Multistatic antenna configuration for radio frequency identification (RFID) systems

• US 7,265,675 B1
• Filed: 03/01/2005
• Issued: 09/04/2007
• Est. Priority Date: 03/01/2005
• Status: Active Grant

• Current Assignee: RUIZHANG TECHNOLOGY LIMITED COMPANY
• Original Assignee: Alien Technology Corporation
• Inventors: Price, John Michael, Carrender, Curtis L.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US11/070,477
• Time in Patent Office: 917 Days
• Field of Search: 340/572.7, 340/572.4, 340/514, 340/515, 340/825.49, 340/10.1, 340/10.5, 455/78, 455/83, 455/67.11, 455/67.16, 342/165, 342/169, 342/126, 342/127, 342/450, 342/465
• US Class Current: 340/572.7
• 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: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element

Abstract

Methods and apparatuses for configuring antennae of radio frequency identification reader systems. In one aspect of an embodiment, a radio frequency identification (RFID) reader system, includes: a receiver; a radio frequency (RF) source for signal transmission; and a switch matrix coupled with the receiver and the radio frequency sources to selectively couple the receiver and the radio frequency source to a plurality of non-collocated antennae. When in a first mode, the switch matrix connects the radio frequency source to a first one of the antennae for signal transmission and the receiver to a second one of the antennae for signal reception; and when in a second mode, the switch matrix connects the first one of the antennae for signal reception and, in one example, the second one or another one of the antennae to the RF source for signal transmission.

Claims

1. A radio frequency identification (RFID) reader system, comprising:

a receiver;

a radio frequency (RF) source for signal transmission;

a switch matrix coupled with the receiver and the radio frequency source, the switch matrix to selectively couple the receiver and the radio frequency source to a plurality of non-collocated antennae;

wherein when in a first mode, the switch matrix connects the radio frequency source to a first one of the antennae for signal transmission and the receiver to a second one of the antennae for signal reception; and

wherein when in a second mode, the switch matrix connects the first one of the antennae for signal reception; and

a timing circuit coupled with the radio frequency source, the timing circuit to determine a signal propagation delay between the first and second ones of the antennae via a radio frequency identification tag.

2. The radio frequency identification reader system of claim 1, further comprising the plurality of antennae.

3. The radio frequency identification reader system of claim 1, wherein when in the second mode, the switch matrix connects the receiver to the first one of the antennae for signal reception.

4. The radio frequency identification reader system of claim 3, wherein when in the second mode, the switch matrix connects the second one of the antennae to the radio frequency source for signal transmission.

5. The radio frequency identification reader system of claim 3, wherein when in the second mode, the switch matrix connects a third one of the antennae to the radio frequency source for signal transmission.

6. The radio frequency identification reader system of claim 1, further comprising a low noise amplifier (LNA) coupled with the switch matrix.

7. The radio frequency identification reader system of claim 6, wherein when in the first mode, the switch matrix connects the low noise amplifier to the second one of the antennae for signal reception;

and wherein when in the second mode, the switch matrix connects the low noise amplifier to the first one of the antennae for signal reception.

8. The radio frequency identification reader system of claim 1 wherein when in the second mode:

the switch matrix connects a third one of the antennae for signal transmission; and

the first one of the antennae is not connected to a radio frequency (RF) source of the reader system.

9. The radio frequency identification reader system of claim 1, further comprising a processor coupled to the timing circuit, the processor to determine location information of the radio frequency identification tag using at least the signal propagation delay.

10. A radio frequency identification (RFID) reader system, comprising:

a receiver;

a radio frequency (RF) source for signal transmission;

a switch matrix coupled with the receiver and the radio frequency source, the switch matrix to selectively couple the receiver and the radio frequency source to a plurality of non-collocated antennae;

wherein when in a first mode, the switch matrix connects the radio frequency source to a first one of the antennae for signal transmission and the receiver to a second one of the antennae for signal reception; and

wherein when in a second mode, the switch matrix connects the first one of the antennae for signal reception; and

a phase comparison circuit to compare relative phases of backscatter received from multiple ones of the non-collocated antennae.

11. The radio frequency identification reader system of claim 10, further comprising a processor coupled to the phase comparison circuit, the processor to determine distance or location information of the radio frequency identification tag using phase differences determined from the relative phases seen at multiple ones of the non-collocated antennae.

