JPH09172322A - Antenna reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve bending stiffness of an outer circumference of a reflector without remarkable increase in a mass and losing a size stability by folding an outer ridge of the reflector toward the rear side. SOLUTION: An outer circumference of a reflector 1 is folded back toward its rear side in a U-shape to form an edge 3. Through the provision of the edge 3 as above, the bending stiffness of an outer ridge of the reflector 1, that is, the geometrical moment of inertia is considerably improved by a multiple of 100 or over. Thus, the natural frequency of the outer ridge of the reflector 1 having been 39Hz without the fold-back is improved to 57Hz, and then the natural frequency of the reflector 1 is sufficiently higher than a natural frequency of a rocket. The edge 3 is formed simply when the reflector 1 is formed. Furthermore, since no adhesives is in use, a high stiffness is realized with a very light weight. Moreover, an outer circumference of a film antenna may sometimes be defective in the case of its handling, but the surrounding of the outer circumference is reinforced through the provision of the foldback.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna mounted on an artificial satellite, and more particularly to an aperture type antenna.

[0002]

2. Description of the Related Art Antennas mounted on space equipment such as artificial satellites are used for communication and radio wave observation.
In order to reduce the weight of satellites and load other mission devices as much as possible, it is required to reduce the weight of antennas to the limit. On the other hand, the performance required for the antenna is resistance to the severe mechanical environment at launch and dimensional stability in the severe thermal environment on the orbit. In order to realize these in a lightweight structure, a honeycomb sandwich structure using a fiber reinforced plastic material having high dimensional stability, specific rigidity and specific strength as a skin has been adopted as an antenna structural member. Examples of the use include a carbon fiber reinforced plastic woven fabric as the skin material, and aluminum or carbon fiber reinforced plastic as the skin material as the core material forming the honeycomb. However,
Due to the demand for further weight reduction, a method of replacing the reflector and the back structure forming the antenna with a film structure has been adopted in recent years. Membrane structure means that the reflector has a minimum thickness that can maintain the shape of the radio wave reflection surface, and is equal to or thinner than the thickness of one skin of the sandwich structure that forms the conventional reflector. A woven fabric of carbon fiber reinforced plastic is an example of the use of the material of the membrane structure. Behind the introduction of the membrane structure is the establishment of a technique for weaving a material having high rigidity and low thermal expansion so as to be isotropic with respect to thermal expansion, and a technique for molding the woven fabric. FIG. 6 shows an example of a conventional antenna. In the figure, 1 is a reflector and 2 is a back structure.

[0003]

Since the conventional reflector having the film structure has almost no bending rigidity, the outer edge portion of the reflector, that is, the portion not supported by the back structure is a cantilever simple support structure of the plate material, This part has an eigenvalue in a low frequency range near the rocket eigenvalue such as 30 Hz to 40 Hz. As a result, the relevant part resonates at the time of launch, and excessive acceleration is applied, which poses a great risk in terms of strength. In order to avoid this risk, it is necessary to make the eigenvalue of the relevant part sufficiently higher than the eigenvalue of the rocket in order to prevent resonance.

In order to suppress such local vibration of the outer edge of the reflector, it is effective to dispose the back structure also on the outer edge of the reflector. However, the additional back structure and the joint between the back structure and the reflector are significantly added. Cause a significant increase in mass.

The present invention has been made for the purpose of increasing the bending rigidity of the outer edge portion of the reflector so that the outer edge portion of the reflector does not resonate with the rocket, and without significantly increasing mass and impairing dimensional stability. Is.

[0006]

Embodiment 1 of the present invention
The antenna reflector according to (1) improves the bending rigidity of the outer periphery of the reflector by bending the outer edge of the reflector to the back side.

The antenna reflector according to the second embodiment of the present invention is thickened as necessary so that the outer edge portion of the reflector has bending rigidity.

Further, in the antenna reflector according to the third embodiment of the present invention, a lightweight and high-rigidity beam is arranged in the form of a cobweb at the outer periphery of the reflector and the outer edge portion of the reflector rear surface,
The rigidity of the outer edge portion is improved.

The antenna reflector according to the fourth embodiment of the present invention has a sandwich structure arranged at the outer edge portion of the rear surface of the reflector to improve the bending rigidity of the outer edge portion.

Further, in the antenna reflector according to the fifth embodiment of the present invention, the bending rigidity of the outer edge portion is improved by forming a part of the back structure with a thin thin rod.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 (a) and 1 (b) are views showing a first embodiment of the present invention, FIG. 1 (a) is an overall view of an antenna, and FIG. 1 (b) is an enlarged sectional view. 1 in the figure
Is a reflector, 2 is a back structure, and 3 is an edge obtained by folding the outer periphery of the reflector 1 in a U-shape on the back side. By providing the edge 3, the bending rigidity of the outer edge portion of the reflector, that is, the second moment of area is remarkably improved to 100 times or more. For this reason, the natural frequency of the outer edge portion of the reflector was 39 Hz when there was no folding back, but it increased to 57 Hz according to the first embodiment shown in FIG. 1, and has a eigenvalue sufficiently higher than the natural frequency of the rocket. . Edge 3
Can be easily formed at the time of molding the reflector 1. Moreover, since no adhesive is used, extremely lightweight and high rigidity can be realized. Further, the membrane antenna is liable to be damaged at the outer periphery during handling, but it has an advantage that the outer peripheral end portion is reinforced by providing the folded portion.

