ANTENNA SWITCHING SYSTEM AND METHOD

• US 20100109873A1
• Filed: 11/05/2008
• Published: 05/06/2010
• Est. Priority Date: 11/05/2008
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Salvo, Joseph James, DeRose, Lynn Ann, Good, Brandon Stephen, Forman, Douglas Roy, Intrator, Morgan Fredric, Bennett, Janet Sue, Schieli, Nicolas Auguste Constant
• Granted Patent: US 8,035,523 B2
• Time in Patent Office: Days
• US Class Current: 340/572.700
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles

Abstract

An improved RFID tag reader is provided. More specifically, an RFID tag reader is provided that includes a plurality of antenna panels arranged to form a sensing volume in which RFID tags are read. Additionally, the RFID tag reader includes a novel switching mechanism that activates the antenna panels in sequence while minimizing cross coupling between the antenna panels. Furthermore, a novel antenna geometry also reduces antenna cross coupling.

Claims

1. A radio frequency tag reading system comprising:

a plurality of radio frequency antennas configured to excite and read radio frequency tags; and

reader circuitry coupled to the antennas and including radio frequency signal reading circuitry and selection circuitry configured to selectively couple the radio frequency signal reading circuitry to each antenna and to alter a resonant response of each antenna when not coupled to the radio frequency signal reading circuitry.

2. The system of claim 1, comprising three radio frequency antennas disposed in generally orthogonal orientations around a sensing volume.

3. The system of claim 2, comprising a fourth radio frequency antenna disposed generally parallel to one of the three radio frequency antennas around the sensing volume.

4. The system of claim 1, wherein the reader circuitry includes a separate selection circuit for each radio frequency antenna.

5. The system of claim 1, comprising control circuitry configured to signal the selection circuitry to couple a selected one of the radio frequency antennas to the radio frequency signal reading circuitry and to decouple other non-selected radio frequency antennas from the radio frequency signal reading circuitry.

6. The system of claim 1, wherein selection circuitry includes processor and a pair of solid state switches, the processor being configured to change conductive states of the solid state switches to couple a selected radio frequency antenna to the radio frequency signal reading circuitry and to decouple non-selected radio frequency antennas from the radio frequency signal reading circuitry, and to alter the resonant response of the non-selected antennas.

7. The system of claim 1, wherein the antennas and the reader circuitry are configured to operate at a nominal excitation frequency of 125 kHz.

8. The system of claim 1, wherein the selection circuitry alters the resonant response of each antenna by switching a capacitor across the respective antenna.

9. A radio frequency tag reading system comprising:

at least three radio frequency antennas disposed about a sensing volume having one or more radio frequency tags;

radio frequency signal reading circuitry configured to read radio frequency signals received from the one or more radio frequency tags via the radio frequency antennas; and

at least three selection circuits, a respective selection circuit being coupled between each radio frequency antenna and the radio frequency signal reading circuitry, the selection circuits being configured to selectively couple the respective radio frequency antenna to the radio frequency signal reading circuitry and to alter a resonant response of the respective antenna when not coupled to the radio frequency signal reading circuitry.

10. The system of claim 9, comprising three radio frequency antennas disposed in generally orthogonal orientations around the sensing volume.

11. The system of claim 10, comprising a fourth radio frequency antenna disposed generally parallel to one of the three radio frequency antennas around the sensing volume.

12. A radio frequency tag reading system comprising:

selection circuitry configured to selectively couple radio frequency signal reading circuitry to each of a plurality of radio frequency antennas and to alter a resonant response of each antenna when not coupled to the radio frequency signal reading circuitry.

13. The system of claim 12, wherein the selection circuitry includes a first solid state switch configured to selectively complete and interrupt a conductive path between each antenna and the radio frequency signal reading circuitry.

14. The system of claim 13, wherein the selection circuitry includes a second solid state switch configured to couple a capacitor across each antenna to alter a resonant response of the respective antenna when not coupled to the radio frequency signal reading circuitry.

15. The system of claim 12, wherein the selection circuitry includes a separate selection circuit board for each antenna.

16. A method for reading radio frequency tags, comprising:

coupling a first radio frequency antenna to a reading circuitry;

tuning the first radio frequency antenna so that the resonant response of the first radio frequency antenna significantly matches the signal frequency generated by the reading circuitry;

sending radio frequency signals from the reading circuitry to the first radio frequency antenna.

17. The method of claim 16 comprising, receiving radio frequency signals from the first radio frequency antenna, the radio frequency signals corresponding to radio frequency tags in wireless communication with the first radio frequency antenna.

18. The method of claim 16, wherein the first radio frequency antenna is orthogonally positioned relative to a second radio frequency antenna and a third radio frequency antenna.

19. The method of claim 16, comprising

electrically decoupling the first radio frequency antenna from the reading circuitry;

detuning the first radio frequency antenna so that the resonant response of the first radio frequency antenna does not significantly match the signal frequency generated by the reading circuitry;

coupling a second radio frequency antenna to a reading circuitry;

tuning the second radio frequency antenna so that the resonant response of the second radio frequency antenna significantly matches the signal frequency generated by the reading circuitry;

sending radio frequency signals from the reading circuitry to the second radio frequency antenna.

20. The method of claim 19, comprising receiving radio frequency signals from the second radio frequency antenna, the radio frequency signals corresponding to radio frequency tags in wireless communication with the second radio frequency antenna.