Inductively coupled loop antenna for a radio frequency identification reader

• US 7,764,181 B2
• Filed: 07/03/2007
• Issued: 07/27/2010
• Est. Priority Date: 07/03/2007
• Status: Active Grant

• Current Assignee: Allflex USA Incorporated (Merck & Co., Inc.)
• Original Assignee: Allflex USA Incorporated (Merck & Co., Inc.)
• Inventors: Martin, Jacques, Stewart, Robert
• Primary Examiner(s): Lee; Benjamin C
• Assistant Examiner(s): BEE, ANDREW W.
• Application Number:
  US11/825,108
• Publication Number:
  US 20090009335A1
• Time in Patent Office: 1,120 Days
• Field of Search: 340/572.7, 340/573.1
• US Class Current: 340/573.1
• CPC Class Codes: A01K 11/006 Automatic identification systems for animals, e.g. electronic devices, transponders for animals identification systems for access to feeding pens A01K1/0209; ear tags with electronic identification means A01K11/004
• CPC Class Codes: G06K 7/10178 including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field comparable booster antennas integrated on the record carrier itself G06K19/07794
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil

Abstract

Systems and methods are described for reading EID tags in difficult to reach locations using a portable RFID reader. In many embodiments, the system includes a portable RFID reader and one or more stationary antenna assemblies. The stationary antenna assemblies typically include a loop antenna in a first location and a ferrite antenna in a second location. EID tags in the reading zone of the loop antenna can be read using the portable RFID reader via an inductive coupling between the resonant antenna in the portable RFID reader and the ferrite antenna in the stationary antenna assembly. One embodiment of the invention includes a portable reader having reader circuitry configured to generate an activation signal, a first resonant antenna, where the first resonant antenna is electrically connected to the reader circuitry, a reader housing containing the reader circuitry and the first resonant antenna, and a stationary antenna assembly having a resonant antenna unit including a housing and a second resonant antenna, a loop antenna unit including a housing and a loop antenna and an electrical connection between the resonant antenna unit and the loop antenna unit. In addition, the first resonant antenna in the portable reader is inductively coupled to the second resonant antenna in the stationary antenna assembly.

Claims

1. A radio frequency identification reader system, comprising:

a portable reader, including;

reader circuitry configured to generate an activation signal;

a first resonant antenna, where the first resonant antenna is electrically connected to the reader circuitry;

a reader housing containing the reader circuitry;

a plurality of stationary antenna assemblies, where each stationary antenna assembly includes;

a resonant antenna unit including a resonant antenna housing and a second resonant antenna contained within the resonant antenna housing, where the second resonant antenna is tuned to a resonant frequency;

a loop antenna unit including a loop antenna housing and a loop antenna contained within the loop antenna housing and configured to provide a larger reading zone and greater reading distance than the first resonant antenna of the portable reader, where the loop antenna is tuned to the resonant frequency; and

an electrical connection between the resonant antenna unit and the loop antenna unit;

wherein the resonant antenna units of the stationary antenna assemblies are located a distance apart so that the first resonant antenna in the portable reader is only capable of inductively coupling to one resonant antenna in a stationary antenna assembly at a time;

wherein the housing of the resonant antenna unit includes a mechanical coupler configured to align the first resonant antenna in the portable reader with the second resonant antenna in each stationary antenna assembly.

2. The radio frequency identification reader system of claim 1, wherein the reader circuitry is configured to generate an activation signal that causes the first resonant antenna to generate a time varying magnetic field.

3. The radio frequency identification reader system of claim 2, wherein:

the portable reader includes an activation switch; and

the reader circuitry is configured to generate the activation signal in response to the activation switch being pressed.

4. The radio frequency identification reader system of claim 2, wherein:

the first resonant antenna and the second resonant antenna are configured so that the second resonant antenna generates a time varying electrical signal indicative of a time varying magnetic field generated by the first resonant antenna;

the electrical connection is configured to convey electrical signals from the second resonant antenna to the loop antenna; and

the loop antenna is configured to generate a time varying magnetic field indicative of a time varying electrical signal generated by the second resonant antenna.

5. The radio frequency identification reader system of claim 1, wherein the loop antenna is configured to receive information data from an electronic identification tag, which automatically responds to the activation signal.

6. The radio frequency identification reader system of claim 5, wherein:

the loop antenna is configured to generate a time varying electrical signal indicative of received information data and to provide the electrical signal to the second resonant antenna via the electrical connection;

the second resonant antenna is configured to generate a time varying magnetic field indicative of an electrical signal generated by the loop antenna;

the first resonant antenna is configured to generate a time varying electrical signal indicative of a time varying magnetic field generated by the second resonant antenna and to provide the time varying electrical signal to the reader circuitry via the electrical connection between the first resonant antenna and the reader circuitry; and

the reader circuitry is configured to extract information data from the time varying electrical signal received from the first resonant antenna.

