Antenna array for an RFID reader compatible with transponders operating at different carrier frequencies

• US 7,439,862 B2
• Filed: 12/16/2004
• Issued: 10/21/2008
• Est. Priority Date: 05/18/2004
• Status: Active Grant

• Current Assignee: Assa Abloy AB
• Original Assignee: Assa Abloy AB
• Inventors: Quan, Ralph W.
• Primary Examiner(s): GOINS, DAVETTA WOODS
• Application Number:
  US11/016,576
• Publication Number:
  US 20050258966A1
• Time in Patent Office: 1,405 Days
• Field of Search: 340/572.7, 340/572.1, 340/572.2, 340/10.1, 340/10.33, 340/572.3, 340/10.3, 340/572.4, 340/572.5, 340/572.6, 342/129
• US Class Current: 340/572.7
• CPC Class Codes: G06K 7/10128 the step consisting of detection of the presence of one or more record carriers in the vicinity of the interrogation device
• 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 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

An antenna array is provided for an RFID reader, which includes a first reader antenna tuned to operate at a first frequency and a second reader antenna tuned to operate at a second frequency different from the first frequency. The first and second antennas are preferably arranged in an overlapping arrangement or an opposing magnetic flux arrangement to reduce the effect of antenna self resonance.

Claims

1. An antenna array for an RFID reader comprising:

a first reader antenna tuned to operate at a first low carrier frequency enabling data communication with a first transponder transmitting data signals at said first low carrier frequency; and

a second reader antenna tuned to operate at a second high carrier frequency different from said first low carrier frequency enabling data communication with a second transponder transmitting data signals at said second high carrier frequency, wherein the first and second antennas are oriented along axes that are substantially parallel to one another.

2. The antenna array of claim 1, wherein said first low carrier frequency is nominally 125 kHz.

3. The antenna array of claim 2, wherein said second high carrier frequency is about 13.56 MHz.

4. The antenna array of claim 1, further comprising a reader housing containing said first and second antennas.

5. An antenna array for an RFID reader comprising:

a first reader antenna tuned to operate at a first carrier frequency enabling data communication with a first transponder transmitting data signals at said first carrier frequency; and

a second reader antenna tuned to operate at a second carrier frequency different from said first carrier frequency enabling data communication with a second transponder transmitting data signals at said second carrier frequency, wherein said first and second antennas are arranged in at least a partially overlapping arrangement on proximate adjacent planes.

6. The antenna array of claim 5, further comprising a reader housing containing said first and second antennas.

7. The antenna array of claim 5, wherein said first reader antenna has a first area, said second reader antenna has a second area, and said first and second reader antennas are arranged relative one another such that only a portion of said first area aligns with only a portion of said second area.

8. The antenna array of claim 5, wherein said first reader antenna has a first area, said second reader antenna has a second area essentially equal to said first area, and said first and second reader antennas have a parallel orientation and are arranged relative one another such that essentially half of said first area aligns with essentially half of said second area.

9. An antenna array for an RFID reader comprising:

a first reader antenna tuned to operate at a first carrier frequency enabling data communication with a first transponder transmitting data signals at said first carrier frequency; and

a second reader antenna tuned to operate at a second carrier frequency different from said first carrier frequency enabling data communication with a second transponder transmitting data signals at said second carrier frequency, wherein said first and second antennas are arranged in an opposing magnetic flux arrangement.

10. The antenna array of claim 9, further comprising a reader housing containing said first and second antennas.

11. The antenna array of claim 9, wherein said first reader antenna has a first area, said second reader antenna has a second area, and said first and second reader antennas are arranged relative one another such that only a portion of said first area aligns with only a portion of said second area.

12. The antenna array of claim 9, wherein said first reader antenna has a first area, said second reader antenna has a second area essentially equal to said first area, and said first and second reader antennas have a parallel orientation and are arranged relative one another such that essentially half of said first area aligns with essentially half of said second area.

13. The antenna array of claim 9, wherein said first and second reader antennas are arranged in an overlapping arrangement simultaneous with said opposing magnetic flux arrangement.

