JP3793110B2 - Monopole antenna with conductor reflector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a monopole antenna with a conductor reflector, and in particular, a monopole antenna with a conductor reflector in which a monopole antenna element is installed on a ground plane and a reflector is installed in parallel with the monopole antenna element at the end of the ground plane. About.
[0002]
[Prior art]
A conventional example will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes a ground plane having a depth a ₁ and a width b. A monopole antenna element 2 having a height h ₁ from the surface of the ground plane 1 is electrically and mechanically fixedly connected to the ground plane 1. The monopole antenna element 2 is fed at a feeding point 3 on the back side of the ground plane 1. 4 is a parasitic element for impedance matching whose height from the surface of the ground plane 1 is h ₂ , and is mechanically fixed at a position away from the monopole antenna element 2 by L ₁ . Reference numeral 5 denotes a conductor reflector having a height h ₃ from the surface of the ground plane 1, which is separated from the monopole antenna element 2 by L ₂ and is connected to the monopole antenna element 2 at one end in the depth direction of the ground plane 1. It is bent in parallel.
[0003]
In this monopole antenna element 2 with the conductor reflector 5, the conductor reflector 5 acts to suppress the radiation of the monopole antenna element 2 in the back direction, and the ratio of the gain in the back direction to the gain in the front direction: FB Ratio improvement. The monopole antenna with a conductor reflector is assumed to be mounted near the window near the ceiling, and the service can be provided with better quality by radiating radio waves obliquely downward. However, since this antenna is installed upside down, that is, with the ground plane facing upward, it may radiate obliquely upward.
In the conventional example of a monopole antenna with a conductor reflector, a ₁ = b = 0.53λ, h ₁ = 0.2λ, h ₂ = 0.17λ, h ₃ = 0.27λ, L ₁ = 0.03λ, L The directivity in the horizontal plane when ₂ = 0.27λ is as shown in FIG. 2, and the directivity in the vertical plane is as shown in FIG. In the horizontal directionality of FIG. 2, 90 ° indicates the front direction and 270 ° indicates the back direction. In the vertical in-plane directivity of FIG. 3, 0 ° indicates the upward direction and 180 ° indicates the downward direction. The FB ratio is about 5 dB.
[0004]
[Problems to be solved by the invention]
It is necessary to increase the FB ratio to prevent the interference wave from the outside in the antenna for the dead zone countermeasure. From this point of view, it is difficult to say that the conventional example of the monopole antenna with a conductor reflector in FIG. 1 has a sufficient FB ratio as observed from the directivities in FIGS.
According to the present invention, by increasing the FB ratio, it is possible to reduce the influence of the interference wave from the outdoors on the service of an automobile phone, mobile phone or other mobile phone in the room, and to provide a good quality service. The present invention provides a monopole antenna with a conductor reflector that solves the problem.
[0005]
[Means for Solving the Problems]
According to the present invention, in a monopole antenna with a conductor reflector, a depth conductor plate is bent and formed at the upper end of the conductor reflector perpendicularly to the reflector and parallel to the ground plane. Furthermore, a vertical conductor plate is bent and formed perpendicular to the ground plate at the other end facing the one end in the depth direction where the conductor reflector of the ground plate is formed. As a result, the FB ratio of the monopole antenna with a conductor reflector was increased.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is an antenna used as an antenna for a mobile station that suppresses unnecessary radio waves in the rear direction, which is attached above a room such as a ceiling, as a countermeasure for dead zones of automobile phones, mobile phones and other mobile phones in the room. It is.
[0007]
【Example】
An embodiment of the present invention will be described with reference to Example 1 in FIG. In the first embodiment, the same reference numerals are given to the members common to the conventional example.
In FIG. 4, the monopole antenna element 2 having a height h ₁ from the surface of the ground plane 1 having the depth a ₁ and the width b is fixedly connected to the ground plane 1 electrically and mechanically. The monopole antenna element 2 is fed at a feeding point 3 on the back side of the ground plane 1. A parasitic element 4 for impedance matching whose height from the surface is h ₂ is mechanically fixed to the ground plane 1 at a distance of L ₁ from the monopole antenna element 2. The conductor reflector 5 having a height h ₃ from the surface of the ground plane 1 is parallel to the monopole antenna element 2 at one end in the depth direction of the ground plane 1 at a distance of L ₂ from the monopole antenna element 2. It is bent.
[0008]
In the above monopole antenna with a conductor reflector, a depth conductor plate 6 having a depth direction dimension a ₂ is bent at the upper end of the conductor reflector 5 so as to be orthogonal to the reflector and parallel to the ground plane 1. In this monopole antenna, the depth-direction conductor plate 6 bent at the upper end of the conductor reflector 5 acts to suppress the emission of radio waves to the back surface, which leads to an improvement in the FB ratio.
