Hybrid radio frequency / inductive loop antenna

• US 9,520,638 B2
• Filed: 05/29/2014
• Issued: 12/13/2016
• Est. Priority Date: 01/15/2013
• Status: Active Grant

• Current Assignee: Fitbit, Inc. (Alphabet Inc.)
• Original Assignee: Fitbit, Inc. (Alphabet Inc.)
• Inventors: Baringer, William B., Martinez, Mark Manuel
• Primary Examiner(s): Levi, Dameon E
• Assistant Examiner(s): Dawkins, Collin
• Application Number:
  US14/290,906
• Publication Number:
  US 20140266939A1
• Time in Patent Office: 929 Days
• Field of Search: 343/729, 343/720, 343/741
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles
• CPC Class Codes: H01Q 1/2291 used in bluetooth or WI-FI devices of Wireless Local Area Networks [WLAN] H01Q1/241 takes precedence; WLAN in general H04W
• 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 1/48 Earthing means; Earth screens; Counterpoises
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• 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: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04W 4/027 using movement velocity, acceleration information
• CPC Class Codes: H04W 4/80 : Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
• CPC Class Codes: Y10T 29/49016 : Antenna or wave energy "plumbing" making

Abstract

Biometric monitoring devices, including various technologies that may be implemented in such devices, are discussed herein. Additionally, techniques, systems, and apparatuses are discussed herein for providing a hybrid antenna including an RF radiator and an electrically coupled inductive loop. The hybrid antenna is capable of providing both RF and induction functionality, e.g., radio frequency transmission/reception capabilities for Bluetooth as well as near-field-communications (NFC) functionality via the inductive loop. The inductive loop may be in conductive contact with the RF radiator or may be inductively coupled with the RF radiator and not in conductive contact with the RF radiator. The inductive loop may act as a planar element of a planar inverted-F antenna (PIFA).

Claims

1. An apparatus comprising:

a ground plane;

a radio-frequency radiator;

a feed post conductively connected to the radio-frequency radiator;

a shorting post, wherein the shorting post is connected to the radio-frequency radiator; and

a near-field communications (NFC) tag including an NFC circuit and

a multi-turn inductive loop configured to couple electrically with the radio-frequency radiator, the multi-turn inductive loop either in conductive contact with the radio-frequency radiator or not in conductive contact with the radio-frequency radiator, the radio-frequency radiator at least partially overlapping the turns in the multi-turn inductive loop, wherein;

the multi-turn inductive loop is conductively connected with the NFC integrated circuit and configured to inductively couple with a near-field magnetic field to provide power to the NFC circuit,

the NFC circuit, when powered, is configured to broadcast information stored within the NFC circuit, and

the multi-turn inductive loop of the NFC tag, the radio-frequency radiator, the ground plane, and the feed post together form a planar inverted-F antenna configured to produce and receive electro-magnetic radio-frequency signals, wherein the multi-turn inductive loop of the NFC tag serves as a radiator extension to the radio-frequency radiator when producing and receiving the electro-magnetic radio-frequency signals.

2. The apparatus of claim 1, wherein the turns of the multi-turn inductive loop of the NFC tag at least partially overlap the ground plane.

3. The apparatus of claim 1, wherein the radio-frequency radiator at least partially overlaps less than 20% of the turns in the multi-turn inductive loop of the NFC tag.

4. The apparatus of claim 1, wherein the turns in the multi-turn inductive loop of the NFC tag that the radio-frequency radiator at least partially overlaps are outermost turns of the multi-turn inductive loop of the NFC tag.

5. The apparatus of claim 1, wherein the radio-frequency radiator follows a path that is substantially aligned with paths followed by the turns of the multi-turn inductive loop of the NFC tag with which the radio-frequency radiator at least partially overlaps.

6. The apparatus of claim 1, wherein the turns in the multi-turn inductive loop of the NFC tag follow a path that defines a major surface that faces towards the radio-frequency radiator.

7. The apparatus of claim 1, wherein the multi-turn inductive loop of the NFC tag is separated from the radio-frequency radiator by a first gap.

8. The apparatus of claim 7, wherein the NFC tag includes an insulating layer that is interposed between the radio-frequency radiator and the multi-turn inductive loop in the first gap.

9. The apparatus of claim 7, further comprising:

a first housing portion; and

a second housing portion, wherein;

the radio-frequency radiator is supported by the first housing portion, the NFC tag is supported by the second housing portion, and

the first housing portion is mated to the second housing portion such that the NFC tag and the radio-frequency radiator are separated by the first gap.

10. The apparatus of claim 7, further comprising:

a plastic carrier; and

a substrate with a printed circuit, wherein;

the radio-frequency radiator is supported by the plastic carrier,

the plastic carrier is supported by the substrate with the printed circuit, the substrate with the printed circuit acts as the ground plane, and the NFC tag is also supported by the plastic carrier.

11. The apparatus of claim 7, further comprising:

a housing having a first surface and a second surface, wherein;

the first surface and the second surface are nominally on opposing sides of a portion of the housing and define the first gap,

the radio-frequency radiator is formed by a metallization layer deposited on the first surface,

the NFC tag is located on or adjacent to the second surface such that the second surface is interposed between the first surface and the NFC tag.

