coupled to the control circuit, the second loop being substantially only magnetically coupled to said first loop; and

said first loop having a main loop axis substantially parallel to the plane of the yoke.

90. The device of claim 89, further comprising:

an actuator coupled to said control circuit to provide a signal thereto to control the status of the controlled electrical device.

91. The device of claim 89, wherein the first loop is electrically isolated from the second loop.

92. The device of claim 91, wherein the second loop is substantially at line voltage potential.