Chip antenna, radio communications terminal and radio communications system using the same and method for production of the same

• US 20020033778A1
• Filed: 05/16/2001
• Published: 03/21/2002
• Est. Priority Date: 05/18/2000
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Sakita, Hiromi, Sasaki, Katsumi, Yoshinomoto, Makoto, Kanmera, Mitsuo, Isozaki, Kenzo, Goto, Kazuhide, Shiiba, Kengo, Kuroki, Masanobu
• Granted Patent: US 6,486,853 B2
• Time in Patent Office: Days
• US Class Current: 343/895
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/362 for broadside radiating helical antennas
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 11/08 Helical antennas

Abstract

A chip antenna simple in structure, producing small variation in antenna characteristics between individual antennas, requiring no circuit adjustments, excellent in productivity, and capable of being mounted on a circuit board, as well as a wireless terminal using the same and a method of fabricating the same. A core body is made from an insulating material in a quadrangular or circular cylinder shape. A conductor in a helical shape is mounted on the side surface of the core body. A terminal portion is provided on the core body and electrically connected with an end portion of the conductor. The width, depth, and height of the core body are within ranges of 0.5-5 mm, 0.5-5 mm, and 4-40 mm, respectively. Intrinsic volume resistance and relative dielectric constant of the material are 10¹³ Ω·m or above and 40 or below, respectively.

Claims

1. An antenna formed of chip components (chip antenna) comprising:

(a) a core body formed in a cylinder shape;

(b) a conductor in a helical shape mounted on a surface of said core body; and

(c) a terminal portion provided on said core body and connected with an end of said conductor, wherein width, depth, and length of said core body are within ranges of 0.5-5 mm, 0.5-5 mm, and 4-40 mm, respectively, intrinsic volume resistance of said core body is 10¹³ Ω

·

m or above, and relative dielectric constant of the same is 40 or less.

2. The chip antenna according to claim 1, wherein

said conductor is formed of a conductive film.

3. The chip antenna according to claim 1, wherein

said conductor is formed of a conductive film and a buffer layer is provided between said conductive film and said core body.

4. The chip antenna according to claim 3, wherein

at least one of carbon layer, layer containing carbon, and Ni—

Cr alloy layer is provided as the buffer layer.

5. The chip antenna according to claim 1, wherein

a protection member for covering said conductor is formed of

at least one material out of a material group of gold, platinum, palladium, silver, tungsten, titanium, nickel, tin, and copper or

at least one material out of alloy materials of the same material and another element not belonging to the material group.

6. The chip antenna according to claim 1, wherein

a resin protection member is provided as a protection member covering said conductor.

7. The chip antenna according to claim 1, wherein

a protection member made by electrolytic deposition is provided as a protection member covering said conductor.

8. The chip antenna according to claim 1, wherein

a resin tube is provided as a protection member covering said conductor.

9. The chip antenna according to claim 1, wherein

a heat-shrinkable resin tube is provided as a protection member covering said conductor.

10. The chip antenna according to claim 2 or 3, wherein

number of turns of said conductive film in a helical shape is an integer.

11. The chip antenna according to claim 1, wherein

said core body is formed in a circular cylinder shape and a line connecting starting point and ending point of a groove is virtually in parallel with center line of said core body.

12. The chip antenna according to claim 1, wherein

said terminal portion is formed of a conductive film.

13. The chip antenna according to claim 12, wherein

at least one of a protection layer for protecting said terminal portion formed of a conductive film and a bonding layer for facilitating electrical connection between said terminal portion and a pattern on a circuit board is provided at said terminal portion.

14. The chip antenna according to claim 1, wherein

said terminal portion is provided at both end portions of said core body and said conductor is electrically connected with said terminal portion.

15. The chip antenna according to claim 1, wherein

one of said terminal portions is electrically connected with an electronic circuit and the other of said terminal portions is not connected with the electronic circuit.

16. The chip antenna according to claim 1, wherein each of said terminal portions is connected with a pattern on a circuit board.

17. The chip antenna according to claim 1, wherein

said terminal portion is provided on entire peripheral surface of both end portions of said core body.

