JPH09270629A - Small-sized antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the small sized antenna capable of miniaturization in which resonance is caused even when a size of a conductor layer is decreased independently of wavelength. SOLUTION: The antenna is provided with a dielectric flat plate 11 sufficiently thinner than a wavelength with respect to the operating signal frequency, two conductor layers 12A, 12B provided to both sides of the dielectric flat plate 11 and a short-circuit wire 15 connecting the two conductor layers 12A, 12B. At least the one two conductor layer 12A in the two conductor layers 12A, 12B is bent repetitively in the broadwise direction of the dielectric flat plate 11 to form recessed grooves 18 so that the total creeping length is 1/4 of the wavelength with respect to the operating signal frequency or over.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small flat plate antenna suitable for being built in and used in a portable wireless device or the like.

[0002]

2. Description of the Related Art A microstrip antenna 50 shown in FIG. 6 and an inverted F-type antenna 60 shown in FIG.
There is. Small antenna 5 shown in FIGS. 6 and 7
0 and 60 are dielectric flat plates 51 and 61, which are sufficiently thin compared to the wavelength of the signal frequency to be used, and dielectric flat plates 51 and
61, the conductor layers 52 and 62 provided on one surface, and the ground conductor layer 5 provided on the other surfaces of the dielectric flat plates 51 and 61.
It has 3, 63. Any of the small antennas 50, 6
Also for 0, the conductor layers 52 and 62 are resonated at a quarter wavelength for downsizing.

That is, the microstrip antenna 50
Then, the length of the conductor layer 52 in the resonance direction is a quarter wavelength, and in the inverted F-type antenna 60, the diagonal length of the conductor layer 62 or the sum of the lengths of the two sides extending to the diagonal is a quarter wavelength. ing.
Also, for the sake of miniaturization, the dielectric flat plates 51 and 61 between the conductor layers 52 and 62 and the ground conductor layers 53 and 63 are
The dielectric constant is larger than 1. Dielectric plate 51,
When the permittivity of 61 is ε, the wavelength of the signal frequency on the conductor layers 52 and 62 is shortened to 1 / √ε as compared with that in vacuum.

As a result, the lengths of the conductor layers 52 and 62 can be shortened at the same ratio. However, in order to satisfy the above conditions, the ground conductor layers 53 and 63 and the dielectric flat plates 51 and 61 need to have an area equal to or larger than that of the conductor layers 52 and 62. In FIG. 6, reference numeral 55 is a short-circuit line, 5
6A and 56B are power supply lines, 57 is a power supply, and 58 is a ground plate. Further, in FIG. 7, reference numeral 65 is a short-circuit line, 66
A and 66B are power supply lines, 67 is a power supply, and 68 is a ground plate.

[0005]

As described above,
In the conventional microstrip antenna and inverted F-type antenna, the size of the conductor layer is determined by the wavelength. That is, in the microstrip antenna, at least one side of the conductor layer has a length of ¼ wavelength, and in the inverted F-type antenna, the length is at least ¼ wavelength.
The sum of the side lengths needs to be ¼ wavelength or more. When the conductor layer is made shorter than the above, resonance does not occur on the conductor layer and the antenna does not function as an antenna. Further, in the antenna having the above-mentioned configuration, a cutout is provided in the conductor layer for downsizing,
It is possible to give a distance of more than a quarter wavelength by forming the conductor layer with a thin line, but this method causes the conductor layer surface area to be small due to manufacturing restrictions, and sufficient antenna gain may not be obtained. The characteristics are often unstable due to surface area variations. For the above reasons, there is a limit to miniaturization of the conductor layer, which naturally shows a limit to miniaturization of the small antenna itself.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a compact antenna which can be miniaturized so that resonance can occur even if the conductor layer is made small regardless of the wavelength. In order to achieve the above object, the present invention has the following means.

The small antenna according to claim 1 of the present invention comprises a dielectric flat plate which is sufficiently thin as compared with the wavelength of the signal frequency to be used,
Two conductor layers provided on both sides of the dielectric flat plate and a short-circuit line connecting the two conductor layers are provided, and the line length of at least one conductor layer of the two conductor layers is used. It is characterized in that a concave groove is formed by repeatedly bending in the thickness direction of the dielectric flat plate so that a quarter of the wavelength of the signal frequency becomes equal to or more.

