Dynamically reconfigurable antennas for RFID label encoders/readers

• US 20070040689A1
• Filed: 11/03/2005
• Published: 02/22/2007
• Est. Priority Date: 08/19/2005
• Status: Active Grant

• Current Assignee: Novanta Corporation (Novanta Inc.)
• Original Assignee: ThingMagic, Inc. (Novanta Inc.)
• Inventors: Reynolds, Matthew
• Granted Patent: US 7,724,141 B2
• Time in Patent Office: Days
• US Class Current: 340/572.700
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: H04B 7/0602 using antenna switching H04B7/0686 takes precedence; antenna beam directivity switching H01Q3/24
• CPC Class Codes: H04B 7/0802 using antenna selection H04B7/0868 takes precedence; antenna beam directivity switching H01Q3/24
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

A dynamically reconfigurable antenna system for an RFID (Radio Frequency Identification) reader/encoder includes a plurality of antenna elements; and a mechanism constructed and adapted to dynamically and selectively configure said plurality of antenna elements during operation thereof. The antenna elements may be arranged in a pattern of conductive areas, and each antenna element is switchably connectable to ground or to a transmission line connectable to the RFID reader/encoder. Each antenna element may be square, rectangle, circular, or diamond shaped. The antenna elements may located on an inner layer of the multi-layer printed circuit and wherein regions above the antenna elements are a dielectric layer or a slot aperture. The antenna system may be incorporated into an RFID encoder/reader.

Claims

1. A dynamically reconfigurable antenna system for an RFID (Radio Frequency Identification) reader/encoder, the antenna system comprising:

a plurality of antenna elements; and

a configuring mechanism constructed and adapted to dynamically and selectively configure said plurality of antenna elements.

2. An antenna system as in claim 1 wherein the plurality of antenna elements are arranged in a pattern of conductive areas, and wherein each antenna element is selectively and dynamically connectable via a switch to ground or to a transmission line connectable to the RFID reader/encoder.

3. An antenna system as in claim 2 wherein each antenna element is selectively and dynamically switchable to one of:

ground, a terminating impedance, or one of two transmission lines carrying excitation signals of differing phases.

4. An antenna system as in claim 2 wherein the pattern is a regular repeating pattern.

5. An antenna system as in claim 4 wherein the antenna elements are arranged in a grid.

6. An antenna system as in claim 2 wherein each antenna element has a shape selected from the group comprising:

squares, rectangles, circles, and diamond shape.

7. An antenna system as in claim 4 wherein the antenna elements are arranged as a grid of square-shaped elements.

8. An antenna system as in claim 1 comprising sixteen square antenna elements arranged in a grid.

9. An antenna system as in claim 1 wherein the configuring mechanism comprises:

a plurality of switches for selectively switching at least some of said antenna elements to a transmission line or to ground.

10. An antenna system as in claim 9 each of said switches is selectively switchable to one of:

ground, a terminating impedance, and one of two transmission lines carrying signals of differing phases.

11. An antenna system as in claim 9 wherein there are N antenna elements and N switches.

12. An antenna system as in claim 11 wherein N is 2, 3 or 4.

13. An antenna system as in claim 1 wherein the antenna elements are formed as isolated conductive areas on a layer of a substrate.

14. An antenna system as in claim 13 wherein the layer is a top layer of the substrate.

15. An antenna system as in claim 1 wherein the antenna elements are formed as isolated conductive areas on a layer of a multi-layer printed circuit (PC).

16. An antenna system as in claim 13 wherein the antenna elements are located on an inner layer of the multi-layer printed circuit and wherein regions above the antenna elements comprise a dielectric layer or a slot aperture.

17. An antenna system as in claim 2 comprising:

four separate rectangular antenna elements arranged in a cross shape on a rectangular region of a layer of an antenna substrate; and

four switches, each connectable to the RFID encoder/reader, and each operable to switch a corresponding one of the antenna elements between ground and the RFID encoder/reader.

