Loop antenna with a parasitic radiator

• US 7,728,785 B2
• Filed: 02/07/2006
• Issued: 06/01/2010
• Est. Priority Date: 02/07/2006
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Ozden, Sinasi
• Primary Examiner(s): MANCUSO, HUEDUNG XUAN CAO
• Application Number:
  US11/350,155
• Publication Number:
  US 20070182658A1
• Time in Patent Office: 1,575 Days
• Field of Search: 343/866, 343/702, 343/748, 343/895, 343/700.MS, 455/575.1, 455/575.7
• US Class Current: 343/866
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 5/321 within a radiating element or between connected radiating elements
• CPC Class Codes: H01Q 5/371 Branching current paths
• CPC Class Codes: H01Q 5/378 Combination of fed elements with parasitic elements
• CPC Class Codes: H01Q 5/385 Two or more parasitic elements
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0442 with particular tuning means
• CPC Class Codes: H01Q 9/265 Open ring dipoles; Circular dipoles

Abstract

It is an objective of the present invention to provide an antenna construction that allows the thickness of an antenna structure be lower than that of planar antennas according to prior art without sacrificing the radiation efficiency at the desired RF-bands as 900 MHz GSM and 1800 MHz/1900 MHz DCS/PCS. A further object of the invention is to provide an antenna construction that is insensitive to changes in positions of electrically conductive objects in the vicinity. The objectives of the invention are achieved by a loop antenna structure equipped with an electrically conductive parasitic radiator that is electro-magnetically coupled with the antenna loop. Performance at the DCS/PCS bands can be further improved by using an electrically conductive tuner element that provides a stronger electromagnetic coupling between the antenna loop and the parasitic radiator.

Claims

1. An antenna arrangement comprising:

a first electrical terminal and a second electrical terminal,

an electrical conductor forming an antenna loop having at least one electrically conductive path extending from the first electrical terminal to the second electrical terminal, the antenna loop being configured to operate as a loop antenna,

an electrically conductive parasitic radiator in a substantially co-planar arrangement with the antenna loop, the electrically conductive parasitic radiator being arranged to couple with the antenna loop, said electrically conductive parasitic radiator having a length that is approximately one quarter of a wavelength at an operating frequency, and

an electrically conductive tuner element in the vicinity of the antenna loop and the electrically conductive parasitic radiator, the distance between the electrically conductive tuner element and the antenna loop being at a distance to increase capacitive coupling between the antenna loop and the parasitic radiator.

2. An antenna arrangement according to claim 1, wherein the distance between the electrically conductive tuner element and the antenna loop is no greater than 20 mm, and the distance between the electrically conductive tuner element and the electrically conductive parasitic radiator is no greater than 20 mm.

3. An antenna arrangement according to claim 1, further comprising an electrically conductive part a surface of which is disposed to constitute a ground plane for at least one of the following:

the antenna loop and the electrically conductive parasitic radiator.

4. An antenna arrangement according to claim 3, further comprising a galvanic coupling between the ground plane and the electrically conductive parasitic radiator.

5. An antenna arrangement according to claim 1, wherein there are more than one electrically conductive parasitic radiator.

6. An antenna arrangement according to claim 5, wherein there are more than one electrically conductive tuner element.

7. An antenna arrangement according to claim 1, wherein the distance between the antenna loop and the parasitic radiator is no greater than 20 mm.

8. An antenna arrangement according to claim 1, wherein the distance between the antenna loop and the parasitic radiator is no greater than 6 mm.

9. An antenna arrangement according to claim 1, wherein the antenna arrangement is configured for use in a mobile communication device.

10. An antenna arrangement comprising:

a first electrical terminal and a second electrical terminal,

an electrical conductor forming an antenna loop having at least one electrically conductive path extending from the first electrical terminal to the second electrical terminal, the antenna loop being configured to operate as a loop antenna,

an electrically conductive parasitic radiator in a substantially co-planar arrangement with the antenna loop, the electrically conductive parasitic radiator being arranged to couple with the antenna loop, said electrically conductive parasitic radiator having a length that is approximately one quarter of a wavelength at an operating frequency, and further comprising a coupling element connecting the electrically conductive parasitic radiator to the antenna loop, the coupling element comprising at least one of a passive electrical component, an active electrical component, and both passive and active electrical components.

