Method of determining performance of RFID devices

• US 7,154,283 B1
• Filed: 02/22/2006
• Issued: 12/26/2006
• Est. Priority Date: 02/22/2006
• Status: Active Grant

• Current Assignee: Avery Dennison Retail Information Services LLC (Avery Dennison Corporation)
• Original Assignee: Avery Dennison Corporation
• Inventors: Weakley, T. Craig, Forster, Ian J.
• Primary Examiner(s): Hirshfeld, Andrew H.
• Assistant Examiner(s): NGUYEN, HOAI AN D
• Application Number:
  US11/359,669
• Time in Patent Office: 307 Days
• Field of Search: 324/667, 324/605, 324/158.1, 324/754, 324/750, 324763-765, 340/572.1, 340/572.2, 340/572.4, 340/572.5, 340/572.6, 340/572.7, 340/10.1, 702/10.1, 702 18-186, 702/194, 702/195
• US Class Current: 324/756.01
• CPC Class Codes: G01R 29/08 Measuring electromagnetic field characteristics
• CPC Class Codes: G01R 31/303 of integrated circuits G01R31/305 - G01R31/315 take precedence
• CPC Class Codes: G06K 7/0095 Testing the sensing arrangement, e.g. testing if a magnetic card reader, bar code reader, RFID interrogator or smart card reader functions properly testing of electrical circuits G01R31/28

Abstract

A method of determining far-field performance of an RFID device, such as in or on a tag, label, package, film, carton, wrap, or a portion of any of these, includes performing near-field testing or measurement of the RFID device, and determining or predicting far-field performance based on the results of the near-field testing or measurement. The determining or predicting of far-field performance may involve calculating a measure of far-field performance based on near-field results or measurements. The predicted far-field performance may include any of a variety of performance factors, including range, sensitivity, frequency performance, read sensitivity, write sensitivity, peak operating frequency, and/or average sensitivity over a given frequency band. Using near-field testing results to predict far-field performance may allow use of compact testing facilities, in situ testing of RFID devices, and/or faster and/or less costly testing of RFID devices.

Claims

1. A method of determining far-field performance of an RFID device, the method comprising:

performing near-field testing on the RFID device;

determining the far-field performance of the RFID device from test results of the near-field testing;

wherein the determining includes using a mathematical algorithm to determine the far-field performance; and

wherein the using the mathematical algorithm includes calculating a far-field performance parameter.

2. The method of claim 1, wherein the performing near-field testing includes:

placing the RFID device in proximity to a near-field coupler of a near-field tester; and

sending signals from the tester to the RFID device, using the near-field coupler, and a reader of the tester.

3. The method of claim 2, wherein the sending signals includes sending signals over a range of frequency.

4. The method of claim 2, wherein the performing near-field testing further includes the tester receiving signals from the RFID device.

5. The method of claim 2, wherein the tester includes a test head that includes the near-field coupler and a dielectric material block in which the near-field coupler is located.

6. The method of claim 5,

wherein the test head also includes a compliant surface on the dielectric material block;

and

wherein the testing includes placing the RFID device on the compliant surface.

7. The method of claim 1, wherein the testing includes performing multiple tests.

8. The method of claim 7, wherein the testing includes testing in multiple operating environments.

9. The method of claim 1, wherein the using the mathematical algorithm includes using a look-up chart or table.

10. The method of claim 1, wherein the determining includes determining a numerical far-field performance parameter.

11. The method of claim 1, wherein the determining includes determining whether the RFID device satisfies a far-field performance threshold.

12. The method of claim 1, wherein the determining includes determining one or more of sensitivity, margin, peak operating frequency, frequency performance response shape, average response over a selected frequency band, read sensitivity, and write sensitivity.

13. The method of claim 1, wherein the determining includes determining suitability of far-field performance in different far-field operating environments.

14. The method of claim 1, wherein the testing includes inducing current and voltage in all critical parts of an antenna structure of the RFID device.

15. The method of claim 7, wherein the testing includes testing over a range of frequency.

16. The method of claim 7, wherein the testing includes testing with multiple testers.