Self-compensating antennas for substrates having differing dielectric constant values

• US 7,055,754 B2
• Filed: 11/03/2003
• Issued: 06/06/2006
• Est. Priority Date: 11/03/2003
• Status: Active Grant

• Current Assignee: Avery Dennison Retail Information Services LLC (Avery Dennison Corporation)
• Original Assignee: Avery Dennison Corporation
• Inventors: Forster, Ian J.
• Primary Examiner(s): Le, Uyen-Chau N.
• Application Number:
  US10/700,596
• Publication Number:
  US 20050092845A1
• Time in Patent Office: 946 Days
• Field of Search: 235/492, 235/439, 235/441, 235/451, 343/700.MS, 343/795
• US Class Current: 235/492
• 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: 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 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

An RFID tag or label includes a wireless communication system that is mounted in electrical proximity to the dielectric material. The wireless communication system includes a wireless communication device associated with an antenna system that has at least one conductive tab, including: a plurality of electrical components forming an impedance matching network, coupled to the conducting tab and wireless communication device, that electrically interact with the dielectric material to maintain a substantial impedance match between the antenna system and the wireless communication device; and/or a structural element forming a frequency selective by-pass trap circuit formed in the conducting tab, and electrically interacting with the dielectric material to maintain a substantial impedance match. The antenna system may be directly mounted on a dielectric substrate, which serves as the dielectric material, or alternatively may be mounted on a backing layer intermediate the dielectric substrate and the antenna system.

Claims

1. A wireless communication system in combination with a dielectric material, comprising:

the dielectric material;

the wireless communication system mounted in electrical proximity to the dielectric material, comprising;

a wireless communication device;

an antenna system comprising at least one conductive tab, including one or both of the following;

(a) a plurality of electrical components selected to form an impedance matching network, coupled to said at least one conductive tab and said wireless communication device wherein the electrical components electrically interact with the dielectric material to maintain a substantial impedance match between the antenna system and the wireless communication device; and

,

(b) a structural element forming a frequency selective by-pass trap circuit formed in said conductive tab and electrically interacting with the dielectric material to maintain a substantial impedance match between the antenna system and the wireless communication device;

wherein the one or both of the plurality of electrical components and the structural element are configured to self-compensate for different electrical characteristics of different dielectric materials, through electrical cross-coupling of conductive parts of the antenna system, to maintain the substantial impedance match for different dielectric materials.

2. The combination as in claim 1 wherein said plurality of electrical components includes a capacitor whose electrical value is varied by interaction with the dielectric material on which said at least one conductive tab is placed in electrical proximity with.

3. The combination as in claim 2 wherein said capacitor is an interdigital capacitor.

4. The combination as in claim 1 wherein said plurality of electrical components includes an inductor.

5. The combination as in claim 4 wherein said inductor is a meander inductor.

6. The combination as in claim 1 wherein said impedance matching network has at least one circuit of capacitive and inductive electrical components in series intermediate said at least one conductive tab and the wireless communications device.

7. The combination as in claim 1 wherein said impedance matching network has at least one circuit of capacitive electrical components in series intermediate with said at least one conductive tab and the wireless communications device.

8. The combination as in claim 1 wherein said impedance matching network has at least one circuit of inductive electrical components in series intermediate with said at least one conductive tab and the wireless communications device.

9. The combination as in claim 1 wherein said structural element is a capacitor.

10. The combination as in claim 9 wherein said capacitor is an interdigital capacitor.

11. The combination as in claim 1 wherein said structural element is a gap formed in the conductive tab that electrically interacts with the dielectric material to form a capacitive element providing a selective by-pass trap circuit formed in said conductive tab.

12. The combination as in claim 1 wherein the structural element is an inductor.

13. The combination as in claim 12 wherein said Inductor is a meander inductor.

14. The combination as defined in claim 1, wherein the dielectric material comprises a dielectric substrate, and the antenna system is directly mounted to the dielectric substrate.

15. The combination as defined in claim 1, wherein the dielectric material comprises a dielectric substrate, and the antenna system is mounted on a backing layer intermediate the dielectric substrate and the antenna system, the backing layer being attached to the dielectric substrate.

16. An antenna system, useful with a wireless communications device, that self-compensates for being placed in electrical proximity to a dielectric material to maintain a substantial impedance match between the antenna system and the wireless communications device, comprising:

at least one conductive tab forming an antenna for receiving and radiating radio frequency energy, said at least one conductive tab adapted for placement in electrical proximity to the dielectric material; and

,

a plurality of electrical components selected to form an impedance matching network coupled to said at least one conductive tab and the wireless communications device, said electrical components further electrically interacting with the dielectric material on which said at least one conductive tab is placed in electrical proximity with, to vary, depending upon electrical characteristics of the dielectric material, the individual impatience values of said electrical components to maintain a substantial impedance match between said at least one conductive tab and the wireless communications device;

wherein in operation conductive parts of the antenna system electrically cross couple to maintain the substantial impedance match.

