JP2010206249A - Grid reflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress decrease in reflector condensation and decrease in radio wave reflectance caused by anisotropy of thermal deformation occurring in grid reflectors. <P>SOLUTION: The grid reflector includes an antenna specular surface comprising a fiber reinforced composite material 3, and a grid pattern 4 that is formed on or inside the surface of the antenna specular surface, and includes a conductive material. As the fiber reinforced composite material 3, anisotropy of a thermal expansion coefficient opposite to that of the grid pattern 4 is achieved. The fiber reinforced composite material 3 includes first reinforced fiber oriented in a direction, where stiffness in a direction parallel to a grid patterning direction 5 and contribution to the thermal expansion coefficient are large, and a second reinforced fiber oriented in a direction, where stiffness in a direction perpendicular to the grid patterning direction 5 and contribution to the thermal expansion coefficient are large. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a grid reflector for a satellite-mounted antenna mounted on a space device such as an artificial satellite or a spacecraft.

  With the demand for increasing the communication capacity using satellites, there is a strong demand for effective use of limited frequencies in satellite communications. One possible solution is to use orthogonal polarization. By using orthogonal polarization, two polarizations can be used in one bandwidth, and twice as many signals can be transmitted.

  Here, the satellite-mounted dual grid antenna (polarized polarization antenna) enables two orthogonally polarized waves to be used, and is also used in commercial communication satellites as an orthogonally polarized wave shared antenna.

  When a normal parabolic antenna is used, cross-polarization is generated from the offset reflector, so that sufficient isolation between polarizations cannot be obtained. In addition, since the feed system is used for orthogonal polarization, there is a problem that the feed circuit becomes complicated and physical restrictions are large. As a result, polarization sharing is difficult.

  One way to solve this problem is to use this dual grid antenna. By using the dual grid antenna, the cross polarization component generated from the mirror surface can be reduced, and the feed system can be separated by the polarization. For this reason, there exists the characteristic which can simplify each electric power feeding circuit.

  From such a background, a grid reflector using two orthogonal linearly polarized waves is employed in a conventional antenna reflector for a communication satellite (for example, see Patent Documents 1 and 2). As a mirror surface material of a conventional grid reflector, for example, fiber reinforced plastic (FRP) is used, and as a grid material, for example, a conductor material such as copper is used.

  In general, the thermal expansion coefficient of the conductor material that is the grid material is larger than that of the fiber reinforced plastic of the mirror material. In the grid reflector, the grid material is linearly patterned on the antenna mirror surface with a width and an interval determined from a design requirement corresponding to a frequency band of communication radio waves. In the technique of Patent Document 2, conductive fibers embedded in a mirror surface are used as a grid material.

JP-A-8-37418 JP 2003-347840 A

However, the prior art has the following problems.
In the configuration as disclosed in Patent Document 1, for example, when a temperature rise occurs in the antenna reflector, thermal stress due to a difference in thermal expansion coefficient is generated in the grid material and the mirror surface material. That is, in a direction parallel to the grid patterning direction, a tensile load is applied to the mirror surface material by the grid material having a relatively large thermal expansion coefficient. As a result, the mirror surface extends.

  On the other hand, in the direction perpendicular to the patterning direction of the grid, the grid pattern is intermittently formed on the mirror surface. For this reason, even if each grid pattern thermally expands in the direction perpendicular to the patterning direction (grid width direction), the tensile stress generated in the fiber-reinforced composite material is locally distributed in the vicinity of the grid crimping part. Will be.

  As a result, the amount of extension deformation of the entire antenna in the direction perpendicular to the patterning direction is smaller than that in the direction parallel to the patterning direction. Furthermore, shrinkage deformation occurs in the direction perpendicular to the patterning direction due to the Poisson effect of the mirror surface material due to the tensile load in the patterning direction. Due to the above effects, anisotropy occurs in the amount of thermal deformation in two directions, ie, a parallel direction and a perpendicular direction to the patterning direction of the grid reflector.

