Antenna With Switchable Inductor Low-Band Tuning

• US 20130169490A1
• Filed: 01/04/2012
• Published: 07/04/2013
• Est. Priority Date: 01/04/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Pascolini, Mattia, Schlub, Robert W., Jin, Nanbo, Mow, Matthew A., Nickel, Joshua G., Hu, Hongfei
• Granted Patent: US 9,350,069 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 5/357 using a single feed point

Abstract

Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antennas. An antenna may be formed from an antenna resonating element arm and an antenna ground. The antenna resonating element arm may have a shorter portion that resonates at higher communications band frequencies and a longer portion that resonates at lower communications band frequencies. A short circuit branch may be coupled between the shorter portion of the antenna resonating element arm and the antenna ground. A series-connected inductor and switch may be coupled between the longer portion of the antenna resonating element arm and the antenna ground. An antenna feed branch may be coupled between the antenna resonating element arm and the antenna ground at a location that is between the short circuit branch and the series-connected inductor and switch.

Claims

1. An electronic device, comprising:

control circuitry; and

an antenna having an antenna resonating element arm and an antenna ground configured to resonate in at least a first communications band and a second communications band that is higher in frequency than the first communications band, having an inductor, and having a switch, wherein the inductor and switch are coupled in series between antenna resonating element arm and the antenna ground, wherein the switch is configured to switch between an open state and a closed state in response to control signals from the control circuitry, and wherein the antenna is configured to resonate in a lower frequency portion of the first communications band and in the second communications band in response to placing the switch in the closed state and wherein the antenna is configured to resonate in a higher frequency portion of the first communications band and in the second communications band in response to placing the switch in the open state.

2. The electronic device defined in claim 1 wherein the antenna comprises an antenna feed branch coupled between the antenna resonating element arm and the antenna ground.

3. The electronic device defined in claim 2 further comprising a cellular telephone transceiver coupled to the antenna at the antenna feed branch.

4. The electronic device defined in claim 3 further comprising a short circuit branch coupled between the antenna resonating element arm and the antenna ground.

5. The electronic device defined in claim 4 wherein the antenna feed branch is interposed between the short circuit branch and the inductor and switch that are coupled in series.

6. The electronic device defined in claim 5 further comprising:

a housing containing conductive structures that form the antenna ground for the antenna and having a peripheral conductive member that runs around at least some edges of the housing, wherein a segment of the peripheral conductive member forms the antenna resonating element arm for the antenna.

7. The electronic device defined in claim 1 wherein the antenna resonating element arm has a longer portion that resonates in the first communications band and a shorter portion that resonates in the second communications band.

8. The electronic device defined in claim 7 further comprising:

a housing containing conductive structures that form the antenna ground for the antenna and having a peripheral conductive member that runs around at least some edges of the housing, wherein a segment of the peripheral conductive member forms the antenna resonating element arm for the antenna.

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

a housing containing conductive structures that form the antenna ground for the antenna and having a peripheral conductive member that runs around at least some edges of the housing, wherein a segment of the peripheral conductive member forms the antenna resonating element arm for the antenna.

10. An antenna, comprising:

an antenna resonating element arm;

an antenna ground;

a series-connected inductor and switch coupled between the resonating element arm and the antenna ground;

a short circuit branch coupled between the antenna resonating element arm and the antenna ground; and

an antenna feed coupled between the antenna resonating element arm and the antenna ground at a location along the antenna resonating element arm that is between the short circuit branch and the series-connected inductor and switch.

11. The antenna defined in claim 10 wherein the antenna is configured to resonate in a lower frequency portion of a first communications band and in a second communications band that is at higher frequencies than the first communications band in response to placing the switch in a closed state and wherein the antenna is configured to resonate in a higher frequency portion of the first communications band and in the second communications band in response to placing the switch in an open state.

12. The antenna defined in claim 11 wherein the antenna resonating element arm comprises a segment of a peripheral conductive member in an electronic device housing.

13. The antenna defined in claim 12 wherein the antenna resonating element arm is configured to handle cellular telephone signals.

14. The electronic device defined in claim 13 wherein the antenna resonating element arm has a longer portion that resonates in the first communications band and a shorter portion that resonates in the second communications band.

15. The antenna defined in claim 14 further comprising an impedance matching circuit coupled in parallel with the antenna feed.

16. The electronic device defined in claim 11 wherein the antenna resonating element arm has a longer portion that resonates in the first communications band and a shorter portion that resonates in the second communications band.

17. An antenna, comprising:

an antenna resonating element arm that has a longer portion that resonates in a first communications band and a shorter portion that resonates in a second communications band that is associated with higher frequencies than the first communications band;

an antenna ground;

a series-connected inductor and switch coupled between the resonating element arm and the antenna ground;

a short circuit branch coupled between the antenna resonating element arm and the antenna ground; and

an antenna feed coupled between the antenna resonating element arm and the antenna ground.

18. The antenna defined in claim 17 wherein the antenna feed is coupled between the antenna resonating element and the antenna ground at a location along the antenna resonating element arm that is between the short circuit branch and the series-connected inductor and switch.

19. The antenna defined in claim 18 wherein the short circuit branch is coupled between the shorter portion of the antenna resonating element and the antenna ground.

20. The antenna defined in claim 19 wherein the series-connected inductor and switch are coupled between the longer portion of the antenna resonating element arm and the antenna ground.

21. The antenna defined in claim 20 wherein the antenna resonating element arm comprises a segment of a peripheral conductive member in an electronic device housing.