JPH0254606A - Antenna - Google Patents

Abstract

PURPOSE:To suppress occurrence of deformation and to suppress the deterioration in the side lobe characteristic without causing a remarkable weight increase by providing a reinforcement means in the vicinity of the middle rear face of a mirror face shell so as to increase the stiffness of the middle part of the mirror surface shell. CONSTITUTION:A reflecting plate 3 forming a mirror surface shell of an antenna 1 is formed by a thin honey-comb core sandwich plate and the antenna 1 is coupled by the reflecting plate 3, a support frame 5 opposite thereto and plural coupling members 7 coupling the reflecting plate 3 and the support frame 5. Then a reinforcement plate 9 forming the reinforcement means is provided to the rear dace middle part of the reflecting plate 3. The reinforcement plate 9 is arranged along a direction causing a large deformation for a long period to increase the stiffness of the rear middle part of the reflecting plate 3. Then as the cross section structure, various structures are to te considered and any shape is used even when a member at a right angle in the lengthwise direction with a high bending stiffness around the shaft such as a honey-comb sandwich plate, a hut shaped cross section, a triangle cross section or a T shaped fin is provided.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to, for example, an antenna mounted on a satellite.

(Prior art) With the recent transmission of satellite communications, satellite broadcasting, etc., there is a trend toward multiple and larger antennas installed on communication satellites, and the communication method is increasing in communication capacity. To cope with this, a so-called multi-beam communication system is often used. In multi-beam communication systems, how to suppress sidelobes (sidelobe characteristics) is an important item.
In particular, the greater the amount of deformation of the antenna mirror surface, the worse the sidelobe characteristics will be, so it is important to use an antenna that is designed with this point in mind.

(1-Problem to be Solved by the Invention) Conventional antennas mounted on artificial satellites have a structure in which the mirror surface has a uniform thickness of the mirror shell, or the mirror shell has a uniform thickness, or the mirror shell has a structure in which the mirror shell has a uniform thickness, or the mirror shell has a structure in which the mirror shell has a uniform thickness. For such a mirror surface, the rigidity and thermal deformation m on the track were determined in the Taliteria. In conventional antennas, the mirror surface is small and the communication method is single beam, so the design does not pay particular attention to sidelobe characteristics, and the mirror surface is simply suppressed by suppressing thermal deformation in orbit. The only consideration was to maintain high accuracy. In other words, thermal deformation tends to increase the amount of displacement at the edges where the constraint is removed, so as an antenna,
Even if a structure with variable thickness is adopted, the thickness of the peripheral part must be not much different from that of the central part, and it was designed and manufactured in such a way.

In addition, as the capacity of communication satellites increases, it becomes necessary to mount an antenna system that mounts multiple large mirror surfaces on the communication satellite, and many of these antenna systems are of the type with a tower. Since the mirror surface is larger than structures such as towers and communication satellite structures, there are many cases where part of the mirror surface is covered by the shadow of other structures. At this time, a significant temperature difference occurs between the sunny and shaded areas of the mirror surface, and the expansion or contraction of the mirror shell material causes large out-of-plane distortion between the sunny and shaded areas, which impairs the electrical performance of the mirror surface. Easy to deteriorate.

However, mounting such an antenna on a communication satellite using the multi-beam communication method, in which the thickness of the peripheral part is not much different from that of the central part, would result in a significant increase in weight due to the increase in the number and size of the antennas. There is a problem with that. Therefore, in order to prevent the occurrence of this distortion, the thickness of the mirror surface is substantially the same at both the center and the periphery.

The present invention has been made in view of the above, and an object of the present invention is to provide an antenna that can suppress deterioration of sidelobe characteristics without causing a significant increase in weight.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the vicinity of the central back surface of the mirror shell forming the reflecting mirror, there is a The gist is that a reinforcing means is provided to suppress the occurrence of deformation of the side lobe in the control direction at the portion.

