JPH07226619A - Emission reflector - Google Patents

Abstract

PURPOSE: To provide a light fabric which is composed of three axes and which can be formed by single ply. CONSTITUTION: The reflection face of a reflector is generated by a thin film formed in a prescribed form. The thin film is composed of the fabric where more than three threads 40 extending along the three different axes 42a, 42b and 42c in the same plane are woven. When constant force operates on the inplane direction of the fabric, uniform distortion occurs which does not depend on the direction of force in the fabric.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD This invention relates to lightweight reflectors for use with antennas, and more particularly to tri-axial fabrics.
It relates to an ultra-light reflector formed in c) and connected to a satellite antenna. Such a reflector can be deformed by acceleration or slight contact, and can return to its original shape after deformation.

[0002]

BACKGROUND ART Reflectors have become an important issue in antenna design. The weight of the antenna is very expensive, because the cost of launch is closely related to the mass of the satellite.
It is also important that the reflector adapts to the external environment of launch and orbit conditions. Such external environment includes gravity,
Includes acoustic noise, extreme temperatures. There is also a demand for so-called "shaped" surfaces of the reflector, which can be intentionally distorted during manufacturing so that the area of radiation emanating from the surface of the reflector can be precisely controlled. is there.

There are numerous reflector designs with woven fabrics. An example is U.S. Pat. No. 4,092,453 by Jonda, issued May 30, 1978.
No. The interweaving of multiple strands of the fabric extends perpendicularly to the other strand (this weave is bi-axial). Although this weaving process provides a considerable strength improvement over the prior art, the problem is that the materials of the above patents exhibit different strength properties when the direction of the force applied to the fabric is different. For example, when a force is applied parallel to the direction of extension of the strands of the fabric, the reflector has a much greater resistance to deformation and strain than when the force makes an angle with the strand in the plane of the fabric. Present.

US Pat. No. 4,868,580 by Wade, issued September 19, 1989, and US Pat. No. 4, by Boan et al., Issued March 14, 1989. , 812,854 show a weaving pattern for a textile reflector different from the vertical textile described in Jonda. Both of the above conventional fabrics exert a considerable resistance to the applied strain due to their weight above Jonda. These fabrics exhibit different properties when a constant force is applied respectively in different directions of the fabric.

Another reflector utilizing woven fabric is Gounder, which was patented on January 6, 1987.
der) et al., U.S. Pat. No. 4,635,071. The woven strands of each layer of fabric extend parallel to all of the other strands of that layer. There are multiple layer fabrics where each layer extends at an angle of approximately 60 degrees with the other layers of the fabric. Textile yarns extending in different directions are not interwoven with each other. Also, the use of multiple layers of fabric results in significant material use and is being considered for manufacturing.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a fabric including a plurality of strands of the fabric and used in a reflector. In such a fabric, a plurality of yarns extending along different axes are interwoven with each other. It should be noted that the multiaxial fabric has at least three axes. From the above, the multi-axial (at least tri-axial) woven fabric produces a certain resistance against strain when a force is applied in the plane of the material, so it is used in spacecraft and other fields. Can be applied to the manufacture of a lightweight and resilient reflector connected to an antenna.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention discloses a reflector for use in a spacecraft, but its application examples (and the specific construction of the reflector) and materials are examples and are limited by the claims. is not. The invention applies to any reflector used with space or terrestrial devices, whether or not the reflector is coupled to the antenna or any structure used. However, the present invention is particularly suitable for use in spacecraft as it forms a structure that is fairly lightweight, sturdy and resilient.

The present invention, as shown in FIG.
It relates to an ultralight thin film reflector 10 suitable for use with an antenna 12 (satellite in the drawing). The spacecraft has a steering surface 15 that does not form part of the invention. As shown in FIG.
The thin film reflector 10 has a support 18 including a peripheral ring 20 and a rear support 22. As will be described below, the thin film 24 formed from the woven fabric 26 including a large number of twisted yarns is also included in the thin film reflector 10. Many of the dimensions of the thin film reflector 10 when properly supported are in the range of 1-3 m, but any dimension may be utilized and deployed as needed.

