Patch antenna for RFID tag

• US 20060255946A1
• Filed: 05/13/2005
• Published: 11/16/2006
• Est. Priority Date: 05/13/2005
• Status: Active Grant

• Current Assignee: Kennedy Group (Ivan Bloom & Associates)
• Original Assignee: NCR Corporation
• Inventors: Khatri, Mohamed Fayaz
• Granted Patent: US 7,605,706 B2
• Time in Patent Office: Days
• US Class Current: 340/572.700
• CPC Class Codes: G06K 19/077 Constructional details, e.g. mounting of circuits in the carrier
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles
• 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 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40

Abstract

An antenna for use with a Radio Frequency Identification, RFID, tag. A well-known, simple “patch antenna” is formed by two metallic plates, one larger than the other, between which is sandwiched a dielectric sheet. Under the invention, the larger metallic plate is provided by the wall of a metallic shipping container. Thus, one form of the invention includes (1) the smaller metallic sheet, (2) the dielectric sheet, and (3) an RFID circuit. When the dielectric sheet is attached to the wall of the shipping container, a patch antenna is generated which the RFID circuit can use.

Claims

1. Apparatus, comprising:

a) a passive, non-self-powered, RFID circuit; and

b) a patch antenna coupled with the RFID circuit.

2. Apparatus according to claim 1, wherein the patch antenna includes a ground plane, and a wall of a shipping container provides the ground plane.

3. Apparatus according to claim 1, wherein (i) the patch antenna comprises a patch above a ground plane, (ii) the patch has a periphery, and (iii) the RFID circuit lies within the periphery.

4. Apparatus, comprising:

a) a shipping container having at least one metallic wall;

b) an RFID circuit attached to a metallic wall of the shipping container; and

c) a patch antenna connected with the RFID circuit, in which said metallic wall provides a ground plane of the patch antenna.

5. Apparatus, comprising:

a) a dielectric sheet;

b) a conductive film attached to the sheet; and

c) an RFID circuit having an antenna signal lead connected to the conductive film.

6. Apparatus according to claim 5, and further comprising:

d) an adhesive effective to connect the dielectric sheet to a metallic plate.

7. Apparatus according to claim 6, and further comprising:

e) printed matter which is visible when the dielectric sheet is connected to the metallic plate.

8. Apparatus according to claim 5, wherein the conductive film has a periphery, and the RFID circuit lies within the periphery.

9. Apparatus according to claim 8, and further comprising:

d) a ground conductor extending from the RFID circuit, and through the dielectric sheet.

10. Apparatus according to claim 9, wherein the dielectric sheet has a top and bottom side, the conductive film is attached to the top side, and further comprising:

e) a conductive pad on the bottom side, which is electrically connected to the ground conductor.

11. Apparatus, comprising:

a) a dielectric sheet having top and bottom surfaces;

b) a conductive sheet attached to the top surface;

c) a conductive pad, which is not coextensive with the dielectric sheet, attached to the lower surface;

d) a passive RFID circuit, which includes

i) a signal lead connected to the conductive pad,

ii) a ground lead connected to the conductive pad,

wherein the conductive pad by itself is not effective to act as a ground plane in a patch antenna.

12. Apparatus according to claim 11, wherein, when the dielectric sheet is attached to a conductive surface, and when the conductive pad makes contact with the conductive surface, a patch antenna is created, which the RFID circuit can use for transmission of data.

13. A method, comprising:

a) maintaining a communication device adjacent a metallic shipping container; and

b) using a patch antenna for communication with the device, wherein a surface of the shipping container is used as a ground plane of the patch antenna.

14. Method according to claim 13, wherein the communication device is classified as an RFID circuit.

15. An RFID tag, comprising:

a) a dielectric sheet having top and bottom surfaces;

b) a conductive sheet adjacent the top surface;

c) an adhesive adjacent the bottom surface;

d) an electrical circuit coupled with the conductive sheet, wherein

1) a patch antenna is created when the adhesive is attached to a metallic sheet, and

2) the electrical circuit is able to use the patch antenna for communication.

16. Apparatus according to claim 15, wherein the electrical circuit is embedded within the dielectric sheet.