JPH10209746A - Antenna-reflecting mirror surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the antenna gain by using a metallic mesh and a wire network for a reflecting mirror mounted on a satellite, so as to suppress circular-arc or polygonal deformation to an inside of a circumferential part of a reflecting mirror surface to be configured. SOLUTION: This mirror surface is configured with a metallic mesh 16 reflecting a radio wave, a wire network 11 configured by connecting the metallic mesh 16 with wires to be formed to a desired curved face, and a support structure 15 that supports the metallic mesh 16 and the wire network 11 at apexes of a polygonal shape macroscopically via rod members. In this case, a metallic mesh called an outer circumferential mesh 17 with a low tension than a tension of the metallic mesh reflecting a radio wave is given tension between an outer circumferential wire 12 coupling the rod members 13, placed at the apexes of the polygonal shape in a circumferential direction and a wire placed at the outer circumference of the outer circumferential wire 12 and the wire network 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna used for a satellite-mounted antenna and the like, and more particularly, to a method for forming a desired curved surface by a wire network, and forming an antenna reflecting mirror surface by using this and a wire mesh having a finer mesh than the wire network. And a reflecting mirror surface of the folded foldable antenna.

[0002]

2. Description of the Related Art When an antenna mounted on an artificial satellite or the like is required to have a light-weight, large-aperture reflecting mirror surface, a mirror surface for reflecting radio waves is formed by a metal mesh, and a plurality of wires are connected to each other. A so-called mesh antenna is used, which is formed into a desired curved surface by using a wire network, and the tension of the metal mesh or the wire is supported by a holding structure.

[0003] Because metal mesh is lightweight and has good storage properties,
Although it is convenient for use as a mirror material for large and lightweight antennas, it does not have a shape by itself, so the metal mesh is supported by a cable network composed of multiple cables to form a predetermined mirror surface. A method of forming an antenna reflector by molding and further using a structure that supports mesh and cable tension is used.

FIG. 8 is a view showing an example of a conventional mesh antenna, which schematically shows the structure thereof. Numeral 101 denotes a reflecting mirror surface made of a metal mesh, and 102 denotes a metal mesh 101 formed on a desired curved surface. Reference numeral 103 denotes a rod-shaped member, and 104 denotes a support structure.

In this figure, for easy understanding, the metal mesh 101, the wire network 102, and the support structure 104 are separately shown as an exploded view. However, actually, the metal mesh 101 is a wire network. 1
A desired curved surface (often a parabolic surface) is formed by superimposing with 02, and attached to the support structure 104 via the bar-shaped member 103.

[0006] As another example of an antenna using a conventional metal mesh, there is an antenna in which a reflecting mirror is formed in the shape of a umbrella. "References: See Japanese Patent Application No. 2-301917" Mesh antenna ""

[0007]

As described above, the method of realizing a reflecting mirror surface so that a metal mesh is formed into a desired curved surface by using a wire network is a very effective method for reducing the weight of an antenna. However, due to its structure, since the wire does not hold the force in the bending direction, the outermost peripheral portion of the antenna reflecting mirror surface has a shape bent inward. For example, when the metal mesh 101 and the support structure 104 are provided in a macroscopic hexagon, they are balanced as shown in FIG. In the same figure, the numeral 105 indicates the part of the outermost peripheral portion of the metal mesh that is bent inward as “digging”.

[0008] When used as an antenna reflecting mirror surface, such recesses in the periphery substantially reduce the opening area, so that in addition to reducing the antenna gain,
It is not desirable because the side lobe level of the radio wave is also deteriorated.

In particular, in the case of a structure in which a large antenna reflecting mirror surface is formed by combining a plurality of antenna reflecting mirror surface structures shown in FIG. A hole is formed inside the reflecting mirror surface, and it is required to reduce the size of the hole in terms of electrical characteristics.

[0010] In order to solve this problem, conventionally, a method has been devised to increase the radius of curvature, that is, to suppress the undercut in the peripheral portion by increasing the extensional rigidity of the wire disposed in the peripheral portion. The technology is also disclosed in the above-mentioned reference (Japanese Patent Application No. 2-301917).

However, since there is a relationship of N = T / R (1) among the tension T of the outer peripheral wire, the mesh tension N, and the peripheral radius of curvature R, the radius of curvature is increased and In order to obtain a desired mesh tension, the tension of the outer peripheral wire also increases. Since the support structure has only finite stiffness, there was a limit in principle to reducing the surrounding undercut by such a method.

It is an object of the present invention to provide means for focusing on this problem and for further reducing recesses in the peripheral portion of an antenna reflecting mirror surface using a metal mesh.