12. The radio frequency identification reader system of claim 10, further comprising the plurality of antennae.

13. The radio frequency identification reader system of claim 10, wherein when in the second mode, the switch matrix connects the receiver to the first one of the antennae for signal reception.

14. The radio frequency identification reader system of claim 13, wherein when in the second mode, the switch matrix connects the second one of the antennae to the radio frequency source for signal transmission.

15. The radio frequency identification reader system of claim 13, wherein when in the second mode, the switch matrix connects a third one of the antennae to the radio frequency source for signal transmission.

16. The radio frequency identification reader system of claim 10, further comprising a low noise amplifier (LNA) coupled with the switch matrix.

17. The radio frequency identification reader system of claim 16, wherein when in the first mode, the switch matrix connects the low noise amplifier to the second one of the antennae for signal reception;

and wherein when in the second mode, the switch matrix connects the low noise amplifier to the first one of the antennae for signal reception.

18. The radio frequency identification reader system of claim 10, wherein when in the second mode:

the switch matrix connects a third one of the antennae for signal transmission; and

the first one of the antennae is not connected to a radio frequency (RF) source of the reader system.

19. A radio frequency identification (RFID) reader system, comprising:

a receiver;

a radio frequency (RF) source for signal transmission;

a switch matrix coupled with the receiver and the radio frequency sources, the switch matrix to selectively couple the receiver and the radio frequency source to a plurality of non-collocated antennae;

wherein when in a first mode, the switch matrix connects the radio frequency source to a first one of the antennae for signal transmission and the receiver to a second one of the antennae for signal reception; and

wherein when in a second mode, the switch matrix connects the first one of the antennae for signal reception; and

a signal modulator coupled with the switch matrix, the signal modulator to generate a modulated signal to emulate a radio frequency identification tag;

wherein when in the first mode, the switch matrix connects a third one of the antennae to the modulated signal for signal transmission.

20. The radio frequency identification reader system of claim 19, wherein when in the first mode, the switch matrix connects a fourth one of the antennae to receive signals reflected from the first one of the antennae;

and the signal modulator generates the modulated signal according to the signals received from the fourth one of the antennae.

21. The radio frequency identification reader system of claim 19, further comprising the plurality of antennae.

22. The radio frequency identification reader system of claim 19, wherein when in the second mode, the switch matrix connects the receiver to the first one of the antennae for signal reception.

23. The radio frequency identification reader system of claim 22, wherein when in the second mode, the switch matrix connects the second one of the antennae to the radio frequency source for signal transmission.

24. The radio frequency identification reader system of claim 22, wherein when in the second mode, the switch matrix connects a third one of the antennae to the radio frequency source for signal transmission.

25. The radio frequency identification reader system of claim 19, further comprising a low noise amplifier (LNA) coupled with the switch matrix.

26. The radio frequency identification reader system of claim 25, wherein when in the first mode, the switch matrix connects the low noise amplifier to the second one of the antennae for signal reception;

and wherein when in the second mode, the switch matrix connects the low noise amplifier to the first one of the antennae for signal reception.

27. The radio frequency identification reader system of claim 19, wherein when in the second mode:

the switch matrix connects a third one of the antennae for signal transmission; and

the first one of the antennae is not connected to a radio frequency (RF) source of the reader system.

28. A radio frequency identification (RFID) reader system, comprising:

a receiver;

a radio frequency (RF) source for signal transmission;

a switch matrix coupled with the receiver and the radio frequency source, the switch matrix to selectively couple the receiver and the radio frequency source to a plurality of non-collocated antennae;

wherein when in a first mode, the switch matrix connects the radio frequency source to a first one of the antennae for signal transmission and the receiver to a second one of the antennae for signal reception; and

wherein when in a second mode, the switch matrix connects the first one of the antennae for signal reception; and

a logic circuitry coupled to the switch matrix, the logic circuitry to control switching activity of the switch matrix to generate a modulated backscatter signal.

29. The radio frequency identification reader system of claim 28, further comprising the plurality of antennae.

30. The radio frequency identification reader system of claim 28, wherein when in the second mode, the switch matrix connects the receiver to the first one of the antennae for signal reception.

31. The radio frequency identification reader system of claim 30, wherein when in the second mode, the switch matrix connects the second one of the antennae to the radio frequency source for signal transmission.

32. The radio frequency identification reader system of claim 30, wherein when in the second mode, the switch matrix connects a third one of the antennae to the radio frequency source for signal transmission.

33. The radio frequency identification reader system of claim 28, further comprising a low noise amplifier (LNA) coupled with the switch matrix.

