Reflective member for antenna, manufacturing method of reflective member for antenna, and terahertz observation antenna

Abstract

To provide a lightweight and highly accurate reflection member having excellent long-term environmental resistance.SOLUTION: A reflection member for an antenna includes: a core material 11 of a curved shape; a first skin 12 provided along an inner surface of the core material 11; a second skin 13 provided along an outer surface of the core material 11; and a reflecting mirror surface deposition 15 provided on a side of the first skin 12 not facing the core material 11. The core material 11, the first skin 12, and the second skin 13 are made of carbon fiber-reinforced resin. The core material 11 is formed with a plurality of columns whose height direction faces a thickness direction. The reflecting mirror surface deposition 15 is formed by metal without an internal void layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a reflecting member for an antenna, a method for manufacturing a reflecting member for an antenna, and an antenna for terahertz observation. [Background technology]

[0002] In reflector antennas, an aluminum layer may be formed on the radio wave reflection layer. For example, a structure has been disclosed in which an anchor coating agent layer is provided on the surface of a resin structural substrate preformed into a parabolic shape, and an aluminum layer is then formed by vacuum deposition (for example, Patent Document 1). Also disclosed is a structure in which a reflective layer is formed by cold spraying on the surface of an anchor layer formed by plasma spraying on the surface of a substrate layer (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 05-002429 [Patent Document 2] Japanese Patent Publication No. 2020-007573 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Patent Document 1, when aluminum is deposited as a reflective surface layer by vacuum deposition, the metal reflective film of the reflective surface layer becomes thin, which results in low long-term durability in the space environment. As shown in Patent Document 2, when a reflecting mirror surface is formed by plasma spraying, a fine void layer remains. This results in a large amount of mirror surface roughness. As a result, it is not possible to manufacture a mirror surface with high mirror shape precision.

[0005] For these reasons, the conventional structure described above cannot be used as a reflector for the terahertz wave band, which requires high precision in the mirror shape. Furthermore, when a reflector is mounted on an artificial satellite and used in space, a reflector that is lightweight and has excellent long-term durability in the space environment is required.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reflective member that is lightweight, highly accurate, and has excellent long-term environmental resistance. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. The reflecting member for an antenna according to the present invention comprises a curved core material, a first skin provided along the inner surface of the core material, a second skin provided along the outer surface of the core material, and a reflective mirror surface coating provided on the side of the first skin that does not face the core material, wherein the core material, the first skin, and the second skin are formed from carbon fiber reinforced resin, the core material is formed by arranging multiple pillars whose height direction faces the thickness direction, and the reflective mirror surface coating is formed from metal without having an internal void layer.

[0008] According to this invention, the core material, the first skin, and the second skin are made of carbon fiber reinforced resin, and the reflecting mirror surface coating is made of metal and has no void layer inside. By providing the first and second skins on both sides of the core material in the thickness direction, a sandwich panel structure that is symmetrical in the thickness direction is created, making it less likely to deform even when subjected to inputs perpendicular to the thickness direction of the core material.

[0009] By forming the core material, first skin, and second skin from carbon fiber reinforced resin, the overall weight of the reflective member can be reduced. Furthermore, carbon fiber reinforced resin has high thermal stability and is less affected by thermal expansion. In other words, deformation due to thermal expansion caused by ambient temperature or direct sunlight can be minimized. Therefore, it is possible to prevent the overall size of the reflective member from changing significantly due to thermal expansion. In addition, it is possible to improve the durability of the reflective member.

[0010] Furthermore, if there is a void layer inside the metal, when the surface of the reflective mirror coating is mirror-finished by cutting, the void layer will cause unevenness on the surface. By forming the reflective mirror coating from metal without a void layer inside, the roughness of the reflective mirror surface of the reflective member after processing can be smoothed. Furthermore, compared to when the structure used for the reflective member is made entirely of metal, the amount of metal used can be minimized. By minimizing the amount of metal, deformation due to thermal expansion of the metal caused by ambient temperature or direct sunlight can be minimized.

[0011] These features prevent thermal strain from occurring in the first skin and the reflective mirror surface coating, thereby improving the durability of the reflective mirror surface coating and maintaining high precision in the reflective mirror surface coating for a long period of time. From the above, it is possible to obtain a reflective member that is lightweight, highly accurate, and has excellent long-term environmental resistance. A reflective member having such properties brings about remarkable effects when applied to, for example, lightweight, highly accurate reflector antennas for space use or onboard artificial satellites.

