Methods for slot antenna design for wearable electronic devices and conductive housings

• US 10,320,063 B2
• Filed: 12/14/2017
• Issued: 06/11/2019
• Est. Priority Date: 12/14/2016
• Status: Active Grant

• Current Assignee: Fitbit, Inc. (Alphabet Inc.)
• Original Assignee: Fitbit, Inc. (Alphabet Inc.)
• Inventors: Wei, Yonghua, Li, Kevin, Markan, Patrick James, Wang, Allen Yu-Li, Kaiponen, Teemu Taneli Raafael, Ioannou, Christos Kinezos
• Primary Examiner(s): Phan, Tho G
• Application Number:
  US15/842,689
• Publication Number:
  US 20180166772A1
• Time in Patent Office: 544 Days
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles
• CPC Class Codes: H01Q 1/2266 disposed inside the computer
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/27 Adaptation for use in or on movable bodies H01Q1/08, H01Q1/12, H01Q1/18 take precedence
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• 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 13/10 Resonant slot antennas
• CPC Class Codes: H01Q 13/18 the slot being backed by, or formed in boundary wall of, a resonant cavity longitudinally slotted cylinder H01Q13/12 ; Open cavity antennas
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters

Abstract

A wearable computing device can include a monopole-excited slot antenna formed by a gap between a housing (such as a highly conductive housing) and a bracket (such as a highly conductive bracket) within the highly conductive housing and by a back cavity between the highly conductive bracket and the PCB. The antenna configuration can include a monopole antenna electrically coupled to a printed circuit board and a slot antenna that is excited through coupled electromagnetic fields. The highly conductive bracket is positioned near a display window of the device, mostly below and partially enclosing a battery. The highly conductive bracket is positioned above the printed circuit board. This configuration allows for a relatively small dead band in the display window, a larger battery, compact and mechanically simple configuration, and superior water resistance.

Claims

1. A device, comprising:

a conductive housing having one or more interior surfaces;

a power source;

a conductive bracket having one or more edges or surfaces, the conductive bracket contained within and separate from the conductive housing, the one or more edges or surfaces of the conductive bracket and the one or more interior surfaces of the conductive housing forming a gap therebetween;

a monopole antenna;

an antenna matching circuit;

a display within the conductive housing, wherein a dead band of the display overlaps with a dead band of the monopole antenna; and

a printed circuit board (PCB) having one or more edges, the one or more edges of the PCB and the one or more interior surfaces of the conductive housing forming a second gap there between, a portion of the first gap forming a slot antenna, the PCB coupled to the monopole antenna through the antenna matching circuit and configured to drive a monopole radiator of the monopole antenna, wherein electromagnetic fields generated by the monopole antenna induce the slot antenna to transmit or receive radio frequency signals, further wherein the PCB and the conductive bracket form a back cavity therebetween, the back cavity comprising a dielectric gap and facilitating resonance of the slot antenna, and wherein the power source, the conductive bracket, the monopole antenna, the antenna matching circuit, and the PCB are within walls of the conductive housing.

2. The device of claim 1, wherein the dead band of the display and the dead band of the monopole antenna each include a space between an interior surface of the conductive housing and an edge or surface of the conductive bracket.

3. The device of claim 1, wherein the dead band of the monopole antenna is within the dead band of the display.

4. The device of claim 1, wherein the dead band of the monopole antenna is located within a defined distance of a top of the display.

5. The device of claim 1, wherein the slot antenna is formed at more than two edges or surfaces of the conductive bracket.

6. The device of claim 1, wherein the slot antenna is not directly excited by an antenna feed physically coupled to the PCB.

7. The device of claim 1, further comprising a near field communication antenna, wherein the near field communication antenna is above the power source within the conductive housing and below the display.

8. The device of claim 1, wherein the power source is at least partially enclosed by the conductive bracket such that a bottom surface of the power source is adjacent to a top surface of the conductive bracket and within the conductive housing, wherein the PCB is below the conductive bracket.

9. The device of claim 1, wherein the conductive bracket includes a first grounding connection at a first end of the slot antenna and a second grounding connection at a second end of the slot antenna, the first grounding connection and the second grounding connection configured to electrically couple the conductive bracket and the conductive housing.

10. The device of claim 9, wherein the conductive bracket further includes a third grounding pin across the first gap between the conductive bracket and the conductive housing, wherein the third grounding pin is not in a portion of the first gap forming the slot antenna.

11. The device of claim 1, wherein the slot antenna is completely disposed within the conductive housing, and the display is coupled to the conductive housing forming a water tight seal.

12. The device of claim 1, further comprising a touch sensor between a display window and the display.

13. The device of claim 1, wherein the PCB is grounded to the conductive housing at multiple points around a perimeter of the PCB and is proximate the bottom of the conductive housing.

14. The device of claim 1, wherein the power source is at least partially enclosed by the conductive bracket such that a top surface of the power source is adjacent to a bottom surface of the conductive bracket and within the conductive housing, wherein the PCB is below the power source.

15. A device, comprising:

a conductive housing having one or more interior surfaces;

a power source;

a conductive bracket at least partially above and enclosing at least a portion of the power source such that a top surface of the power source is adjacent to a bottom surface of the conductive bracket;

a printed circuit board (PCB) having one or more edges, the one or more edges of the PCB and the one or more interior surfaces of the conductive housing forming a gap there between, a portion of the gap forming a slot antenna, wherein the PCB and the conductive bracket form a back cavity there between, the back cavity comprising a dielectric gap and facilitating resonance of the slot antenna; and

a direct feed coupling a matching circuit on the PCB to the conductive bracket, wherein the direct feed is configured to induce the slot antenna to transmit or receive radio frequency signals, further wherein the power source, the conductive bracket, the PCB, and the direct feed are within the conductive housing.

16. The device of claim 15, wherein the slot antenna is formed at more than two sides of the PCB.

17. The device of claim 15, further comprising a near field communication antenna, wherein the near field communication antenna is above the PCB and below a display within the conductive housing.

18. The device of claim 15, further wherein the conductive bracket is below the PCB and is grounded to the conductive housing at a plurality of locations around a perimeter of the conductive bracket and is positioned proximate the bottom of the conductive housing.

19. The device of claim 15, wherein the PCB includes a first grounding connection at a first end of the slot antenna and a second grounding connection at a second end of the slot antenna, the first grounding connection and the second grounding connection configured to electrically couple the PCB and the conductive housing.

20. The device of claim 19, wherein the PCB further includes a third grounding pin across a gap between the PCB and the conductive housing not in a portion of the gap forming the slot antenna.