  On the other hand, when the temperature drop occurs, the behavior is opposite to that when the temperature rise occurs, and anisotropy occurs in the amount of thermal deformation in two directions. As described above, when the grid reflector has anisotropy in the amount of thermal deformation, the shape after thermal deformation due to temperature change is not similar to the original shape, and the light collecting property of the reflector is reduced. I will invite you.

  Moreover, in the technique of patent document 2, the conductive fiber embedded in the mirror surface inside is used as a grid material. For this reason, the thermal deformation anisotropy similar to the above occurs due to the difference in characteristics from the dielectric fiber which is the reinforcing fiber constituting the mirror surface. Patent Document 2 discloses means for solving this problem by cutting the conductive fibers into short pieces and mixing them. However, this method causes a reduction in radio wave reflectance.

The present invention has been made in order to solve the above-described problems, and suppresses a decrease in the light collecting property of the reflector and a decrease in the radio wave reflectance caused by the anisotropy of thermal deformation occurring in the grid reflector. It aims at obtaining the grid reflector which can do.

  A grid reflector according to the present invention is a grid reflector comprising an antenna mirror surface made of a fiber reinforced composite material and a grid pattern made of a conductor material formed on the surface of the antenna mirror surface or inside thereof, and as a fiber reinforced composite material, Anisotropy of thermal expansion coefficient opposite to that of the grid pattern is provided.

  According to the present invention, the fiber-reinforced composite material has an anisotropy of a thermal expansion coefficient opposite to that of the grid pattern, and a conductive material is used as the grid material, resulting in anisotropy of thermal deformation generated in the grid reflector. Thus, it is possible to obtain a grid reflector that can suppress a decrease in light collecting performance and a decrease in radio wave reflectance of the reflector.

It is an enlarged view which shows the dual grid reflector in Embodiment 1 of this invention. It is an enlarged view which shows the dual grid reflector in Embodiment 2 of this invention. It is an enlarged view which shows the dual grid reflector in Embodiment 3 of this invention.

  Hereinafter, a preferred embodiment of a grid reflector of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is an enlarged view of a dual grid reflector according to Embodiment 1 of the present invention. The dual grid reflector in FIG. 1 includes an antenna mirror surface formed by a plain woven fiber reinforced composite material 3 composed of reinforcing fibers 1 and reinforcing fibers 2, and a grid pattern 4. Further, the reinforcing fiber 1 and the reinforcing fiber 2 are respectively oriented in a direction parallel to the patterning direction 5 and in a direction perpendicular thereto. The grid pattern 4 is formed of a conductive material that is formed on the surface or inside of the antenna mirror surface and patterned.

The reinforcing fiber 2 has a fiber direction thermal expansion coefficient or fiber direction tensile elastic modulus different from that of the reinforcing fiber 1. More specifically, the reinforcing fiber 2 is
(Case 1) A reinforcing fiber having a fiber direction thermal expansion coefficient comparable to that of the reinforcing fiber 1 and a fiber direction tensile elastic modulus smaller than that of the reinforcing fiber 1,
(Case 2) Reinforcing fiber having a fiber direction tensile elastic modulus comparable to that of the reinforcing fiber 1 and having a fiber direction thermal expansion coefficient larger than the reinforcing fiber 1,
(Case 3) One of the reinforcing fibers whose fiber direction tensile elastic modulus is smaller than that of the reinforcing fiber 1 and whose fiber direction thermal expansion coefficient is larger than that of the reinforcing fiber 1.

  Examples of the combination of the reinforcing fiber 1 and the reinforcing fiber 2 include PBO (polyparaphenylene benzoxazole) fiber and p-aramid fiber, respectively. Moreover, as a material of the grid pattern 4, copper etc. are used, for example. Furthermore, as resin which comprises the plain weave fiber reinforced composite material 3, cyanate resin etc. are used, for example, and the tensile elasticity modulus is one digit or more smaller than the fiber direction tensile elasticity modulus of a reinforced fiber.

  On the other hand, as for the thermal expansion coefficient, the fiber-direction thermal expansion coefficient of the reinforcing fiber shows a negative value, whereas the thermal expansion coefficient of the resin material is one or more orders of magnitude larger than the thermal expansion coefficient of the reinforcing fiber as an absolute value. Indicates a positive value.

