A thermally decoupled metal support structure for a spaceborne multi-beam antenna feed array

Abstract

This invention proposes a thermally decoupled metal support structure for a spaceborne multi-beam antenna feed array, comprising a front panel, a rear panel, a first side panel, a second side panel, a base plate, and mounting bases. The base plate is installed at the bottom of the support frame structure formed by the front panel, rear panel, first side panel, and second side panel. Several mounting bases are installed radially on the lower surface of the base plate's frame, with the projection point of the feed array's phase center onto the base plate as the center. This invention solves the problem of planar shear thermal stress between the aluminum alloy support structure and the composite satellite module. The detachable assembly structure design improves assembly accuracy and efficiency, reduces development costs, and its rigidity and strength can meet the launch environment requirements of extended platforms.

Description

Technical Field

[0001] This invention relates to a thermally decoupled metal support structure for a satellite-borne multibeam antenna feed array, belonging to the field of thermal-structural technology for large-scale feed components of high-throughput / very high-throughput satellite multibeam antennas. Background Technology

[0002] High-throughput communication satellites are currently a hot technology in the international communication satellite industry. Their core payload—the Ka-band multi-beam antenna—is a key technology for increasing satellite communication capacity tenfold or even a hundredfold due to its high bandwidth, frequency reuse, dense high-gain beams, and wide-area coverage. Antenna design parameters related to communication capacity include spectral efficiency, beam bandwidth, and the number of beams. The first two are closely related to the type of multi-beam antenna, operating frequency, coverage area gain, and C / I ratio. Increasing the number of beams is mainly achieved by increasing the number of feed sources, which means a feed array with a larger envelope size. Considering the thermal stress caused by the wide temperature range of -160℃ to 140℃ for high-orbit communication satellite antennas and the high pointing accuracy requirements of multi-beam antennas, more stringent requirements are placed on the design of large-scale, high-density feed arrays and their supporting structures.

[0003] 1. The support structure of the feed array needs to have a certain stiffness and strength safety margin to ensure that the feed array and its support structure remain intact under the action of periodic vibration load and random vibration load during rocket launch. For large-scale feed arrays with large concentrated mass, the mechanical environment design is more demanding.

[0004] 2. The application of multi-beam antennas requires accurate antenna beam pointing. In order to avoid the problem of the feed at the edge position being out of focus, the pointing angle of the feed must be adjusted to point to the center of the reflector. Therefore, the pointing angle and installation angle of dozens or even hundreds of feeds are different and have slight differences. Therefore, the structural plate of the support structure used to install the feed horn needs to have the ability to install and position feeds at different angles with high precision.

[0005] 3. The feed array has an on-orbit extreme high and low temperature range of approximately -160℃ to 140℃. The feed components are made of aluminum alloy with a high coefficient of thermal expansion (24e-6), while the satellite cabin material is a carbon fiber aluminum honeycomb sandwich structure with a low coefficient of thermal expansion (2-3e-6). Under temperature change conditions, the thermal stress between the metal feed components and the composite material cabin can cause structural deformation, which will affect the antenna pointing accuracy. In severe cases, excessive connection stress can lead to the failure and damage of the embedded parts connecting the satellite cabin interface.

[0006] To avoid the aforementioned problems, previous multi-beam feed arrays often used a carbon fiber-aluminum honeycomb sandwich structure as the support structure for large-scale feed arrays. A machined titanium alloy mounting plate was installed in front of the support structure to position and install the feed horn. The advantage of this design is that both the support structure material and the satellite module material are carbon fiber composite materials with low coefficients of thermal expansion, reducing the thermal stress between the support structure and the satellite module. However, the following problems exist:

[0007] 1. Multi-beam antennas have dozens of feed sources. In order to ensure the strength of the feed sources in the mechanical environment, a large number of support brackets need to be set for the feed sources and the waveguides behind them. The connection holes of the support brackets require a corresponding number of metal embedded parts in the carbon fiber honeycomb sandwich structure. The large number of embedded parts, the foam adhesive around the embedded parts, and the filling adhesive and structural adhesive used for reinforcement when splicing composite honeycomb panels will generate a lot of weight, making the advantage of the low density of the original carbon fiber-aluminum honeycomb sandwich structure almost negligible.