(Function) In the antenna according to the present invention, focusing on the fact that the sidelobe characteristics deteriorate the most when a long-period large deformation occurs in the center of the mirror shell, By providing reinforcing means to increase the rigidity of the central portion of the mirror shell, the occurrence of deformation as described above is suppressed.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIGS. 1(A) and 1(B) are views showing an antenna 1 having a 1-rath shaped mirror surface according to an embodiment of the present invention, in which (A) is a rear perspective view, and (B) is an a-a FIG. 3 is a partial cross-sectional view of the line. In this antenna 1, a mirror plate 3 constituting a mirror shell is formed of a thin honeycomb core sand-inch plate, and this reflector plate 3 and a support frame 5 facing it are connected together. They are connected by a plurality of connecting members 7. Reference numeral 9 denotes a reinforcing plate constituting reinforcing means provided at the center of the back surface of the reflecting plate 3. This reinforcing plate 9 is arranged along the direction in which large deformation with a long period occurs as will be described later, and is intended to increase the rigidity of the central portion of the back surface of the reflecting mirror 3. As for its cross-sectional configuration, the seed itself can be considered, but as shown in (A) to (D) in Fig. 2, the cross-sectional structure can be sequentially formed into a honeycomb core sandwich plate, a hat-shaped cross section, a triangular cross-section, and a T-shaped fin. Any type of member may be used as long as it has high bending rigidity around one axis perpendicular to the longitudinal direction.

The antenna 1 having the above-described configuration is fixed to a body 13 of the communication satellite 10 via a fixed support 11, as shown in FIG. 3, for example. In FIG. 3, 15 is a tower, 17 is a solar panel, and 18 is another antenna, all of which are installed on the structure 13.

By the way, when the antenna 1 is mounted on the communication satellite 10, the reinforcing plate 9 is arranged so that the longitudinal direction of the reinforcing plate 9 is substantially perpendicular to the direction in which the tower 15 is arranged with respect to the structure 13. That is, in the communication satellite 10, the solar panel 17 is oriented toward the sun in order to secure driving power. The shadow 16 of the tower 15 appears on the center of the mirror surface 19 of 3, changing from moment to moment depending on the direction of the sunlight, as shown in FIG. 4 (A> to (C)).

The generation of this shadow 16 causes a significant temperature difference between the sunny and shaded areas of the mirror surface 19, and expansion or contraction of the mirror shell material causes large out-of-plane distortion between the sunny and shaded areas. The electrical performance as 19 deteriorates. Therefore, the reinforcing plate 9 is used as a mirror surface 1 where the shadow 16 of the tower 15 changes over a long period of time.
9 is arranged so that the central direction is the longitudinal direction, and the rigidity in the same direction is increased to suppress deformation.

Specifically, the tower 1 shown in (A) to (C) in FIG.
The thermal deformation of the mirror surface 19 according to the temporal change of the shadow 16 of FIG. 5 is Ao, Bo,
On the other hand, the sidelobe characteristics during this thermal deformation are shown as the level ratio (D/U) between the main beam and the sidelobes from the adjacent beams in the multi-beam communication system, as shown by the broken line in Figure 5. It is. In addition,
The data shown in Figure 5 shows that Japan is
This figure shows the sidelobe characteristics between Tokyo and Osaka when covered with three beams. As is clear from Fig. 5, the shadow 16 of the tower 15, where the thermal deformation is maximum, is elongated from the comparison between the thermal deformation and the sidelobe level in Fig. 4 (B).
It can be seen that the sidelobe characteristics are most degraded in the state shown in FIG. 4<A) in which the shadow 16 extends by about half compared to the case shown in FIG. The cross-sectional state of the deformed mirror surface 19 in the state of FIG. 4(A) is shown by a solid line in FIG. 7<A) and (8). It can be seen that when the sidelobe characteristics are at their worst, a large displacement occurs at the center of the mirror surface 19. In other words, the electrical characteristics deteriorate the most when a long-period large deformation occurs in the center of the mirror surface 19 such that the phase of the air waves reflected by the mirror surface 19 changes periodically as a function of location. It is.