  The thermal expansion coefficient of the plain weave fiber reinforced composite material 3 is determined by the tensile elastic modulus and thermal expansion coefficient of the reinforcing fiber and the resin, and the volume content of the reinforcing fiber and the resin. Generally, the thermal expansion coefficient of the conductor material forming the grid pattern 4 is larger than the thermal expansion coefficient in the patterning direction 5 of the plain weave fiber reinforced composite material 3.

  According to such a configuration, for example, when a temperature rise occurs in the grid reflector, the grid pattern 4 extends in the patterning direction 5. As a result, a tensile stress is generated in the patterning direction 5 in the plain weave fiber reinforced composite material 3. At this time, the plain weave fiber reinforced composite material 3 contracts in a direction perpendicular to the patterning direction 5 by the Poisson effect.

  With the above-described action, the thermal expansion coefficient in the direction parallel to the patterning direction 5 of the grid reflector is larger than the thermal expansion coefficient in the same direction of the plain weave fiber reinforced composite material 3 alone. On the other hand, the thermal expansion coefficient in the direction perpendicular to the patterning direction 5 of the grid reflector is smaller than the thermal expansion coefficient in the same direction of the plain weave fiber reinforced composite material 3 alone.

  Here, as in the first embodiment, in the direction perpendicular to the patterning direction 5, the reinforcing fiber has the same fiber direction thermal expansion coefficient as the reinforcing fiber 1 and a smaller fiber direction tensile elastic modulus than the reinforcing fiber 1. Consider the case of (Case 1) with 2 oriented. In this case, the thermal expansion coefficient in the direction perpendicular to the patterning direction 5 of the plain weave fiber reinforced composite material 3 is larger than the thermal expansion coefficient in the patterning direction 5.

  The anisotropy of the thermal expansion coefficient of the plain weave fiber reinforced composite material 3 thus generated and the anisotropy of the thermal deformation caused by the grid pattern 4 cancel each other. As a result, the amount of thermal deformation in the patterning direction 5 and the direction perpendicular to the patterning direction 5 become equal, and the isotropic thermal deformation behavior can be realized as the whole antenna reflector.

  Further, when (case 2) or (case 3) described above is employed as the reinforcing fiber 2, the same effect can be obtained, and the anisotropy of thermal deformation can be eliminated.

  The specifications of the grid pattern 4 can change depending on the frequency band of radio waves to be transmitted and received. The parameters that determine the specifications of the grid pattern 4 mainly include the grid width, the grid interval, the grid thickness, and the like. The magnitude of the anisotropic effect due to the grid pattern 4 varies depending on these parameters.

  In the configuration of FIG. 1 in the first embodiment, the case where 100% of one of the reinforcing fibers 1 or the reinforcing fibers 2 is used as the reinforcing fiber in each orientation direction is shown. However, the fiber blending ratio in each orientation direction can be changed. That is, it is also possible to use a fiber bundle in which the reinforcing fiber 1 and the reinforcing fiber 2 are blended in a desired ratio in each orientation direction. Accordingly, the thermal expansion coefficient reverse anisotropy of the plain weave fiber reinforced composite material 3 can be adjusted in accordance with the magnitude of the anisotropic effect of the thermal expansion coefficient by the grid pattern 4.

  As described above, according to the first embodiment, the fiber-reinforced composite material includes the reinforcing fiber oriented in the direction in which the contribution to the rigidity and the thermal expansion coefficient in the direction parallel to the patterning direction of the grid is large, and the patterning of the grid. It is composed of reinforcing fibers oriented in a direction having a large contribution to rigidity and thermal expansion coefficient in a direction orthogonal to the direction. Furthermore, by giving the fiber reinforced composite material the anisotropy of the coefficient of thermal expansion opposite to that of the grid pattern, the anisotropy of both is offset.

  Thereby, the thermal expansion coefficient as a whole antenna can be controlled to be isotropic. As a result, since non-similar thermal deformation is suppressed, a reduction in the light collecting performance of the antenna reflector caused by such thermal deformation is avoided. Furthermore, since a conductor material is used as the grid material, the radio wave reflectance does not decrease.

