RFID ANTENNA STRUCTURE FOR INCREASED RANGE WHEN COUPLED WITH A MOBILE DEVICE

• US 20180277957A1
• Filed: 05/21/2018
• Published: 09/27/2018
• Est. Priority Date: 07/19/2013
• Status: Active Grant

• Current Assignee: GeoToll, Inc.
• Original Assignee: GeoToll, Inc.
• Inventors: Geist, Wyatt Drake, BORRAS, JAIME ANDRES
• Granted Patent: US 10,418,711 B2
• Time in Patent Office: Days
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06K 7/10386 the interrogation device being of the portable or hand-handheld type, e.g. incorporated in ubiquitous hand-held devices such as PDA or mobile phone, or in the form of a portable dedicated RFID reader
• 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 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/248 provided with an AC/DC converting device, e.g. rectennas
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 5/335 at the feed, e.g. for impedance matching
• 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 7/08 Ferrite rod or like elongated core
• CPC Class Codes: H01Q 9/065 Microstrip dipole antennas patch antenna H01Q9/0407
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407
• CPC Class Codes: H04B 5/72 for local intradevice communication

Abstract

An RFID tag device with an RFID antenna assembly that increases transmission range of the RFID tag device when adhesively coupled to a mobile device. The RFID tag device includes a RF interface that operates at a first RF frequency, a controller coupled to the RF interfaces, and the RFID antenna assembly. The RFID antenna assembly includes a first and a second dipole elements, each shaped as a half rectangle with an additional segment joining the respective element to a tuning element. The RFID antenna also includes a tuning element, which is a loop antenna, connecting the RF interface to the controller and a ferrite dielectric on the back of one of the dipole elements. A structure of the RF antennal assembly, when the RFID tag device is coupled to a mobile device, causes the mobile device to function as a reflector to increase gain of the RFID antenna assembly thereby improving transmission range.

Claims

1. A radio frequency identification (RFID) tag device, comprising:

a radio frequency (RF) interface that operates at a first RF frequency;

a controller coupled to the RF interface; and

an RFID antenna assembly comprising;

a first and a second dipole elements a first side of a circuit board, wherein the first and second dipole elements are shaped as a half rectangle with an additional segment joining the respective element to a tuning element;

a ferrite dielectric disposed on a second side of the circuit board, opposite the first side, wherein the ferrite dielectric is located in correspondence with one of the dipole elements; and

the tuning element, which is a loop antenna, wherein the first and second dipole elements are printed on a surface of a printed circuit board,

wherein a structure of the RFID tag device establishes a distance between the RFID antenna assembly and the internal components of a mobile device that functions as a ground plane such that, when the RFID tag device is coupled to the mobile device, the mobile device functions as a reflector to increase gain of the RFID antenna assembly, whereby improving transmission range of the RFID tag device relative to a range of the RFID tag device when not coupled to the mobile device, wherein the transmission range of the RFID tag device is improved by the mobile device functioning as the reflector is at least twenty feet.

2. The RFID tag device of claim 1, wherein the RFID antenna assembly is further configured such that a vertical centerline exists at a mid-point of the tuning element, such that the first and second dipole elements are electrical mirror images of each other from the vertical centerline.

3. The RFID tag device of claim 1, wherein no direct connection exists between the first and second dipole elements other than through the tuning element, to which the first and second dipole elements connect.

4. The RFID tag device of claim 1, wherein the RFID tag device is a multilayered structure, one layer comprising the RF interface, the controller, and the RFID antenna assembly, wherein the one layer is joined to an upper layer and to a lower layer of the multilayered structure is a low surface energy, press adhesive.

5. The RFID tag device of claim 4, wherein one of the layers of the multilayered structure is a foam layer, wherein the lower layer of the multilayered structure is an adhesive layer for coupling the RFID tag device to an exterior case of the mobile device, wherein the foam layer establishes a distance between the circuit board and the internal components of the mobile device that function as a ground plane to ensure the mobile device functions as the reflector to increase gain of the RFID antenna assembly as opposed to the ground plane attenuating a RF signal from the RFID antenna assembly.

6. The RFID tag device of claim 1, further comprising a near field communication (NFC) antenna assembly for capturing RF energy emitted from the mobile device to power circuitry of the RFID tag device.

