JP2003309418A - Dipole antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact dipole antenna the total length of which can remarkably be reduced. <P>SOLUTION: Wide conductor parts 2B, 3B wider than parts closer to feeding points 12, 13 are provided respectively to ends of a pair of radiation conductors 2, 3 placed separately to both front and rear sides of a dielectric board 1. Since the capacitance of the radiation conductors 2, 3 is thereby increased, the length of the radiation conductors 2, 3 required for resonance to a desired frequency can be reduced. Further, since the wavelength reduction effect by the dielectric board 1 is added, the total length of the dipole antenna can remarkably be reduced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center-feed type dipole antenna, and more particularly to a dipole antenna in which a radiation conductor (radiation element) is formed on a plate surface of a dielectric substrate to reduce the size.

[0002]

2. Description of the Related Art A dipole antenna of a type in which a conductor extending in a straight line is separated at the center and fed from there,
Since it has a simple structure and does not require a grounding conductor, it is widely used in various fields as a highly practical antenna. However, this type of antenna has a total length of λ / 2 (where λ is the free space wavelength of the radio wave), so it is called a half-wave dipole, so the frequency of the radio wave used is quite high. Even if the wavelength is short, there is a problem that the total length of the antenna becomes considerably long.

Therefore, recently, in order to improve such a problem, a dipole antenna as shown in FIG. 3 has been proposed. The conventionally known dipole antenna shown in FIG. 1 includes a pair of radiation conductors 11 and 12 provided on the same surface of a dielectric substrate 10 such as ceramics, and both radiation conductors 11 and 12.
And a coaxial cable 13 connected to the radiating conductors 11 and 12 via which the high-frequency signal is fed. Both radiation conductors 11, 1
Reference numeral 2 denotes a conductor formed by a method such as printing or etching, the shape of which is substantially the same rectangle and extends linearly.
Then, the outer conductor 14 and the inner conductor 15 of the coaxial cable 13 are connected to the ends (the central portion of the whole) of the pair of radiating conductors 11 and 12 that are close to each other to supply electric power. Therefore, according to the dipole antenna thus configured, the total length can be shortened by about 20% by shortening the wavelength by the dielectric.

[0004]

As described above, the dipole antenna in which the pair of radiation conductors 11 and 12 are formed on the surface of the dielectric substrate 10 can shorten the total length to some extent. For example, a wireless LAN. (In-house information and communication network)
In order to realize a portable dipole antenna applicable to, for example, it is necessary to further shorten the overall length and promote compactness.

The present invention has been made in view of the circumstances of the prior art as described above, and an object thereof is to provide a dipole antenna capable of greatly shortening the total length.

[0006]

In order to achieve the above-mentioned object, in the dipole antenna of the present invention, a dielectric substrate and a pair of radiation conductors of substantially the same shape provided on the plate surface of the dielectric substrate. A pair of radiation conductors are connected to end portions on the side close to each other, and the end portions on the opposite side to the end portions of the pair of radiation conductors, respectively, than a portion closer to the feeding point. A wide conductor portion having a wide width is provided.

In such a structure, the end portions of both radiating conductors of the dipole antenna are capacitance regions in which the voltage changes greatly, so if the conductors are formed wide at these end portions, the capacitance becomes large. In a resonance circuit, the resonance frequency generally decreases as the capacitance increases, so that the length of the radiation conductor required to resonate at a desired frequency can be shortened. At that time, if a pair of radiation conductors are formed separately on one surface and the back surface of the dielectric substrate and the feed line is connected to one radiation conductor through a through hole provided in the dielectric substrate, ,
Since it is possible to prevent a short circuit without separating the feeding points of the radiation conductors in the length direction, it is possible to further reduce the total length, which is preferable.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a dipole antenna according to an embodiment of the present invention.

The dipole antenna shown in FIG. 1 includes a dielectric substrate 1 made of ceramic or the like, and a pair of radiation conductors 2 and 3 formed on one side and the back side of the dielectric substrate 1, respectively.
The radiating conductors 2 and 3 are provided with a coaxial cable 4 connected to both the radiating conductors 2 and 3, and a connector 5 is connected to a transmitting and receiving circuit (not shown) to connect the radiating conductors 2 and 3 via the coaxial cable 4 serving as a power supply line. A high frequency signal is supplied. The pair of radiating conductors 2 and 3 are conductors formed in the same shape by a method such as printing or etching, and the shape is such that the base end side (sides close to each other) is narrow and the end side is wide. That is, one radiating conductor 2 is composed of the base end side strip-shaped conductor portion 2A and the end side wide conductor portion 2B, and the other radiating conductor 3 having the same shape is the base end side strip-shaped conductor portion 3A.
A and a wide conductor portion 3B on the terminal side. A feeding point 7 connected to the outer conductor of the coaxial cable 4 is provided at the end of the radiation conductor 2 on the base end side, and a dielectric substrate is provided at the end of the radiation conductor 3 on the base end side. A feeding point 8 connected to the inner conductor of the coaxial cable 4 through the through hole 6 is provided.

