RFID READER ANTENNA PORT ISOLATION

• US 20160180125A1
• Filed: 12/17/2015
• Published: 06/23/2016
• Est. Priority Date: 12/22/2014
• Status: Active Grant

• Current Assignee: Intermec (Honeywell International Inc.)
• Original Assignee: Intermec (Honeywell International Inc.)
• Inventors: SCHUSTER, Thomas John, JORGENSON, John, GE, Fengyu
• Granted Patent: US 10,009,000 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator
• 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: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 1/521 reducing the coupling between adjacent antennas
• CPC Class Codes: H03H 7/38 Impedance-matching networks

Abstract

A device includes a switch having multiple ports, an antenna coupled to each corresponding port, a tunable matching network coupled between each antenna and each port, and a controller to detune ports having antennas that are not transferring power when a selected antenna is transferring power.

Claims

1. A device comprising:

a switch having multiple ports;

an antenna coupled to each corresponding port;

a tunable matching network coupled between each antenna and each port; and

a controller that controls the tunable matching network to detune ports having antennas that are not transferring power when a selected antenna is transferring power.

2. The device of claim 1 wherein the controller tunes a tunable impedance of the matching network on the selected port to optimize antenna power transfer, wherein the controller detunes the ports by changing the input impedance to each antenna that is to be detuned.

3. The device of claim 1 wherein a tunable impedance of the matching network comprises one or multiple tunable capacitors.

4. The device of claim 3 wherein the tunable capacitor comprises a high Q capacitor.

5. The device of claim 1 wherein a tunable impedance of the matching network comprises:

an inductor; and

an adjustable capacitor coupled in parallel with the inductor.

6. The device of claim 1 wherein a tunable impedance of the matching network comprises:

an inductor;

a first capacitor coupled between one side of the inductor and ground; and

a second capacitor coupled between another side of the inductor and ground, wherein at least one of the first and second capacitors is adjustable.

7. The device of claim 1 wherein a tunable impedance of the matching network comprises:

an inductor;

a first capacitor coupled between one side of the inductor and ground;

a second capacitor coupled between another side of the inductor and ground; and

a third capacitor coupled in parallel with the inductor, wherein at least one of the first, second, and third capacitors is adjustable.

8. The device of claim 7 wherein each of the first, second, and third capacitors is adjustable.

9. A system comprising:

an RFID reader signal path;

a switch having multiple ports coupled to the RFID reader signal path;

an antenna coupled to each corresponding port;

a tunable matching network coupled between each antenna and each port and coupled to the RFID reader controller; and

a controller to control the switch and the tunable impedances to detune the tunable impedances coupled to antennas that are not transferring power when a selected antenna is transferring power.

10. The system of claim 9 wherein the controller tunes a tunable impedance of the matching network on the selected port to optimize antenna power transfer.

11. The system of claim 9 wherein a tunable impedance of the matching network comprises a tunable high Q capacitor.

12. The system of claim 9 wherein a tunable impedance of the matching network comprises:

an inductor; and

an adjustable capacitor coupled in parallel with the inductor.

13. The system of claim 9 wherein a tunable impedance of the matching network comprises:

an inductor;

a first capacitor coupled between one side of the inductor and ground; and

a second capacitor coupled between another side of the inductor and ground, wherein at least one of the first and second capacitors is adjustable.

14. The system of claim 9 wherein a tunable impedance of the matching network comprises:

an inductor;

a first capacitor coupled between one side of the inductor and ground;

a second capacitor coupled between another side of the inductor and ground; and

a third capacitor coupled in parallel with the inductor, wherein at least one of the first, second, and third capacitors is adjustable.

15. The system of claim 14 wherein each of the first, second, and third capacitors is adjustable which is used in detuning the ports by changing the input impedance to each antenna that is to be detuned.

16. A method comprising:

selecting a port of a multiport switch on which to transfer energy via an antenna coupled to the selected port;

detuning impedances corresponding to antennas coupled to non-selected ports; and

transferring energy via the antenna coupled to the selected port.

17. The method of claim 16 and further comprising ensuring an impedance between the selected port and corresponding antenna is tuned for optimal power transfer.

18. The method of claim 16 wherein the impedances comprise high Q tunable capacitors.

19. The method of claim 16 wherein the impedances comprise

an inductor;

a first capacitor coupled between one side of the inductor and ground;

a second capacitor coupled between another side of the inductor and ground; and

a third capacitor coupled in parallel with the inductor, wherein detuning the impedance comprises adjusting the capacitance of at least one of the first, second, and third capacitors.

20. The method of claim 16 wherein each of the first, second, and third capacitors is adjusted.