Tunable antennas for handheld devices

• US 20080055164A1
• Filed: 09/05/2006
• Published: 03/06/2008
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Caballero, Ruben, Zhang, Zhijun
• Granted Patent: US 7,671,804 B2
• Time in Patent Office: Days
• US Class Current: 343/702
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 5/371 Branching current paths
• 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

Abstract

A compact tunable antenna for a handheld electronic device and methods for calibrating and using compact tunable antennas are provided. The antenna can have multiple ports. Each port can have an associated feed and ground. The antenna design can be implemented with a small footprint while covering a large bandwidth. The antenna can have a radiating element formed from a conductive structure such as a patch or helix. The antenna can be shaped to accommodate buttons and other components in the handheld device. The antenna may be connected to a printed circuit board in the handheld device using springs, pogo pins, and other suitable connecting structures. Radio-frequency switches and passive components such as duplexers and diplexers may be used to couple radio-frequency transceiver circuitry to the different feeds of the antenna. Antenna efficiency can be enhanced by avoiding the use of capacitive loading for antenna tuning.

Claims

1. A tunable multiport handheld electronic device antenna, comprising:

a radiating element;

a ground terminal that is electrically connected to the radiating element; and

at least first and second antenna feeds, wherein the first antenna feed is electrically connected to the radiating element at a first location, wherein the second antenna feed is electrically connected to the radiating element at a second location that is different from the first location, wherein the first antenna feed and the ground form a first antenna port, and wherein the second antenna feed and the ground form a second antenna port.

2. The tunable multiport handheld electronic device antenna defined in claim 1 wherein the radiating element comprises a patch antenna structure.

3. The tunable multiport handheld electronic device antenna defined in claim 1 wherein the radiating element comprises a metal antenna structure without adjustable capacitive loading.

4. The tunable multiport handheld electronic device antenna defined in claim 1 wherein the radiating element comprises first, second, and third integral elongated portions, wherein the first elongated portion forms the ground, wherein the second elongated portion forms the first feed, and wherein the third elongated portion forms the second feed.

5. The tunable multiport handheld electronic device antenna defined in claim 1 wherein the radiating element comprises metal and is configured to operate at a frequency range associated with a first cellular telephone band when the first port is used and is configured to operate at a frequency range associated with a second cellular telephone band that is different from the first cellular telephone band when the second port is used.

6. A handheld electronic device comprising:

storage that stores data;

processing circuitry coupled to the storage that generates data for wireless transmission and that processes wirelessly-received data; and

wireless communications circuitry that communicates with the processing circuitry, wherein the wireless communications circuitry contains a tunable multiport antenna containing a ground, a first antenna feed, and a second antenna feed, wherein the processing circuitry tunes the antenna by selecting whether to use the first antenna feed or the second antenna feed in wirelessly transmitting and receiving data.

7. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises:

a radio-frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a separate communications band; and

switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path.

8. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises:

a radio-frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a respective one of a set of at least five different communications bands; and

switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path, wherein the antenna transmits and receives signals in a fundamental frequency range and a harmonic frequency range, wherein when the first feed is connected, the antenna'"'"'s fundamental frequency range is used to transmit and receive signals associated with a first one of the five bands and a second one of the five bands and the antenna'"'"'s harmonic frequency range is used to transmit and receive signals associated with a third one of the five bands and a fourth one of the five bands, and wherein when the second feed is connected, the antenna'"'"'s harmonic frequency range is used to transmit and receive signals associated with a fifth one of the five bands.

9. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises:

a radio-frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a respective one of a set of at least five different communications bands; and

switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path, wherein the antenna transmits and receives signals in a fundamental frequency range and a harmonic frequency range, wherein when the first feed is connected, the antenna'"'"'s fundamental frequency range is used to transmit and receive signals associated with a first one of the five bands and a second one of the five bands and the antenna'"'"'s harmonic frequency range is used to transmit and receive signals associated with a third one of the five bands and a fourth one of the five bands, and wherein when the second feed is connected, the antenna'"'"'s harmonic frequency range is used to transmit and receive signals associated with a fifth one of the five bands, wherein the second band has a higher frequency than the first band, wherein the third band has a higher frequency than the second band, wherein the fourth band has a higher frequency than the third band, wherein the fifth band has a higher frequency than the fourth band, wherein the first, second, third, and fourth communications bands are cellular telephone bands and wherein the fifth band is a data band.

10. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises:

a radio-frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a respective one of a set of at least five different communications bands; and

switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path, wherein the antenna transmits and receives signals in a fundamental frequency range and a harmonic frequency range, wherein when the first feed is connected, the antenna'"'"'s fundamental frequency range is used to transmit and receive signals associated with a first one of the five bands and a second one of the five bands and the antenna'"'"'s harmonic frequency range is used to transmit and receive signals associated with a third one of the five bands and a fourth one of the five bands, and wherein when the second feed is connected, the antenna'"'"'s harmonic frequency range is used to transmit and receive signals associated with a fifth one of the five bands, wherein the first band is centered at about 850 MHz, wherein the second band is centered at about 900 MHz, wherein the third band is centered at about 1800 MHz, wherein the fourth band is centered at about 1900 MHz, and wherein the fifth band is centered at about 2170 MHz.

11. Tunable multiport antenna circuitry comprising:

a radiating element;

a circuit board having a ground conductive path and first and second antenna feed conductive paths;

a ground electrical connecting structure that connects the ground conductive path to the radiating element and serves as a ground terminal for the radiating element;

a first feed electrical connecting structure that electrically connects the first feed conductive path on the circuit board to the radiating element at a first location and serves as a first feed terminal for the radiating element; and

a second feed electrical connecting structure that electrically connects the second feed conductive path on the circuit board to the radiating element at a second location distinct from the first location and serves as a second feed terminal for the radiating element.

12. The tunable multiport circuitry defined in claim 11 wherein at least one of the ground electrical connecting structure, the first feed electrical connecting structure, and the second feed electrical connecting structure comprises a spring-loaded pin.

13. The tunable multiport circuitry defined in claim 11 wherein at least one of the ground electrical connecting structure, the first feed electrical connecting structure, and the second feed electrical connecting structure comprises a piece of bent conductor that serves as a spring.

14. The tunable multiport circuitry defined in claim 11 wherein at least one of the ground electrical connecting structure, the first feed electrical connecting structure, and the second feed electrical connecting structure comprises a piece of bent conductor formed as an integral part of the radiating element that serves as a spring and that is soldered to one of the conductive paths on the circuit board.

15. The tunable multiport circuitry defined in claim 11 wherein the circuit board has a third feed conductive path, the circuitry further comprising:

a third feed electrical connecting structure that electrically connects the third feed conductive path on the circuit board to the radiating element at a third location distinct from the first and second locations and that serves as a third feed terminal for the radiating element.

16. A method for calibrating and using a tunable multiport antenna in a handheld electronic device, comprising:

fabricating a circuit board assembly that contains a radio-frequency module, a radiating antenna element that is connected to the radio-frequency module with a ground and at least first and second antenna feeds, processing circuitry, and non-volatile memory, wherein the radio-frequency module contains at least a first radio-frequency switch connector for tapping into the first feed with a test probe and a second radio-frequency switch connector for tapping into the second feed with the test probe; and

sending control signals to the processing circuitry from a tester while measuring output signal powers for the first and second antenna feeds using the first and second radio-frequency switch connectors, wherein only a single one of the first and second antenna feeds is active at a given time.

17. The method defined in claim 16 further comprising:

determining calibration settings based on the measured output signal powers; and

storing the calibration settings in the non-volatile memory.

18. The method defined in claim 16 further comprising:

determining calibration settings based on the measured output signal powers;

storing the calibration settings in the non-volatile memory; and

transmitting and receiving data through the antenna radiating element using the calibration settings.

19. A method for using a tunable multiport antenna in a handheld electronic device, wherein the tunable multiport antenna has a first antenna port formed from a ground and a first antenna feed and has a second antenna port formed from a ground and a second antenna feed, wherein the handheld electronic device comprises a radio-frequency transceiver having associated data paths each of which carries signals for a different communications band, and wherein the handheld electronic device comprises switching circuitry that is coupled between the radio-frequency transceiver and the first and second antenna feeds, the method comprising:

adjusting the switching circuitry to activate a single selected one of the first and second antenna ports while deactivating the other of the first and second antenna ports; and

conveying signals between the transceiver and the single selected antenna port using one of the data paths and the antenna feed and ground of the single selected antenna port.