Embodiment 2. FIG.
In the first embodiment, the dual grid reflector having the antenna mirror surface formed by the plain weave fiber reinforced composite material 3 has been described. In the second embodiment, a case where a triaxial woven fiber reinforced composite material 6 is used instead of the plain woven fiber reinforced composite material 3 will be described.

  FIG. 2 is an enlarged view of the dual grid reflector according to the second embodiment of the present invention. The dual grid reflector in FIG. 2 includes an antenna mirror surface formed by a triaxial woven fiber reinforced composite material 6 (fiber orientation: +30 degrees, −30 degrees, 90 degrees) composed of reinforcing fibers 1 and reinforcing fibers 2, and a grid pattern 4. It consists of

  Furthermore, the reinforcing fiber 1 and the reinforcing fiber 2 have different fiber-direction thermal expansion coefficients or fiber-direction tensile elastic moduli, and are oriented as shown in FIG. The grid pattern 4 is formed of a conductive material that is formed on the surface or inside of the antenna mirror surface and patterned.

In the triaxial woven fiber reinforced composite material 6 in the second embodiment, when the patterning direction 5 is 0 degree, the reinforcing fibers are oriented at +30 degrees, −30 degrees, and 90 degrees, and the +30 degrees, −30 degrees directions Reinforcing fibers 1 are oriented in the direction, and reinforcing fibers 2 are oriented in the direction of 90 degrees. More specifically, the reinforcing fiber 2 is
(Case 1) A reinforcing fiber having a fiber direction thermal expansion coefficient comparable to that of the reinforcing fiber 1 and a fiber direction tensile elastic modulus smaller than that of the reinforcing fiber 1,
(Case 2) Reinforcing fiber having a fiber direction tensile elastic modulus comparable to that of the reinforcing fiber 1 and having a fiber direction thermal expansion coefficient larger than the reinforcing fiber 1,
(Case 3) One of the reinforcing fibers whose fiber direction tensile elastic modulus is smaller than that of the reinforcing fiber 1 and whose fiber direction thermal expansion coefficient is larger than that of the reinforcing fiber 1.

  Examples of the combination of the reinforcing fiber 1 and the reinforcing fiber 2 include PBO (polyparaphenylene benzoxazole) fiber and p-aramid fiber, respectively. Moreover, as a material of the grid pattern 4, copper etc. are used, for example. Furthermore, as resin which comprises the triaxial woven fiber reinforced composite material 6, cyanate resin etc. are used, for example, and the tensile elastic modulus is one digit or more smaller than the fiber direction tensile elastic modulus of a reinforced fiber.

  On the other hand, as for the thermal expansion coefficient, the fiber-direction thermal expansion coefficient of the reinforcing fiber shows a negative value, whereas the thermal expansion coefficient of the resin material is one or more orders of magnitude larger than the thermal expansion coefficient of the reinforcing fiber as an absolute value. Indicates a positive value.

  The thermal expansion coefficient of the triaxial woven fiber reinforced composite material 6 is determined by the tensile elastic modulus and thermal expansion coefficient of the reinforcing fiber and the resin, and the volume content of the reinforcing fiber and the resin. Generally, the thermal expansion coefficient of the conductor material forming the grid pattern 4 is larger than the thermal expansion coefficient in the patterning direction 5 of the triaxial woven fiber reinforced composite material 6.

  According to such a configuration, for example, when a temperature rise occurs in the grid reflector, the grid pattern 4 extends in the patterning direction 5. As a result, tensile stress is generated in the patterning direction 5 in the triaxial woven fiber reinforced composite material 6. At this time, the triaxial woven fiber reinforced composite material 6 contracts in a direction perpendicular to the patterning direction 5 by the Poisson effect.