[0012] The reflecting mirror surface film may be made of aluminum.

[0013] According to this invention, the reflective mirror surface coating is made of aluminum, which can contribute to further reducing the weight of the reflective member.

[0014] The thickness of the reflective mirror coating may be 20 μm or more and 40 μm or less.

[0015] According to this invention, the thickness of the reflective mirror surface coating is 20 μm or more and 40 μm or less, thereby ensuring a sufficient thickness of the reflective mirror surface coating and contributing to improving long-term durability in the space environment.

[0016] The reflecting member for an antenna according to the present invention may also be used in outer space.

[0017] According to this invention, the reflecting member is used in outer space, thereby making it possible to significantly bring about the above-mentioned effects.

[0018] Furthermore, the method for manufacturing a reflecting member for an antenna according to the present invention is a method for manufacturing a reflecting member for an antenna, and comprises a spraying process for spraying metal onto the first skin, a shot peening process for removing a void layer inside the metal sprayed onto the first skin, and a cutting process for cutting the surface of the metal after the shot peening process.

[0019] According to this invention, the method includes a spraying step of spraying metal onto the first skin, a shot peening step of removing voids inside the metal sprayed onto the first skin, and a cutting step of cutting the surface of the metal after the shot peening step. That is, after the shot peening step is performed on the metal sprayed onto the first skin, the surface is smoothed by the cutting step to form a reflective mirror coating.

[0020] The shot peening process can remove the void layer inside the metal after thermal spraying. By cutting the surface of the metal in the cutting process, the surface of the metal after the shot peening process can be corrected. Here, the void layer inside the metal is removed by the above-mentioned shot peening process. Therefore, it is possible to eliminate the unevenness that occurs on the metal surface after the cutting process due to the void layer. Therefore, it is possible to smooth the surface roughness of the reflective mirror coating. This allows for a reflective member with high mirror shape precision.

[0021] In the thermal spraying step, the metal may be sprayed to a thickness of 250 μm or more.

[0022] According to this invention, the metal is sprayed to a thickness of 250 μm or more, which ensures that the thickness of the reflective mirror coating is sufficient even after the subsequent shot peening and cutting processes.

[0023] Moreover, the terahertz observation antenna according to the present invention includes a reflecting member for the antenna.

[0024] According to this invention, a terahertz observation antenna is provided with the antenna reflector according to the present invention. By using a carbon fiber reinforced resin in its construction, the antenna can be lightweight and have stable performance. Furthermore, the reflector surface coating according to the present invention can be used for applications in the terahertz wave band. Therefore, a lightweight, high-precision reflector antenna can be provided that is compatible with the terahertz wave band for space use or onboard an artificial satellite, and is highly reliable. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a reflective member that is lightweight, highly accurate, and has excellent long-term environmental resistance. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view showing an example of a terahertz observation antenna provided with a reflecting member according to the present invention. [Figure 2] 2 is a schematic diagram showing the structure of each layer of a reflective member in part II shown in FIG. 1. FIG. [Figure 3] FIG. 1 is a first diagram showing a lamination process of the reflective member according to the present invention. [Figure 4] FIG. 2 is a second diagram showing the lamination process of the reflective member according to the present invention. [Figure 5] FIG. 2 is an enlarged view of a reflective mirror surface coating in the reflective member according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, a reflecting member for an antenna according to one embodiment of the present invention will be described with reference to the drawings. 1 is a so-called parabolic antenna that includes a reflecting member 10, a radiator 20, a support portion 30, and a base portion 40. Antenna 100 according to this embodiment is suitable for use in space or on an artificial satellite, for example, as an antenna for terahertz observation.

[0028] The reflecting member 10 reflects the radio waves to be observed, including those in the terahertz wave band, toward the radiator 20 . The radiator 20 observes the radio waves reflected by the reflecting member 10 and transmits them to a receiver (not shown). The radiator 20 is provided at the focal point of the reflecting member 10. The support portion 30 serves to connect and support the reflecting member 10 and the base portion 40 . Base unit 40 is a portion that supports reflecting member 10, radiator 20, and support unit 30. Base unit 40 is a portion that is connected to an artificial satellite when antenna 100 is mounted on the artificial satellite, for example. Alternatively, base unit 40 may be provided on the ground when antenna 100 is installed on the ground.