[0013]

According to the present invention, there is provided a metal mesh for reflecting a radio wave, a wire network for forming the metal mesh into a desired curved surface, and a metal mesh and a wire network. In addition to the support structure held at the vertex of a simple polygonal shape,
The support structure is composed of a wire called an outer peripheral wire that connects the vertices of the polygonal shape of the support structure in the circumferential direction, and a metal mesh called an outer peripheral mesh provided between the outer peripheral wire and the outermost peripheral wire of the wire network.

The present invention is characterized in that the outer peripheral wire is not connected to the wire network by the wire and that the outer peripheral mesh is laid on the outer peripheral wire and the wire network. When the outer peripheral mesh is set to a tension lower than that of the metal mesh stretched over the wire network, it is effective to reduce the depression of the antenna reflecting mirror surface.

[0015] In order to set the outer mesh to a low tension, the wire network, the metal mesh stretched between the wire networks, and the outermost wire of the wire network in a state where the outer wire is structurally balanced. Should be installed between the wires.

Of course, equation (1) holds true for the outer peripheral wire and the outer peripheral mesh. However, even if the tension of the outer peripheral wire is not increased by setting the tension N of the outer peripheral mesh to be small, the outer peripheral portion is clogged. Noise can be reduced. The configuration described so far is the configuration described in claim 1.

In the configuration described so far, the outer peripheral wire is connected between the vertices of the support structure by a straight line. However, in this case, the outer peripheral mesh portion becomes a planar shape, and approximates a desired curved surface. The error may be extremely deteriorated as compared with the curved surface portion where the wire network is formed. In such a case, the outer peripheral holding wire is installed approximately parallel to the outer peripheral wire in the depth direction of the mirror surface, a wire called a connecting wire for joining between the outer peripheral wire and the outer peripheral holding wire is provided, and the tension is adjusted to adjust the reflecting mirror. May be shaped. This is the configuration of claim 2.

[0018]

FIG. 1 shows a first embodiment of the present invention.
5A is a diagram showing an example of the antenna reflector, and FIG. 5A shows the entire structure of the antenna reflector before the metal mesh is superimposed, and FIG. In the figure, numeral 11 denotes a wire network, 12 denotes an outer peripheral wire, 13 denotes a rod-shaped member, 14 denotes a central axis, 15 denotes a support structure, 16 denotes a metal mesh forming a reflection surface, and 17 denotes an outer peripheral mesh.

As shown in FIG. 1A, a wire network 11 is attached to upper and lower ends of a bar member 13 called a stand-off attached to a support structure 15, and an outer peripheral wire 12 has its upper end joined to each other. doing.
The metal mesh 16 that reflects radio waves is superposed so as to cover the upper surface of the wire network 11 as shown in FIG. 2B, and the outer mesh 17 is located between the outermost wire of the wire network 11 and the outer wire 12. It will be erected.

FIGS. 2A and 2B are views showing a second example of the embodiment of the present invention, wherein FIG. 2A shows the entire structure of the antenna reflector before the metal mesh is superposed, and FIG. The figure which looked at the characteristic part from the side is shown typically. Numeric code 1
1 to 15 are the same as those in FIG. 1, 18 is an outer peripheral holding wire, 19 is a connection wire, and 10 is a connector.

In this example, an outer peripheral holding wire 18 that connects the lower ends of the rod-shaped members 13 is connected in parallel with the outer peripheral wire 12, and a connecting wire 19 is connected to the outer peripheral holding wire 18 and the outer peripheral wire 12. The length of the connection wire 19 is adjusted so that the connector 10 connecting the connection wire 12 and the connection wire 19 is located on a curved surface to be approximated by the antenna reflector.

Although the illustration of the metal mesh forming the reflecting mirror surface and the outer peripheral mesh is omitted in this figure, in actuality, the metal mesh covers the wire network 11 as in the case of FIG. The outer peripheral mesh is provided between the outermost peripheral portion of the wire network 11 and the outer peripheral wire 12.

Hereinafter, effects of the present invention will be described with reference to specific examples. In the conventional mesh antenna, since the antenna reflecting mirror surface is formed of an integral metal mesh and a wire network, the outermost peripheral portion of the wire network is clogged, and the opening area is lost.

In this regard, according to the antenna reflecting mirror surface of the present invention, it is possible to reduce the loss of the opening area in the outer peripheral portion of the lightweight antenna reflecting mirror surface using the metal mesh. For example, a focal length of 10.4 m and a side of 2.4 m
The effect is quantitatively shown by taking the hexagonal antenna reflecting mirror surface as an example. The calculation was performed on a 1/6 portion of the hexagon.