  With the above-described action, the thermal expansion coefficient in the direction parallel to the patterning direction 5 of the grid reflector becomes larger than the thermal expansion coefficient in the same direction of the triaxial woven fiber reinforced composite material 6 alone. On the other hand, the thermal expansion coefficient in the direction perpendicular to the patterning direction 5 of the grid reflector is smaller than the thermal expansion coefficient in the same direction of the triaxial woven fiber reinforced composite material 6 alone.

  Here, as in the second embodiment, in the direction perpendicular to the patterning direction 5, the reinforcing fiber has the same fiber direction thermal expansion coefficient as the reinforcing fiber 1 and a smaller fiber direction tensile elastic modulus than the reinforcing fiber 1. Consider the case of (Case 1) with 2 oriented. In this case, the thermal expansion coefficient in the direction perpendicular to the patterning direction 5 of the triaxial woven fiber reinforced composite material 6 is larger than the thermal expansion coefficient in the patterning direction 5.

  The anisotropy of the thermal expansion coefficient of the triaxial woven fiber reinforced composite material 6 thus generated and the anisotropy of the thermal deformation caused by the grid pattern 4 cancel each other. As a result, the amount of thermal deformation in the patterning direction 5 and the direction perpendicular to the patterning direction 5 become equal, and the isotropic thermal deformation behavior can be realized as the whole antenna reflector.

  Further, when (case 2) or (case 3) described above is employed as the reinforcing fiber 2, the same effect can be obtained, and the anisotropy of thermal deformation can be eliminated.

  The specifications of the grid pattern 4 can change depending on the frequency band of radio waves to be transmitted and received. The parameters that determine the specifications of the grid pattern 4 mainly include the grid width, the grid interval, the grid thickness, and the like. The magnitude of the anisotropic effect due to the grid pattern 4 varies depending on these parameters.

  In the configuration of FIG. 2 in the second embodiment, the case where 100% of the reinforcing fiber 1 or the reinforcing fiber 2 is used as the reinforcing fiber in each orientation direction is shown. However, the fiber blending ratio in each orientation direction can be changed. That is, it is also possible to use a fiber bundle in which the reinforcing fiber 1 and the reinforcing fiber 2 are blended in a desired ratio in each orientation direction. Thereby, the thermal expansion coefficient reverse anisotropy of the triaxial woven fiber reinforced composite material 6 can be adjusted according to the magnitude of the anisotropic effect of the thermal expansion coefficient by the grid pattern 4.

  As described above, according to the second embodiment, even when a triaxial woven fiber reinforced composite material is used instead of the plain woven fiber reinforced composite material, the same effect as in the first embodiment can be obtained. .

Embodiment 3 FIG.
In the third embodiment, a case where a triaxial woven fiber reinforced composite material 7 having a structure different from that of the second embodiment is used will be described.

  FIG. 3 is an enlarged view of a dual grid reflector according to Embodiment 3 of the present invention. The dual grid reflector in FIG. 3 includes an antenna mirror surface formed by a triaxial woven fiber reinforced composite material 7 (fiber orientation: 0 degrees, +60 degrees, −60 degrees) composed of reinforcing fibers 1 and reinforcing fibers 2, and a grid pattern 4. It consists of

  Further, the reinforcing fiber 1 and the reinforcing fiber 2 have different fiber-direction thermal expansion coefficients or fiber-direction tensile elastic moduli, and are oriented as shown in FIG. The grid pattern 4 is formed of a conductive material that is formed on the surface or inside of the antenna mirror surface and patterned.

In the triaxial woven fiber reinforced composite material 7 in Embodiment 3, when the patterning direction 5 is 0 degrees, the reinforcing fibers are oriented at 0 degrees, +60 degrees, and −60 degrees, and the reinforcing fibers 1 are oriented in the 0 degree direction. Are oriented, and the reinforcing fibers 2 are oriented in the +60 degree and -60 degree directions. More specifically, the reinforcing fiber 2 is
(Case 1) A reinforcing fiber having a fiber direction thermal expansion coefficient comparable to that of the reinforcing fiber 1 and a fiber direction tensile elastic modulus smaller than that of the reinforcing fiber 1,
(Case 2) Reinforcing fiber having a fiber direction tensile elastic modulus comparable to that of the reinforcing fiber 1 and having a fiber direction thermal expansion coefficient larger than the reinforcing fiber 1,
(Case 3) One of the reinforcing fibers whose fiber direction tensile elastic modulus is smaller than that of the reinforcing fiber 1 and whose fiber direction thermal expansion coefficient is larger than that of the reinforcing fiber 1.