18. A method of operating an RFID reader/encoder, the method comprising:

(A) providing a dynamically reconfigurable antenna system comprising;

(a1) a plurality of antenna elements; and

(a2) a configuring mechanism constructed and adapted to dynamically and selectively configure said plurality of antenna elements; and

(B) dynamically configuring the antenna system by selectively configuring at least some of the antenna elements prior to or during operation of the RFID reader/encoder.

19. A method as in claim 18 wherein the plurality of antenna elements are arranged in a regular repeating pattern of conductive areas, and wherein each antenna element is connectable via a switch to ground or to a transmission line connectable to the RFID reader/encoder.

20. A method as in claim 18 wherein the antenna elements are arranged in an N×

N grid of square-shaped elements formed as isolated conductive areas on a layer of a substrate.

21. A method as in claim 20 where the value of N is 2, 3 or 4.

22. A method as in claim 18 wherein there are four rectangular antenna elements arranged in a cross shape on a region of a layer of an antenna substrate, and wherein the configuring mechanism comprises four switches configured to switch corresponding ones of said antenna elements between ground and a transmission line connectable to the RFID reader/encoder.

23. An RFID (Radio Frequency Identification) reader/encoder comprising:

a dynamically reconfigurable antenna system, the antenna system comprising;

a plurality of antenna elements; and

a configuring mechanism constructed and adapted to dynamically and selectively configure said plurality of antenna elements during operation thereof.

24. A method of configuring an RFID (Radio Frequency Identification) reader/encoder antenna system, the method comprising:

(A) obtaining antenna configuration data; and

(B) dynamically configuring the antenna system in response to said antenna configuration data.

25. A method as in claim 24 wherein a source of the antenna configuration data comprises at least one of the following:

human input, a bar code reader;

an RFID tag;

a photoelectric sensor;

a switch; and

a data stream produced by a computer program executing on a remote computer.

26. A method as in claim 24 wherein the antenna configuration data are encapsulated as a data structure within a printer control language.

27. A configuring mechanism for a dynamically reconfigurable multi-element antenna system for an RFID (Radio Frequency Identification) reader/encoder, the configuring mechanism comprising:

a plurality of switches connected to at least some of the antenna'"'"'s elements; and

a controller constructed and adapted to selectively control at least some of the antenna'"'"'s elements using the plurality of switches; and

a data connection mechanism constructed and adapted to connect the controller to an external data system to provide antenna element configuration data to the controller.

28. A configuring mechanism as in claim 27 wherein the plurality of switches comprise of one or more of:

an FET switch, an electromechanical switch, a microelectromechanical switch, a diode switch, and a phototransistor switch.

29. A configuring mechanism as in claim 27 wherein the controller comprises of one or more of:

a microprocessor, a digital signal processor, a general purpose processor, a combinational logic array, or a finite state machine.

30. A configuring mechanism as in claim 27 wherein the data connection mechanism comprises of one or more of:

an asynchronous serial bus, a synchronous serial bus, a memory mapped interface, a port mapped interface, a fiber optic data connection, and an Ethernet network.

31. A configuring mechanism as in claim 27 wherein the data connection mechanism transfers data along an antenna feedline.

32. A method of configuring a dynamically reconfigurable antenna system for an RFID (Radio Frequency Identification) reader/encoder, the method comprising:

(A) setting the dynamically reconfigurable antenna to a first configuration;

(B) attempting to read and/or encode one or more RFID tags;

(C) making at least one measurement based on said attempting; and

(D) setting the dynamically configurable antenna to a second configuration based, at least in part, on said at least one measurement.

33. A method as in claim 32 wherein said at least one measurement is selected from the group comprising:

(a) a number of successful read and/or failed attempts to read or encode said one or more RFID tags, (b) a tag signal strength, (c) a frequency of a tag response, and (d) one or more tag data bits.

34. A method as in claim 32 that is repeated for multiple possible configurations of the dynamically configurable antenna.

35. A method as in claim 32 wherein the first and second configurations are determined by a computer program executing on a processor.

36. A method as in claim 32 wherein the first and second configurations are determined by a finite element or harmonic balance simulation.