11. An antenna arrangement comprising:

a first electrical terminal and a second electrical terminal between which RF-signal is fed into the antenna arrangement or received from the antenna arrangement,

an electrical conductor forming an antenna loop having at least one electrically conductive path extending from the first electrical terminal to the second electrical terminal, the antenna loop being configured to operate as a loop antenna that is arranged to emit RF-electromagnetic radiation to surrounding space when RF-voltage is coupled between the first electrical terminal and the second electrical terminal, and to form RF-voltage between the first electrical terminal and the second electrical terminal when RF-electromagnetic radiation falls to the antenna loop,

an electrically conductive parasitic radiator disposed to receive RF-electromagnetic energy from the antenna loop via an mutual electromagnetic coupling over an electrically insulating area, and to emit a part of the received electromagnetic energy in a form of RF-electromagnetic radiation to the surrounding space, and to capture RF-electromagnetic energy from RF-electromagnetic radiation falling to the electrically conductive parasitic radiator, and to transfer a part of the captured RF-electromagnetic energy to the antenna loop via the mutual electromagnetic coupling over an electrically insulating area, wherein the electrically conductive parasitic radiator is in a substantially co-planar arrangement with the antenna loop, said electrically conductive parasitic radiator having a length that is approximately one quarter of a wavelength at an operating frequency, and

an electrically conductive tuner element disposed to mediate RF-electromagnetic energy between the antenna loop and the electrically conductive parasitic radiator via electrical coupling between the electrically conductive tuner element and the antenna loop and via electrical coupling between the electrically conductive tuner element and the electrically conductive parasitic radiator.

12. An antenna arrangement according to claim 11, wherein at least one of

the electrical coupling between the electrically conductive tuner element and the antenna loop,

the electrical coupling between the electrically conductive tuner element and the electrically conductive parasitic radiator;

is realized as electric and magnetic field coupling over an electrically insulating area.

13. An antenna arrangement according to claim 11, wherein at least one of

the electrical coupling between the electrically conductive tuner element and the antenna loop,

the electrical coupling between the electrically conductive tuner element and the electrically conductive parasitic radiator;

comprises a galvanic coupling via an electrically conductive area.

14. An antenna arrangement according to claim 11, further comprising an electrically conductive part a surface of which is disposed to constitute a ground plane for at least one of the following:

the antenna loop and the electrically conductive parasitic radiator.

15. An antenna arrangement according to claim 14, further comprising a galvanic coupling between the ground plane and the electrically conductive parasitic radiator.

16. An antenna arrangement according to claim 11, further comprising a coupling element connecting the electrically conductive parasitic radiator to the antenna loop, the coupling element comprising at least one of a passive electrical component, an active electrical component, and both passive and active electrical components.

17. An antenna arrangement according to claim 11, wherein there are more than one electrically conductive parasitic radiator.

18. An antenna arrangement according to claim 17, wherein there are more than one electrically conductive tuner element.

19. A mobile communication device comprising:

a first electrical terminal and a second electrical terminal between which an RF-signal transmitted from the mobile communication device is fed and between which an RF-signal received at the mobile communication device is detected,

an electrical conductor forming an antenna loop having at least one electrically conductive path extending from the first electrical terminal to the second electrical terminal, the antenna loop being configured to operate as a loop antenna that is arranged to emit RF-electromagnetic radiation to surrounding space when RF-voltage is coupled between the first electrical terminal and the second electrical terminal and to form RF-voltage between the first electrical terminal and the second electrical terminal when RF-electromagnetic radiation falls to the antenna loop,

an electrically conductive parasitic radiator disposed to receive RF-electromagnetic energy from the antenna loop via an mutual electromagnetic coupling over an electrically insulating area, and to emit a part of the received electromagnetic energy in a form of RF-electromagnetic radiation to the surrounding space, and to capture RF-electromagnetic energy from RF-electromagnetic radiation falling to the parasitic radiator, and to transfer a part of the captured RF-electromagnetic energy to the antenna loop via the mutual electromagnetic coupling over an electrically insulating area, wherein the electrically conductive parasitic radiator is in a substantially co-planar arrangement with the antenna loop, said electrically conductive parasitic radiator having a length that is approximately one quarter of a wavelength at an operating frequency, and

an electrically conductive tuner element disposed to mediate RF-electromagnetic energy between the antenna loop and the electrically conductive parasitic radiator via electrical coupling between the electrically conductive tuner element and the antenna loop and via electrical coupling between the electrically conductive tuner element and the electrically conductive parasitic radiator.

20. A mobile communication device according to claim 19, wherein said mobile communication device is a mobile phone.

21. A mobile communication device comprising according to claim 19, further comprising an electrically conductive part a surface of which is disposed to constitute a ground plane for at least one of the following:

the antenna loop and the electrically conductive parasitic radiator.

22. A method comprising:

using an antenna arrangement that includes;

a first electrical terminal and a second electrical terminal,

an electrical conductor forming an antenna loop having at least one electrically conductive path extending from the first electrical terminal to the second electrical terminal, the antenna loop being configured to operate as a loop antenna,

an electrically conductive parasitic radiator in a substantially co-planar arrangement with the antenna loop, the electrically conductive parasitic radiator being arranged to couple with the antenna loop, said electrically conductive parasitic radiator having a length that is approximately one quarter of a wavelength at an operating frequency, and

an electrically conductive tuner element in the vicinity of the antenna loop and the electrically conductive parasitic radiator, the distance between the electrically conductive tuner element and the antenna loon being at a distance to increase capacitive coupling between the antenna loop and the parasitic radiator.