JPH0695605B2 - Antenna mirror structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a mirror surface (reflecting mirror) of a parabolic antenna that is required to have high accuracy and that is used in a severe thermal environment. It is applied to mirror surfaces such as large antennas.

<Prior Art> The mirror surface of the conventional antenna mounted on the satellite is
As shown in FIG. 6 and FIG. 7 which is a longitudinal cross section of a part thereof, it is formed of one mirror shell 1. That is, mirror surface 2
Is obtained by a single mirror-like shell 1 and is supported by the frame structure 4 through the columns 3.

By the way, in the mirror surface 2 having such a structure, as shown in FIG. 9, depending on the direction of sunlight (indicated by an arrow in the figure), another structure 5 of the artificial satellite or the like (for example, 5 , A tower) is partially formed (shaded portion in the figure), a remarkable temperature difference occurs between the sunlit portion and the shaded portion on the mirror surface 2, and the sunlit portion is expanded or contracted due to expansion or contraction of the mirror surface shell material. And the shade part tries to change discontinuously.

Therefore, a large out-of-plane distortion occurs between the sunlit part and the shaded part, which deteriorates the performance as a mirror surface.

<Problems to be Solved by the Invention> In order to solve the above problems, as shown in FIG. 8, the mirror shell 1 is divided into several (here, three), and each split mirror shell 1a , 1b and 1c are considered to have a gap between them.

On this mirror surface, the deformation caused by the temperature deviation due to the partial shadow is absorbed in the gap as the deformation in the in-plane direction of each of the split mirror shells 1a, 1b, 1c.

As for the gap, the mirror shell 1 has the highest temperature (about 10
(0 ° C), the split mirror shells 1a, 1b, 1c must be adjusted so that they expand and become zero. Therefore, when the mirror shell 1 reaches the minimum temperature (about -200 ° C), Split mirror shell 1
a, 1b, 1c contract and become a large gap.

Normally, the mirror shell 1 has a lightweight and high-rigidity structure by sandwiching an aluminum honeycomb core with a skin of carbon fiber reinforced plastic (CFRP) having a small linear expansion coefficient. At this time, the coefficient of linear expansion of the mirror shell 1 is It will be about 5 × 10 ^-6 / ° C.
On the other hand, the skeleton structure 4 supporting the mirror shell 1 has a linear expansion coefficient smaller than that of the mirror shell 1 by an order of magnitude or sometimes a negative value due to the orientation of the carbon fibers. Therefore, for example, a large mirror shell 1 with an opening diameter of 5 meters
Is divided into three parts as shown in FIG.
The maximum gap between 1a, 1b and 1c is about 4mm,
This leads to a decrease in gain. Furthermore, if there is a partial shadow,
Since the mirror surface shell portion under sunshine and the mirror surface shell portion in the shade are deformed so as to have different curvatures, a step 6 is formed at the edge portion as shown in FIG. Such a step greatly deteriorates the side lobe characteristic. Therefore, as in the prior art, merely by dividing the mirror surface, it was not possible to sufficiently solve the performance deterioration of the mirror surface due to thermal deformation.

<Means for Solving the Problems> In order to solve the above problems, in the present invention, the mirror shell that forms the reflecting surface of the reflector antenna is divided into a plurality of pieces, and along the outer edge where the boundary of each divided mirror shell contacts. , While allowing different movements in the in-plane direction at the boundary between adjacent split mirror shells, different movements in the out-of-plane direction at the boundary between adjacent split mirror shells, and between adjacent split mirror shells. A fitting structure is formed to prevent deformation such that the tangent of the curved surface becomes discontinuous across the boundary, and at the fitting portion, a part of one of the split mirror surface shells is provided with one of the reflecting surfaces of the other split mirror surface shell. When the reflecting surface formed by the split specular shells has a gap at the boundary due to different movements of the split specular shells in the in-plane direction, the reflecting surface of the fitting portion is Anne which becomes the reflective surface in the gap The Tena mirror surface structure was adopted.