According to a second aspect of the present invention, in the small antenna, the conductor layer, which is repeatedly bent in the thickness direction of the dielectric flat plate to form the concave groove, has the concave groove formed in the thickness direction of the dielectric flat plate. It is characterized in that it is provided integrally with the dielectric flat plate in accordance with the strip.

According to the small antenna of the first aspect of the present invention, one conductor layer of the conductor layers is repeatedly bent in the thickness direction of the dielectric flat plate, and the line length of the conductor layer substantially uses the signal frequency used. Since the wavelength is equal to or more than a quarter of the wavelength, the conductor layer can be resonated in a smaller dielectric plate area by repeatedly bending the conductor layer in the thickness direction of the dielectric plate, and the conductor layer can be made smaller. As a result, the size of the dielectric flat plate can be reduced, so that the small antenna itself can be downsized.

According to the second aspect of the small antenna of the present invention, the conductor layer provided integrally with the dielectric flat plate in accordance with the concave grooves formed in the thickness direction of the dielectric flat plate is, for example, electroless. Since it can be easily formed by plating or laminating and bonding metal foils, miniaturization of the antenna can be easily achieved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to embodiments. (Embodiment 1) FIG. 1 is a plan view, bottom view and sectional view showing an embodiment of a small antenna of the present invention. FIG.
1, the small antenna 10 is provided on the dielectric flat plate 11, one surface of the dielectric flat plate 11, the main conductor layer 12A provided on the upper surface in FIG. 1, and the other surface of the dielectric flat plate 11 on the lower surface in FIG. The ground conductor layer 12B is formed. A part of the main conductor layer 12A on the upper surface of the dielectric flat plate 11 is provided with a ground conductor layer 12B provided on the lower surface of the dielectric flat plate 11 by a feeder line 14 formed in a through hole 13A provided on the dielectric flat plate 11. Is short-circuited to the feeding end 12C which is formed so as to be separated by the distance.

The main conductor layer 1 on the upper surface of the dielectric flat plate 11
2A and the ground conductor layer 12B on the lower surface of the dielectric flat plate 11 are short-circuited by a short-circuit wire 15 formed in a through hole 13B provided in the dielectric flat plate 11. Dielectric plate 1
The main conductor layer 12A and the ground conductor layer 12B on the lower surface of 1 are connected to the power supply source 17 via feeder lines 16A and 16B, respectively. The dielectric flat plate 11 has a permittivity larger than 1 and a thickness sufficiently smaller than the wavelength of the signal frequency used, for example, 1/1 with respect to the wavelength λ of the signal frequency used.
It is about 00 to 1/10.

Most of the main conductor layer 12A on the right side of the upper surface of the dielectric flat plate 11 in FIG. 1C is repeatedly bent on the upper surface of the dielectric flat plate 11 in the thickness direction of the dielectric flat plate 11 to V.
A groove 18 is formed in a groove shape and is integrally provided on the upper surface of the dielectric flat plate 11. The main conductor layer 12A is repeatedly bent in a V-groove shape in the thickness direction of the dielectric flat plate 11,
It is a rectangle having an area substantially larger than the size of the dielectric flat plate 11.

For example, as shown in FIG. 2 (a), when the concave groove is repeatedly bent to form a V groove and the angle of the valley or peak is 90 °, a length of √2 is obtained. Further, as shown in FIG. 2B, when the concave groove is repeatedly bent in a rectangular shape, a double length can be obtained. Further, as shown in FIG. 2C, when the concave groove is repeatedly bent in a semi-circular shape, π
/ 2 times the length is obtained. Therefore, even if the size of the dielectric flat plate 11 is made smaller than a quarter of the wavelength of the signal frequency used by the main conductor layer 12A, the main conductor layer 12A substantially has the line length of the main conductor layer 12A. Can be greater than a quarter of the wavelength of the signal frequency used by.

In order to provide the main conductor layer 12A so as to be bent repeatedly in the thickness direction of the dielectric flat plate 11, for example, the surface of the dielectric flat plate 11 is mechanically processed to have unevenness, and the upper surface thereof is made conductive, for example. It can be easily formed by electroless plating of a conductive metal. The irregularities on the surface of the dielectric flat plate 11 may be formed electrochemically or may be formed by injection molding or the like. Further, a conductor foil is laminated and adhered to the grooves and protrusions of the dielectric flat plate 11 appropriately formed as described above, and the main conductor layer 12A is integrally provided so as to be repeatedly bent in the thickness direction of the dielectric flat plate 11. May be.

