Antennas integrated with speakers and methods for suppressing cavity modes

• US 9,178,268 B2
• Filed: 07/03/2012
• Issued: 11/03/2015
• Est. Priority Date: 07/03/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhu, Jiang, Li, Qingxiang, Gomez Angulo, Rodney A., Samardzija, Miroslav, Coutts, Gordon, Schlub, Robert W.
• Primary Examiner(s): DUONG, DIEU HIEN
• Application Number:
  US13/540,999
• Publication Number:
  US 20140009344A1
• Time in Patent Office: 1,218 Days
• Field of Search: 343/702, 455/575.1
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/2266 disposed inside the computer
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

An electronic device may be provided with a speaker box antenna for transmitting and receiving radio-frequency signals. A speaker box antenna may be formed from a hollow dielectric speaker box containing a speaker driver. An opening in the speaker box adjacent to the speaker driver may be aligned with a speaker port opening in a conductive electronic device housing structure. The speaker box may be surrounded by conductive structures that form a cavity for the antenna. The conductive structures may include parts of the conductive electronic device housing structure. The speaker box may have opposing upper and lower surfaces. Metal plates may form parts of the upper and lower surfaces and may be shorted together using a conductive layer such as a strip of metal tape. Frequencies of operation may be selected for the antenna that suppress undesired cavity modes and enhance antenna performance.

Claims

1. A cavity antenna that is configured to operate in an electronic device within a frequency band extending from a lower band edge to an upper band edge, comprising:

a speaker box;

a conductive antenna cavity formed from conductive structures surrounding the speaker box; and

an antenna resonating element on the speaker box, wherein the conductive structures are configured to cut off an electromagnetic mode of order N at a cutoff frequency that lies below the lower band edge and to cut off an electromagnetic mode of order N+1 at a cutoff frequency that lies above the upper band edge.

2. The cavity antenna defined in claim 1 wherein the speaker box has opposing upper and lower surfaces containing respective first and second metal plates.

3. The cavity antenna defined in claim 2 further comprising a conductive layer that electrically connects the first metal plate to the second metal plate.

4. The cavity antenna defined in claim 3 wherein the conductive layer comprises a strip of metal tape.

5. The cavity antenna defined in claim 4 wherein at least one of the conductive structures comprises metal electronic device housing structures.

6. The cavity antenna defined in claim 5 wherein at least one of the conductive structures comprises button structures.

7. The cavity antenna defined in claim 6 wherein the metal electronic device housing structures have an opening configured to form a speaker port for the speaker box and wherein the strip of metal tape has an opening that matches the opening in the metal electronic device housing structures.

8. An electronic device, comprising:

a conductive electronic device housing including an opening; and

a cavity antenna having;

a speaker box configured to emit sound through the opening;

a conductive antenna cavity formed from conductive structures surrounding the speaker box including at least part of the conductive electronic device housing; and

an antenna resonating element on the speaker box, wherein the conductive structures are configured to cut off an electromagnetic mode of order N at a cutoff frequency that lies below the lower band edge and to cut off an electromagnetic mode of order N+1 at a cutoff frequency that lies above the upper band edge.

9. The electronic device defined in claim 8 wherein the speaker box is hollow and has speaker box walls surrounding a hollow interior, the electronic device further comprising a speaker driver in the hollow interior.

10. The electronic device defined in claim 9 further comprising at least one metal member that forms part of the speaker box walls.

11. The electronic device defined in claim 10 further comprising a layer of metal tape that is electrically connected to the metal member.

12. The electronic device defined in claim 11 wherein the at least one metal member and the metal tape cover portions of the speaker box adjacent to the speaker driver and wherein the metal tape has an opening through which sound from the speaker driver passes.

13. The electronic device defined in claim 11 further comprising at least one additional metal member that forms part of the speaker box walls, wherein the speaker box has opposing upper and lower surfaces, and wherein the metal member forms part of the upper surface and the additional metal member forms part of the lower surface.

14. The electronic device defined in claim 13 wherein the speaker box has an elongated shape with first and second opposing ends and wherein the speaker driver, the metal member, and the additional metal member are located nearer to the first end than to the second end.

15. The electronic device defined in claim 14 further comprising a display and a display cover layer that covers the display.

16. The electronic device defined in claim 15 wherein a portion of the display cover layer overlaps the speaker box.

17. The electronic device defined in claim 16 wherein the speaker box is located in a corner portion of the conductive electronic device housing and wherein the conductive electronic device housing is configured to overlap at least three wall surfaces on the speaker box.

18. The electronic device defined in claim 8 wherein the antenna resonating element comprises a flexible printed circuit antenna resonating element.

19. The electronic device defined in claim 8 wherein the speaker box has an elongated length and has at least one wall running along the elongated length and wherein the conductive structures include a metal tape that covers only part of the elongated length so that some of the wall is uncovered by metal tape.

20. A method of operating a speaker box cavity antenna having a cavity formed from conductive structures surrounding a speaker box, comprising:

transmitting and receiving radio-frequency electromagnetic signals with the speaker box cavity antenna within a frequency band having a lower band edge and an upper band edge selected to cut off an electromagnetic mode of order N at a cutoff frequency that lies below the lower band edge and to cut off an electromagnetic mode of order N+1 at a cutoff frequency that lies above the upper band edge;

wherein transmitting and receiving the radio-frequency electromagnetic signals with the speaker box cavity antenna comprises using a flexible printed circuit antenna resonating element on the speaker box to transmit and receive signals.