First, it was calculated to what extent the undercut formed on the outer peripheral portion of the antenna reflecting mirror surface can be reduced by the outer peripheral mesh provided with a weaker tension than the tension of the metal mesh attached to the wire network. At this time, the outer peripheral wire is not stretched over the antenna reflecting mirror surface, that is, the effect of the related art is shown.

The calculation is performed by stretching a metal mesh attached to a wire network with a tension of 0.5 kgf / m,
The maximum amount of undercut in the outer peripheral portion was calculated when the outer peripheral mesh was erected on the outer side while changing the tension. The result is shown in "Table 1" as a table showing "change in maximum undercut amount due to tension setting of outer peripheral mesh in the absence of outer peripheral wire".

[0027]

[Table 1]

In "Table 1", the outer mesh tension is set to 0.
The column of 5 Kgf / m represents a case where no consideration was given to reducing engraving.

As shown in Table 1, when the tension of the outer peripheral mesh is reduced, the maximum undercut is improved by about 25%. However, the tension is 0.1 kgf / m and 0.1 kgf / m.
Since there is not much difference at 05 Kgf / m, there is not much effect even when the tension of the outer peripheral mesh is extremely reduced. The appearance of the mesh at each tension is as shown in FIGS.

That is, in the figure, (a) shows that both the metal mesh tension and the outer mesh tension are 0.5 kgf / m.
(B) shows the metal mesh tension of 0.5 kgf / m and the outer mesh tension of 0.
It shows the appearance of the mesh at 1 kgf / m,
(C) shows the appearance of the mesh when the metal mesh tension is 0.5 kgf / m and the outer mesh tension is 0.05 kgf / m.

Next, the above-mentioned "Reference: Japanese Patent Application No. 2-30119"
17), a comparison between the antenna reflecting mirror surface with a reinforcing wire inserted at the outermost periphery of the wire network proposed in Section 17 and the maximum penetration amount when the outer peripheral wire and the outer peripheral mesh proposed in the present invention are attached is described. "Table 2" shows a table showing "change in maximum undercut amount due to tension setting of outer peripheral mesh in a certain state".

[0032]

[Table 2]

Comparing the columns of Table 1 and Table 2 with the outer mesh tension of 0.5 Kgf / m, the maximum penetration of the outer periphery is reduced to about 1/5 due to the presence of the reinforcing wire. You can see that. This is "Literature: Japanese Patent Application No. 2
-301917 ".
On the other hand, if the antenna reflecting mirror surface according to the present invention is used, the maximum undercut amount was 208.5 mm without any contrivance (tension of 0.5 kgf / m in Table 1).
Of 19.34 mm (the tension of 0.1 kgf /
m).

This is based on the conventional technology (Japanese Patent Application No. 2-301191).
7) is twice as effective. It can also be seen that a greater effect can be obtained by reducing the tension of the outer mesh. FIG. 4 shows the appearance when the outer peripheral mesh tension is 0.05 Kgf / m. The effect of reducing the amount of undercut according to the present invention is apparent from comparison with FIG.

When the outer peripheral wire is laid in a straight line between the vertices of the support structure, the curved surface approximation error of the outer peripheral mesh is 33 mm at the maximum, and the RMS value is 16 mm. Therefore, as in the second aspect of the present invention, when two outer peripheral wires are installed substantially parallel to the direction outside the mirror surface, and one wire connecting them is provided at an intermediate point, a maximum of 12 mm and an RMS of 6 m
The accuracy can be improved to about m.

Next, the effect of improving the electric characteristics according to the present invention will be described. For that purpose, analysis was performed using the specific antennas shown in FIGS. FIG. 5 shows an offset parabolic antenna composed of a primary reflector and a primary reflector composed of hexagonal antenna reflectors 1, 2 and 3 each having a side length of D. FIG. ) Is an antenna coordinate system, FIG. 6B is a configuration diagram of a main reflecting mirror surface, and FIG. 6 is an enlarged view of a recess.

As shown in FIG. 6, there are four points,
FIG. 5 shows a square shape formed by points 1 to 4.
As shown in (b), there are only six locations between each hexagonal antenna reflecting mirror surface. In analyzing the characteristics of this antenna, the radio wave radiated from the primary radiator is used to avoid the influence of the outer shape of the main reflecting mirror surface appearing in FIG.
It is assumed that the inside of the circle in the main reflecting mirror surface shown in (b) is covered by the 3 dB beam width.