An exploded perspective view and a side view of the support 18 are shown in FIGS. 3 and 4, respectively. The support body is formed of an outer peripheral ring 20 and a rear support portion 22. Both the outer ring 20 and the inner supporting portion are formed by the thin film 24 (see FIG. 1).
(Shown in Fig.) Is required for a flat surface, parabolic shape,
It is configured to support a hyperboloid shape or an arbitrary geometric shape. The support is attached to the spacecraft utilizing any known and suitable fasteners attached to the connection 29. The outer ring 20 may be made of any lightweight material (usually a synthetic material) with a much lower coefficient of expansion, but is preferably made to form a sturdy and lightweight structure and keep thermal expansion fairly low. , Having a core formed from a graphite honeycomb structure. The composite member is formed using well-known manufacturing methods except foam molding which is considered suitable.

The reason that the coefficient of thermal expansion is important in satellite applications is due to the severity of the temperature change when comparing the face of the reflector facing the sun with the face of the reflector behind the sun. is there. The temperature of the spacecraft is 130 ℃ when facing the sun.
To -180 ° C when in the shade. Due to this temperature change, when the satellite reflector is used reliably in the communication field, it is important that the coefficient of thermal expansion be approximately one part per million for a temperature change of 1 ° C. Different applications of satellite reflectors may require higher or lower coefficients of thermal expansion than the above numbers.

The thin film 24 is fixed only to the outer peripheral ring 20 and is supported only by the outer peripheral ring 20. The rear support portion 22 includes a plurality of support members 32 and an inner peripheral ring 3 of one.
3 and 3. The outer peripheral ring 20 is supported by a plurality of support members 32 (preferably at least 6) which are fixed only to the inner peripheral ring 33 and are supported by the inner peripheral ring 33. The rear support preferably comprises a unidirectional expanded fabric formed from a graphite composition having a high modulus and a low coefficient of thermal expansion. Outer ring 2
The materials and manufacturing methods as described above with reference to No. 0 also apply to the inner ring 33 and the support member 32. The rear support 22 is formed from a minimum number of integrally formed tubular members to reduce weight. Multiple layers of insulation are provided to protect all or part of the reflector and support structure from the thermal environment exposed to the tracks. Thin film 24
The front side of the is left uncoated to avoid the thermal effects of paint and other coatings.

As shown in FIG. 5, the thin film 24 comprises a high modulus (preferably graphite) fiber 40 provided as a tri-axial coarse mesh pre-impregnated with a reinforced resin. Stranded film (thickness approximately 0.254 mm (0.010 inches) to 1.016 m
m (0.040 inch)). The dimensions of such films are typically used to reflect radiation in the microwave spectrum. Although the size range of the above membrane materials is not available in the visible or short wavelength electromagnetic spectrum (radiation can be transmitted through the membrane or deflected from each fiber at any angle), radiation from microwave radiation can It interfaces with membranes that are 0.254 mm (0.010 inches) to 1.016 mm (0.040 inches) thick as if it were a continuous material. Therefore, the woven thin film of the present invention is widely used in the microwave field.

The present invention is applied to a triaxial woven fabric, but may be applied to any multiaxial woven fabric as long as the polyaxial is at least triaxial. For example, in the triaxial fabric shown in FIG. 5, each fiber extends along three co-axial axes 42a, 42b, 42c, each axis forming an angle of intersection of approximately 60 degrees with each other. Each axially extending fiber is woven with fibers that do not extend in the same axial direction.

The effect of the multiaxial woven fabric shown in FIG. 5 will be described in comparison with the conventional biaxial woven fabric shown in FIG. Biaxial fabric is
When the strain force F1 is applied substantially parallel to one of the axes 46 and 48, a considerably higher flexural resistance is exhibited as compared with when the strain force F2 is applied in the directions of the angles 50a and 50b with respect to both axes. . The triaxial woven fabric of the present invention shown in FIG.
Is applied substantially parallel to one of the axes 42a, 42b, 42c, or the strain force F4 is applied to the three axes 42a, 42b, 42c.
Strain force F4 is closer to being parallel to one or more of the axes than normal strain force F2, regardless of whether each is applied at a non-zero angle 54a, 54b, 54c. Present. The uniformity of this flexural resistance (the material exhibits isotropicity in four directions in the plane of the fabric) ensures that the membrane undergoes a constant strain when any force is applied to the fabric. Not only that, it ensures that the fabric opposes forces that tend to cause irreversible strains in the membrane 24. The triaxial fabric ensures that the desired resistance to the forces applied from any direction is provided without increasing the weight of the membrane 24.