7. A RFID tag device, comprising:

a RF interface that operates at a first RF frequency;

a controller coupled to the RF interface;

an RFID antenna assembly comprising;

a first and a second dipole elements disposed on a first side of a circuit board;

a ferrite dielectric disposed on a second side of the circuit board, opposite the first side, wherein the ferrite dielectric is located in correspondence with one of the dipole elements; and

a tuning element, which is a loop antenna connecting each of the first and the second dipole elements to each other; and

a NFC antenna assembly for capturing RF energy emitted from a mobile device to which the RFID tag device is proximate, wherein the RF energy captured by the NFC antenna assembly powers circuitry of the RFID tag device to power signal transmissions from the RFID antenna assembly;

wherein a structure of the RFID tag device establishes a distance between the RFID antenna assembly and the internal components of the mobile device that function as a ground plane such that, when the RFID tag device is coupled to the mobile device, the mobile device functions as a reflector to increase gain of the RFID antenna assembly thereby improving transmission range of the RFID tag device relative to a range of the RIFD tag device when not coupled to the mobile device, wherein the transmission range of the RIFID tag device when not coupled to the mobile device, wherein the transmission range of the RFID tag device as improved by the mobile device functioning as the reflector is at least twenty feet.

8. The RFID tag device of claim 7, wherein the RFID antenna assembly is further configured such that a vertical centerline exists at a mid-point of the tuning element, such that the first and second dipole elements are an electrical mirror image of each other from the vertical centerline.

9. The RFID tag device of claim 7, wherein the RFID tag device is a multilayered structure with a circuit board comprising one layer, said circuit board comprising the RF interface, the controller, the RF antenna assembly, and the NFC antenna assembly, wherein the circuit board is joined to an upper layer and to a lower layer of the multilayer structure via a low surface energy, press adhesive layer.

10. The RFID tag device of claim 9, wherein one of the layers of the multilayered structure is a foam layer, wherein the lower layer of the multilayered structure is an adhesive layer for coupling the RFID tag device to an exterior case of the mobile device.

11. A RFID tag device, comprising:

a RF interface that operates at a first RF frequency;

a controller coupled to the RF interface;

an RFID antenna assembly comprising;

a first and a second dipole elements disposed on a first side of a circuit board;

a ferrite dielectric disposed on a second side of the circuit board, opposite the first side, wherein the ferrite dielectric is located in correspondence with one of the dipole elements; and

a tuning element, which is a loop antenna connecting each of the first and the second dipole elements to each other;

wherein the RFID tag device is a multilayered structure with a circuit board comprising one layer, said circuit board comprising the RF interface, the controller, the RF antenna assembly, wherein the circuit board is joined to an upper layer and to a lower layer of the multilayered structure via a low surface energy, press adhesive layer, wherein one of the layers of the multilayered structure is a foam layer, wherein the lower layer of the multilayered structure is an adhesive layer for coupling the RFID tag device to an exterior case of the mobile device, wherein the foam layer establishes a distance between the circuit board and the internal components of the mobile device that function as a ground plane to ensure the mobile device functions as the reflector to increase gain of the RFID antenna assembly as opposed to the ground plane attenuating a RF signal from the RFID antenna assembly, wherein the transmission range of the RFID tag device as improved by the mobile device functioning as the reflector is at least twenty feet.

12. The RFID tag device of claim 11, wherein the RFID antenna assembly is further configured such that a vertical centerline exists at a mid-point of the tuning element, such that the first and second dipole elements are mirror images of each other from the vertical centerline.

13. The RFID tag device of claim 11, wherein no direct connection exists between the first and second dipole elements other than through the tuning element, to which the first and second dipole elements connect.

14. The RFID tag device of claim 11, further comprising a near field communication (NFC) antenna assembly for capturing RF energy emitted from the mobile device to power circuitry of the RFID tag device.

15. The RFID tag device of claim 11, further comprising, wherein a distance between internal components of the mobile device functioning as a ground plane and the RFID tag device'"'"'s RFID antenna assembly when the RFID antenna assembly is attached via the lower layer is greater than 0.5 millimeters and less than 3 millimeters.

16. A RFID tag device, comprising:

a circuit board having a first side and a second side;

an antenna structure disposed on the first side that includes a loop antenna element having feed side and a dipole side, a pair of “

L”

shaped dipole elements, each of which is connected to the loop antenna element at a different point on the dipole side of the loop antenna element at a short leg portion of each dipole element, and where each dipole element has a long leg portion that extends down below the loop antenna element on the first side of the circuit board, on opposite sides of the loop antenna element; and

a longitudinal ferrite element disposed on the second side of the circuit board in correspondence with the long leg portion of one of the dipole elements.

17. The RFID tag device of claim 16, wherein the circuit board is a multilayer circuit board and includes a ground plane between the first and second sides.

18. The RFID tag device of claim 16, wherein the long leg portions are at least five times longer than a height of the loop antenna element.

19. The RFID tag device of claim 16, wherein the long leg portion of one of the dipole elements is at least twice as wide as the long leg portion of the other dipole element.

20. The RFID tag device of claim 16, wherein the longitudinal ferrite element has a length that is at least 70% of the long leg portion of the dipole element to which it corresponds.