[0029] As described above, the reflecting member 10 reflects radio waves from an observation target. As shown in Fig. 2, the reflecting member 10 includes a core material 11, a first skin 12, a second skin 13, an adhesive layer 14, and a reflective mirror surface coating 15. The core material 11 is a member having a circular outer periphery and a curved surface. The curved surface of the core material 11 is formed so that any cross-sectional curve passing through the center of the core material 11 is, for example, a parabola. This allows the core material 11 to have a focal point for incoming radio waves, and forms the basis of the reflecting member 10 in the antenna 100. Alternatively, the cross-sectional curve may not be parabolic, but may be determined as appropriate based on the electrical design of the antenna 100 and the optical system. The core material 11 is preferably made of carbon fiber reinforced plastic (CFRP). The core material 11 is formed by arranging a plurality of pillars whose height direction faces the thickness direction. For example, as shown in FIG. 2, the core material 11 preferably has a so-called honeycomb structure in which the pillars are hexagonal pillars. This suppresses deformation of the core material 11 in the thickness direction. The pillars may be triangular pillars, quadrangular pillars, or may be formed by arranging a plurality of circular pillars. The pillars may be hollow or solid.

[0030] The first skin 12 is a sheet-like member provided along the curved inner surface of the core material 11. In other words, the first skin 12 is a curved member similar to the core material 11. A reflective mirror surface deposition film 15 (described later) is formed on the side of the first skin 12 that does not face the core material 11. The second skin 13 is a sheet-like member provided along the curved outer surface of the core material 11. In other words, the second skin 13 is a curved member similar to the core material 11. Alternatively, depending on the design of each component, the second skin 13 does not have to be curved. For example, it may be flat. In this embodiment, for example, a support part 30 is attached to the side of the second skin 13 that does not face the core material 11.

[0031] The first skin 12 and the second skin 13 are preferably made of carbon fiber reinforced resin. Specifically, it is preferable that sheets of carbon fiber reinforced resin are laminated and autoclave molded in a molding die D as shown in Fig. 3. At this time, it is preferable that a mold release agent P is placed between the molding die D and the first skin 12 or second skin 13.

[0032] The adhesive layer 14 fixes the core material 11 to the first skin 12 and the core material 11 to the second skin 13. For example, an epoxy resin is preferably used for the adhesive layer 14. In this way, the first skin 12 and the second skin 13 formed from carbon fiber reinforced resin are provided so as to sandwich both side surfaces of the core material 11, thereby forming a sandwich panel structure in the reflecting member 10.

[0033] As described above, the core material 11, the first skin 12, and the second skin 13 are preferably all formed of carbon fiber reinforced resin. Specifically, they preferably have a quasi-isotropic laminate structure using unidirectional fiber material of pitch-based high-elasticity carbon fiber. Furthermore, the high-elasticity carbon fiber preferably has an elastic modulus of, for example, 60t. This reduces thermal deformation of each of the above-mentioned components. Furthermore, it is preferable that the structure has no in-plane directionality. Furthermore, the matrix resin in the carbon fiber reinforced resin is preferably a polycyanate resin, which reduces moisture absorption and thus reduces moisture decomposition deformation of the panel in a vacuum state. It is more preferable to set the carbon fiber content of the carbon fiber reinforced resin to 60% to further reduce thermal deformation.

[0034] The reflective mirror surface coating 15 is provided on the side of the first skin 12 that does not face the core material 11. The reflective mirror surface coating 15 reflects radio waves (particularly in the terahertz wave band) that travel toward the reflecting member 10. As described above, the first skin 12 is provided along the curved surface of the core material 11, and the curved surface has a focal point. Therefore, the radio waves reflected by the reflective mirror surface coating 15 are concentrated at the focal point. The reflective mirror surface coating 15 is preferably formed of a metal such as aluminum without having an internal void layer. In this embodiment, "without an void layer" refers to a state in which the void layer inside the metal forming the reflective mirror surface coating 15 is less than 5%. A method for manufacturing the reflective member 10 and a method for forming the reflective mirror surface coating 15 will be described below.