  Examples of the combination of the reinforcing fiber 1 and the reinforcing fiber 2 include PBO (polyparaphenylene benzoxazole) fiber and p-aramid fiber, respectively. Moreover, as a material of the grid pattern 4, copper etc. are used, for example. Furthermore, as resin which comprises the triaxial woven fiber reinforced composite material 7, cyanate resin etc. are used, for example, The tensile elastic modulus is smaller by one digit or more than the fiber direction tensile elastic modulus of a reinforced fiber.

  On the other hand, as for the thermal expansion coefficient, the fiber direction thermal expansion coefficient of the reinforcing fiber shows a negative value, whereas the thermal expansion coefficient of the resin material is larger by one or more digits than the thermal expansion coefficient of the reinforcing fiber as an absolute value. Indicates a positive value.

  The thermal expansion coefficient of the triaxial woven fiber reinforced composite material 7 is determined by the tensile elastic modulus and thermal expansion coefficient of the reinforcing fiber and the resin, and the volume content of the reinforcing fiber and the resin. In general, the thermal expansion coefficient of the conductive material forming the grid pattern 4 is larger than the thermal expansion coefficient in the patterning direction 5 of the triaxial woven fiber reinforced composite material 7.

  According to such a configuration, for example, when a temperature rise occurs in the grid reflector, the grid pattern 4 extends in the patterning direction 5. As a result, a tensile stress is generated in the patterning direction 5 in the triaxial woven fiber reinforced composite material 7. At this time, the triaxial woven fiber reinforced composite material 7 contracts in a direction perpendicular to the patterning direction 5 by the Poisson effect.

  With the above-described action, the thermal expansion coefficient in the direction parallel to the patterning direction 5 of the grid reflector becomes larger than the thermal expansion coefficient in the same direction of the triaxial woven fiber reinforced composite material 7 alone. On the other hand, the thermal expansion coefficient in the direction perpendicular to the patterning direction 5 of the grid reflector is smaller than the thermal expansion coefficient in the same direction of the triaxial woven fiber reinforced composite material 7 alone.

  Here, as in the third embodiment, the reinforcing fiber 2 having a fiber direction thermal expansion coefficient comparable to that of the reinforcing fiber 1 and having a fiber direction tensile elastic modulus smaller than that of the reinforcing fiber 1 is +60 degrees with respect to the patterning direction 5. Consider the case of (Case 1) oriented in the direction of -60 degrees. In this case, the thermal expansion coefficient in the direction perpendicular to the patterning direction 5 of the triaxial woven fiber reinforced composite material 7 is dominated by the fiber direction thermal expansion coefficient and the fiber direction tensile elastic modulus of the reinforcing fibers 2. Accordingly, the thermal expansion coefficient in the direction perpendicular to the patterning direction 5 of the triaxial woven fiber reinforced composite material 7 is larger than the thermal expansion coefficient in the patterning direction 5.

  The anisotropy of the thermal expansion coefficient of the triaxial woven fiber reinforced composite material 7 thus generated and the anisotropy of thermal deformation caused by the grid pattern 4 cancel each other. As a result, the amount of thermal deformation in the patterning direction 5 and the direction perpendicular to the patterning direction 5 become equal, and the isotropic thermal deformation behavior can be realized as the whole antenna reflector.

  Further, when (case 2) or (case 3) described above is employed as the reinforcing fiber 2, the same effect can be obtained, and the anisotropy of thermal deformation can be eliminated.

  The specifications of the grid pattern 4 can change depending on the frequency band of radio waves to be transmitted and received. The parameters that determine the specifications of the grid pattern 4 mainly include the grid width, the grid interval, the grid thickness, and the like. The magnitude of the anisotropic effect due to the grid pattern 4 varies depending on these parameters.

