Transparent Micropatterned RFID Antenna and Articles Incorporating Same

• US 20130264390A1
• Filed: 11/17/2011
• Published: 10/10/2013
• Est. Priority Date: 12/16/2010
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Frey, Matthew H., Zu, Lijun, Egbert, William C., Banerjee, Swagata R., Sainati, Robert A.
• Granted Patent: US 8,998,099 B2
• Time in Patent Office: Days
• US Class Current: 235/492
• CPC Class Codes: C23F 1/02 Local etching
• CPC Class Codes: G06K 19/07773 Antenna details antennas for wireless devices, e.g. RFID tags, in general H01Q1/22
• CPC Class Codes: G06K 19/07783 the coil being planar
• 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 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• 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

Abstract

Antennas suitable for use in RFID devices include an insulating substrate and a first conductive micropattern disposed on or in the substrate, the first conductive micropattern defining a contiguous mesh conductor. The first conductive micropattern forms an antenna responsive to at least a frequency of 915 MHz, and includes interconnected traces having a trace width in a range from 0.5 to 20 microns. Furthermore, the first conductive micropattern is characterized by an open area fraction of at least 80% or 90%. RFID devices include such an antenna and an integrated circuit configured to transmit and receive signals using the antenna. Cards, such as financial transaction cards or identification cards, include such an antenna carried by a card layer.

Claims

1. An antenna suitable for use in an RFID device, comprising:

an insulating substrate; and

a first conductive micropattern disposed on or in the substrate, the first conductive micropattern defining a contiguous mesh conductor;

wherein the first conductive micropattern forms an antenna responsive to at least a frequency of 915 MHz;

wherein the first conductive micropattern comprises interconnected traces having a trace width in a range from 0.5 to 20 microns; and

wherein the first conductive micropattern is characterized by an open area fraction of at least 80%.

2. The antenna of claim 1, wherein the open area fraction is at least 90%.

4. The antenna of claim 1, wherein the first conductive micropattern is composed of an opaque material comprising a metal.

5. The antenna of claim 4, wherein the metal is selected from silver, gold, palladium, platinum, aluminum, copper, nickel, tin, alloys, and combinations thereof.

6. The antenna of claim 1, wherein the first conductive micropattern has a thickness of less than 2 microns.

8. The antenna of claim 1, wherein the first conductive micropattern has a thickness in a range from 30 nanometers to 1 micron.

9. The antenna of claim 1, wherein the trace width is in a range from 1 to 10 microns.

11. The antenna of claim 1, wherein the trace width is in a range from 1.5 to 4 micrometers.

12. The antenna of claim 1, wherein the first conductive micropattern is characterized by an effective sheet resistance in a range from 0.1 to 200 ohms/square.

14. The antenna of claim 1, wherein the insulating substrate is transparent.

15. The antenna of claim 1, wherein the antenna has a visible light transmission value of greater than 70%.

16. An RFID device, comprising:

the antenna of claim 1; and

an integrated circuit configured to transmit and receive signals using the antenna.

17. The device of claim 16, wherein the antenna is tailored to yield a maximum distance at which an RFID reader operating at 1 Watt radiated power in a 902-928 MHz frequency hopping mode can communicate with the device, the maximum distance being in a range from 1 centimeter to 2 meters.

18. A system comprising the device of claim 17 in combination with a first RFID reader operating at between 0.2 Watt and 5 Watts radiated power at a frequency or frequencies between 860 MHz and 960 MHz, wherein a maximum distance at which the first RFID reader can communicate with the device is in a range from 1 centimeter to 2 meters.

3. (canceled)

7. (canceled)

10. (canceled)

13. (canceled)

19. A card, comprising:

a card layer;

an antenna carried by the card layer; and

an integrated circuit configured to transmit and receive signals using the antenna;

wherein the antenna comprises a conductive micropattern defining a contiguous mesh conductor, the conductive micropattern forming an antenna responsive to at least a frequency of 915 MHz, the conductive micropattern comprising interconnected traces having a trace width in a range from 0.5 to 20 microns, and the conductive micropattern being characterized by an open area fraction of at least 80%.

20. The card of claim 19, wherein the card layer is light transmissive for visible wavelengths.

21. The card of claim 20, wherein the open area fraction is in a range from 95 to 98%.

22. The card of claim 19, wherein the first conductive micropattern is composed of an opaque material comprising a metal selected from silver, gold, palladium, platinum, aluminum, copper, nickel, tin, alloys, and combinations thereof.

23. The card of claim 19, wherein the first conductive micropattern has a thickness in a range from 30 nanometers to 1 micron.

24. The card of claim 19, wherein the trace width is in a range from 2 to 5 microns.