A spatially deployable antenna reflector

Abstract

This invention provides a spatially deployable antenna reflector, comprising a thin-film reflective surface and a support structure disposed on the back side of the thin-film reflective surface. The support structure is used to drive the thin-film reflective surface to unfold and retract. After unfolding, the thin-film reflective surface forms a single-curved cylindrical geometric surface. The support structure includes a support rod and end hinge portions disposed at both ends of the support rod. The support rod is made of a first composite material. One of the end hinge portions of a support rod is connected to one of the end hinge portions of an adjacent support rod. A central hinge portion is provided in the middle of any support rod. The end hinge portions and / or the central hinge portions deform, causing the plurality of support rods to unfold and retract, thereby driving the thin-film reflective surface to unfold and retract along the longitudinal and transverse directions of the thin-film reflective surface.

Description

Technical Field

[0001] This invention relates to the field of microwave antenna technology in satellite payloads, and more particularly to a space-deployable antenna reflector. Background Technology

[0002] Space-deployable, ultra-large-sized single-curved cylindrical thin-film antenna reflectors enable unique observation capabilities for synthetic aperture radar (SAR) antennas. Existing concepts for space-deployable, ultra-large-sized single-curved cylindrical antenna reflectors all use a metal mesh as the reflective surface, connected to front and rear cable nets, whose final geometry is determined by the cable nets. The front and rear cable nets are connected by longitudinal cables to form a double-layer cable net. The desired single-curved cylindrical geometry is formed through tensioning the front and rear cable nets and the longitudinal cable nets, with the cable net system supporting the metal mesh reflective surface. The flexible double-layer cable net is supported by a deployable truss, forming a stable structure.

[0003] The existing double-layer cable net system for single-curved cylindrical antenna reflectors is relatively complex. A large truss supporting a double-layer cable net system and its deployment mechanism are even more complex, inevitably resulting in significant weight.

[0004] Furthermore, the double-layer cable mesh reflector and its support system of existing single-curved cylindrical antenna reflectors are generally relatively independent from the feed and its support system. Structurally, they do not form a stable whole with a certain rigidity, which leads to a series of problems such as low natural frequency of the entire antenna structure system, poor geometric accuracy after deployment, and difficulty in coordinating the deployment synchronization of the reflector system and the feed system.

[0005] In existing double-layer cable-net reflector systems, electromagnetic waves are reflected by a layer of metal mesh. However, during the weaving process, mesh holes inevitably form. These holes cause significant insertion loss for high-frequency electromagnetic waves, leading to a degradation in antenna performance. Furthermore, while the mesh can be woven more densely to reduce the size of the holes, current weaving techniques are insufficient for high-frequency applications. Simultaneously, the thickness and weight of the mesh increase with smaller holes, making it unsuitable for ultra-large, ultra-lightweight deployable antennas. Summary of the Invention

[0006] In order to overcome the above-mentioned technical defects, the purpose of this invention is to provide a spatially deployable antenna reflector suitable for high-frequency electromagnetic waves.

[0007] This invention discloses a spatially deployable antenna reflector, comprising a thin-film reflective surface and a support structure disposed on the back side of the thin-film reflective surface. The support structure is used to drive the thin-film reflective surface to unfold and retract. After unfolding, the thin-film reflective surface forms a single-curved cylindrical geometric surface. The support structure includes a support rod and end hinge portions disposed at both ends of the support rod. The support rod is made of a first composite material, the coefficient of thermal expansion of which is less than a first threshold. The end hinge portions are made of a metal material or a second composite material. One end hinge portion of a support rod is connected to one end hinge portion of an adjacent support rod. The end hinge portions deform, causing the plurality of support rods to unfold and retract, thereby driving the thin-film reflective surface to unfold and retract along the longitudinal and transverse directions of the thin-film reflective surface.

