JPS6138261Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of the fan-shaped beam antenna according to Japanese Patent Application No. 78900/1983.

The fan-shaped beam antenna according to the prior application includes a compound curved reflector 1 having the configuration shown in FIGS. 1 and 2. In other words, the reflector 1 has two original axisymmetric rotating parabolic reflectors 2 shown by dashed lines in FIG. 2 that are parallel to the optical axis Two partial parabolic reflectors 4, each having the same shape, are obtained at both ends by dividing the mirror into three parts by the two planes (the two-dot chain lines 3 and 3' in the figure indicate the dividing lines).
4' is the focal point F of the axisymmetric rotating paraboloid reflector 2.
are respectively shifted toward the specular side by the angle α shown in the following formula with the center at The gain is higher than that of the antenna consisting of the original axially symmetric rotating paraboloid reflector 2.
Directional power half-width of the same type of antenna, 6 dB lower In addition, the deflected partial parabolic reflector 4,
The space between the edges of the divided portion 4' is closed by a parabolic cylindrical reflecting mirror 5 made of a curved flat plate.

The compound curved reflector 1 having such a configuration,
The operation in the horizontal plane of the fan beam antenna consisting of the primary horn 6 located at the focal point F in the manner shown in FIG. 5 is as follows. That is, when the reflecting mirror 1 is excited by the primary horn 6, the main beam of one of the partially parabolic reflecting mirrors 4 is rotated clockwise by the angle α with respect to the optical axis X, as shown by the broken line in FIG. The main beam of the parabolic cylindrical reflecting mirror 5 exhibits directivity along the optical axis X as shown by the dotted line. Furthermore, the main beam of the other partially parabolic reflecting mirror 4' exhibits a directivity that is offset counterclockwise by the angle α with respect to the optical axis X. Therefore, the main beam of the compound curved reflector 1 exhibits a directivity as shown by the dashed line, which is a combination of the above-mentioned directional components and.

On the other hand, the main beam in the vertical plane of the antenna using this compound curved reflector 1 is formed by the original paraboloid of revolution reflector 5 and the same primary horn as above placed at the focal point F of the reflector 5. It exhibits directivity with a beam width approximately equal to the main beam width in the vertical plane of an antenna consisting of As a result, the overall main beam directivity of the antenna consisting of the compound curved reflector 1 and the primary horn 6 exhibits a fan shape with a flat horizontal plane and the desired half width of the power. Functions as a beam antenna.

The size (aperture diameter) of the original paraboloid of revolution reflector 5 is determined based on the desired gain of the fan beam antenna.

The rises on both sides of the fan-shaped beam are almost equivalent to the rises of the main beam directivity in an antenna of the same type, which has a gain 6 dB lower than that of the antenna using the original paraboloid of revolution reflector 5. In other words, its rise is steep. The front side ratio and front-to-back ratio characteristics of this fan beam antenna are such that the peripheral edges of the partial parabolic reflectors 4, 4' of the compound curved reflector 1 cover the primary horn 6 from both sides as shown in FIG. It is in very good condition as it protrudes forward. That is, in the conventional parabolic antenna, a so-called shielding plate is attached around the original paraboloid of revolution reflector to improve its front-to-front ratio and front-to-back ratio characteristics, but according to the fan-shaped beam antenna, Good front-to-back ratio characteristics can be obtained without using the above-mentioned shielding plate.

In order to equalize the peak value levels of each of the main beam directivity components and to make the tip of the overall beam of each of the main beams more flat, the parts located at both ends of the compound curved reflector 1 are The opening area of the parabolic reflecting mirrors 4, 4' and the parabolic cylindrical reflecting mirror 5
It is only necessary to divide the aperture areas so that they are equal in area according to the illuminance distribution characteristics of the primary horn 6. The distance l shown in Figure 2 above for proportional distribution in this way
can be easily calculated from the illuminance distribution of the primary horn 6 described above. Reference numeral 7 shown in FIGS. 1 and 2 is a seat for attaching the composite curved reflector 1 to a steel tower, pedestal, etc. using direction adjustment bolts.

By the way, in the fan-shaped beam antenna according to the above-mentioned prior application, when the desired gain is high or the desired half-width of power is large, the main beam directivity components shown in FIG. There is a drawback that a null occurs in each angle γ direction between the optical axis X at the tip of the composite directivity shown by a dashed line in the figure.

In view of these points, the present invention has been developed so that even when the desired gain is high and the desired power half-width is large, the above-mentioned null does not occur, that is, the tip is flat and the main beam rises. steep,
It is an object of the present invention to provide a fan-shaped beam antenna with good directivity and excellent front-side ratio and front-to-back ratio characteristics.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

The compound curved reflector used in the fan beam antenna according to the present invention is as shown in FIGS. 3 and 4.
Partial parabolic reflectors 40, 4 located on both sides thereof
0', a parabolic cylindrical reflecting mirror 50 located at the center thereof, and paraboloids of appropriate widths interposed between the reflecting mirror 50 and each of the partial parabolic reflecting mirrors 40, 40'. It is composed of cylindrical reflecting mirrors 90 and 90'.

