Omnidirectional RFID antenna

• US 6,720,930 B2
• Filed: 01/15/2002
• Issued: 04/13/2004
• Est. Priority Date: 01/16/2001
• Status: Expired due to Term

• Current Assignee: Destron Fearing Corporation (Merck & Co., Inc.)
• Original Assignee: Digital Angel Corporation
• Inventors: Johnson, Daniel L., Smirnov, Yuri
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): CHEN, SHIH CHAO
• Application Number:
  US10/050,278
• Publication Number:
  US 20020109636A1
• Time in Patent Office: 819 Days
• Field of Search: 343/742, 343/867, 343/842, 340/572.1, 340/572.7, 340/572.8, 119/51.02
• US Class Current: 343/742
• 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: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

An omni-directional RFID antenna is provided for use with a remote interrogator/reader system used for identifying tagged animals. A pair of antenna coils are arranged in a crossing pattern that results in the creation of an omni or multi-directional electromagnetic field. Additionally, the crossing pattern creates out of phase null zones at quadrants within the crossing pattern of the antennae that reduces interference caused by RF noise generated from the environment. The omni-directional electromagnetic field effectively surrounds each of the null zones thereby allowing an RFID transponder to be successfully interrogated despite the orientation of the transponder as it passes through the electromagnetic field.

Claims

1. An antenna for use with a remote interrogator/reader unit used to detect information specific to each of a plurality of radio frequency transponders attached to animals, said antenna comprising:

a first antenna coil arranged in a closed loop configuration and extending along a first axis;

a second antenna coil arranged in a closed loop configuration and extending along a second axis, said first coil positioned in close proximity to said second coil and oriented so that first axis extends substantially perpendicular to said second axis forming a crossing pattern;

a housing containing said first and second coils, said housing capable of being positioned in the proximity of said transponders; and

wherein said antenna generates multi-directional electromagnetic fields when powered by said remote interrogator/reader unit, and said first and second antenna coils are activated in opposite orientation said activation thereby reducing RF noise from the environment.

2. The antenna, as claimed in claim 1, wherein:

said generated electromagnetic fields have a total inductance of less than 400 μ

H.

3. The antenna, as claimed in claim 1, wherein:

said coils are made of approximately 22-gauge wire.

4. The antenna, as claimed in claim 1, wherein:

each coil contains about 25 windings.

5. The antenna, as claimed in claim 1, wherein:

said first antenna coil is substantially contained in a first plane;

said second antenna coil is substantially contained in a second plane; and

wherein said first and second planes are substantially parallel.

6. An antenna for use with a remote interrogator/reader used to detect information specific to each of a plurality of radio frequency transponders attached to animals, said antenna comprising:

a pair of cross oriented antenna coils having an out of phase orientation to cancel external RF noise, said pair of cross oriented antenna coils further creating multi-directional electromagnetic fields extending away from said coils and effective to interrogate said transponders.

7. The antenna, as claimed in claim 6, wherein:

said electromagnetic fields have a total inductance of less than 400 μ

H.

8. The antenna, as claimed in claim 6, wherein:

said coils are made of approximately 22-gauge wire.

9. The antenna, as claimed in claim 6, wherein:

each coil contains about 25 windings.

10. An antenna for use with a remote interrogator/reader unit used to detect information specific to each of a plurality of radio frequency transponders attached to animals, said antenna comprising:

means for creating an omni-directional field of electromagnetic energy effective to interrogate said transponders;

means for creating out of phase relationships within said omni-directional field to reduce RF noise generated from the surrounding environment; and

wherein said antenna is arranged in a crossing pattern of antenna coil members.

11. The antenna, as claimed in claim 10, wherein:

said omni-directional field of electromagnetic energy has a total inductance of less than about 400 μ

H.

12. The antenna, as claimed in claim 10, wherein:

said coil members are made of approximately 22 gauge wire.

13. The antenna, as claimed in claim 10, wherein:

said coil members contain approximately 25 windings each.

14. A method of interrogating a radio frequency transponder by an antenna used within a remote interrogator/reader system, the radio frequency transponder being adapted especially for use in tagging animals, said method comprising the steps of:

providing a first antenna coil having a closed loop configuration;

positioning a second antenna coil having a closed loop configuration such that said second coil extends substantially perpendicular to said first coil thus creating a crossing pattern between the first and second antenna coils;

exciting the antenna to create an omni-directional field of electromagnetic energy, and to create an out of phase relationship within the crossing pattern, the out of phase relationship being effective to cancel RF noise generated from the surrounding environment; and

passing the transponder through the electromagnetic field resulting in the transponder being activated to transmit a radio frequency signal unique to the transponder.

15. An antenna for use with a remote interrogator/reader unit used to detect information specific to each of a plurality of radio frequency transponders, said antenna comprising:

a first antenna coil arranged in a closed loop configuration extending along a first axis and substantially contained in a first plane; and

a second antenna coil arranged in a closed loop configuration extending along a second axis and substantially contained in a second plane, said first coil positioned in close proximity to said second coil and oriented so that said first axis extends substantially perpendicular to said second axis forming a crossing pattern and said first plane is substantially parallel to said second plane.

16. The antenna, as claimed in claim 15, further comprising:

a housing containing said first and second coils, said housing capable of being positioned in the proximity of said transponders.

17. The antenna, as claimed in claim 15, wherein:

said antenna generates multi-directional electromagnetic fields when powered by said remote interrogator/reader unit.

18. The antenna, as claimed in claim 15, wherein:

said first and second coils are activated in opposite orientation to provide cancellation of RF noise from the environment.

19. The antenna, as claimed in claim 15, wherein:

said generated electromagnetic fields have a total inductance of less than 400 μ

H.

20. The antenna, as claimed in claim 15, wherein:

said coils are made of approximately 22 gauge wire.

21. The antenna, as claimed in claim 15, wherein:

each coil contains about 25 windings.

22. A method of interrogating a radio frequency transponder by an antenna used within a remote interrogator/reader system, the radio frequency transponder being adapted especially for use in tagging animals, said method comprising the steps of:

providing a first antenna coil having a closed loop configuration extending along a first axis;

providing a second antenna coil having a closed loop configuration extending along a second axis;

electrically connecting said first and second antenna coils in parallel and in phase to a reader/interrogator;

positioning said first and second antenna coils within a housing wherein said second antenna coil is positioned relative to said first antenna coil such that electromagnetic fields generated from the first and second antenna coils are out of phase and such that said first axis is substantially perpendicular to said second axis thus creating a crossing pattern between the first and second antenna coils;

exciting the antenna to create an omni-directional field of electromagnetic energy;

passing the transponder adjacent to said housing and through the electromagnetic field resulting in the transponder being activated to transmit a radio frequency signal unique to the transponder; and

summing the signals received at the first and second antenna coils to cancel noise from the surrounding environment and obtain said radio frequency signal unique to the transponder.

23. The method, as claimed in claim 22, wherein:

said first antenna coil is substantially contained in a first plane;

said second antenna coil is substantially contained in a second plane; and

wherein said first and second planes are substantially parallel.

24. The method, as claimed in claim 22, wherein:

said generated electromagnetic fields have a total inductance of less than 400 μ

H.

25. The method, as claimed in claim 22, wherein:

said coils are made of approximately 22 gauge wire.

26. The method, as claimed in claim 22, wherein:

each coil contains 25 windings.