34. The radio frequency identification reader system of claim 33, wherein when in the first mode, the switch matrix connects the low noise amplifier to the second one of the antennae for signal reception;

and wherein when in the second mode, the switch matrix connects the low noise amplifier to the first one of the antennae for signal reception.

35. The radio frequency identification reader system of claim 28, wherein when in the second mode:

the switch matrix connects a third one of the antennae for signal transmission; and

the first one of the antennae is not connected to a radio frequency (RF) source of the reader system.

47. The reader system of claim 29, wherein in the second configuration a third one of the antennae is connected to a radio frequency source for signal transmission to radio frequency identification tags.

36. A method to operate a radio frequency identification (RFID) reader system, the method comprising:

switching connectivity to a plurality of non-collocated antennae for operation in a first configuration, wherein in the first configuration;

a first one of the antennae is connected to a radio frequency source for signal transmission to radio frequency identification tags; and

a second one of the antennae is disconnected from a radio frequency source and reconnected for signal reception from the radio frequency identification tars in the first configuration;

switching connectivity to a plurality of antennae for operation in a second configuration, wherein in the second configuration;

the first one of the antennae is disconnected from the radio frequency source and reconnected for signal reception from radio frequency identification tags in the second configuration;

determining signal propagation delay on a path from the first one of the antennae to a radio frequency identification tag and then to the second one of the antennae; and

determining a location of the radio frequency identification tag using the signal propagation delay.

37. The method of claim 36, wherein in the second configuration a third one of the antennae is to be connected to a radio frequency source for signal transmission to radio frequency identification tags.

38. The method of claim 36, wherein signal propagation delays via the radio frequency identification tag between the first one of the antennae and each of the antennae except the first one are used in determining the location of the radio frequency identification tag.

39. The method of claim 36, wherein signal propagation delays via the radio frequency identification tag between selected pairs of the antennae are used to determine the location of the radio frequency.

40. The method of claim 36, further comprising determining a position of the tag from phase information contained in the backscatter signal from the tag by determining differences between the phase information.

41. The method of claim 36, wherein in the first configuration a third one of the antennae is to be connected to a radio frequency source for transmission of a first signal emulating a backscattered signal from a radio frequency identification tag.

42. The method of claim 41, further comprising determining whether or not the first signal is properly received at the second one of the antennae in the first configuration.

43. The method of claim 36, wherein in the first configuration a third one of the antennae is to be connected to an impedance modulator for reflection of a first signal emulating a backscattered signal from a radio frequency identification tag.

44. The method of claim 36, wherein in the second configuration the first one of the antennae is to reflect a first signal to emulate a backscattered signal from a radio frequency identification tag;

and the method further comprises determining whether or not the first signal is properly received at the second one of the antennae in the second configuration.

45. The method of claim 44, wherein a first reader comprises the first one of the antennae;

and the first signal is from a second reader which is different from the first reader.

46. A radio frequency identification (RFID) reader system, comprising:

means for switching connectivity to a plurality of non-collocated antennae for operation in a first configuration, wherein in the first configuration;

a first one of the antennae is connected to a radio frequency source for signal transmission to radio frequency identification tags; and

a second one of the antennae is disconnected from a radio frequency source and reconnected for signal reception from radio frequency identification tars in the first configuration;

means for switching connectivity to a plurality of antennae for operation in a second configuration, wherein in the second configuration;

the first one of the antennae is disconnected from a radio frequency source and reconnected for signal reception from radio frequency identification tags in the second configuration;

means for determining signal propagation delay on a path from the first one of the antennae to a radio frequency identification tag and then to the second one of the antennae; and

means for determining a location of the radio frequency identification tag using the signal propagation delay.

48. The reader system of claim 46, further comprising:

means for determining a position of the tag from phase information contained in the backscatter signal from the tag by determining differences between the phase information available from at least some of the antennae.

49. The reader system of claim 46, wherein in the first configuration a third one of the antennae is to be connected to a radio frequency source for transmission of a first signal emulating a backscattered signal from a radio frequency identification tag.

50. The reader system of claim 49, further comprising means for determining whether or not the first signal is properly received at the second one of the antennae in the first configuration.

51. The reader system of claim 46, wherein in the second configuration the first one of the antennae is to reflect a first signal to emulate a backscattered signal from a radio frequency identification tag;

and the reader system further comprises means for determining whether or not the first signal is properly received at the second one of the antennae in the second configuration.