<Operation> In the antenna mirror surface structure having the above configuration, even if there is contraction or expansion due to a temperature difference between the divided split mirror surface shells, the fitting structure portion is restrained from the relative movement in the in-plane direction. Instead, it is absorbed by sliding the mating engagement part.
In addition, even if the adjacent split mirror shells move differently in the in-plane direction and the portions forming the reflecting surface are separated from each other, the fitting portion serves as the reflecting surface in the gap portion. Furthermore, the relative movement of the split mirror shells in the out-of-plane direction and the fact that the reflecting surfaces formed by the adjacent mirror shells are discontinuous curved surfaces at their boundaries are constrained by the fitting of the fitting structure, It is possible to maintain a continuous curved surface without forming a step between the split mirror surfaces.

<Embodiment> FIGS. 1 (a) and 1 (b) show partially enlarged perspective views of respective divided mirror shells in an antenna mirror structure according to an embodiment of the present invention, and FIG. 2 and FIG. The different mating states of the two split mirror shells are shown.

1 to 3 show two of the three divided mirror shells (the divided mirror shells 1a and 1b) that divide the mirror surface 2 into three, as shown in FIG. As described above, each of the split mirror shells has a sandwich structure in which CFRP skins 7 are provided on both sides of the aluminum honeycomb core 8 in order to have a certain degree of bending rigidity, and the overall wall thickness is 5 to 5. It is about 10 mm.

The mating surface of each split mirror surface shell 1a, 1b is, for example, linear as shown in the figure, and the split mirror surface is a mating surface so as to form one curved surface in the state where they are put together. They have the same curvature. A fitting structure 9 is formed between these mating surfaces. The fitting structure 9 is provided at the fitting portion of the split mirror surface shell 1a on one side and has a concave cross-sectional shape, and on the fitting portion of the split mirror surface shell 1b on the other side, The fitting member 11 has a convex cross section and is fitted with the fitting member 11. The fitting members 10 and 11 can freely slide in the in-plane direction (direction parallel to the surface of the mirror surface 2) in the fitted state, and can be displaced in the out-of-plane direction (direction orthogonal to the surface of the mirror surface 2). It suppresses the deformation that the curvatures on the mating surfaces tend to become discontinuous. As shown in FIG. 8, it is divided into three,
With a mirror surface having an opening diameter of about 5 meters, the maximum displacement in the in-plane direction is about 3 to 4 mm.
The depth of the concave portion 10a or the height of the convex portion 11a of the fitting member 11 is
About 10 mm is enough. Since the upper surface 10b of the fitting member 10 can also be a part of the mirror surface 2, metal or C
Manufactured by FRP.

In this embodiment, the fitting structure is a combination of a single concavo-convex shape, but the fitting structure is not limited to this, and the point is that it can slide in the in-plane direction and Any one may be used as long as it constrains each other in the direction.

In the parabolic antenna having the above antenna mirror surface structure, the split mirror shells 1a, 1b, 1c expand at the highest temperature, and the fitting members 10, 11 are closely fitted to each other as shown in FIG. It will be in the state of doing.

Further, at the lowest temperature, the split mirror shells 1a, 1b, 1c contract, and as shown in FIG. 3, the fitting members 10, 11 are displaced in the in-plane direction while maintaining the fitted state. Become. At this time, a gap c is formed between the skins 7, and the surface 10b of the fitting member 10 becomes a part of the mirror surface. A step h corresponding to the thickness of the skin 7 is formed between the surface (mirror surface) of each split mirror shell 1a, 1b, 1c and the surface 10b of the fitting member 10. The step h is about 0.1 mm. Therefore, when using a radio wave having a wavelength of several millimeters or more, the performance of the mirror surface 2 is hardly affected.

Furthermore, as shown in FIG. 9, a shadow is partially formed on the mirror surface 2, for example, one of the adjacent split mirror shells receives sunlight and becomes hot, and the other becomes shadow and becomes cold, Even in the situation where displacement occurs in the opposite direction as shown in FIG. 10, the displacement is canceled by the expansion and contraction of each split mirror surface shell 1a, 1b, 1c, and the displacement in the out-of-plane direction (curvature is (Different deformations) are also restrained by the fitting of the fitting members 10 and 11, and as a result, the split mirror shells 1a, 1b and 1c are kept in a smoothly connected state.