[0035] (Method of manufacturing the reflective member 10) The reflecting member 10 is formed by bonding a core material 11, a first skin 12, and a second skin 13 with an adhesive layer 14, and providing a reflective mirror surface coating 15 on the first skin 12. Specifically, it is manufactured as follows. That is, as shown in Fig. 4, an adhesive layer 14 is placed on the first skin 12 or the second skin 13 that has been autoclave-molded using the mold D as described above, and then a core material 11 is placed on top of that. Thereafter, the adhesive layer 14 is placed on the core material 11, and then the second skin 13 or the first skin 12 is placed on top of that. This forms the basic structure of the reflective member 10. Next, the reflective mirror coating 15 is formed on the first skin 12 of the structure formed as described above. The procedure for forming the reflective mirror coating 15 includes a thermal spraying process, a shot peening process, and a cutting process.

[0036] (Thermal spraying process) In the thermal spraying process, aluminum (metal) is sprayed onto the first skin 12 (skin). Specifically, atmospheric plasma spraying is preferably used. When spraying aluminum onto the first skin 12, an undercoat layer UC is preferably provided on the surface of the first skin 12, as shown in FIG. 5. The undercoat layer UC is preferably made of an inorganic material containing silica, for example. Here, a void layer is generated inside the aluminum sprayed by atmospheric plasma spraying. The void layer is removed by the shot peening process described below.

[0037] (Shot peening process) As described above, this is a process for removing the void layer inside the aluminum sprayed onto the first skin 12. Specifically, countless shots are collided with the surface of the aluminum. For example, carbon steel beads with a diameter of about 70 μm are preferably used as the shots. The impact speed of the shots is preferably about 40 m / s. This process removes the void layer that has formed inside the aluminum and also modifies and hardens the surface of the aluminum.

[0038] (cutting process) This is the process of cutting the aluminum surface after the shot peening process. Specifically, the aluminum layer formed as described above is cut using CNC machine cutting to create the designed curved surface. By correcting the aluminum layer through machine cutting, a highly accurate mirror shape is formed, or precision errors are reduced. This results in a highly accurate aluminum reflective surface shape (for example, a surface roughness of 1 μm or less).

[0039] The above-mentioned steps, particularly the thermal spraying step and shot peening step, can be performed as follows. That is, for example, a relatively thick aluminum layer (e.g., about 40 μm) may be formed by a single thermal spraying step so that the first skin 12 is not exposed even in the subsequent shot peening step and cutting step. Alternatively, the thermal spraying step and the shot peening step may be alternately repeated to form a thin aluminum layer (e.g., about 20 μm) by a single thermal spraying step.

[0040] When forming an aluminum layer, it is preferable to form a layer having a thickness of at least 250 μm in order to ensure a cutting allowance during cutting work. Through these steps, a reflective mirror coating 15 is formed, as shown in the cross section of FIG. 5, which does not have a void layer inside the aluminum layer and has a smooth aluminum surface roughness.

[0041] As described above, in the reflecting member 10 according to this embodiment, the core material 11, the first skin 12, and the second skin 13 are formed from carbon fiber reinforced resin, and the reflecting mirror surface coating 15 is formed from metal without having an internal void layer. The first skin 12 and the second skin 13 are provided on both thickness-wise sides of the core material 11, resulting in a sandwich panel structure that is symmetrical in the thickness direction. This makes it possible to create a structure that is less likely to deform even when subjected to input from a direction perpendicular to the thickness direction of the core material 11.

[0042] By forming the core material 11, the first skin 12, and the second skin 13 from carbon fiber reinforced resin, the overall weight of the reflecting member 10 can be reduced. Furthermore, carbon fiber reinforced resin has high thermal stability and is less affected by thermal expansion. In other words, deformation due to thermal expansion caused by ambient temperature or direct sunlight can be minimized. Therefore, it is possible to prevent the overall size of the reflecting member 10 from changing significantly due to thermal expansion. In addition, it is possible to improve the durability of the reflecting member 10.

[0043] Furthermore, if there is a void layer inside the metal, the void layer will cause unevenness on the surface when the surface of the reflective mirror surface coating 15 is mirror-finished by cutting. By forming the reflective mirror surface coating 15 from metal without a void layer inside, the roughness of the reflective mirror surface of the reflective member 10 after processing can be smoothed. Furthermore, compared to when the structure used in the reflective member 10 is made entirely of metal, the amount of metal used can be minimized. By minimizing the amount of metal, deformation due to thermal expansion of the metal caused by ambient temperature or direct sunlight can be minimized.