12. The apparatus of claim 7, further comprising:

a housing having a first surface and a second surface, wherein;

the first surface and the second surface are nominally on opposing sides of a portion of the housing and define the first gap,

the radio-frequency radiator is formed by a metallization layer deposited on the second surface,

the NFC tag is located on or adjacent to the second surface such that the radio-frequency radiator is interposed between the second surface and the NFC tag.

13. The apparatus of claim 7, wherein the ground plane is provided by a structure located on an opposite side of the first housing portion from the radio-frequency radiator.

14. The apparatus of claim 13, wherein the structure is selected from the group consisting of:

a printed circuit board, a flexible circuit board, a metal plate contained within the apparatus, and a metal plate at least partially providing an exterior surface of the apparatus.

15. The apparatus of claim 7, wherein:

the radio-frequency radiator has a nominal width of between about 0.5 mm and 1.5 mm and an average length of between about 10 mm and 25 mm, and

the multi-turn inductive loop of the NFC tag has an average path length of about 500 mm to 600 mm.

16. The apparatus of claim 7, wherein the radio-frequency radiator is substantially the shape of a rectangle having a length-to-width aspect ratio of at least 10:

1.

17. The apparatus of claim 7, wherein the radio-frequency radiator is L-shaped.

18. The apparatus of claim 7, wherein the radio-frequency radiator is U-shaped or C-shaped.

19. The apparatus of claim 1, wherein the multi-turn inductive loop is offset from the ground plane in a direction normal to the ground plane.

20. The apparatus of claim 1, wherein the radio-frequency radiator is offset from the ground plane by a first distance.

21. The apparatus of claim 1, wherein the ground plane is a non-planar surface.

22. The apparatus of claim 1, wherein the radio-frequency radiator and the multi-turn inductive loop of the NFC tag are in electrically-conductive contact with one another.

23. The apparatus of claim 1, wherein the radio-frequency radiator and the multi-turn inductive loop of the NFC tag are formed from the same electrically-conductive trace.

24. The apparatus of claim 1, further comprising:

a shorting post conductively connecting the radio-frequency radiator to the ground plane, wherein;

the multi-turn inductive loop of the NFC tag, the radio-frequency radiator, the ground plane, the shorting post, and the feed post together form a planar inverted-F antenna (PIFA) configured to produce and receive electro-magnetic radio-frequency signals in a Bluetooth-compatible frequency band, wherein the multi-turn inductive loop of the NFC tag serves as a radiator extension to the radio-frequency radiator when producing and receiving the electro-magnetic radio-frequency signals in the Bluetooth-compatible frequency band.

25. The apparatus of claim 24, wherein:

the radio-frequency radiator, the ground plane, and the multi-turn inductive loop of the NFC tag are formed from a common conductive trace.

26. The apparatus of claim 1, further comprising:

a shorting post conductively connecting the radio-frequency radiator to the ground plane, wherein;

the multi-turn inductive loop of the NFC tag, the radio-frequency radiator, the ground plane, the shorting post, and the feed post together form a planar inverted-F antenna (PIFA) configured to produce and receive electro-magnetic radio-frequency signals in a GPS-compatible frequency band, wherein the multi-turn inductive loop of the NFC tag serves as a radiator extension to the radio-frequency radiator when producing and receiving the electro-magnetic radio-frequency signals in the GPS-compatible frequency band.

27. The apparatus of claim 1, wherein:

the radio-frequency radiator, the ground plane, and the multi-turn inductive loop of the NFC tag are located on a common, non-recurvate reference surface.

28. The apparatus of claim 1, wherein a path length of the multi-turn inductive loop of the NFC tag is at least 20 to 50 times greater than nominal dimensions of the NFC tag.

29. The apparatus of claim 1, wherein the multi-turn inductive loop of the NFC tag is configured to inductively couple with a near-field magnetic field at a range of about 10 cm or less.

30. The apparatus of claim 1, wherein the multi-turn inductive loop comprises a plurality of turns of decreasing size.

31. The apparatus of claim 1, wherein the turns in the multi-turn inductive loop of the NFC tag follow a path that defines a major surface that is parallel to the radio-frequency radiator.

32. A method comprising:

a) providing a radio-frequency radiator;

b) mounting the radio-frequency radiator to a first surface of a first housing component;

c) providing a near-field communications (NFC) tag, wherein the NFC tag includes a multi-turn inductive loop and an NFC integrated circuit;

d) placing the multi-turn inductive loop such that the multi-turn inductive loop is configured to couple electrically with the radiator, the radio-frequency radiator at least partially overlapping the turns in the multi-turn inductive loop, the multi-turn inductive loop being conductively connected with the NFC integrated circuit and configured to inductively couple with a near-field magnetic field to provide power to the NFC circuit.

33. The method of claim 32, wherein the turns in the multi-turn inductive loop of the NFC tag follows a path that defines a major surface that faces towards the radio-frequency radiator.

34. The method of claim 32, wherein the NFC tag is bonded to the first surface and the radio-frequency radiator is interposed between the NFC tag and the first surface.

35. The method of claim 32, wherein a path length of the multi-turn inductive loop of the NFC tag is at least 20 to 50 times greater than nominal dimensions of the NFC tag.

36. The method of claim 32, wherein the multi-turn inductive loop of the NFC tag is configured to inductively couple with a near-field magnetic field at a range of about 10 cm or less.