ANTENNA DIVERSITY SYSTEMS FOR PORTABLE ELECTRONIC DEVICES

• US 20090295648A1
• Filed: 06/03/2008
• Published: 12/03/2009
• Est. Priority Date: 06/03/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Kough, Douglas B., Dorsey, John G.
• Granted Patent: US 8,159,399 B2
• Time in Patent Office: Days
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/2266 disposed inside the computer
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

Antenna diversity systems are provided for portable electronic devices that have wireless communications circuitry and environment sensors. The wireless communications circuitry may include multiple redundant antennas that operate in one or more overlapping radio-frequency communications bands. The environment sensors and redundant antennas may be used in implementing an antenna diversity system. For example, an electronic device may use environment sensors to select an antenna for use in handling wireless communications. The electronic devices may monitor the wireless performance of an active antenna. When the wireless performance of the active antenna degrades, the electronic devices may select a new antenna for wireless communications using the antenna diversity system and environment sensors. Antenna selection may also be made based on which features are being used in the electronic device.

Claims

1. An electronic device, comprising:

a plurality of antennas that each transmit and receive radio-frequency signals in at least a first radio-frequency band;

a proximity sensor associated with one of the antennas in the plurality of antennas;

a radio-frequency transceiver; and

switching circuitry that selectively couples a given antenna in the plurality of antennas to the radio-frequency transceiver.

2. The electronic device defined in claim 1 wherein the switching circuitry comprises circuitry that selectively couples the given antenna to the radio-frequency transceiver based on signals from the proximity sensor.

3. The electronic device defined in claim 1 wherein the plurality of antennas comprises a first antenna and a second antenna, wherein the proximity sensor detects when objects come within a given distance of the first antenna, and wherein when the proximity sensor detects that a given object has come within the given distance of the first antenna, the second antenna is selectively coupled by the switching circuitry to the radio-frequency transceiver.

4. The electronic device defined in claim 3 further comprising:

a second proximity sensor that detects when objects come within a second distance of the second antenna, wherein;

when the proximity sensor has not detected that a given object has come within the given distance of the first antenna and the second proximity sensor has detected that a given object has come within the second distance of the second antenna, the first antenna is selectively coupled by the switching circuitry to the radio-frequency transceiver.

5. The electronic device defined in claim 1 wherein the proximity sensor comprises a light emitting diode that emits light at an infrared frequency from the electronic device and a light detecting diode that detects light at the infrared frequency that has been reflected back to the electronic device.

6. The electronic device defined in claim 1 wherein the electronic device comprises a tablet computer.

7. The electronic device defined in claim 1 wherein the plurality of antennas comprises three antennas that each transmit and receive radio-frequency signals in at least the first radio-frequency band.

8. The electronic device defined in claim 1 further comprising:

a plurality of proximity sensors, wherein there are an equal number of proximity sensors and antennas and wherein each proximity sensor is located adjacent to a corresponding antenna.

9. The electronic device defined in claim 1 wherein the first radio-frequency band comprises a 2.4 GHz communications band.

10. A portable electronic device with wireless communications circuitry, comprising:

an orientation sensor that determines an orientation of the portable electronic device relative to a horizontal plane;

a plurality of antennas that each transmit and receive radio-frequency signals in at least a first radio-frequency band;

a radio-frequency transceiver; and

switching circuitry that selectively couples one of the plurality of antennas to the radio-frequency transceiver.

11. The portable electronic device defined in claim 10 wherein the switching circuitry comprises circuitry that selectively couples a given antenna in the plurality of antennas to the radio-frequency transceiver based on the orientation of the portable electronic device relative to the horizontal plane.

12. The portable electronic device defined in claim 10 further comprising:

processing circuitry that uses signals from the orientation sensor to determine when a given antenna out of the plurality of antennas is facing away from the horizontal plane, wherein the given antenna is selectively coupled by the switching circuitry to the radio-frequency transceiver when the given antenna is facing away from the horizontal plane.

13. The portable electronic device defined in claim 10 wherein the plurality of antennas comprises a first antenna and a second antenna, the portable electronic device further comprising:

a proximity sensor that detects when an object comes within a given distance of the first antenna, wherein when the proximity sensor detects that an object has come within the given distance of the first antenna, the switching circuitry selectively couples the second antenna to the radio-frequency transceiver.

14. The portable electronic device defined in claim 13 wherein the first antenna is located at one end of the portable electronic device and the second antenna is located at an opposite end of the portable electronic device.

15. The portable electronic device defined in claim 13 wherein when the proximity sensor has not detected that an object has come within the given distance of the first antenna, the switching circuitry selectively couples the first antenna to the radio-frequency transceiver.

16. The portable electronic device defined in claim 13 further comprising:

processing circuitry that uses signals from the orientation sensor that indicate the orientation of the portable electronic device to determine that a given antenna out of the first and second antennas is facing away from the horizontal plane, wherein when the proximity sensor does not detect that an object has come within the given distance of the first antenna, the given antenna is selectively coupled by the switching circuitry to the radio-frequency transceiver.

17. The portable electronic device defined in claim 10 where the orientation sensor comprises an accelerometer that measures the orientation of gravitational acceleration relative to the portable electronic device.

18. A portable electronic device comprising:

first and second antennas that each transmit and receive radio-frequency signals in at least a first radio-frequency band;

a first proximity sensor that is located adjacent to the first antenna and that detects objects relative to the first antenna;

a second proximity sensor that is located adjacent to the second antenna and that detects objects relative to the second antenna;

a radio-frequency transceiver; and

switching circuitry that selectively couples a selected one of the first and second antennas to the radio-frequency transceiver.

19. The portable electronic device defined in claim 18 wherein the switching circuitry comprises circuitry that selectively couples the selected one of the first and second antennas to the radio-frequency transceiver based on signals from the first and second proximity sensors.

20. The portable electronic device defined in claim 18 wherein each proximity sensor comprises a light emitting diode that emits light at an infrared frequency from the portable electronic device and a light detecting diode that detects light at the infrared frequency that has been reflected back to the portable electronic device.

21. The portable electronic device defined in claim 18 wherein the switching circuitry selectively couples a selected one of the first and second antennas to the radio-frequency transceiver based on whether a given communications protocol is being used by the radio-frequency transceiver.

22. The portable electronic device defined in claim 21 wherein the given communications protocol comprises a Bluetooth®

communications protocol.

23. The portable electronic device defined in claim 18 wherein the first antenna is located at one end of the portable electronic device and the second antenna is located at an opposite end of the portable electronic device.