THIN SLOT ANTENNA HAVING CAVITY, ANTENNA POWER FEEDING METHOD, AND RFID TAG DEVICE USING THE ANTENNA AND THE METHOD

• US 20100188306A1
• Filed: 09/03/2007
• Published: 07/29/2010
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Hitoshi Kitayoshi
• Original Assignee: Hitoshi Kitayoshi
• Inventors: Sawaya, Kunio, Kitayoshi, Hitoshi
• Granted Patent: US 8,253,640 B2
• Time in Patent Office: Days
• US Class Current: 343/767
• CPC Class Codes: H01Q 1/085 Flexible aerials; Whip aerials with a resilient base
• CPC Class Codes: H01Q 13/18 the slot being backed by, or formed in boundary wall of, a resonant cavity longitudinally slotted cylinder H01Q13/12 ; Open cavity antennas

Abstract

Provided are a highly efficient thin slot antenna having a cavity, and a RFID tag device. The thin slot antenna can be attached to curved surfaces of a human body, things and the like, and furthermore, has relatively freely deformable flexible characteristics, and has an extremely small characteristic change due to deformation and that due to bodies to be attached to. A bag-like body having a cavity (12) is formed by using a conductor foil of aluminum or the like or a foil deposited with a conductive metal such as aluminum and by forming the foil in bag shape. A relatively soft dielectric sheet (13) is put in the cavity (12), and a slot (14) is arranged at the width direction center position on one surface of the bag-like body, in the longitudinal direction.

Claims

1-16. -16. (canceled)

17. A thin slot antenna having a cavity for use in wireless communications, characterized by comprising:

a bag-shaped product having a cavity defined with conductive foil or foil formed with a conductive thin film on the surface thereof,

wherein a dielectric sheet is provided inside the cavity, and

a slot is provided on one side of the foil by removing a conductor, thereby providing flexibility to the antenna such that the antenna is allowed to be mounted on a flat surface or a curved surface.

18. The thin slot antenna having a cavity according to claim 17, characterized in that with respect to a radio frequency wavelength λ

, the cavity has a thickness ranging from 0.01 to 0.05λ

, a length ranging from 0.8 to 1.2λ

, and a width ranging from 0.47 to 0.53λ

.

19. The thin slot antenna having a cavity according to claim 17, characterized in that the slot is provided lengthwise on one side of the cavity at a center position in a width direction, the slot having a width ranging from 0.01 to 0.05λ

and a length ranging from 0.65 to 0.85λ

.

20. The thin slot antenna having a cavity according to claim 17, characterized in that the dielectric sheet is formed of any one material of polypropylene and polystyrene.

21. The thin slot antenna having a cavity according to claim 17, characterized in that the thickness of the dielectric sheet ranges from 0.01 to 0.05λ

.

22. The thin slot antenna having a cavity according to claim 17, characterized in that the conductive foil or the conductive thin film is formed of a single layer or a composite layer containing any one material of aluminum and copper.

23. The thin slot antenna having a cavity according to claim 17, characterized in that the thickness of the conductive foil ranges from 5 μ

m to 20 μ

m.

24. The thin slot antenna having a cavity according to claim 17, characterized in that the thickness of the conductive thin film ranges from 0.5 μ

m to 10 μ

m.

25. The thin slot antenna having a cavity according to claim 17, characterized in that the foil to be a base material for forming the conductive thin film is formed of any one material of polypropylene and polyester.

26. The thin slot antenna having a cavity according to claim 17, characterized in that an adhesive conductive tape has a slot (hereinafter, referred to as a tape slot) in the same shape as the slot and has an IC chip and a coaxial cable connected thereto in advance such that the IC chip and the coaxial cable are electrically connected across the tape slot, and

the adhesive conductive tape is bonded to the foil such that positions of the slot and the tape slot are matched.

27. The thin slot antenna having a cavity according to claim 17, characterized in that an IC chip and a coaxial cable are electrically connected in advance to two adhesive conductive electrodes, the two adhesive conductive electrodes being relatively easily electrically connectable, and

the two adhesive conductive electrodes are bonded over the slot such that the two adhesive conductive electrodes do not block the slot, thereby using capacitive coupling of cavity conductors above and below the slot to the two adhesive conductive electrodes, respectively.

28. The thin slot antenna having a cavity according to claim 17, characterized in that a feeding point is provided at a position 0.1 to 0.2λ

apart from one end of the slot to obtain 50 Ω

feed point impedance.

29. The thin slot antenna having a cavity according to claim 17, characterized in that on the side of the conductive foil or the foil on which the conductive thin film is formed, several holes are uniformly made on a side on which the slot is not provided and on the dielectric sheet as the vicinity of the slot is avoided.

30. An RFID tag device characterized by using the thin slot antenna having a cavity according to claim 17.

31. An RFID tag device characterized by using the antenna according to claim 17 to configure a structure, wherein an IC chip is connected across the slot and a third terminal is provided for modulating a return reflected wave in addition to two feed terminals,

wherein one end of the slot is extended to cause feed point impedance not to match with a receiving power matching state, and a variable impedance device is mounted on the extended slot, and

the variable impedance device is controlled by the third terminal.

32. An RFID tag device characterized by using the antenna according to claim 17 to configure a structure, wherein an IC chip is connected across the slot and a third terminal is provided for modulating a return reflected wave in addition to two feed terminals,

wherein a semiconductor device is mounted at a position off from a feeding point of the slot, and

the semiconductor device is controlled by the third terminal.

33. The thin slot antenna having a cavity according to claim 18, characterized in that the slot is provided lengthwise on one side of the cavity at a center position in a width direction, the slot having a width ranging from 0.01 to 0.05λ

and a length ranging from 0.65 to 0.85λ

.

34. The thin slot antenna having a cavity according to claim 18, characterized in that the dielectric sheet is formed of any one material of polypropylene and polystyrene.

35. The thin slot antenna having a cavity according to claim 19, characterized in that the thickness of the dielectric sheet ranges from 0.01 to 0.05λ

.

36. The thin slot antenna having a cavity according to claim 18, characterized in that the conductive foil or the conductive thin film is formed of a single layer or a composite layer containing any one material of aluminum and copper.