Self-compensating antennas for substrates having differing dielectric constant values

• US 20050092845A1
• Filed: 11/03/2003
• Published: 05/05/2005
• 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.
• Granted Patent: US 7,055,754 B2
• Time in Patent Office: Days
• 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 in combination with a dielectric material comprises a dielectric material and a wireless communication system that is mounted in electrical proximity to the dielectric material. The wireless communication system comprises a wireless communication device associated with an antenna system that has at least one conductive tab, including one or both of the following: (a) a plurality of electrical components that are selected to form an impedance matching network, that are coupled to the conducting tab and wireless communication device. 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 the conducting tab and electrically interacting with the dielectric material to maintain a substantial impedance match between the antenna system and the wireless communication device. The antenna system may be directly mounted on a dielectric substrate, which serves as the dielectric material Alternatively, the antenna system may be mounted on a backing layer intermediate the dielectric substrate and the antenna system, the backing layer in turn being attached to the dielectric substrate, wherein the backing layer and the dielectric substrate collectively serve as the dielectric material.

Claims

1. An electronic labeling system in combination with a dielectric material, comprising:

a dielectric material;

a 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 conducting 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 conducting tab and electrically interacting with the dielectric material to maintain a substantial impedance match between the antenna system and the wireless communication device.

2. An antenna system 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 tab is placed in electrical proximity with.

3. An antenna system as in claim 2 wherein said capacitor is an interdigital capacitor.

4. An antenna system as in claim 1 wherein said plurality of electrical components includes an inductor.

5. An antenna system as in claim 4 wherein said inductor is a meander inductor.

6. An antenna system 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. An antenna system 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. An antenna system 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. An antenna system as in claim 1 wherein said structural element is a capacitor.

10. An antenna system as in claim 9 wherein said capacitor is an interdigital capacitor.

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

12. An antenna system as in claim 1 wherein structural element is an inductor.

13. An antenna system as in claim 12 wherein said inductor is a meander inductor.

14. A wireless communication system 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. A wireless communication system 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 conducting tab forming an antenna for receiving and radiating radio frequency energy, said at least one 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 conducting tab and the wireless communications device, said electrical components further electrically interacting with the dielectric material on which said at least one tab is placed in electrical proximity with, to vary the individual impedance values of said electrical components to maintain a substantial impedance match between said at least one conductive tab and the wireless communications device.

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 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 conducting tab forming an antenna for receiving and radiating radio frequency energy, said 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 conducting tab providing an impedance matching network coupled to said conducting tab and the wireless communications device, said frequency selective by-pass trap circuit electrically interacting with the dielectric material to maintain a substantial impedance match between said conductive tab and the wireless communications device.

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 conducting tab that electrically interacts with the dielectric material to form a capacitive element providing a selective by-pass trap circuit formed in said conducting 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 conducting tabs forming a dipole antenna for receiving and radiating radio frequency energy, each of said tabs 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 conducting 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 the individual impedance values of said electrical components to maintain a substantial impedance match between said conductive tabs and the wireless communications device.

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.