[0008] The middle part of any of the support rods may be provided with a central hinge portion, and the central hinge portion contains a third composite material, which is a shape memory material;

[0009] The end hinge and the middle hinge deform simultaneously, causing the support rods to expand and contract, thereby driving the thin film reflective surface to expand and contract along the longitudinal and transverse directions of the thin film reflective surface.

[0010] Preferably, all the longitudinally located end hinge portions and middle hinge portions are assembled to form a longitudinal hinge group; all the transversely located end hinge portions and middle hinge portions are assembled to form a transverse hinge group; the longitudinal hinge group and the transverse hinge group operate synchronously or in stages, so that the longitudinal and transverse directions of the thin film reflective surface are orderly contracted and expanded.

[0011] Preferably, the Poisson's ratio of the thin film reflective surface in the tension direction is zero.

[0012] Preferably, the thin film reflective surface is provided with a lattice structure, the lattice structure making the Poisson's ratio of the thin film reflective surface zero in the tension direction; the shape of the lattice structure includes Silicomb type, Aux-Hex type, cross type, Arrow type, Star type and Novel type.

[0013] Preferably, the coefficient of thermal expansion of the first composite material is less than or equal to 1×10⁻⁶. -6 / ℃.

[0014] Preferably, the support rods are connected by the end hinges to form triangular, quadrilateral, or polygonal support units, and several end hinges are connected by a disc, so that several support units form the support structure; the end hinges and the middle hinges deform simultaneously to change the angle of convergence and deconvexity between the support units.

[0015] Preferably, the support rod includes multiple sub-rods, which are connected by the central hinge portion; the support rod can be folded or unfolded by the deformation of the central hinge portion.

[0016] Preferably, the support structure includes a first support portion and a second support portion, which are connected by the end hinge portion; the antenna reflector further includes a feed assembly, the thin film reflective surface is connected to the first support portion, and the feed assembly is connected to the second support portion.

[0017] Compared with existing technologies, the above technical solution has the following advantages:

[0018] 1. This invention uses a lightweight, continuous, flexible thin film material instead of a traditional metal mesh as the reflective surface of the antenna reflector. Due to the continuity of the thin film material, the electrical performance degradation caused by the presence of mesh holes in the metal mesh reflective surface is avoided, and it can be applied to higher radio wave frequencies.

[0019] 2. Due to the zero Poisson's ratio characteristic of the thin film reflective surface, a single-curved cylindrical surface with a specific geometry can be formed by tensioning at both ends of the thin film reflective surface, and the geometric accuracy is high; it can also avoid the shrinkage of the thin film material perpendicular to the tensioning direction, as well as the wrinkles caused by the compressive stress of this shrinkage; and, since the double-layer cable net system of the traditional metal mesh reflective surface is avoided, the complexity of the entire system is greatly simplified.

[0020] 3. Due to the extremely low coefficient of thermal expansion of the first composite material (support rod), the high thermal stability of the support structure in orbit is ensured.

[0021] 4. The central hinge portion of the third composite material has shape memory characteristics, which allows for large deformation, thus enabling the support structure to unfold into a large size, and therefore it can be applied to ultra-large reflective surfaces;

[0022] 5. The support structure achieves rigid support through the support rods and flexible deformation through the hinge.

[0023] 6. The thin-film reflective surface and the feed assembly are mounted on the same support structure, which effectively ensures the relative geometric accuracy between the thin-film reflective surface and the feed assembly as well as the synchronization of the unfolding process, resulting in high precision, high rigidity and structural stability of the entire system.

[0024] 7. The support unit is triangular, which has high stability. Through the design of different support rod lengths and the layout design of the end hinge and the middle hinge, the maximum convergence ratio can be achieved. Attached Figure Description

[0025] Figure 1 A schematic diagram of a simplified structure of the spatially deployable antenna reflector provided by the present invention when deployed;

[0026] Figure 2 A simplified diagram of the spatially deployable antenna reflector provided by the present invention when folded up;

[0027] Figure 3 A schematic diagram of the structure of the first support portion of the spatially deployable antenna reflector provided by the present invention;

[0028] Figure 4 A schematic diagram of the structure of the second support portion of the spatially deployable antenna reflector provided by the present invention;

[0029] Figure 5 A simplified structural diagram of the spatially deployable antenna reflector provided by the present invention, showing its dimensions when deployed.