17. An antenna system as in claim 16 wherein said plurality of electrical components includes a capacitor whose electrical value is varied by interaction with the dielectric material on which said at least one conductive tab is placed in electrical proximity with.

18. An antenna system as in claim 17 wherein said capacitor is an interdigital capacitor.

19. An antenna system as in claim 16 wherein said plurality of electrical components includes an inductor.

20. An antenna system as in claim 19 wherein said inductor is a meander inductor.

21. An antenna system as in claim 16 wherein said impedance matching network has at least one circuit of capacitive and inductive electrical components in series intermediate said at least one conductive tab and the wireless communications device.

22. An antenna system as in claim 16 wherein said impedance matching network has at least one circuit of capacitive electrical components in series intermediate with said at least one conductive tab and the wireless communications device.

23. An antenna system as in claim 16 wherein said impedance matching network has at least one circuit of inductive electrical components in series intermediate with said at least one conductive tab and the wireless communications device.

24. An antenna system, useful with a wireless communications device that self-compensates for being placed in electrical proximity to a dielectric material to maintain a substantial impedance match between the antenna system and the wireless communications device, comprising:

a conductive tab forming an antenna for receiving and radiating radio frequency energy, said conductive tab adapted for placement in electrical proximity to the dielectric material; and

,

a structural element forming a frequency selective by-pass trap circuit formed in said conductive tab providing an impedance matching network coupled to said conductive tab and the wireless communications device, said frequency selective by-pass trap circuit electrically interacting with the dielectric material to self-compensate for electrical characteristics of different dielectric materials, to maintain a substantial impedance match between said conductive tab and the wireless communications device;

wherein in operation conductive parts of the antenna system electrically cross couple to maintain the substantial impedance match.

25. An antenna system as in claim 24 wherein said structural element is a capacitor.

26. An antenna system as in claim 25 wherein said capacitor is an interdigital capacitor.

27. An antenna system as in claim 24 wherein said structural element is a gap formed in the conductive tab that electrically interacts with the dielectric material to form a capacitive element providing a selective by-pass trap circuit formed in said conductive tab.

28. An antenna system as in claim 24 wherein structural element is an inductor.

29. An antenna system as in claim 28 wherein said inductor is a meander inductor.

30. An antenna system, useful with a wireless communications device that self-compensates for being placed in electrical proximity to a dielectric material to maintain a substantial impedance match between the antenna system and the wireless communications device, comprising:

a pair of conductive tabs forming a dipole antenna for receiving and radiating radio frequency energy, each of said conductive tabs adapted for placement in electrical proximity to the dielectric material; and

,

a plurality of electrical components selected to ban an impedance matching network coupled to said conductive tabs and the wireless communications device, said electrical components further electrically interacting with the dielectric material on which said tabs are placed in electrical proximity with, to vary, depending upon electrical characteristics of the dielectric material, the individual impedance values of said electrical components to maintain a substantial impedance match between said conductive tabs and the wireless communications device;

wherein in operation conductive parts of the antenna system electrically cross couple to maintain the substantial impedance match.

31. An antenna system as in claim 30 wherein said plurality of electrical components includes a capacitor.

32. An antenna system as in claim 31 wherein said capacitor is an interdigital capacitor.

33. An antenna system as in claim 30 wherein said plurality of electrical components includes an inductor.

34. An antenna system as in claim 33 wherein said inductor is a meander inductor.

35. An antenna system as in claim 30 wherein said impedance matching network has at least one circuit of capacitive and inductive electrical components in series intermediate at least one of said conductive tabs and the wireless communications device.

36. An antenna system as in claim 30 wherein said impedance matching network has at least one electrical component acting as a capacitive shunt between said two conductive tabs.

37. An antenna system as in claim 30 wherein said impedance matching network has at least one circuit of capacitive and inductive electrical components in series intermediate at least one of said conductive tabs and the wireless communications device, and further has at least one electrical component acting as a capacitive shunt between said two conductive tabs.

38. An antenna system as in claim 30 wherein said impedance matching network has at least one circuit of capacitive electrical components in series intermediate with at least one of said conductive tabs and the wireless communications device.

39. An antenna system as in claim 30 wherein said impedance matching network has at least one circuit of inductive electrical components in series intermediate with at least one of said conductive tabs and the wireless communications device.