Therefore, according to this embodiment in which the reinforcing plate 9 is selectively attached to the central part of the mirror surface 19, the rigidity of the central part of the mirror surface 19 is increased by the reinforcing plate 9, as shown by the broken line in FIG.
It is possible to suppress a large deformation of the central portion of the mirror surface 19 compared to the above, and it is possible to suppress the deformation of the central portion of the mirror surface 19, which causes deterioration of the side lobe characteristics, so that the side lobe characteristics can be effectively improved. In addition, in Fig. 7,
Negative displacement indicates displacement from 1 to the lath side, and positive displacement indicates displacement in the opposite direction.

Regarding the improvement of the side lobe characteristics according to this embodiment, FIG. 8 shows the radiation pattern of a mirror surface with an aperture of 2.5 m having the deformed shape shown in FIGS. 7(A) and 7(B). FIG. 8(A) is a conventional one, and FIG. 8(B) is one according to this embodiment. The radiation pattern is an example of a multi-beam system that has two beams, one covering the Tokyo area and the other beam covering the Osaka area.

In this case, in order to avoid interference,
It is necessary to take a large value for D/U, which is the ratio of the beam gain to be used, but in Fig. 8(A), the minimum value is 20.5 ds and 27.4 da at the center of the area.

In FIG. 8 (8), the minimum value is 22.2 ds and the center part of the rear is 30.4 ds, and by applying this embodiment, the minimum value can be improved by 1.7 ds and the center part can be improved by 3.0 ds. Conventionally, in order to obtain such an improvement, the thickness of the mirror surface was increased over the entire mirror surface.

When this embodiment is applied, the weight increase in the case of a φ2.5+1 mirror surface is about 2002', whereas in the conventional method of increasing the thickness of the honeycomb core, an increase in weight of 8002' or more is required. For larger mirrors, the weight difference becomes even more pronounced.

The above-mentioned embodiment shows an example that is particularly effective when multiple beams are lined up almost in a line along the Japanese archipelago, but when beams are lined up closely in both east-west and north-south directions, Instead of reinforcing it, use reinforcement material 2 in a cross shape as shown in Figure 9.
It may be necessary to deploy 0.

Further, in this embodiment, the case of the antenna having a truss-shaped mirror surface has been described, but the antenna is not limited to this. It is also applicable to an antenna 23 having a mirror surface with ribs 23 on the back surface for improving rigidity.

Furthermore, in this embodiment, one reinforcing plate 9 is provided, but
For example, as shown in Fig. 11, a plurality of mirror surfaces may be provided, and in cases where a reinforcing plate cannot be placed in the center due to the arrangement of the connecting members in a truss-shaped mirror surface, or in cases where other types of mirror surfaces are larger. It is effective for

[Effects of the Invention] As explained above, according to the present invention, focusing on the fact that the sidelobe characteristics are most degraded when a large deformation with a long period occurs in the central part of the mirror film, the central rear surface of the mirror film is By increasing the rigidity of the central part of the mirror membrane by providing reinforcing means near it,
Above) Since the occurrence of deformation as shown in E was suppressed υ1,
Deterioration of the night lobe characteristics can be suppressed without causing a significant increase in hand stitching.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an antenna according to an embodiment of the present invention, FIG. 2 is a diagram showing the constituent members of the antenna, FIG. 3 is a diagram showing an example of mounting the antenna, and FIGS. 4 to 8 9 is a diagram for explaining the features of this embodiment, and FIGS. 9 to 11 are diagrams showing modified examples. 1...Antenna 3...Reflector 5...Support frame 7...Coupling member 9...Reinforcement plate
10...Communication satellite 11...Fixed support 13...
Structure 15...Tower 19...Mirror surface 21...Antenna 25...Antenna

Claims (1)

[Claims] A reinforcing means is provided in the vicinity of the central back surface of the mirror shell forming the reflecting mirror to suppress deformation of the side lobe in the direction in which the side lobe is to be controlled in the central portion of the mirror shell. antenna.