Embodiment 2. 2A and 2B are views showing a second embodiment of the present invention, FIG. 2A is an overall view of an antenna, and FIG. 2B is an enlarged sectional view.
Reference numeral 1 is a reflector, 2 is a back structure, and 4 is a doubler. The doubler is a member made of a material having exactly the same layer and thickness as the reflector material. The doubler increases the thickness of the reflector by adhering it to the reflector or heating it when molding the reflector to reinforce the reflector. The doubler 4 is arranged in a range extending from the joint between the back structure 2 and the reflector 1 to the outer edge portion of the reflector 1. Flexural rigidity of the outer edge of the reflector due to the doubler 4 (second moment of area)
Improves with the cube of the film thickness. The natural frequency of the outer edge portion of the reflector when the doubler was not provided was 39 Hz, but according to the embodiment shown in FIG.
It has an eigenvalue sufficiently higher than the natural frequency of the rocket.
Furthermore, according to this mode, the external dimensions are almost the same, which is effective when the envelope area of the antenna when the satellite is mounted is limited.

Embodiment 3 3 is a diagram showing a third embodiment of the present invention. In the figure, 1 is a reflector, 2 is a back structure, and 5 is a reinforcing beam. The outer edge of the reflector is divided into two parts by arranging a beam made of lightweight fiber reinforced composite material with small thermal expansion etc. on the rear edge of the reflector and having sufficient rigidity to suppress deformation of the outer edge in a spider web shape. By reducing the vibrating area of the outer edge of the reflector, the natural value of the local vibration of the outer edge of the reflector can be increased without increasing the mass significantly. The number of unique signals at the outer edge of the reflector when the reinforcing beam was not arranged was 39 Hz, but according to the third embodiment shown in FIG.
z, and has an eigenvalue sufficiently higher than the natural frequency of the rocket.

Embodiment 4 4A and 4B are views showing a second embodiment of the present invention, FIG. 4A is an overall view of the antenna, and FIG. 4B is an enlarged sectional view.
In the figure, 1 is a reflector, 2 is a back structure,
6 is a sandwich plate. The rigidity of the outer edge portion of the reflector 1 can be increased by arranging a sandwich structure having a light weight and extremely high bending rigidity on the outer edge portion of the back surface of the reflector. The natural frequency of the outer edge of the reflector when the sandwich plate was not provided was 39 Hz.
According to the fourth embodiment shown in (1), the frequency is improved to 55 Hz, which has a eigenvalue sufficiently higher than the natural frequency of the rocket. Further, although the outer periphery of the membrane antenna is likely to be damaged during handling, the outer edge portion is reinforced by the sandwiched outer edge portion.

Embodiment 5 5 is a diagram showing a fifth embodiment of the present invention, in which 1 is a reflector, 2 is a back structure, and 7 is a beam member. Reflector 1
By assembling the beam member 7 in the truss structure between the outer periphery and the back structure 2, it is possible to suppress local vibration of the outer edge portion of the reflector 1. The natural frequency of the outer edge of the reflector of 39 Hz when the truss structure is not provided is increased to 60 Hz according to the fifth embodiment shown in FIG. 5, and has a eigenvalue sufficiently higher than the natural frequency of the rocket.

[0016]

According to the first embodiment of the present invention, by bending the outer periphery of the reflector, it is possible to prevent vibration of the outer edge portion of the reflector at low frequencies.

According to the second embodiment of the present invention, the rigidity of the outer edge portion can be improved by making the outer edge portion of the reflector thicker than the central portion.

According to the third embodiment of the present invention, the rigidity of the outer edge portion can be improved by arranging the thin rods in the shape of a spider web on the outer edge portion of the rear surface of the reflector.

According to the fourth embodiment of the present invention, the outer peripheral portion of the reflector rear surface has a sandwich structure, whereby the rigidity of the outer edge portion can be improved.

According to the fifth embodiment of the present invention, the rigidity of the outer edge portion can be improved by connecting the outer periphery of the reflector and the back structure with a thin rod truss.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of an antenna reflector according to the present invention.

FIG. 2 is a diagram showing a second embodiment of the antenna reflector according to the present invention.

FIG. 3 is a diagram showing Embodiment 3 of the antenna reflector according to the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the antenna reflector according to the present invention.

FIG. 5 is a diagram showing a fifth embodiment of an antenna reflector according to the present invention.

FIG. 6 is a diagram showing a conventional antenna reflector.

[Explanation of symbols]

1 antenna reflector, 2 back structure, 3
Edges, 4 doublers, 5 reinforcement beams, 6 sandwich structures, 7 beam members.

Claims (5)

[Claims] 1. A reflector having a metal surface or a radio wave reflecting surface equivalent thereto and having a film-like structure, and a back structure coupled to the back surface of the reflector and supporting the reflector, wherein an edge of an outer periphery of the reflector is formed. Antenna reflector characterized by being bent. 2. A reflector having a metal surface or a radio wave reflection surface equivalent thereto and having a film-like structure, and a back structure coupled to the back surface of the reflector to support the reflector, and the other outer portion of the reflector. An antenna reflector having a thicker portion than the portion. 3. A reflector having a metal surface or a radio wave reflection surface equivalent thereto and having a film-like structure, and a back structure coupled to the back surface of the reflector to support the reflector, and a spider web on the back surface of the reflector. Antenna reflector characterized by arranging thin rods. 4. A reflector having a metal surface or a radio wave reflecting surface equivalent thereto and having a film-like structure, and a back structure coupled to the back surface of the reflector to support the reflector, and an outer edge of the back surface of the reflector. An antenna reflector having a sandwich structure in its part. 5. A back having a metal surface or a radio wave reflection surface equivalent thereto and having a film-like structure, and a back which is coupled to the back surface of the reflector and supports the reflector, and a part of which is a thin rod truss. An antenna reflector characterized by comprising a structure.