Antenna apparatus

• US 7,535,364 B2
• Filed: 12/13/2005
• Issued: 05/19/2009
• Est. Priority Date: 08/25/2005
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sakama, Isao, Ashizawa, Minoru
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US11/299,671
• Publication Number:
  US 20070046465A1
• Time in Patent Office: 1,253 Days
• Field of Search: 340/572.1, 340/572.3, 340/572.4, 340/572.7, 340/572.8, 340/5.61, 340/5.66, 340/10.2, 340/10.3, 340/572.5, 235/492, 235/380, 342/44, 343/841
• US Class Current: 340/572.7
• 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: H01Q 1/22 by structural association with other equipment or articles
• CPC Class Codes: H01Q 19/30 the primary active element being centre-fed and substantially straight, e.g. Yagi antenna
• CPC Class Codes: H01Q 9/28 Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines waveguide horns or mouths H01Q13/00; slot antennas H01Q13/00

Abstract

An antenna apparatus which ensures a wide reading area on a reader antenna and a reading operability of information recorded in a small-sized radio frequency IC tag is provided. The apparatus includes an auxiliary antenna of λ/2 long disposed near to a radiating antenna of λ/2 long and including plural conductive elements in an array. When the IC tag approaches the auxiliary antenna, a subsidiary tuning circuit is formed between it and an inlet antenna of IC tag, so making tuning complementary to each other. The inlet antenna having an antenna length shorter than the tuning frequency can receive energy from the auxiliary antenna efficiently and is excited integrally with the auxiliary antenna to thereby spread a reading area by apparatus and increase the communication distance.

Claims

1. An antenna apparatus for making communication with a radio frequency IC tag to read information stored in an integrated circuit chip included in the radio frequency IC tag and serving as a reader/writer, comprising:

a radiating antenna which generates an electric field by electric power supplied to a feeding point thereof; and

an auxiliary antenna which resonates by the electric field generated by the radiating antenna to generate an induced current;

the radiating antenna and the auxiliary antenna having the same length,

the auxiliary antenna comprising a plurality of conductive elements arranged in an array, each conductive element having the same length as that of said radiating antenna, and

the plurality of conductive elements being disposed on the same plane and parallel to each other.

2. An antenna apparatus according to claim 1, wherein the length of the radiating antenna and the length of the auxiliary antenna is λ

/2, respectively where λ

is a wavelength of radio wave used when the antenna apparatus communicates with the radio frequency IC tag.

3. An antenna apparatus according to claim 1, wherein the radiating antenna and the plurality of conductive elements are arranged at spaces shorter than or equal to the width or the length of the radio frequency IC tag.

4. An antenna apparatus according to claim 1, wherein the plurality of conductive elements are arranged at spaces of 0.01λ

to 0.20λ

.

5. An antenna apparatus according to claim 4, wherein the plurality of conductive elements are arranged on a radiation axis of the radiating antenna.

6. An antenna apparatus according to claim 4, wherein the plurality of conductive elements are arranged at a predetermined angle of inclination on a radiation axis of the radiating antenna.

7. An antenna apparatus according to claim 4, wherein the width of conductive elements disposed at ends, of the plurality of conductive elements is wider than that of the other conductive elements.

8. An antenna apparatus according to claim 7, wherein width of the other conductive elements is 1 to 3 mm.

9. An antenna apparatus according to claim 7, wherein the conductive elements are directly arranged in an antenna substrate made of resin.

10. An antenna apparatus according to claim 9, wherein the plurality of conductive elements are arranged in parallel with a direction of polarization of the radiating antenna.

11. An antenna apparatus according to claim 9, wherein the plurality of conductive elements are arranged in perpendicular to a direction of polarization of the radiating antenna.

12. An antenna apparatus according to claim 1, wherein the radiating antenna and the plurality of conductive elements are arranged on the same plane.

13. An antenna apparatus according to claim 1, wherein the plurality of conductive elements are arranged above a top surface of the radiating antenna.

14. An antenna apparatus according to claim 1, wherein the radiating antenna, at least one conductive element of the auxiliary antenna and a reader circuit of the radio frequency IC tag are all formed on the same substrate.

15. An antenna apparatus according to claim 14, wherein a plurality of conductive elements of the auxiliary antenna are mounted on at least one of an inner wall of a housing of the antenna apparatus, an outer wall of the housing of the antenna apparatus and a member of the housing of the antenna apparatus.

16. An antenna apparatus for making communication with a radio frequency IC tag to read information stored in an integrated circuit chip included in the radio frequency IC tag and serving as a reader/writer, comprising:

a radiating antenna which generates an electric field by electric power supplied to a feeding point thereof; and

an auxiliary antenna which resonates by the electric field generated by the radiating antenna to generate an induced current;

wherein;

the radiating antenna and the auxiliary antenna have the same length,

the auxiliary antenna comprises a plurality of conductive elements arranged in an array, each conductive element having the same length as that of said radiating antenna,

the plurality of conductive elements are disposed on the same plane and parallel to each other, and

the plane of the conductive elements is above the radiating antenna.

17. An antenna apparatus according to claim 16, wherein the length of the radiating antenna and the length of the auxiliary antenna is λ

/2, respectively where λ

is a wavelength of radio wave used when the antenna apparatus communicates with the radio frequency IC tag.

18. An antenna apparatus according to claim 16, wherein the radiating antenna and the plurality of conductive elements are arranged at spaces shorter than or equal to the width or the length of the radio frequency IC tag.

19. An antenna apparatus according to claim 16, wherein the plurality of conductive elements are arranged at spaces of 0.01λ

to 0.20λ

.

20. An antenna apparatus according to claim 19, wherein the plurality of conductive elements are arranged at a predetermined angle of inclination on a radiation axis of the radiating antenna.

21. An antenna apparatus according to claim 19, wherein the width of conductive elements disposed at ends, of the plurality of conductive elements is wider than that of the other conductive elements.

22. An antenna apparatus according to claim 21, wherein width of the other conductive elements is 1 to 3 mm.

23. An antenna apparatus according to claim 21, wherein the conductive elements are directly arranged in an antenna substrate made of resin.

24. An antenna apparatus according to claim 23, wherein the plurality of conductive elements are arranged in parallel with a direction of polarization of the radiating antenna.

25. An antenna apparatus according to claim 23, wherein the plurality of conductive elements are arranged in perpendicular to a direction of polarization of the radiating antenna.

26. An antenna apparatus according to claim 23, wherein the radiating antenna, at least one conductive element of the auxiliary antenna and a reader circuit of the radio frequency IC tag are all formed on the same substrate.

27. An antenna apparatus according to claim 26, wherein a plurality of conductive elements of the auxiliary antenna are mounted on at least one of an inner wall of a housing of the antenna apparatus, an outer wall of the housing of the antenna apparatus and a member of the housing of the antenna apparatus.