[0030] Figure 6 A simplified structural diagram of the spatially deployable antenna reflector provided by the present invention, showing its dimensions when folded up;

[0031] Figure 7 A schematic diagram of a preferred embodiment of the spatially deployable antenna reflector provided by the present invention.

[0032] Wherein: 1-thin film reflector, 2-feed source, 3-support structure, 301-support rod, 302-hinge part. Detailed Implementation

[0033] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0035] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0036] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0037] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0039] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0040] See appendix Figure 1-2 7. This invention discloses a spatially deployable antenna reflector, comprising a thin-film reflective surface 1 and a support structure 3 disposed on the back side of the thin-film reflective surface 1. The support structure 3 is used to drive the deployment and retraction of the thin-film reflective surface 1. Unlike the metal mesh materials of the prior art, due to the continuity of the thin-film material, on the one hand, the degradation of antenna electrical performance caused by the mesh openings of the metal mesh reflective surface is avoided; on the other hand, since the thin film is continuous and has no mesh openings, it can be applied to higher frequency bands. Furthermore, by avoiding the double-layer cable net system of the traditional metal mesh reflective surface, the complexity of the entire system is greatly simplified.

[0041] The Poisson's ratio of the thin-film reflective surface 1 is zero in the tensioning direction. Based on this, tensioning the thin-film reflective surface 1 is relatively simple; tensioning only needs to be applied to both ends of the thin-film reflective surface 1 to form a specific geometric surface with high geometric accuracy. Furthermore, it avoids the shrinkage stress generated in the thin-film material perpendicular to the tensioning direction, and the wrinkles caused by this shrinkage stress. The thin-film reflective surface 1 of this invention, when unfolded, forms a single-curved cylindrical geometric surface.

[0042] Furthermore, for the single-curved cylindrical thin-film reflective surface 1, a cut slit pattern can be designed on the thin-film reflective surface 1 to achieve zero Poisson's ratio. The lattice structure can include Siliconomb type honeycomb, Aux-Hex type honeycomb, cross type honeycomb, Arrow type honeycomb, Star type honeycomb, and Novel type honeycomb, etc., and is not limited here. By setting this zero Poisson pattern, the purpose of preventing wrinkles during longitudinal tension is achieved while ensuring the continuity of the electrical properties of the thin-film reflective surface 1.

[0043] The support structure 3 of the present invention includes support rods 301 and end hinge portions 302 disposed between the support rods 301. The support rods 301 provide rigid support, and the end hinge portions 302 change the angle between the support rods 301 after deformation, allowing the support rods 301 to fold together and unfold. The end hinge portions 302 are made of metal or a second composite material. One end hinge portion of a support rod is connected to one end hinge portion of an adjacent support rod.

[0044] Specifically, the support rod 301 is made of a first composite material, which has an extremely small coefficient of thermal expansion, less than or equal to 1×10⁻⁶. -6 ℃. This extremely low coefficient of thermal expansion ensures the high thermal stability of support structure 3 in orbit.

[0045] The middle of any support rod is provided with a central hinge part 303, which contains a third composite material, which is a shape memory material.

[0046] The end hinge portion 302 and / or the middle hinge portion 303 deform, causing the plurality of support rods 301 to expand and contract, thereby driving the thin film reflective surface to expand and contract along the longitudinal and transverse directions of the thin film reflective surface. Specifically, the transverse expansion and contraction along the thin film reflective surface is achieved by the end hinge portion 302 and the middle hinge portion 303, and the longitudinal expansion and contraction along the thin film reflective surface is achieved by the end hinge portion 302 and the middle hinge portion 303. Furthermore, the transverse expansion and contraction and the longitudinal expansion and contraction can be performed simultaneously or separately, for example, the transverse expansion and contraction can be performed first and then the longitudinal expansion and contraction, or vice versa.

