ANTENNA DEVICE

Abstract

A flexible printed board has a principal plane. A sleeve antenna pattern is formed on the principal plane of the flexible printed board.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view showing a structure of a sleeve antenna;

FIG. 2 is a plan view showing an antenna device according to an embodiment of the present invention; and

FIG. 3 is a front view showing a coaxial cable used as a feeder line of the antenna device shown in FIG. 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the invention will be described in detail with reference to the drawings.

Referring to FIG. 2, an antenna device 10 of an embodiment of the present invention will be explained. FIG. 2 is a plan view of the antenna device 10. The antenna device 10 shown in FIG. 2 can be obtained when the sleeve antenna 1 shown in FIG. 1 is deformed as described later.

In the antenna device 10, a coaxial cable 20 shown in FIG. 3 is used as a feeder line 12. As shown in FIG. 3, the coaxial cable 20 is a coaxial electric signal transmitting medium including a cylindrical external conductor 21 and a central conductor 22 arranged at the center of the external conductor 21. The external conductor 21 and the central conductor 22 are insulated from each other by a cylindrical insulator 23. The external conductor 21 is covered with a sheath 24.

As shown in FIG. 2, the antenna device 10 includes a flexible printed board 30 having a principal plane 30a. On the principal plane 30a of this flexible printed board 30, a sleeve antenna pattern described later is formed.

The sleeve antenna pattern includes: a first wiring pattern 31 extending in a predetermined direction on the principal plane 30a of the flexible printed board 30; a pair of second wiring patterns 32; a signal pattern 36; and a pair of ground patterns 37. The first wiring pattern 31 has one end portion 31a and extends from the one end portion 31a in a predetermined direction. The pair of second wiring patterns 32 have one end portion 32a in the vicinity of the one end portion 31a of the first wiring pattern 31, extend from the one end portions 32a in a direction opposite to the predetermined direction (extending direction of the first wiring pattern 31) and are arranged in parallel with each other being separate from each other. The signal pattern 36 has one end portion 36a electrically connected to the one end portion 31a of the first wiring pattern 31. The signal pattern 36 extends from the one end portion 36a in the direction opposite to the predetermined direction (extending direction of the first wiring pattern 31). A pair of ground patterns 37 have one end portion 37a electrically connected to one end portions 32a of the pair of second wiring patterns 32 through a pair of connecting patterns 38. The pair of ground patterns 37 extend from the one end portions 37a in the direction opposite to the predetermined direction (extending direction of the first wiring pattern 31) and are arranged being separate from the signal pattern 36 and the pair of second wiring patterns 32 between the pair of second wiring patterns 32.

In this case, a combination of the signal pattern 36, the pair of ground patterns 37 and the pair of connecting patterns 38 acts as a coaxial pattern extending in the direction opposite to the predetermined direction and arranged between the pair of second wiring patterns 32.

Next, explanations will be made into a correspondence relationship between the antenna device 10 shown in FIG. 2 and the sleeve antenna 1 shown in FIG. 1. The first wiring pattern 31 acts as a radiating section 3. The second wiring pattern 32 fulfills a function of the metallic sleeve 2. The signal pattern 36 corresponds to a central conductor of the feeder line (coaxial cable) 4 inserted into the metallic sleeve 2. The pair of ground patterns 37 correspond to an external conductor of the feeder line (coaxial cable) 4 inserted into the metallic sleeve 2.

Accordingly, it can be understood that the antenna device shown in FIG. 2 acts as a sleeve antenna.

In this connection, concerning the feeder line (coaxial cable) 12, at the tip end portion, the central conductor 22 is electrically connected to the other end portion 36b of the signal pattern 36 by a solder 41. The external conductor 21 is electrically connected to the other end portions 37b of the pair of ground patterns 37 by a solder 42.

As described above, the antenna device 10 of the embodiment of the present invention includes: a flexible printed board 30 having a principal plane 30a; and a sleeve antenna pattern 31, 32, 36, 37, 38 formed on the principal plane 30a of the flexible printed board 30. Therefore, the antenna device 10 of the embodiment of the present invention is very flexible. Since only the sleeve antenna pattern is formed on the principal plane 30a of the flexible printed board 30, it is possible to provide the antenna device 10 of a simple structure.

The present invention has been explained above referring the preferable embodiment. However, it should be noted that the present invention is not limited to the above specific embodiment.

Claims

1. An antenna device comprising: a flexible printed board, having a principal plane; anda sleeve antenna pattern, formed on the principal plane of the flexible printed board.

2. The antenna device as set forth in claim 1, wherein the sleeve antenna pattern includes: a first wiring pattern, having a first end portion and extending from the first end portion in a first direction on the principal plane;a pair of second wiring patterns, having second end portions positioned in the vicinity of the first end portion, extending from the second end portions in a second direction opposite to the first direction on the principal plane, arranged in parallel with each other and separated from each other; anda coaxial pattern, arranged between the second wiring patterns and extending in the second direction on the principal plane.

3. The antenna device as set forth in claim 2, wherein the coaxial pattern includes: a signal pattern, having a third end portion electrically connected to the first end portion and extending from the third end portion in the second direction on the principal plane; anda pair of ground patterns, having fourth end portions electrically connected to the second end portions, extending from the fourth end portions in the second direction on the principal plane, and arranged between the second wiring patterns while being separated from the first wiring pattern and the second wiring patterns.

4. The antenna device as set forth in claim 3, further comprising a coaxial cable, having a central conductor and an external conductor, wherein: the signal pattern has a fifth end portion opposite to the third end portion;the ground patterns have sixth end portions opposite to the fourth end portions;the central conductor is electrically connected to the fifth end portion of the signal pattern at a tip end of the coaxial cable; andthe external conductor is electrically connected to the sixth end portions of the ground patterns at the tip end of the coaxial cable.