The two parabolic cylindrical reflecting mirrors 90, 90' have their surfaces γ≒α/2 (α is the above-mentioned partial parabolic reflecting mirrors 40, 4
0' deviation angle) and the first
Partial parabolic reflector 4 shown in FIG.
4' and the parabolic cylindrical reflecting mirror 5, along the intersection line 8, 8'. Therefore, the partial parabolic reflecting mirrors 40, 40' and the parabolic cylindrical reflecting mirror 50
The width of the mirror surface in the lateral direction is narrower than that of the partial parabolic reflecting mirrors 4, 4' and the parabolic cylindrical reflecting mirror 5 shown in FIGS. 1 and 2. Therefore, the second
When cutting the original parabolic reflector 2 shown in the figure to produce the double-part parabolic reflector 40, 40', the width of the parabolic cylindrical reflector 90, 90' is determined in advance. Taking this into consideration, the original reflecting mirror 2 may be divided into three by two surfaces inclined laterally at an appropriate angle with respect to the axis X.

The shape of the parabolic reflector 90, 90' is as follows:
It is calculated according to the depth and width of the null portion shown in FIG. 5, that is, the required height of gain and the size of the power half width.

Since the fan beam antenna according to the present invention includes the composite curved reflector 10 having the above configuration, it functions as follows. That is, as shown in FIG. 6, a primary horn 60 is placed at the focal point F of the original paraboloid of revolution reflector 2, and this composite curved reflector 10 is
When excited, the main beam of the parabolic cylindrical reflector 90 exhibits the directivity shown by the dotted line, which is deviated clockwise from the optical axis X by an angle γ. The main beam 90' exhibits directivity shown by a dotted line that is deviated counterclockwise from the optical axis X by the same angle γ. These bidirectional components act to fill in the null portion of the directivity caused by the partial parabolic reflectors 40, 40' and the parabolic cylindrical reflector 50, which are indicated by dashed lines in the figure. As a result, the composite directivity of the compound curved reflector 10 is as follows:
As shown by the solid line, it has a fan shape with a flat tip.

Note that the composite curved reflector 1 shown in the above embodiment
0 is the parabolic cylindrical reflecting mirror 90, 90' between the mirror edge of each of the partial parabolic reflecting mirrors 40, 40' and the mirror edge of the central parabolic cylindrical reflecting mirror 50. However, both the parabolic cylindrical reflecting mirrors 90, 90' are arranged so as to cover the intersection lines 8, 8' of the respective mirror surfaces of the compound curved reflecting mirror 1 shown in FIG. It may be arranged and fixed in an overlapping manner on the mirror surface located at the intersection lines 8 and 8'. In this way, both the parabolic cylindrical reflecting mirrors 90, 90' are replaced by the respective reflecting mirrors 4, 5 and 4' constituting the reflecting mirror 1.
Since it also functions as a reinforcing material for the joint, the strength of the antenna can be further increased, and the compound mirror surface has the advantage of being easy to design and process.

Since the fan-shaped beam antenna according to the present invention operates as described above, even when the desired gain is high and the desired half-width of power is large, the tip is smooth and the main beam rises steeply, and the front side ratio and With excellent front-to-back ratio characteristics, a fan-shaped beam with directivity can be obtained, and its practicality is extremely high. Of course, the antenna according to the present invention has all the advantages of the fan beam antenna according to the earlier application.

[Brief explanation of the drawing]

1 and 2 are a front view and a partially cutaway side view of a reflector in a conventional fan beam antenna, and FIGS. 3 and 4 are a front view and a partially cutaway side view of a reflector in a fan beam antenna according to the present invention. The cutaway side view, FIG. 5, and FIG. 6 are diagrams for comparing and explaining the operation of the conventional antenna and the antenna of the present invention. 10... Composite curved reflector, 40, 40'... Partial parabolic reflector, 50, 90, 90'... Parabolic cylindrical reflector.

Claims (1)

[Claims for Utility Model Registration] An axially symmetric rotating parabolic reflecting mirror is divided into two planes that are parallel to the optical axis of the mirror and that are equally spaced apart from the optical axis and sandwich the optical axis and face each other. Therefore, the two partial parabolic reflectors of the same shape obtained on both sides are aligned with each other so that their aperture surfaces approximate the angle β determined by the following formula, and the focal points are made to coincide with each other. β=180°−2α α=(Φ−Θ)/2 Where, Φ=Directional power half width of the desired fan beam Θ=More than the above antenna using the axisymmetric rotating parabolic reflector Directional power half-width of the same type of antenna with 6 dB lower gain The missing mirror surface formed between each of the partial parabolic reflectors shifted above is closed with a parabolic cylindrical reflector made of a curved flat plate. In a fan beam antenna consisting of a compound curved reflector consisting of a composite curved reflector and a primary horn arranged so that the focal point of each of the partial parabolic reflectors is approximately the center of radiation, each of the partial parabolic reflectors and the At the intersection line with the parabolic cylindrical reflecting mirror, along the intersection line and with respect to the mirror surface of the parabolic cylindrical reflecting mirror, γ≒
A fan-shaped beam antenna characterized in that each parabolic cylindrical reflector is formed of a curved flat plate with a mirror angle of α/2.