JP2002198719A - Small antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small antenna that can be manufactured at a low cost without the possibility of exfoliation caused between a dielectric chip and an antenna element. SOLUTION: The small antenna formed by imbedding a flat antenna element 12 into the dielectric chip, is characterized in that at least both side edges the circumferential edges of the antenna element 12 has a projection 12a whose outer end reaches a circumferential face of the dielectric chip 10 and dielectric layers 10a, 10b of the dielectric chip 10 covering both sides of the flat plate antenna element 12 is formed as an integrated member that are continuous at parts with no projection 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small antenna used for a small communication device such as a mobile phone.

[0002]

2. Description of the Related Art As one of such small antennas,
As shown in FIG. 4, a flat antenna element 12 is formed on the surface of a rectangular parallelepiped dielectric chip 10, and a feed terminal 14 is formed so as to go around the end face of the dielectric chip 10 from the edge of the antenna element 12. The one in which the ground terminal portion 16 is formed is known. In the case of this antenna, the antenna element 12, the feed terminal 14, and the ground terminal 16 are formed by plating or the like.

[0003]

However, the small antenna having the above-described structure has a problem in terms of long-term reliability because the antenna element may be separated from the dielectric chip when subjected to a heat cycle.

In order to solve this problem, as shown in FIG. 5, a protective coating layer 18 is formed on the surface of the dielectric chip 10 on which the antenna element 12 is formed by means such as molding or painting. It is possible to do. However, even if the protective coating layer 18 is provided, the protective coating layer 18 may peel off together with the antenna element 12, so that it is difficult to reliably prevent the antenna element and the dielectric chip from peeling off. Also, providing the protective coating layer 18
Since the number of molding steps or painting steps increases, the cost increases.

An object of the present invention is to provide a small antenna that can prevent the dielectric chip and the antenna element from being separated from each other and that can be manufactured at low cost in view of the above problems.

[0006]

Means for Solving the Problems In order to achieve this object, a small antenna of the present invention has a planar antenna element embedded in a dielectric chip, and the antenna element has at least one of its peripheral edges. On both side edges, at appropriate intervals, the outer end has a convex portion reaching the peripheral surface of the dielectric chip, and the dielectric chip has a dielectric layer covering both surfaces of the flat antenna element. It is characterized in that it is formed as a continuous integral body at a part without a part.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In this small antenna, a flat antenna element 12 formed of a thin metal plate or the like is embedded in a dielectric chip 10. The antenna element 12 is usually rectangular, and has a shape in which a plurality of convex portions 12a are formed on both side edges at appropriate intervals. A feed terminal 14 and a ground terminal 16 are formed continuously at one end of the antenna element 12, and a fixed terminal 20 is formed continuously at the other end. Note that the fixed terminal portion 20 is provided as needed, and may be omitted in some cases.

The dielectric chip 10 is made of a resin composition that can be molded, and a dielectric layer 10 a covering the upper surface of the antenna element 12 and a dielectric layer 10 b covering the lower surface of the antenna element 12 are formed by a protrusion 12 a
It is formed as a continuous integral part at a portion without (a hatched portion in FIG. 1A). The dielectric layers 10a and 10b covering the upper and lower surfaces of the antenna element 12 are, as shown in the figure, portions at both ends of the antenna element 12 without the feed terminal portion 14 and the ground terminal portion 16 and portions without the fixed terminal portion 20. However, these portions are preferably continuous, but these portions may be discontinuous. The outer end of each protrusion 12a is a dielectric chip 10
Has reached the circumference. When the width of the antenna element 12 is wide, a similar convex portion may be formed on the edge of the antenna element.

As described above, the small antenna according to this embodiment includes the dielectric layers 10 a and 10 a on both sides of the antenna element 12.
Since the dielectric chip 10 is formed as an integral body by continuously forming a portion b without the convex portion 12a, the dielectric chip 10 and the plate-shaped antenna element 12 do not have a possibility of being separated even if subjected to a heat cycle, and Reliability can be ensured. Also, this small antenna can be easily manufactured in a small number of steps as described below.

In order to manufacture a small antenna as shown in FIG. 1, first, an antenna pattern as shown in FIG. 2 is manufactured by punching or etching a thin metal plate. This pattern has an antenna element 12 and a frame part 22 surrounding the antenna element 12, and a space between the antenna element 12 and the frame part 22 is provided between the power supply terminal part 14, the ground terminal part 16, the fixed terminal part 20, and the bridge part 24. It is a form connected by. 26 is an opening formed by punching or the like, and 28 is a positioning hole.

Next, the antenna pattern is set on a mold 30 as shown in FIG. That is, the entire antenna element 12, a part on the inner end side of each of the terminal portions 14, 16, and 20, and a part on the inner end side of the bridge portion 24 are set so as to be located in the cavity of the mold 30. In this state, a resin is injected to form a dielectric chip. That is, the dielectric layer 10a,
Form 10b at a time. Thereafter, the molded product is taken out of the mold, the bridge portion 24 is cut along both side surfaces of the dielectric chip, and each of the terminal portions 14, 16, and 20 is cut off from the frame 22 and bent. Such a small antenna can be obtained.

As described above, in this small antenna, since the antenna element 12 can be embedded in the dielectric chip 10 simultaneously with the molding of the dielectric chip 10, the number of manufacturing steps can be reduced, and the production cost can be reduced. it can. In addition, the protrusion 12a in FIG.
It is the part that remains in 10. This projection 12a is a dielectric chip
The antenna element 12 accurately positions the antenna element 10 and functions to stabilize the antenna performance. The small antenna is mounted such that the lower surface (the right surface in FIG. 1B) is in contact with the circuit board. Also antenna element 12
The dielectric layer 10b covering the lower surface side of the
It is formed thicker than a.

[0013]

According to the present invention as described above,
Since the dielectric layer covering both sides of the flat antenna element is continuously formed as an integral dielectric chip at the portions of both sides of the antenna element that do not have protrusions, even if subjected to a heat cycle, the dielectric element and A small antenna with high long-term reliability can be obtained without the possibility of the dielectric chip peeling off. Also, at the same time as forming the dielectric chip,
Since the antenna element can be embedded in the dielectric chip, the number of manufacturing steps can be reduced, and a small antenna with low cost can be provided.

[Brief description of the drawings]

1A and 1B show an embodiment of a small antenna according to the present invention, wherein FIG. 1A is a front view, FIG. 1B is a side view, FIG. 1C is a plan view, and FIG.

FIG. 2 is a plan view showing a first step of a process of manufacturing the small antenna of FIG.

FIG. 3 is a sectional view showing a second stage in the same manner.

FIG. 4 is a perspective view showing a conventional small antenna.

FIG. 5 is a perspective view showing a state in which a protective coating layer is provided on the small antenna of FIG. 4;

[Explanation of symbols]

 10: Dielectric chip 12: Flat antenna element 12a: Convex part 14: Feeding terminal part 16: Ground terminal part 20: Fixed terminal part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayuki Isawa 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 5J046 AA10 AA19 AB13 PA07 QA02 5J047 AA19 AB13 FD01

Claims (1)

[Claims] 1. A small antenna in which a planar antenna element (12) is embedded in a dielectric chip (10), wherein said antenna element (12) has an appropriate distance between at least both side edges of its periphery. In the above, the outer end has a projection (12a) reaching the peripheral surface of the dielectric chip (10), and the dielectric chip (10) covers both surfaces of the flat antenna element (12). A small antenna characterized in that the dielectric layers (10a, 10b) are formed as a continuous integral body at a portion without the convex portion (12a).