JP4927921B2 - Antenna and array antenna - Google Patents

Description

  The present invention relates to an antenna and an array antenna, and more particularly to an antenna having a wide beam width.

As a horizontally polarized antenna used for a base station antenna for mobile communication, an antenna having a wide beam width (for example, an antenna having a beam width of about 90 °) is used. Conventionally, a dipole antenna described in Patent Document 1 below is known as such an antenna.
In the dipole antenna described in Patent Document 1, a pair of non-excited monopole antennas are arranged at both ends of the dipole antenna to widen the beam width.

JP 2004-147040 A

However, in the antenna described in Patent Document 1, it is necessary to fix the non-excited monopole antenna to the reflecting plate by soldering or the like. Therefore, the antenna described in Patent Document 1 has a problem that not only the assembly is complicated, but also the variation in characteristics increases.
The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide an antenna and an array antenna having a wide beam width over a wide band that is easier to assemble than in the past. is there.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
(1) and the reflector, and the dipole antenna element disposed on the reflective plate, the ends of the dipole antenna elements, at both ends at a predetermined distance of the dipole antenna elements, and the extension direction of the dipole antenna element An antenna having a pair of parasitic elements arranged in a crossing direction, and the pair of parasitic elements is not connected to any part of the antenna .
(2) (1) has a first dielectric substrate disposed on the reflective plate, and the dipole antenna element, the pair of parasitic element is formed on the first dielectric substrate Tei The
(3) a reflector, a dipole antenna element disposed on the reflective plate, the ends of the dipole antenna elements, at both ends at a predetermined distance of the dipole antenna elements, and the extension direction of the dipole antenna element A pair of first parasitic elements arranged in a crossing direction, and a second parasitic element arranged at a predetermined interval from the dipole antenna element on the opposite side of the reflector of the dipole antenna element. The pair of first parasitic elements is not connected to any part of the antenna.
(4) In (3), the first dielectric substrate disposed on the reflector is provided, and the dipole antenna element, the pair of first parasitic elements, and the second parasitic element are the first parasitic element. It is formed on a dielectric substrate.
(5) An array antenna comprising the antennas according to any one of (1) to (4) described above arranged in an array.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the antenna and array antenna which expanded the beam width which was easier to assemble than before.

It is a model perspective view which shows the antenna of Example 1 of this invention. It is a figure for demonstrating the dipole antenna element for horizontal polarization of Example 1 of this invention, a pair of 1st parasitic element, and a 2nd parasitic element. It is a graph which shows an example in the horizontal surface (XZ surface of FIG. 1) directivity of the radio wave of 1.7 GHz band of the antenna of Example 1 of this invention. 3 is a graph illustrating an example of directivity characteristics in the horizontal plane (XZ plane in FIG. 1) of radio waves in the 2.0 GHz band of the antenna of the first embodiment. It is a graph which shows an example of the VSWR characteristic of the antenna of Example 1 of this invention. It is a figure for demonstrating the specific structure of the dipole antenna for horizontal polarization shown in FIG. It is a figure for demonstrating the specific structure of the dipole antenna for horizontal polarization shown in FIG. It is a model perspective view which shows the antenna of Example 2 of this invention. It is a graph which shows an example of the directivity characteristic in the horizontal surface of the radio wave of 1.7 GHz band of a general dipole antenna. It is a graph which shows an example of the directivity characteristic in the horizontal surface of the radio wave of the 2.0 GHz band of a general dipole antenna.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof is omitted.
[Example 1]
FIG. 1 is a schematic perspective view showing an antenna according to Embodiment 1 of the present invention. In the figure, reference numeral 1 denotes a reflection plate, and 2 denotes a dielectric substrate. The dielectric substrate 2 is disposed on the reflection surface of the reflection plate 1.
On the dielectric substrate 2, a horizontally polarized dipole antenna element 3, a pair of first parasitic elements (4 ₁ , 4 ₂ ), and a second parasitic element 5 are formed.
A horizontally polarized dipole antenna element 3 shown in FIG. 1 is a dual-frequency antenna that radiates a 1.7 GHz band radio wave and a 2.0 GHz band radio wave.
First, the configuration of the 1.7 GHz band will be described. The first parasitic elements (4 ₁ , 4 ₂ ) are arranged to widen the beam width of the horizontally polarized radio wave in the 1.7 GHz band. The first parasitic elements (4 ₁ , 4 ₂ ) are spaced apart from both ends of the dipole antenna element 3 in a direction intersecting the extension direction of the dipole antenna element 3 (here, a direction orthogonal thereto) (Th in FIG. 2). ) Is placed. As can be seen from FIG. 1, in the present embodiment, the first parasitic elements (4 ₁ , 4 ₂ ) are arranged without being short-circuited to the reflector 1.