7. The radio frequency identification reader system of claim 1, wherein at least one of the resonant antennas is a ferrite antenna.

8. The radio frequency identification reader system of claim 7, wherein the ferrite antenna comprises:

a ferrite core;

an insulating form surrounding a portion of the ferrite core; and

a coil wrapped around the insulating form.

9. The radio frequency identification reader system of claim 8, wherein the ferrite core has a circular geometry.

10. The radio frequency identification reader system of claim 1, wherein both resonant antennas are ferrite antennas.

11. The radio frequency identification reader system of claim 10, wherein both of the ferrite antennas include a circular geometry, have the same cross-section geometry and include the same number of turns.

12. The radio frequency identification reader system of claim 1, wherein at least one of the resonant antennas is an air-core antenna.

13. The radio frequency identification reader system of claim 1, wherein the electrical connection between the second resonant antenna and the loop antenna includes a pair of wires.

14. The radio frequency identification reader system of claim 1, wherein:

the first resonant antenna and second resonant antenna have circular cross sections; and

the mechanical coupler is configured to attach the portable reader housing to the housing of the resonant antenna unit so that the first and second resonant antennas are axially aligned.

15. The radio frequency identification reader system of claim 1, further comprising an antenna identification tag located proximate each resonant antenna unit.

20. The radio frequency identification reader system of claim 1,

wherein:

the second resonant antenna includes loops configured to circumscribe the first resonant antenna; and

the mechanical coupler is configured to align the portable reader so that the first resonant antenna is positioned within the loops of the second resonant antenna.

21. The radio frequency identification reader system of claim 1, wherein the second resonant antenna is tuned to the resonant frequency using a tuning capacitor.

22. The radio frequency identification reader system of claim 21, wherein the loop antenna is tuned to the resonant frequency using a second tuning capacitor.

16. A method of obtaining identification data from an animal electronic identification tag in a location tagged with a location electronic identification tag using a portable reader having a resonant antenna and configured to generate an activation signal, comprising:

positioning the portable reader so that the resonant antenna is inductively coupled to a first antenna that is electronically connected to a second antenna, where the second antenna is configured to provide a larger reading zone and greater reading distance than the resonant antenna of the portable reader;

wherein a housing of the first antenna includes a mechanical coupler configured to align the resonant antenna in the portable reader with the first antenna when positioning the portable reader so that the resonant antenna is inductively coupled to the first antenna;

generating an activation signal in the reading zone of the second antenna by generating an activation signal using the portable reader;

reading identification data from the animal electronic identification tag using the portable reader, when the animal electronic identification tag is located within the reading zone of the second antenna and the animal electronic identification tag is configured to automatically respond to the activation signal; and

positioning the portable reader so that the location electronic identification tag is located within the reading zone of the portable reader'"'"'s resonant antenna;

generating an activation signal using the portable reader and directly reading identification data from the location electronic identification tag using the portable reader, where the location electronic identification tag is configured to automatically respond to the activation signal.

17. method of claim 16, wherein the reader includes a ferrite antenna.

18. The method claim 16, wherein the first antenna is a ferrite antenna.

19. The method of claim 16, wherein the second antenna is a loop antenna.

23. A radio frequency identification reader system, comprising:

a portable reader, including;

reader circuitry configured to generate an activation signal;

a first resonant antenna, where the first resonant antenna is a ferrite antenna electrically connected to the reader circuitry;

a reader housing containing the reader circuitry;

wherein the reader circuitry is configured to read identification data from animal electronic identification tags, which are configured to automatically respond to an activation signal;

a plurality of stationary antenna assemblies, where each stationary antenna assembly includes;

a resonant antenna unit including a resonant antenna housing and a mechanical coupler configured to align the first resonant antenna with a second resonant antenna contained within the resonant antenna housing, where the second resonant antenna is tuned to a resonant frequency;

a loop antenna unit including a loop antenna housing and a loop antenna contained within the loop antenna housing and configured to provide a larger reading zone and greater reading distance than the first resonant antenna of the portable reader, where the loop antenna is tuned to the resonant frequency; and

an electrical connection between the resonant antenna unit and the loop antenna unit;

wherein the resonant antenna units of the stationary antenna assemblies are located a distance apart so that the first resonant antenna in the portable reader is only capable of inductively coupling to one resonant antenna in a stationary antenna assembly at a time.

24. The radio frequency identification reader system of claim 23, wherein the second resonant antenna is a ferrite antenna.

25. The radio frequency identification reader system of claim 23, wherein:

the second resonant antenna is a loop antenna that includes loops capable of circumscribing the first resonant antenna; and

the mechanical coupler is configured to align the portable reader so that the first resonant antenna is positioned within the loops of the second resonant antenna.