As a specific example of FIG. 4, a ₁ = b = 0.53λ, h ₁ = 0.2λ, h ₂ = 0.17λ, h ₃ = 0.27λ, L ₁ = 0.03λ, L ₂ = 0.27λ , A ₂ = 0.17λ monopole antenna with a conductor reflector. The directivity in the horizontal plane of this monopole antenna is as shown in FIG. 5, and the directivity in the vertical plane is as shown in FIG. In the horizontal directivity of FIG. 5, 90 ° indicates the front direction and 270 ° indicates the back direction. In the directivity in the vertical plane of FIG. 6, 0 ° indicates the upward direction and 180 ° indicates the downward direction. The FB ratio is about 15 dB, which is an improvement over the conventional example of about 5 dB. FIG. 7 is a diagram showing the relationship between the depth direction dimension a ₂ and the FB ratio. The application range of the conductor plate 6 in the depth direction is a ₂ ≦ L ₂ , but shows the best characteristics when a ₂ : 0.17λ.
[0009]
A second embodiment will be described with reference to FIG. Example 2 of FIG. 8 is orthogonal to the base plate 1 at the other end of the base plate 1 opposite to one end in the depth direction in which the conductor reflector 5 of the base plate 1 is formed in the example 1 of FIG. The vertical conductor plate 7 having a height h ₄ is bent.
As a specific example of the monopole antenna with a conductor reflector in FIG. 8, a ₁ = b = 0.53λ, h ₁ = 0.2λ, h ₂ = 0.17λ, h ₃ = 0.27λ, L ₁ = 0. A monopole antenna with a conductor reflector of 03λ, L ₂ = 0.27λ, a ₂ = 0.17λ, h ₄ = 0.07λ is formed.
[0010]
The horizontal in-plane directivity of the specific example of Example 2 is as shown in FIG. 9, and the vertical in-plane directivity is as shown in FIG. In the monopole antenna of Example 1, the point where the level drop in the back direction in the vertical in-plane directivity was the lowest was slightly above the direction directly behind. On the other hand, the monopole antenna of Example 2 has a height h ₄ perpendicular to the ground plane 1 at the other end facing the one end in the depth direction where the conductor reflector 5 of the ground plane 1 is formed. The FB ratio in the horizontal plane is further improved as compared with the first embodiment because the point with the lowest level has approached the back direction due to the influence of the vertical conductor plate 7.
[0011]
Compared with Example 1 above, the range of the height h ₄ of the vertical conductor plate 7 of Example 2 in which the FB ratio is further improved is h ₄ ≦ h ₁ . Here, FIG. 11 is a diagram showing the relationship between h ₄ and the FB ratio. Referring to this, the FB ratio shows about 25 dB at a value in the vicinity of h ₄ = 0.1λ, which is about 15 dB of the first embodiment. Compared with, it is greatly improved.
2, 3, 5, 6, 9, and 10, and the data in FIGS. 7 and 11 are the types of antennas using software that numerically calculates the electromagnetic field distribution. Enter the length of the antenna, the excitation frequency of the excitation source, the shape of the reflector, the size of the reflector, the feed point, the positional relationship between the antenna and the reflector, and other conditions, and calculate them using an electronic computer. be able to.
[0012]
【The invention's effect】
As described above, according to the present invention, the FB ratio can be improved as compared with the prior art by installing the conductor plate in the upper part of the reflector plate and in front of the ground plate of the monopole antenna with the conductor reflector plate.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a conventional example.
FIG. 2 is a diagram illustrating a directivity in a horizontal plane according to a conventional example.
FIG. 3 is a diagram showing a vertical in-plane directivity of a conventional example.
4 is a perspective view illustrating Example 1. FIG.
FIG. 5 is a diagram illustrating the directivity in the horizontal plane according to the first embodiment.
FIG. 6 is a diagram showing directivity in a vertical plane according to the first embodiment.
7 is a graph showing the relationship between a ₂ and the FB ratio in Example 1. FIG.
8 is a perspective view illustrating Embodiment 2. FIG.
FIG. 9 is a diagram illustrating the directivity in the horizontal plane according to the second embodiment.
FIG. 10 is a diagram illustrating the directivity in the vertical plane according to the second embodiment.
11 is a graph showing the relationship between h ₄ and the FB ratio in Example 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ground plane 2 Monopole antenna element 3 Feeding point 4 Parasitic element 5 Conductor reflecting plate 6 Depth direction conductor plate 7 Vertical direction conductor plate

Claims (2)

A monopole antenna element having a height of 0.2λ is fixedly connected to a square ground plate having a depth of 0.53λ (λ is a reciprocal of the used frequency) and a width of 0.53λ, and is 0.27λ away from the monopole antenna element. monopole along which the end portion in the depth direction of the main plate antenna element parallel to the height 0.27Ramuda, forming a conductive reflective plate width 0.53λ, 0 monopole antenna elements in the direction of the conductive reflector. In a monopole antenna with a conductor reflector in which a parasitic element having a height of 0.17λ and a distance of 03λ is formed in parallel with the monopole antenna element,
A depth direction conductor plate extending in the forward direction perpendicular to the reflector along the upper end of the conductor reflector is formed,
A monopole antenna with a conductor reflector, wherein the length of the conductor plate in the depth direction is set to be shorter than the distance between the conductor reflector and the monopole antenna element and longer than 0.08λ. In the monopole antenna with a conductor reflector according to claim 1,
A vertical conductor plate having a height set to be 0.03λ or less at a height equal to or less than the height of the monopole antenna element at an end portion of the ground plate facing the end portion on which the conductor reflector is installed is perpendicular to the ground plate. A monopole antenna with a conductor reflector, characterized by being formed.

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