[0044] These prevent thermal strain from occurring in the first skin 12 and the reflective mirror surface coating 15. This improves the durability of the reflective mirror surface coating 15, and allows the precision of the reflective mirror surface coating 15 to be maintained at a high level for a long period of time. From the above, it is possible to obtain a lightweight, highly accurate, and long-term environmentally resistant reflector 10. The reflector 10 having such properties brings about remarkable effects when applied to, for example, a lightweight, highly accurate reflector antenna for space use or for use on an artificial satellite.

[0045] The reflecting mirror surface coating 15 is made of aluminum, which can contribute to making the reflecting member 10 even lighter.

[0046] The thickness of the reflective mirror surface coating 15 is 20 μm or more and 40 μm or less, which ensures a sufficient thickness of the reflective mirror surface coating 15 and contributes to improving long-term durability in the space environment.

[0047] Furthermore, the reflecting member 10 is used in outer space, which can significantly bring about the above-mentioned effects.

[0048] The method also includes a spraying process of spraying metal onto the first skin 12, a shot peening process of removing void layers inside the metal sprayed onto the first skin 12, and a cutting process of cutting the surface of the metal after the shot peening process. That is, after the shot peening process is performed on the metal sprayed onto the first skin 12, the surface is smoothed by the cutting process to form the reflective mirror coating 15.

[0049] The shot peening process can remove the void layer inside the metal after thermal spraying. By cutting the surface of the metal in the cutting process, the metal surface after the shot peening process can be corrected. Here, the void layer inside the metal is removed by the above-mentioned shot peening process. Therefore, it is possible to eliminate the unevenness that occurs on the metal surface after the cutting process due to the void layer. Therefore, it is possible to further smooth the surface roughness of the reflective mirror surface deposition 15. This allows for a reflective member 10 with high mirror shape precision.

[0050] In addition, the metal is sprayed to a thickness of 250 μm or more, which ensures that the reflective mirror surface coating 15 has a sufficient thickness even after the subsequent shot peening and cutting processes.

[0051] The reflecting member 10 according to the present invention is also provided in an antenna for terahertz observation. By using carbon fiber reinforced resin in its construction, the antenna 100 can be made lightweight and have stable performance. Furthermore, the reflecting mirror surface coating 15 according to the present invention can be used in applications for the terahertz wave band. Therefore, a lightweight, high-precision reflector antenna that can be used in space or on an artificial satellite and is compatible with the terahertz wave band and has high reliability can be provided.

[0052] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the surface of the core material 11 on the side where the second skin 13 is provided, that is, the side on which the reflective mirror surface coating 15 is not provided, does not need to be curved. Furthermore, the reflecting mirror surface film 15 may be made of a metal other than the above-mentioned aluminum. Furthermore, the antenna 100 may not have the support portion 30 or the base portion 40, and the reflecting member 10 may be attached directly to the satellite. Moreover, by increasing the thickness of the above-mentioned sandwich panel structure, that is, the core material 11, it may be possible to further suppress deformation due to heat.

[0053] In addition, within the scope of the spirit of the present invention, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Explanation of symbols]

[0054] 10 Reflective member 11 Core material 12 First epidermis 13 Second epidermis 15 Reflective mirror coating 100 Antennas

Claims

1. A curved core material, a first skin provided along an inner surface of the core material; a second skin provided along the outer surface of the core material; a reflective mirror coating provided on the side of the first skin that does not face the core material; Equipped with The core material is formed by arranging a plurality of pillars, the plurality of pillars are arranged such that the height direction of the plurality of pillars is along the thickness direction of the core material, The reflective mirror coating is formed of metal without an internal void layer. Reflective material for antennas.

2. The reflective mirror coating is made of aluminum. The reflector for an antenna according to claim 1.

3. The thickness of the reflective mirror coating is 20 μm or more and 40 μm or less. The reflector for an antenna according to claim 1 or 2.

4. The reflecting member for an antenna according to any one of claims 1 to 3, which is used in outer space.

5. A method for manufacturing a reflecting member for an antenna according to any one of claims 1 to 4, comprising the steps of: a thermal spraying step of thermally spraying a metal onto the first skin; a shot peening process for removing a void layer inside the metal sprayed on the first skin; a cutting step of cutting the surface of the metal after the shot peening step; Equipped with A method for manufacturing a reflector for an antenna.

6. In the thermal spraying step, the metal is sprayed to a thickness of 250 μm or more. A method for manufacturing the reflector for an antenna according to claim 5.

7. A reflector for an antenna according to any one of claims 1 to 4, Antenna for terahertz observation.

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