The above-described configuration of the thin film reflector 10 is ultra-light and suitable for use as an antenna reflector of the communications satellite 14. The thin film 24 fabric is fairly lightweight, thermally stable, durable, sensitive, and radio frequency (RF).
And forming a reflecting surface at microwave frequencies. The fabric is
Easily molded as a flat surface, paraboloid, hyperboloid, or any desired surface. The membrane 24 is deformable by the forces (either gravity or contact forces) encountered by the membrane reflector 10 when the spacecraft is launched or deployed.

The thin film 24 is so-called "shaped".
It is also possible to form the surface into a unique shape.
Such a shaping surface is arranged such that the radiation is reflected at the surface of the membrane in the desired form. For example, the thin film reflector 10
May be used to supply radiation across the continent, which may require limiting the direction in which the radiation should be directed into the interior of the continent (usually an irregular shape). is there. It may be necessary to modify the configuration of the membrane 24 so that the ratio of emitted or received radiation is higher for the desired area. Forming the membrane aids in the above applications. With respect to molding, an advantage of the present invention compared to a heavy duty reflector is that the molding of thin film 24 of the current system is easy to manufacture. Since conventional reflectors are thick and relatively strong, it has been difficult in many cases to form them with high precision.

The ability to manufacture a single layer thin film 24 reduces the thermal mass of the thin film reflector 24 and further reduces the coefficient of thermal expansion (CTE) to near zero, thus improving thermal stability and also. , The manufacturing process will be much easier. Due to the coarse texture of the fabric, the acoustic vibration force (pressure applied by sound waves) is mitigated by the thin film. The acoustic vibration environment acting during launch of the satellite 14 is a fairly severe design requirement for lightweight surfaces such as the thin film reflector 10.

[Brief description of drawings]

1 is a perspective view of one embodiment of a spacecraft (14) including an antenna (12) and a reflector (10) of the present invention.

2 is a side view of one embodiment of the reflector (10) of the present invention for use with the spacecraft (14) shown in FIG.

3 is a perspective view of a support (18) of the reflector of FIG.

FIG. 4 is a side view of the support (18) of FIG.

FIG. 5 is an exploded view of an example of a multiaxial fabric used in the reflector of FIG.

FIG. 6 is a view similar to FIG. 5 of a conventional biaxial woven fabric.

[Explanation of symbols]

 10 reflector 24 thin film 40 twisted yarn 42a, 42b, 42c axis

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display part H01Q 15/16

Claims (20)

[Claims] 1. A lightweight radiation reflector for use with an antenna, comprising a plurality of strands extending in the same plane along at least three different axes and braided together. A radiation reflector characterized in that it has a lightweight and multi-axis, singly-ply and shaped woven fabric composed of twisted yarns. 2. The reflector according to claim 1, further comprising a support for supporting the reflector. 3. The reflector according to claim 2, wherein the support has a honeycomb structure. 4. The reflector according to claim 2, wherein the multiaxial fabric is molded into a geometric shape, and the support is attached to the fabric formed at a plurality of locations. 5. The reflector according to claim 2, wherein the support has an outer peripheral ring member. 6. The reflector according to claim 5, wherein the outer peripheral ring member is made of graphite. 7. The reflector according to claim 5, wherein the outer peripheral ring member has a honeycomb structure. 8. The reflector according to claim 5, wherein the outer peripheral ring member is made of a material having a small thermal expansion. 9. The reflector according to claim 2, wherein at least a part of the support is molded. 10. The reflector according to claim 9, wherein the support is molded by foam molding. 11. The reflector according to claim 1, wherein the woven fabric is molded into a paraboloidal shape. 12. The reflector according to claim 1, wherein the woven fabric is molded in a planar shape. 13. The reflector according to claim 1, wherein the reflector is molded into a hyperboloid shape. 14. The twisted yarn has a high modulus.
Reflector according to claim 1, characterized in that it comprises an odulus) graphite fiber. 15. The reflector according to claim 1, wherein the braided yarn is woven. 16. The reflector of claim 1, further comprising a multi-layer insulator that protects all or a portion of the reflector from the thermal environment of the track. 17. A lightweight multiaxial fabric suitable for use in a radiation reflector, comprising a plurality of fibers comprising at least three strands extending along at least three different axes and braided together. A multiaxial woven fabric comprising a single-layer woven fabric composed of the twisted yarns of. 18. The fabric of claim 17, wherein the fiber comprises a high modulus graphite fiber. 19. The woven fabric according to claim 17, which is molded into a geometric shape. 20. The woven fabric according to claim 17, wherein the entangled twisted yarn is knitted.