In the present embodiment, the radio wave is generated based on the current flowing through the first parasitic element (4 ₁ , 4 ₂ ) due to the coupling between the dipole antenna element 3 and the first parasitic element (4 ₁ , 4 ₂ ). Since it is radiated to the side, the beam width can be expanded.
That is, the length Lh of the first parasitic element ₍₄ 1, _{4 2),} and both ends of the dipole antenna element 3, the distance between the first parasitic element ₍₄ 1, _{4 2)} (Th) appropriate By adjusting, the beam of horizontally polarized radio waves can be expanded.
FIG. 3 is a graph showing an example of the directivity characteristics in the horizontal plane (XZ plane in FIG. 1) of the 1.7 GHz band radio wave of the antenna of the present embodiment. In FIG. 3, it can be seen that the beam width of the radio wave in the 1.7 GHz band is 86.3 °.
For comparison, FIG. 8 shows an example of a directivity characteristic in the horizontal plane of a 1.7 GHz band radio wave in a general dipole antenna. In FIG. 8, the beam width of the 1.7 GHz radio wave is 65.3 °. Thus, in the present embodiment, it can be seen that the beam width is increased by about 21 ° by providing the first parasitic elements (4 ₁ , 4 ₂ ). The beam width is an angle in a range where the relative gain is −3 dB or less.

Next, the configuration of the 2.0 GHz band will be described. The second parasitic element 5 is arranged to limit the beam width of the horizontally polarized radio wave in the 2.0 GHz band.
In the present embodiment, by providing the first parasitic element (4 ₁ , 4 ₂ ), the directivity in the horizontal plane has frequency characteristics, and the beam width in the high frequency band becomes wider than the desired beam width. Therefore, the second parasitic element 5 is disposed.
The second parasitic element 5 is disposed on the side opposite to the reflector of the dipole antenna element 3 with a predetermined distance (Tn) from the dipole antenna element 3. By appropriately adjusting the length Ln of the second parasitic element 5, the distance between the dipole antenna element 3 and the second parasitic element 5 (Tn in FIG. 2), the beam width of the horizontally polarized radio wave Can be limited.
FIG. 4 is a graph showing an example of the directivity characteristics within the horizontal plane (XZ plane in FIG. 1) of the 2.0 GHz band radio wave of the antenna of the present embodiment. In FIG. 4, it can be seen that the beam width of the radio wave in the 2.0 GHz band is 85.3 °.
For comparison, FIG. 9 shows an example of a directivity characteristic in a horizontal plane of a 2.0 GHz radio wave in a general dipole antenna. In FIG. 9, the beam width of the radio wave in the 2.0 GHz band is 72.2 °. Thus, in this embodiment, it can be seen that the beam width is increased by about 13 ° by providing the first parasitic element (4 ₁ , 4 ₂ ) and the second parasitic element 5.
FIG. 5 is a graph showing an example of the VSWR characteristics of the antenna of this embodiment. In the figure, the horizontal axis is frequency, the center frequency is 1.955 GHz, and the scale interval is 0.047 GHz. As can be seen from FIG. 5, in the antenna of this example, the VSWR is 1.5 or less over the range of 1.72 GHz to 2.19 GHz.

FIG. 2 is a diagram for explaining the horizontally polarized dipole antenna element 3, the pair of first parasitic elements (4 ₁ , 4 ₂ ), and the second parasitic element 5 according to the present embodiment.
Now, the free space wavelength of the design center frequency of the 1.7 GHz band of the dipole antenna element 3 of the present embodiment is λh, and the free space wavelength of the design center frequency of the dipole antenna element 3 of the present embodiment is λn. In this case, Lh and Ln are values satisfying the following expression (1).
0.8 × (λh / 4) ≦ Lh ≦ 1.2 × (λh / 4)
0.8 × (λn / 4) ≦ Ln ≦ 1.2 × (λn / 4)
・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (1)
Further, when the width of the pair of first parasitic elements (4 ₁ , 4 ₂ ) of the present embodiment is Wh and the width of the second parasitic element 5 is Wn, Wh, Wn satisfies the following expression (2). Value.
0.5 × (λh / 12) ≦ Wh ≦ 1.5 × (λh / 12)
0.5 × (λn / 50) ≦ Wn ≦ 1.5 × (λn / 50)
(2)