[0047] The shape memory composite material can achieve large deformation, which allows the thin film reflective surface 1 of the present invention to be applied to ultra-large sizes.

[0048] The first, second, and third composite materials have high specific stiffness, high specific strength, and low coefficient of thermal expansion (approximately 10⁻⁷ / ℃). Therefore, through structural optimization design and analysis, the overall structural stiffness and on-orbit thermal stability of the antenna reflector can be effectively guaranteed.

[0049] It can be understood that the central hinge portion 303 of the present invention is a component integrating structure and function. Specifically, when retracting or unfolding, the central hinge portion 303, as a functional component, realizes the retraction and unfolding of the support structure 3 through its own large deformation; when the antenna reflector is retracted or unfolded and is running in orbit, the central hinge portion 303 itself can become rigid and stiff as a structural component, forming a structural whole with the surrounding composite material support rods 301 to provide rigid support for the thin film reflective surface 1.

[0050] Furthermore, unlike a hinge in the usual sense (which is a mechanical structure, a part formed by connecting various mechanical components, which is not continuous internally and has gaps due to the connection), the central hinge part 303 is a material structure, and there are no gaps inside and in the connection part with the support rod 301. This ensures the geometric uniqueness of the support structure 3 after it is unfolded in space, thus completely avoiding the spatial micro-dynamics phenomenon of the unfolded support structure 3.

[0051] Furthermore, by controlling the deformation of the central hinge section 303, the deployment of the antenna reflector system can be ensured to be orderly and controllable, without the need for any other auxiliary deployment system, thus reducing the complexity and weight of the entire system.

[0052] In a preferred embodiment, the support rods 301 are connected by end hinges 302 to form triangular, quadrilateral, or polygonal support units. The triangular structure has high stability, and through optimized design of the rod length and the layout of the unfolding hinges, it can achieve the maximum retraction ratio. Several end hinges are connected by a disc, so that several support units form a support structure. The end hinges 302 deform to change the retraction and unfolding angles between the support units. Based on this, the end hinges 302 deform to change the angles between the support units, and also change the angles between the individual support rods 301 within the support unit, thereby forming the retraction and unfolding of the support rods 301.

[0053] In a further preferred embodiment, the support rod 301 includes a plurality of sub-rods, which are connected by a central hinge portion 303; the support rod 301 is folded or unfolded by the deformation of the central hinge portion 303, which is suitable for larger-sized thin film reflective surfaces 1 and achieves a high retraction ratio for retraction and unfolding.

[0054] Preferably, the support structure 3 includes a first support portion and a second support portion, which are connected by an end hinge portion 302. The antenna reflector also includes a feed 2 assembly, with the thin-film reflector 1 assembly connected to the first support portion and the feed 2 assembly connected to the second support portion.

[0055] It is important to note that dividing the support structure 3 into a first support section and a second support section does not constitute a division of the support structure 3 itself. It merely serves to differentiate between the portion supporting the feed 2 and the portion supporting the thin-film reflector 1. This means that both the reflector subsystem and the feed 2 subsystem are directly connected to the same support structure 3. This effectively ensures the relative geometric accuracy between the reflector subsystem and the feed 2 subsystem, as well as the synchronization of the deployment process, resulting in high precision, high rigidity, and structural stability of the entire system. Therefore, the first and second support sections can include the same support units. Different relative positions between the feed and the reflector can be achieved through the angle design between the support structures.

[0056] See appendix Figure 1-6 The first support section and the second support section each include three support units.

