Tunable multiband antenna with passive and active circuitry

• US 10,008,764 B2
• Filed: 09/13/2016
• Issued: 06/26/2018
• Est. Priority Date: 04/17/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Jiang, Yi, Yong, Siwen, Coutts, Gordon, Zhang, Lijun, Li, Qingxiang, Schlub, Robert W.
• Primary Examiner(s): Han, Jessica
• Assistant Examiner(s): KIM, JAE K
• Application Number:
  US15/264,500
• Publication Number:
  US 20170005397A1
• Time in Patent Office: 651 Days
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/245 with means for shaping the antenna pattern, e.g. in order to protect user against rf exposure
• CPC Class Codes: H01Q 1/44 using equipment having another main function to serve additionally as an antenna , e.g. means for giving an antenna an aesthetic aspectH01Q1/27 - H01Q1/34 take precedence
• CPC Class Codes: H01Q 1/48 Earthing means; Earth screens; Counterpoises
• CPC Class Codes: H01Q 3/22 varying the orientation in accordance with variation of frequency of radiated wave
• CPC Class Codes: H01Q 5/392 the parasitic elements having dual-band or multi-band characteristics

Abstract

An electronic device may have an antenna for providing coverage in wireless communications bands of interest such as a low frequency communications band and a high frequency communications band. The antenna may have an antenna ground and an antenna resonating element. The antenna resonating element may have a high band arm that contributes to a first high band resonance in the high band and may have a low band arm that exhibits a low band resonance in the low band. A passive filter that is coupled between first and second portions of the antenna resonating element may be configured to exhibit a short circuit impedance associated with a bypass path that allows the antenna resonating element to contribute to a second high band resonance in the high band. A tunable inductor coupled to the antenna resonating element may be used to tune the low band resonance.

Claims

1. An antenna, comprising:

a resonating element having a first arm and a second arm, wherein the second arm has first, second, and third portions, the first portion extends parallel to the second portion, and the third portion extends from an end of the first portion to an end of the second portion;

an antenna ground, wherein the second arm and the antenna ground are configured to resonate in a low communications band and the first arm and the antenna ground are configured to resonate in a high communications band;

a first antenna feed terminal coupled to the resonating element;

a second antenna feed terminal coupled to the antenna ground;

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

a filter coupled between the first portion and the second portion of the second arm, wherein the filter is configured to form a path length between the first and second portions of the second arm that is shorter than the second arm.

2. The antenna defined in claim 1, wherein the first arm and the second arm of the resonating element are formed on opposing sides of the short circuit path.

3. The antenna defined in claim 1, wherein the filter is configured to form the path length in an additional high communication band and the filter is configured to form an open circuit in the low communications band.

4. The antenna defined in claim 1, wherein the third portion of the second arm extends perpendicular to the first and second portions of the second arm.

5. The antenna defined in claim 1, further comprising:

a tunable component coupled between the second portion of the second arm and the antenna ground, wherein the tunable component is configured tune the low communications band.

6. The antenna defined in claim 5, wherein the tunable component comprises a switch.

7. The antenna defined in claim 6, wherein the filter is a passive filter.

8. The antenna defined in claim 1, wherein the filter comprises a passive filter.

9. The antenna defined in claim 8 wherein the passive filter comprises an inductor and capacitor coupled in parallel between the first and second portions of the second arm.

10. The antenna defined in claim 1 wherein the first arm, the second arm, and the short circuit path comprise metal traces formed on a planar surface of a dielectric carrier.

11. An electronic device, comprising:

a housing;

an antenna ground;

a dielectric carrier;

an antenna resonating element formed on the dielectric carrier, wherein the antenna resonating element has a first arm and a second arm, the first arm and the antenna ground are configured to exhibit a low band antenna resonance, and the second arm and the antenna ground are configured to exhibit a high band antenna resonance;

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

a first antenna feed terminal coupled to the antenna resonating element;

a second antenna feed terminal coupled to the antenna ground; and

a filter coupled between a first portion of the first arm and a second portion of the first arm, wherein the first portion of the first arm extends parallel to the second portion of the first arm, the first and second portions of the first arm are coupled together by a third portion of the first arm that extends between the first and second portions, and the filter is configured to form a path length that is shorter than the first arm.

12. The electronic device defined in claim 11, wherein the housing comprises a metal housing having an opening and an antenna window in the opening.

13. The electronic device defined in claim 11, further comprising:

a tunable component coupled between the second portion of first arm and the antenna ground.

14. The electronic device defined in claim 13 wherein the tunable component comprises switching circuitry and the electronic device further comprises:

control circuitry that provides control signals to the switching circuitry that adjust a state of the switching circuitry to tune the low band antenna resonance.

15. The electronic device defined in claim 11 wherein the filter is configured to exhibit a short circuit impedance at a frequency within the high band resonance.

16. The electronic device defined in claim 11, wherein the filter is configured to exhibit an open circuit impedance at a frequency within the low band resonance.

17. The electronic device defined in claim 11 further comprising:

a display cover layer having a portion that overlaps that antenna resonating element, wherein the antenna resonating element is configured to receive radio-frequency signals through the portion of the display cover layer that overlaps the antenna resonating element.

18. An antenna comprising:

an antenna ground;

an antenna resonating element having a first arm and a second arm, wherein the antenna ground and the first arm are configured to resonate in a low frequency band, the antenna ground and the second arm are configured to resonate in a first high frequency band;

an antenna feed having a first feed terminal coupled to the antenna ground and a second feed terminal coupled to the antenna resonating element;

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

a filter coupled between a first portion of the first arm and a second portion of the first arm, wherein the filter forms a short circuit that creates a path length that is shorter than the first arm at frequencies in a second high frequency band and forms an open circuit for at least some frequencies other than the frequencies in the second high frequency band.

19. The antenna defined in claim 18, wherein at least some of the first and second portions of the first arm, the second arm, and the short circuit path are formed from metal traces on a planar surface of a dielectric carrier.

20. The antenna defined in claim 18, wherein the short circuit path is interposed between the second arm and the second portion of the first arm.