6A and 6B are diagrams for explaining a specific configuration of the dipole antenna element 3 shown in FIG. 1, and FIG. 6A is a first diagram of the dielectric substrate 2 shown in FIG. FIG. 6B is a diagram illustrating a configuration of the second surface (back surface or front surface) of the dielectric substrate 2 illustrated in FIG. 1.
As shown in FIG. 6A, a conductive film 7 is formed on the first surface of the dielectric substrate 2, and a slit 6 extending from both ends to a part of the connecting portion is formed in the conductive film 7. . The first surface of the dielectric substrate 2, radiating element composed of a conductive film divided portions in the slit 6 (3 _{1, 3 2)} is formed by the radiating element (3 _{1, 3 2)} The dipole antenna element 3 is configured.
On the other hand, a feed line 8 for horizontal polarization is formed on the second surface of the dielectric substrate 2. The feed line 8 and the conductive film 7 in which the slit 6 is formed constitute a balanced / unbalanced conversion circuit.
As described above, in the antenna of the present embodiment, the pair of first parasitic elements (4 ₁ , 4 ₂ ) disposed at both ends of the dipole antenna element 3 and the first pole disposed at the front of the dipole antenna element 3. 2 The parasitic element 5 can realize a desired beam width in the entire band.
In the above description, the horizontally polarized dipole antenna element 3, the pair of first parasitic elements (4 ₁ , 4 ₂ ), and the second parasitic element 5 are formed on the dielectric substrate 2. However, the horizontally polarized dipole antenna element 3, the pair of first parasitic elements (4 ₁ , 4 ₂ ), and the second parasitic element 5 are made of a conductor such as a metal plate or a metal rod. The conductor may be arranged on the reflector 1 via a spacer made of an appropriate material.

[Example 2]
FIG. 7 is a schematic perspective view showing an antenna of Example 2 of the present invention. The antenna according to the embodiment of the present invention is obtained by arranging the antennas according to the first embodiment in an array.
In general, a base station antenna for mobile communication is configured by arranging vertically polarized antennas and horizontally polarized antennas in multiple stages. The antenna of this embodiment is replaced with a base station antenna for mobile communications. By using the antenna for horizontal polarization, it is possible to optimize horizontal directivity characteristics in the horizontal plane of horizontal polarization.
As described above, according to the present embodiment, since it is not necessary to solder the non-excited monopole antenna to the reflecting plate, it is easier to assemble the antenna than in the past, and the antenna and the array that can widen the beam width over a wide band An antenna can be provided.
As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

DESCRIPTION OF SYMBOLS 1 Reflector 2 Dielectric substrate 3 Horizontally polarized dipole antenna element 3 ₁ , 3 ₂ Radiating element 4 ₁ , 4 ₂ First parasitic element 5 Second parasitic element 6 Slit 7 Conductive film 8 Feed line

Claims (5)

A reflector,
A dipole antenna element disposed on the reflector;
An antenna having a pair of parasitic elements disposed at both ends of the dipole antenna element at a predetermined interval from both ends of the dipole antenna element and arranged in a direction intersecting with the extending direction of the dipole antenna element ,
The pair of parasitic elements is not connected to any part of the antenna. A first dielectric substrate disposed on the reflector;
The antenna according to claim 1, wherein the dipole antenna element and the pair of parasitic elements are formed on the first dielectric substrate. A reflector,
A dipole antenna element disposed on the reflector;
A pair of first parasitic elements disposed at both ends of the dipole antenna element at a predetermined distance from both ends of the dipole antenna element and in a direction intersecting with the extending direction of the dipole antenna element;
An antenna having a second parasitic element disposed on the side opposite to the reflector of the dipole antenna element and spaced apart from the dipole antenna element ,
The pair of first parasitic elements is not connected to any part of the antenna. A first dielectric substrate disposed on the reflector;
The antenna according to claim 3, wherein the dipole antenna element, the pair of first parasitic elements, and the second parasitic element are formed on the first dielectric substrate.   An array antenna comprising the antennas according to any one of claims 1 to 4 arranged in an array.

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