[0057] This invention provides a preferred embodiment to illustrate the solution in detail. For a deployable monocurved parabolic cylindrical antenna reflector with a mechanical aperture of 3.5m × 2.5m and a focal length of 1.8m, one section of this example monocurved parabolic cylindrical antenna reflector can be directly arrayed longitudinally in practical engineering, ultimately forming an ultra-large, ultra-long monocurved cylindrical antenna reflector.

[0058] See appendix Figure 3 In this embodiment, the deployable support structure 3 (first support part) of the thin film reflective surface 1 is composed of three triangles on the right side forming a high-rigidity, high-structural-stability deployable truss.

[0059] See appendix Figure 4 In this embodiment, the deployable support structure 3 (second support part) of the feed source 2 is composed of three triangles on the left side forming a deployable truss with high rigidity and high structural stability.

[0060] See appendix Figure 5-6 Through the aforementioned design of the transverse triangular structure, the length of the support rod 301, and the drive design of the end hinge part 302 and the middle hinge part 303, the size of the single-curved parabolic cylindrical antenna reflector in this example is reduced from 4080mm×3118mm to 1600mm×1550mm after being folded.

[0061] This invention can achieve a large longitudinal shrinkage ratio. For example, the thin film reflective surface 1, which unfolds to 50 meters or even 100 meters, can also be unfolded and folded up.

[0062] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A spatially deployable antenna reflector, characterized by, The antenna reflector comprises a thin film reflector and a support structure arranged at the back of the thin film reflector, the support structure being used to drive the unfolding and folding of the thin film reflector; The thin film reflector forms a single-curved cylindrical geometric surface after being unfolded; The support structure comprises support rods and end hinge portions arranged at the two ends of the support rods, the support rods being made of a first composite material, the thermal expansion coefficient of the first composite material being less than a first threshold value; the end hinge portions being made of a metal material or a second composite material; one of the end hinge portions of a support rod is connected with one of the end hinge portions of an adjacent support rod; The end hinge portions are deformed, so that the unfolding and folding between the support rods is realized, thereby driving the thin film reflector to unfold and fold along the longitudinal direction and the transverse direction of the thin film reflector; The middle of any support rod is provided with a middle hinge portion, the middle hinge portion containing a third composite material, the third composite material being a shape memory material; The end hinge portions and the middle hinge portions are deformed at the same time, so that the unfolding and folding between the support rods is realized, thereby driving the thin film reflector to unfold and fold along the longitudinal direction and the transverse direction of the thin film reflector; The Poisson's ratio of the thin film reflector in the tension direction is zero; The thin film reflector is provided with a dot array structure, the dot array structure making the Poisson's ratio of the thin film reflector in the tension direction zero; The shape of the dot array structure includes Silicomb type, Aux-Hex type, cross type, Arrow type, Star type and Novel type; The first composite material has a coefficient of thermal expansion less than or equal to 1 x 10 -6 / °C. The support rods are connected through the end hinge portions to form triangular, quadrilateral or polygonal support units, a plurality of end hinge portions are connected through a chuck to make a plurality of support units form the support structure; The end hinge portions and the middle hinge portions are deformed at the same time to change the folding and unfolding angles between the support units; The support structure comprises a first support portion and a second support portion, the first support portion and the second support portion being connected through the end hinge portions; The antenna reflector further comprises a feed source assembly, the thin film reflector being connected with the first support portion, and the feed source assembly being connected with the second support portion.

2. The antenna reflector of claim 1, wherein, All the end hinge portions and the middle hinge portions in the longitudinal direction form a longitudinal hinge group; all the end hinge portions and the middle hinge portions in the transverse direction form a transverse hinge group; The longitudinal hinge group and the transverse hinge group are synchronized or step by step, so that the longitudinal direction and the transverse direction of the thin film reflector are sequentially folded and unfolded.

3. The antenna reflector of claim 1, wherein, The support rod comprises a plurality of sub-rods, the sub-rods being connected through the middle hinge portions; The sub-rods are folded or unfolded through the deformation of the middle hinge portions.

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