  In the configuration of FIG. 3 in the third embodiment, the case where 100% of the reinforcing fiber 1 or the reinforcing fiber 2 is used as the reinforcing fiber in each orientation direction is shown. However, the fiber blending ratio in each orientation direction can be changed. That is, it is also possible to use a fiber bundle in which the reinforcing fiber 1 and the reinforcing fiber 2 are blended in a desired ratio in each orientation direction. Thereby, the thermal expansion coefficient reverse anisotropy of the triaxial woven fiber reinforced composite material 7 can be adjusted in accordance with the magnitude of the anisotropic effect of the thermal expansion coefficient by the grid pattern 4.

  As described above, according to the third embodiment, even when a triaxial woven fiber reinforced composite material having a structure different from that of the second embodiment is used instead of the plain woven fiber reinforced composite material, the previous implementation is performed. The effect similar to the form 1 of this can be acquired.

  In the first to third embodiments described above, (Case 1) to (Case 3) are exemplarily shown, and a configuration of a dual grid reflector having a fiber-reinforced composite material composed of reinforcing fibers 1 and reinforcing fibers 2 is shown. And explained the effect. However, the present invention is not limited to these three cases, and the fiber reinforced composite material has an anisotropy of thermal expansion coefficient opposite to the grid pattern (that is, anisotropy that cancels out). The same effect can be obtained by adopting a configuration capable of achieving the above.

  DESCRIPTION OF SYMBOLS 1 Reinforcing fiber (first reinforcing fiber) 2 Reinforcing fiber (second reinforcing fiber) 3 Plain woven fiber reinforced composite material (fiber reinforced composite material) 4 Grid pattern 5 Patterning direction 6, 7 Triaxial woven fiber Reinforced composite material (fiber reinforced composite material).

Claims (5)

An antenna mirror surface made of a fiber-reinforced composite material;
A grid reflector comprising a grid pattern made of a conductive material formed on or inside the antenna mirror surface,
A grid reflector characterized in that the fiber-reinforced composite material has an anisotropy of a thermal expansion coefficient opposite to that of the grid pattern. The grid reflector according to claim 1,
The fiber reinforced composite material includes a first reinforcing fiber oriented in a direction having a large contribution to rigidity and a thermal expansion coefficient in a direction parallel to the grid patterning direction, a rigidity in a direction orthogonal to the grid patterning direction, and The second reinforcing fiber oriented in the direction that has a large contribution to the thermal expansion coefficient,
The second reinforcing fiber is
Reinforcing fibers having a fiber direction thermal expansion coefficient comparable to that of the first reinforcing fibers and having a fiber direction tensile elastic modulus smaller than that of the first reinforcing fibers;
Alternatively, a reinforcing fiber having a fiber direction tensile elastic modulus comparable to that of the first reinforcing fiber and a fiber direction thermal expansion coefficient larger than that of the first reinforcing fiber,
Alternatively, the grid reflector is characterized in that the fiber direction tensile elastic modulus is smaller than that of the first reinforcing fiber and the fiber direction thermal expansion coefficient is larger than that of the first reinforcing fiber. The grid reflector according to claim 2, wherein
The fiber reinforced composite material is a plain weave fiber reinforced composite material,
The first reinforcing fibers are oriented parallel to the patterning direction;
The second reinforcing fiber is oriented perpendicularly to the patterning direction. A grid reflector. The grid reflector according to claim 2, wherein
The fiber reinforced composite material is a triaxial woven fiber reinforced composite material,
When the patterning direction is 0 degree, the first reinforcing fibers are oriented in +30 degrees and -30 degrees directions,
The grid reflector is characterized in that the second reinforcing fibers are oriented in a 90 degree direction when the patterning direction is 0 degree. The grid reflector according to claim 2, wherein
The fiber reinforced composite material is a triaxial woven fiber reinforced composite material,
The first reinforcing fiber is oriented in the 0 degree direction when the patterning direction is 0 degree,
The grid reflector is characterized in that the second reinforcing fibers are oriented in +60 degrees and -60 degrees directions when the patterning direction is 0 degrees.

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