14. An RFID reader for an RFID system comprising:

an antenna array including a first reader antenna tuned to operate at a first low carrier frequency enabling data communication with a first transponder transmitting data signals at said first low carrier frequency and a second reader antenna tuned to operate at a second high carrier frequency different from said first low carrier frequency enabling data communication with a second transponder transmitting data signals at said second high carrier frequency, wherein the first and second antennas are oriented along axes that are substantially parallel to one another; and

a signal generator coupled with said first and second reader antennas.

15. The RFID reader of claim 14, wherein said signal generator is an integrated signal generator including integral means for generating signals for transmission from said first and second reader antennas.

16. The RFID reader of claim 14, wherein said signal generator includes a discrete first signal generator coupled with said first reader antenna for generating signals for transmission from said first reader antenna and a discrete second signal generator coupled with said second reader antenna separate from said discrete first signal generator for generating signals for transmission from said second reader antenna.

17. An RFID reader for an RFID system comprising:

an antenna array including a first reader antenna tuned to operate at a first low carrier frequency enabling data communication with a first transponder transmitting data signals at said first low carrier frequency and a second reader antenna tuned to operate at a second high carrier frequency different from said first low carrier frequency enabling data communication with a second transponder transmitting data signals at said second high carrier frequency, wherein the first and second antennas are arranged in at least a partially overlapping arrangement along proximate adjacent planes; and

receiver electronics coupled with said first and second reader antennas.

18. The RFID reader of claim 17, wherein said receiver electronics is integrated receiver electronics including integral means for conditioning signals received by said first and second reader antennas.

19. The RFID reader of claim 17, wherein said receiver electronics includes discrete first receiver electronics coupled with said first reader antenna for conditioning signals received by said first reader antenna and discrete second receiver electronics coupled with said second reader antenna separate from said discrete first receiver electronics for conditioning signals received by said second reader antenna.

20. An antenna array for an RFID reader comprising:

a first reader loop antenna having a first loop and tuned to operate at a first carrier frequency enabling data communication with a first transponder transmitting data signals at said first carrier frequency; and

a second reader loop antenna having a second loop and tuned to operate at a second carrier frequency different from said first carrier frequency enabling data communication with a second transponder transmitting data signals at said second carrier frequency, wherein a first plane defined by the first area is substantially orthogonal to a direction of magnetic flux created through the first antenna, wherein a second plane defined by the second area is substantially orthogonal to a direction of magnetic flux created through the second antenna, wherein said first and second loops are arranged relative to one another such that a portion of the first area in the first plane overlaps a portion of the second area in the second plane.

21. The antenna array of claim 20, wherein the directions of magnetic flux created through the first and second antennas are not orthogonal.

22. The antenna array of claim 20, wherein said first and second loops have a parallel orientation and are arranged relative one another such that a size of the portion of the first area aligning with the portion of the second area is less than at least one of a size of the first area and a size of the second area.

23. An antenna array for an RFID reader comprising:

a first reader loop antenna having a first loop and tuned to operate at a first carrier frequency enabling data communication with a first transponder transmitting data signals at said first carrier frequency; and

a second reader loop antenna having a second loop and tuned to operate at a second carrier frequency different from said first carrier frequency enabling data communication with a second transponder transmitting data signals at said second carrier frequency, wherein said first and second loops are arranged in an opposing magnetic flux arrangement where the direction of magnetic flux created through the first loop is substantially parallel but opposite to the direction of magnetic flux created through the second loop.

24. The antenna array of claim 23, wherein said first loop has a first area, said second loop has a second area, and said first and second loops are arranged relative one another such that only a portion of said first area aligns with only a portion of said second area.

25. The antenna array of claim 23, wherein said first loop has a first area, said second loop has a second area essentially equal to said first area, and said first and second loops have a parallel orientation and are arranged relative one another such that essentially half of said area aligns with essentially half of said second area.

26. The antenna array of claim 23, wherein said first and second loops are arranged in an overlapping arrangement simultaneous with said opposing magnetic flux arrangement.