4 and 5 show a deformed state of the mirror surface 2 when a shadow is produced on the mirror surface 2 as shown in FIG. The mirror shell 1 is divided into three parts, and the one shown in FIG. 4 relates to the present invention, that is, the fitting structure is provided between the divided mirror shells 1a, 1b, 1c, and FIG. What is shown is a conventional one, that is, each of the split mirror shells 1a, 1b, 1c is completely independent. The stripes in the figure represent contour lines, and the stripe number is a line with a displacement of 0. The younger stripe number indicates the downward displacement, and the upper stripe number indicates the upward displacement.

In the present invention shown in FIG. 4, the number of contour lines is small,
It can be seen that the amount of deformation is small with almost all stripe numbers.
Further, contour lines are smoothly connected between the divided mirror shells 1a, 1b, 1c.

On the other hand, in the conventional one shown in FIG. 5, the contour lines are dense and the deformation amount is more than twice, and the stripe numbers are different at the edges even between the adjacent split mirror shells. From this, it can be seen that there is a large step. Further, although not shown in the figure, a large gap also occurs between each split mirror shell.

In the structure according to the present invention, for example, the opening diameter is 5
When applied to meters and three-part ones, the weight increase is
It only takes about 1.5kg. On the other hand, in order to obtain the same accuracy as the one according to the present invention, it is necessary to take measures such as significantly increasing the number of columns 3 and significantly increasing the thickness of the mirror-like shell 1, and at that time, Will increase the weight (in the case of similar things, more than 5kg).

<Effects of the Invention> According to the antenna mirror surface structure of the present invention, since the fitting structure is provided between the split mirror surface shells, the deformation due to the expansion and contraction of the mirror surface shell due to the temperature change of the mirror surface forms the fitting structure. It is absorbed by the sliding between the members, and the deformation in the out-of-plane direction is also suppressed by the restraint of the fitting members, so that a smooth mirror surface is always obtained and the performance is not deteriorated. Further, the weight increase due to the adoption of this structure is slight, which is also advantageous in this respect.

[Brief description of drawings]

1 (a) and 1 (b) are enlarged partial perspective views of a split mirror surface shell constituting an antenna mirror surface according to an embodiment of the present invention, FIG.
FIG. 3 is a partial perspective view showing a different state of the embodiment, FIG. 4 is an explanatory view showing the deformed state of the antenna mirror surface according to the embodiment with contour lines, and FIG. The same explanatory view, FIG. 6 is a perspective view of the parabolic antenna mirror surface, FIG.
The figure is its cross-sectional view, Figure 8 is a perspective view of the mirror surface divided into three parts, and Figures 9 and 10 show the shadow of the antenna mirror surface.
It is an explanatory view of a state in which deformation occurs due to a temperature difference. In the drawing, 1 is a mirror surface shell, 1a, 1b, 1c are split mirror surface shells, 2 is a mirror surface, 3 is a pillar, 4 is a skeleton structure, 7 is a skin, 8 is an aluminum honeycomb core, 9 is a fitting structure, 10, Reference numeral 11 is a fitting member, 10a is a concave portion, and 11a is a convex portion.

Claims (1)

[Claims] 1. A mirror shell forming a reflecting surface of a reflector antenna is divided into a plurality of pieces, and further along an outer edge where the boundaries of the respective split mirror shells are in contact with each other, in an in-plane direction at a boundary portion between adjacent split mirror shells. While allowing different movements of the two split specular shells, different movements in the out-of-plane direction at the boundary between the adjacent split specular shells and the deformation so that the tangent of the curved surface becomes discontinuous across the boundary of the adjacent split specular shells And a reflecting structure formed by the split mirror surface shell, which has a structure in which a part of the split mirror surface shell of one of the split mirror surfaces overlaps with a part of the reflecting surface of the other split mirror surface shell. An antenna mirror surface characterized in that when a gap is generated at the boundary by different movements of the split mirror shell in the in-plane direction, the surface of the fitting portion on the reflection surface side becomes the reflection surface in the gap portion. Construction.