In each of the cuts 1 to 6, two points of the cut, points 1 and 2, which are on the vertices of the hexagon as shown in FIG.
Is provided. Each recess 1-6 is closed by plane 1 closed by three points 1-4-5, plane 2 closed by three points 3-4-5, and closed by three points 2-3-5. The surface is divided into planes 3, and an outer peripheral mesh is formed by these three planes 1, 2, and 3, and a hexagonal antenna reflecting mirror surface is formed so that the undercut does not become a missing portion (hole).

In this case, when the hexagonal antenna reflecting mirror surface according to the first aspect is used, the height of the point 5 is located at the midpoint of a line segment connecting the points 1 and 2 with a straight line. When the hexagonal antenna reflecting mirror surface described in Item 2 is used, the height of this point 5 is located on the parabolic surface forming the main reflecting mirror surface.

FIG. 7 shows an example of a graph showing the effect of improving the electric characteristics according to the present invention. As shown in FIG. 5, the ratio d of the maximum recess d [m] to the length D [m] of one side of the antenna shown in FIG.
FIG. 9 is a graph showing a gain deterioration amount [dB] with respect to an antenna gain without dimple when / D [%] is changed.

Symbol A in the graph indicates the case where the antenna reflecting mirror according to the prior art is used, B indicates the case where the antenna reflecting mirror according to the present invention is used, and C indicates the antenna according to the invention according to claim 2. The case where a reflecting mirror surface is used is shown. From this figure, it can be seen that the amount of gain deterioration can be reduced when the antenna reflector according to the present invention is used, as compared with the case where the antenna reflector according to the prior art is used.

Further, it can be seen that the effect of reducing the amount of gain deterioration is larger when the antenna reflector according to the second aspect is used than when the antenna reflector according to the first aspect is used. Further, it can be seen that as the ratio d / D of the maximum undercut amount d [m] to the length D [m] of one side increases, that is, as the undercut amount increases, the effect of reducing the gain deterioration amount according to the present invention increases. .

[0043]

As described above, the use of the antenna reflecting mirror surface according to the present invention makes it possible to reduce the structural depression at the outermost peripheral portion to about half as compared with the conventional case. From the viewpoint of electrical characteristics, when the ratio of the maximum undercut to the length of one side is 10%, the amount of antenna gain deterioration is reduced by 90% as compared with the conventional antenna reflecting mirror surface.
It is possible to reduce the degree.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first example of an embodiment of the present invention.

FIG. 2 is a diagram showing a second example of the embodiment of the present invention.

FIG. 3 is a diagram illustrating a shape of a peripheral portion of a reflecting mirror when a tension of a metal mesh is changed.

FIG. 4 is a diagram illustrating a shape of a peripheral portion of a reflecting mirror in the case of the present invention.

FIG. 5 is a diagram (part 1) for describing an improvement in electrical characteristics according to the present invention.

FIG. 6 is a diagram (part 2) for describing an improvement in electrical characteristics according to the present invention.

FIG. 7 is a diagram showing an improvement in electrical characteristics according to the present invention.

FIG. 8 is a diagram illustrating an example of a conventional mesh antenna.

FIG. 9 is a diagram showing a shape of a peripheral portion of a conventional mesh antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Connector 11,102 Wire network 12 Outer peripheral wire 13,103 Bar-shaped member 14 Central axis 15,104 Support structure 16,101 Metal mesh 17 Outer peripheral mesh 18 Outer peripheral holding wire 19 Connection wire 105

Claims (2)

[Claims] 1. A metal mesh for reflecting a radio wave, a wire network formed by connecting wires for forming the metal mesh into a desired curved surface, and a vertex portion of a macroscopic polygonal shape formed by connecting the metal mesh and the wire network. In the antenna reflecting mirror surface composed of a supporting structure held through a rod-shaped member, an outer peripheral wire connecting circumferentially between the rod-shaped members located at the vertices of the polygonal shape, and the outermost wire of the outer peripheral wire and the wire network An antenna reflecting mirror surface, wherein a metal mesh called an outer peripheral mesh having a tension lower than the tension of a metal mesh that reflects radio waves is stretched between the wire and a positioned wire. 2. A wire called an outer peripheral holding wire which is substantially parallel to the outer peripheral wire is fixedly mounted on a rod-shaped member or a support structure at both ends at a position opposite to a boresight direction and a focal point of the antenna reflecting mirror surface. The antenna reflecting mirror surface according to claim 1, wherein a wire called a connection wire is stretched between the wire and the outer peripheral wire.