Since the pair of radiation conductors 2 and 3 have the same shape, the shape of one radiation conductor 2 will be described in detail.
Now, assuming that the free space wavelength of the radio wave used by the dipole antenna according to the present embodiment is λ, the length dimension of the strip conductor portion 2A is a, and the length dimension of the wide conductor portion 2B is b, (λ / 16) ≦ a ≦ (λ / 8), (λ / 30) ≦ b ≦
It suffices if the conditional expression (λ / 8) is satisfied, and for example, the value of b is λ / 16
It is preferable to set it to a degree. In addition, the strip conductor 2A
Where c is the width dimension of the wide conductor portion 2B and d is the width dimension of the wide conductor portion 2B, it suffices to satisfy the conditional expression c <(λ / 10), 3c ≦ d ≦ (λ / 2). / 13
It is preferable to set it to a degree. As a specific example, 5.2
When transmitting and receiving GHz radio waves, the value of λ is about 58 mm, so b is about 4 mm, c is about 2 mm, and a is 4 to 7 mm.
It is sufficient to set d to 6 to 29 mm.

In the dipole antenna thus constructed, the wide conductor portions 2B and 3B are provided at the respective end portions of the radiation conductors 2 and 3.
Is provided, the capacitance is large. In a resonance circuit, the resonance frequency generally decreases as the capacitance increases, so that the length of the radiation conductors 2 and 3 required to resonate at a desired frequency can be shortened. In addition, in the present embodiment, since the pair of radiation conductors 2 and 3 are formed separately on one side and the back side of the dielectric substrate 1, the feeding points 7 and 8 of each radiation conductor 2 and 3 are long. There is no fear of short circuit even if they are not displaced in the vertical direction, and therefore the length dimension from the end of the radiation conductor 2 to the end of the radiation conductor 3 can be reduced without impairing reliability. Furthermore, since the wavelength shortening effect of the dielectric substrate 1 is also added, the total length of this dipole antenna can be considerably shortened after all. For example, when the frequency of the radio wave used is 5.2 GHz for wireless LAN, the total length can be shortened. It can be suppressed to about 2 cm, and a dipole antenna suitable as a portable antenna can be realized.

In the above embodiment, the radiation conductor 2,
The case where the wide conductor portions 2B and 3B of No. 3 are formed in a rectangular shape has been described, but as shown in FIGS. 2 (a) and 2 (b),
The wide conductor portions 2B and 3B may be formed in a circular shape or a diamond shape.
Moreover, as shown in FIG. 2C, each of the radiation conductors 2 and 3 may be formed in a triangular shape that gradually widens from the base end side toward the end side.

[0013]

The present invention is carried out in the form as described above, and has the following effects.

Since the pair of radiating conductors (radiating elements) arranged on the plate surface of the dielectric substrate is provided with a wide conductor portion having a width wider than that of the portion near the feeding point, it is a dipole antenna. The capacitance can be increased to reduce the length of the radiating conductor required to resonate at the desired frequency. In addition, since the wavelength shortening effect of the dielectric substrate is also added, a compact dipole antenna whose length can be significantly shortened can be obtained.

Further, if the pair of radiation conductors are formed separately on one surface and the back surface of the dielectric substrate, a short circuit can be prevented without separating the feeding points of the radiation conductors in the longitudinal direction. The total length of the dipole antenna can be further shortened.

[Brief description of drawings]

FIG. 1 is a plan view of a dipole antenna according to an exemplary embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a modified example of a radiation conductor.

FIG. 3 is a plan view of a conventionally proposed dipole antenna.

[Explanation of symbols]

1 Dielectric substrate A few radiation conductors 2A, 3A strip conductor 2B, 3b Wide conductor 4 coaxial cable (feed line) 6 through holes 7,8 feeding point

Claims (2)

[Claims] 1. A dielectric substrate, a pair of radiation conductors of substantially the same shape provided on the plate surface of the dielectric substrate, and a feeder line connected to the ends of the pair of radiation conductors on the side close to each other. And a wide conductor portion having a width wider than a portion near a feeding point is provided at each end portion of the pair of radiation conductors opposite to the end portions. 2. The method according to claim 1, wherein the pair of radiation conductors are separately formed on one surface and the back surface of the dielectric substrate, and the feed line is provided through a through hole provided in the dielectric substrate. A dipole antenna characterized by being connected to one radiation conductor.