18. The chip antenna according to claim 2 or 3, wherein

entire end face at both end portions of said core body or center portion of the end face lacks conductive surface.

19. The chip antenna according to claim 1, wherein cross-sectional size of both end portions of said core body is made larger than cross-sectional size of center portion in a stepped manner, and wherein

said terminal portion is provided at both the end portions and said conductor is provided at the center portion.

20. The chip antenna according to claim 1, wherein

said terminal portion is provided by putting a conductive cap on both end portions of said core body.

21. The chip antenna according to claim 2 or 3, wherein a bonding film is provided in a layer over said terminal portion and said conductive film.

22. The chip antenna according to claim 21, wherein

said bonding film is made of at least one of tin, tin alloy excluding tin-lead alloy, gold, and gold alloy.

23. The chip antenna according to claim 1, wherein

a position of center in longitudinal direction of said conductor in a helical shape is located within a range of 0.3×

L from both end faces of said core body, where L represents total length of said chip antenna.

24. The chip antenna according to claim 1, wherein

a position of center in longitudinal direction of said conductor in a helical shape is located within a range of 0.3×

L to 0.7×

L from both end faces of said core body, where L represents total length of said chip antenna.

25. The chip antenna according to claim 1, wherein

said conductor is formed of a conductive wire.

29. The method for manufacturing a chip antenna according to claim 28, wherein

step (e) includes a step of producing said protection member by plating a metallic film highly resistive to corrosion including gold and tin.

30. The method for manufacturing a chip antenna according to claim 28, further comprising

a step, following step (b), for producing a buffer layer on surface of said core body by vapor deposition or coating-and-sintering.

31. The method for manufacturing a chip antenna according to claim 28, further comprising

a step, following step (e), for producing a protection member by plating one of a nickel layer and a solder layer on both the end portions.

26. A wireless terminal for communicating with a communication apparatus comprising:

an antenna for transmitting and receiving a signal to and from the communication apparatus; and

a transmit/receive portion coupled with said antenna, wherein said antenna is formed of chip components (chip antenna) and comprises;

(a) a core body formed in a cylinder shape;

(b) a conductor in a helical shape mounted on surface of said core body; and

(c) a terminal portion provided on said core body and connected with an end portion of said conductor, wherein

width, depth, and length of said core body are within ranges of 0.5-5 mm, 0.5-5 mm, and 4-40 mm, respectively, intrinsic volume resistance of said core body is 10¹³ Ω

·

m or above, and relative dielectric constant of the same is 40 or below.

27. A wireless communication system comprising:

a wireless terminal including an antenna;

a mobile terminal for transmitting and receiving data to and from said wireless terminal;

a base station for transmitting and receiving data or voice signal to and from said wireless terminal; and

a server connected with said base station by a communication line, wherein

said antenna is formed of chip components (chip antenna) and comprises;

(a) a core body formed in a cylinder shape;

(b) a conductor in a helical shape mounted on surface of said core body; and

(c) a terminal portion formed on said core body and connected with an end portion of said conductor, wherein

width, depth, and length of said core body are within ranges of 0.5-5 mm, 0.5-5 mm, and 4-40 mm, respectively, intrinsic volume resistance of said core body is 10¹³ Ω

·

m or above, and relative dielectric constant of the same is 40 or below.

28. A method for manufacturing a chip antenna which comprises:

a core body in a cylinder shape;

a conductive film formed on surface of said core body;

a groove cut in peripheral surface of said core body in a helical shape to form said conductive film into a helical shape; and

a protection member for protecting said conductive film, said method for manufacturing a chip antenna comprising steps of;

(a) producing said core body from a plate-shaped insulating material by pressing or extrusion processing;

(b) following step (a), cutting said core body such that cross-section in longitudinal direction of center portion of said core body is made smaller than that of both end portions in a stepped manner;

(c) following step (b), producing said conductive film;

(d) following step (c), cutting a groove in a helical shape in surface of the center portion; and

(e) following step (d), producing said protection member on surface of said core body.