Coupling of RFID straps to antennae using a combination of magnetic and electric fields

• US 10,373,045 B2
• Filed: 12/01/2016
• Issued: 08/06/2019
• Est. Priority Date: 12/01/2016
• Status: Active Grant

• Current Assignee: Avery Dennison Retail Information Services LLC (Avery Dennison Corporation)
• Original Assignee: Avery Dennison Retail Information Services LLC (Avery Dennison Corporation)
• Inventors: Forster, Ian J.
• Primary Examiner(s): Vo, Tuyen K
• Application Number:
  US15/366,788
• Publication Number:
  US 20180157955A1
• Time in Patent Office: 978 Days
• Field of Search: 235451, 235492
• CPC Class Codes: G06K 19/06187 with magnetically detectable marking
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole
• CPC Class Codes: G06K 19/07794 the record carrier comprising a booster or auxiliary antenna in addition to the antenna connected directly to the integrated circuit
• CPC Class Codes: G06K 19/08 using markings of different kinds or more than one marking of the same kind in the same record carrier, e.g. one marking being sensed by optical and the other by magnetic means
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• 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 9/065 Microstrip dipole antennas patch antenna H01Q9/0407
• CPC Class Codes: H01Q 9/16 with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole H01Q9/44 takes precedence

Abstract

An RFID device includes an antenna and an RFID strap. The RFID strap is coupled to the antenna by a combination of magnetic and electric fields. The RFID strap includes an RFID chip and a strap conductor coupling the RFID chip to the antenna. The strap conductor has a loop section positioned generally adjacent to the antenna to magnetically couple the RFID strap to the antenna. The strap conductor also has an extension section overlapping and crossing the antenna to electrically couple the RFID strap to the antenna. By adjusting the size of the RFID strap, the configuration of the RFID strap, the degree of overlap between the extension section and the antenna, and/or the angular orientation of the RFID strap with respect to the antenna, the impedance transformation between the RFID chip and the antenna may be varied to better match the RFID chip and the antenna.

Claims

1. An RFID device, comprising:

an antenna;

an RFID strap, including a chip attached to the strap, the strap is coupled to the antenna by a combination of magnetic and electric fields; and

the strap comprises a strap conductor that includes a loop and an extension, the extension overlapping and crossing the antenna and the strap conductor has a center line extending generally in a direction between the RFID chip and the antenna;

where the RFID strap is encapsulated to provide a robust structure.

2. The RFID device of claim 1, wherein the loop section is positioned generally adjacent to the antenna.

3. The RFID device of claim 1, wherein the loop section is generally circular and the extension section is generally rectangular.

4. The RFID device of claim 1, wherein the strap conductor is generally rectangular.

5. The RFID device of claim 1, wherein

the loop section and the extension section each include legs separated by a gap and extending in a direction between the RFID chip and the antenna, and

the size of the gap between the legs of the loop section is different from the size of the gap between the legs of the extension section.

6. The RFID device of claim 5, wherein the size of the gap between the legs of the loop section is greater than the size of the gap between the legs of the extension section.

7. The RFID device of claim 1, wherein the strap conductor has a generally elliptical shape.

8. The RFID device of claim 1, wherein

the extension section includes a leg extending in a direction between the RFID chip and the antenna, and

a width of the leg varies.

9. The RFID device of claim 8, wherein

the extension section includes a second leg extending in a direction between the RFID chip and the antenna, and

the width of each of the legs varies.

10. The RFID device of claim 8, wherein the width of each leg tapers from a maximum width at an end of the RFID strap to the RFID chip to a minimum width at an opposite end such that the width of each leg is greater adjacent to the RFID chip than adjacent to the antenna.

11. The RFID device of claim 1, wherein

the center line is substantially perpendicular to the antenna at a location where the center line crosses the antenna.

12. The RFID device of claim 1, wherein

the center line crosses the antenna at a non-perpendicular angle.

13. A method of coupling an RFID strap of an RFID device to an antenna of the RFID device, comprising:

coupling the RFID strap to the antenna by a magnetic field and the RFID strap includes an RFID chip; and

coupling the RFID strap to the antenna by an electric field such that the RFID strap comprises a strap conductor that includes a loop and an extension such that the loop section is positioned generally adjacent to the antenna and the strap conductor has a center line extending generally in a direction between a RFID chip and the antenna.

14. The method of claim 13, further comprising adjusting an impedance transformation between the RFID chip and the antenna by varying a size of the RFID strap, a configuration of the RFID strap, and/or an angular orientation of the RFID strap with respect to the antenna.

15. The method of claim 13 further comprising adjusting a tuned loop frequency of the loop section by adjusting an effective perimeter of the loop section.

16. The method of claim 13, wherein said coupling the RFID strap to the antenna by the electric field includes overlapping and crossing the antenna with the extension section of the RFID strap.

17. The method of claim 16, wherein

the RFID strap overlaps the antenna at two locations, and further comprising adjusting an impedance transformation between the RFID chip and the antenna by varying a distance between the two locations.

18. The method of claim 16, wherein

the extension section includes a leg extending in a direction between the RFID chip and the antenna, and

a width of the leg varies, and further comprising adjusting the strength of the electric field by adjusting the position of the leg with respect to the antenna.