(Second Embodiment) FIG. 3 is a perspective view of a small antenna 20 showing another embodiment of the present invention. The feature of the small antenna 20 shown in FIG. 3 is that the dielectric flat plate 21 is a flat plate having no grooves or ridges.
That is, only 2A is repeatedly bent in the thickness direction of the dielectric flat plate 21 to form the wavy groove 28. In FIG. 3, reference numeral 22B is a ground conductor layer, 24 is a power supply line, and 25
Is a short-circuit line.

(Embodiment 3) FIG. 4 is a perspective view of a small antenna 30 showing another embodiment of the present invention.
The feature of the small antenna 30 shown in FIG.
Not only that, the ground conductor layer 32B is repeatedly bent in the thickness direction of the dielectric flat plate 31 to form the rectangular recessed groove 38 and is integrated with the dielectric flat plate 31. In FIG. 4, reference numeral 32B is a ground conductor layer, 34 is a feeder line, and 35 is a short-circuit line.

When the small antenna 30 is mounted on a printed board 39 by soldering as shown in FIG. 5, the soldering portion 40 of the groove 38 formed in the ground conductor layer 32B is used.
Since the fillet 41 is formed on the surface, the reliability of soldering is improved. With an antenna having a smooth soldering surface, it was difficult to confirm whether or not good soldering was performed, but according to the present embodiment, since the appearance of the fillet can be confirmed, not only the strength is increased but also the Reliability is increased in that destructive inspection is possible.

[0019]

As described above, according to the small antenna of the first aspect of the present invention, one conductor layer of the conductor layers is repeatedly bent in the thickness direction of the dielectric flat plate so that the conductor layer is substantially formed. Since the line length exceeds 1/4 of the wavelength of the signal frequency used, resonating in a smaller dielectric plate area by repeatedly bending the conductor layer in the thickness direction of the dielectric plate. And the conductor layer can be made smaller. As a result, the size of the dielectric flat plate can be reduced, so that the small antenna itself can be downsized.

According to the small antenna of the second aspect of the present invention, the conductor layer integrally provided with the dielectric flat plate in accordance with the concave groove convex line formed in the thickness direction of the dielectric flat plate is, for example, electroless. Since it can be easily formed by plating or laminating and bonding metal foils, miniaturization of the antenna can be easily achieved.

[Brief description of drawings]

FIG. 1 shows an embodiment of a small antenna of the present invention, (a) is a plan view, (b) is a bottom view, and (c) is a cross-sectional view.

2 (a), (b) and (c) are explanatory views showing the shape of a concave groove that is repeatedly bent in the conductor layer of the small antenna of the present invention.

FIG. 3 is a perspective view showing another embodiment of the small antenna of the present invention.

FIG. 4 is a perspective view showing another embodiment of the small antenna of the present invention.

5 is an explanatory diagram showing a main part of soldering mounting of the small antenna of FIG. 4. FIG.

FIG. 6 is a perspective view showing an example of a conventional microstrip antenna.

FIG. 7 is a perspective view showing an example of a conventional inverted F-type antenna.

[Explanation of symbols]

 10 Small Antenna 11 Dielectric Plate 12A Main Conductor Layer 12B Ground Conductor Layer 14 Feed Line 15 Short Circuit Line 18 Recessed Groove

Claims (2)

[Claims] 1. A dielectric flat plate that is sufficiently thinner than the wavelength of a signal frequency to be used, two conductor layers provided on both sides of the dielectric flat plate, and a short-circuit wire connecting the two conductor layers. At least one conductor layer of the two conductor layers is repeatedly bent in the thickness direction of the dielectric flat plate so as to have a line length of ¼ or more of a wavelength of a signal frequency to be used, and is concave. A small antenna characterized by having a groove formed therein. 2. The conductor layer, which is repeatedly bent in the thickness direction of the dielectric flat plate to form a concave groove, is integrally formed with the dielectric flat plate in accordance with the concave groove ridge formed in the thickness direction of the dielectric flat plate. The small antenna according to claim 1, wherein the small antenna is provided.