20. The method defined in claim 19 wherein the handheld electronic device comprises non-volatile memory in which calibration settings for the first and second antenna ports have been stored and wherein conveying the signals comprises:

transmitting signals from the transceiver using the calibration settings, wherein when the first antenna port is activated by the switching circuitry, the tunable multiport antenna transmits and receives signals in a fundamental frequency range containing at least a first communications band and transmits and receives signals over a harmonic frequency range containing at least a second communications band, wherein when the second antenna port is activated by the switching circuitry, the tunable multiport antenna transmits and receives signals in the harmonic frequency range containing at least a third communications band, and wherein the second and third communications bands are different.

21. Wireless communications circuitry comprising:

a tunable multiport radiating element having a ground terminal and at least first and second feed terminals, wherein the first feed terminal and the ground terminal form a first antenna port, wherein the second feed terminal and the ground terminal form a second antenna port;

a transceiver having a number of associated signal input-output paths that convey signals to and from the antenna; and

switching circuitry that tunes the tunable multiport radiating element by selectively activating the first port and the second port, wherein the switching circuitry activates the first port by connecting a first one of the input-output paths to the first feed while disconnecting the second feed from the input-output paths and wherein the switching circuitry activates the second port by connecting a second one of the input-output paths to the second feed while disconnecting the first feed from the input-output paths.

22. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range and wherein the signal input-output paths comprise:

a first input-output path that is configured to transmit and receive signals for a first communications band;

a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band; and

a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein when the first port is active, the first communications band lies within the fundamental frequency range and the second communications band lies within the harmonic frequency range and wherein when the second port is active, the third communications band lies within the harmonic frequency range.

23. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range, the wireless communications circuitry further comprising power amplifiers that amplify at least some of the signals on the input-output paths and at least one radio-frequency duplexer, wherein the signal input-output paths comprise:

a first input-output path that is configured to transmit and receive signals for a first communications band;

a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band; and

a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein when the first port is active, the first communications band lies within the fundamental frequency range and the second communications band lies within the harmonic frequency range, wherein when the second port is active, the third communications band lies within the harmonic frequency range, and wherein the duplexer is coupled within the third input-output path between the transceiver and the switching circuitry.

24. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range, the wireless communications circuitry further comprising power amplifiers that amplify at least some of the signals on the input-output paths and at least one radio-frequency duplexer, wherein the signal input-output paths comprise:

a first input-output path that is configured to transmit and receive signals for a first communications band;

a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band;

a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein the duplexer is coupled within the third input-output path between the transceiver and the switching circuitry;

a fourth input-output path that is configured to transmit and receive signals for a fourth communications band that is different than the first, second, and third communications bands; and

a fifth input-output path that is configured to transmit and receive signals for a fifth communications band that is different than the first, second, third, and fourth communications bands, wherein when the first port is active, the first and fourth communications bands lie within the fundamental frequency range and the second and fifth communications bands lie within the harmonic frequency range and wherein when the second port is active, the third communications band lies within the harmonic frequency range.

25. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range, the wireless communications circuitry further comprising power amplifiers that amplify at least some of the signals on the input-output paths and at least one radio-frequency duplexer, wherein the signal input-output paths comprise:

a first input-output path that is configured to transmit and receive signals for a first communications band;

a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band;

a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein the duplexer is coupled within the third input-output path between the transceiver and the switching circuitry;

a fourth input-output path that is configured to transmit and receive signals for a fourth communications band that is different than the first, second, and third communications bands; and

a fifth input-output path that is configured to transmit and receive signals for a fifth communications band that is different than the first, second, third, and fourth communications bands and that is associated with a data service, wherein when the first port is active, the first and fourth communications bands lie within the fundamental frequency range and the second and fifth communications bands lie within the harmonic frequency range, wherein when the second port is active, the third communications band lies within the harmonic frequency range, and wherein the first, second, third, and fourth communications bands each include non-overlapping transmit and receive subbands.