[0008] 2. Carbon fiber composite materials are typical anisotropic materials, while the thermal expansion coefficient of the embedded foam filling material is orders of magnitude different from that of the honeycomb sandwich structure. Under extreme high and low temperature conditions in orbit, the composite material support structure will produce unpredictable torsional deformation, affecting the antenna pointing accuracy.

[0009] 3. Although the titanium alloy feed mounting plate used for positioning the feed can also be precisely manufactured with horn positioning holes by traditional milling methods, the coefficient of thermal expansion of titanium alloy is about 3 to 5 times that of the carbon fiber composite material of the supporting structure, and half that of aluminum alloy feed horn. These differences in thermal expansion coefficients will generate thermal stress under high and low temperature environments, affecting the antenna pointing. In particular, the precise fit between the shaft hole of the titanium alloy mounting plate and the aluminum alloy horn will cause the horn to be squeezed at high temperatures, and there is still a risk of fatigue damage during long-term on-orbit operation.

[0010] 4. Carbon fiber composite materials have a long molding time and high cost. Moreover, once the main support structure is formed, it becomes a closed structure. The closed installation space, combined with dozens of extremely dense feed waveguides and bracket components, results in extremely limited operating space. This places high demands on the design of the human-machine operating environment and also brings great difficulties to the precision installation of the feed components. Summary of the Invention

[0011] The technical problem to be solved by this invention is: addressing the problems existing in traditional design methods, this invention proposes a thermally decoupled metal support structure for the feed array of a spaceborne multi-beam antenna, which avoids the random release of thermal stress of the high-rigidity feed array to a certain weak point, affecting the feed pointing or causing fatigue stress damage to components; at the same time, the all-metal feed array support structure has the advantages of high processing and assembly precision, low production cost, and convenient operation, which can effectively improve the economic benefits and working efficiency of the spaceborne multi-beam antenna feed.

[0012] The technical solution adopted in this invention is: a thermally decoupled metal support structure for a satellite-borne multi-beam antenna feed array, including a front panel, a rear panel, a first side panel, a second side panel, a base plate, and mounting bases; the base plate is installed at the bottom of the support frame structure formed by the front panel, rear panel, first side panel, and second side panel; a plurality of mounting bases are installed radially on the lower surface of the frame of the base plate in a concentric circle manner with the projection point of the feed array phase center on the base plate as the center.

[0013] Furthermore, the front panel, rear panel, first side panel, second side panel, and bottom plate are made of aluminum alloy, and several light-reducing cavities are provided inside the front panel, rear panel, first side panel, second side panel, and bottom plate.

[0014] Furthermore, the front panel and the feed horn of the power supply component are positioned using a shaft hole fit, with an accuracy of H7 / g7.

[0015] Furthermore, the mounting base is made of titanium alloy.

[0016] Furthermore, the mounting base includes a horizontal plate and supporting lugs, with the supporting lugs disposed on both sides of the horizontal plate. Screw holes are respectively provided at the ends of the supporting lugs and the horizontal plate for connecting the base plate and the satellite compartment plate.

[0017] Furthermore, the mounting base includes a first mounting base and a second mounting base; the support lugs of the first mounting base are disposed along the short side of the horizontal plate; the support lugs of the second mounting base are disposed along the long side of the horizontal plate.

[0018] Furthermore, the first mounting base has stress relief grooves at the center of the two short sides of the horizontal plate.

[0019] Furthermore, the stress relief groove of the second mounting base is connected to the center point of the two long sides of the horizontal plate, and stress relief grooves are also opened at the center point of the ends of the two support lugs.

[0020] Furthermore, when the mounting base is installed, each mounting base is π-shaped on the cross-section along the radiation direction of the feed array.

[0021] Furthermore, the base plate has several spokes arranged radially along the radial direction, with the projection point of the feed array phase center on the base plate as the center, and connected to the frame of the base plate.

[0022] The advantages of this invention compared to the prior art are:

[0023] (1) The present invention adopts a unidirectional weak stiffness mounting base for thermal decoupling design and adopts a radial circular layout with the phase center of the feed array as the center. This solves the problem of large thermal stress and possible fatigue damage and large pointing error caused by the different materials of large-size, large-scale feed arrays and satellite cabin panels. The unidirectional weak stiffness mounting base design and radial layout can also meet the design requirements of stiffness and strength design of high-concentration mass feed arrays. This enables the successful application of the all-metal large-scale feed array support structure in the design of spaceborne multi-beam antennas. The advantages of the all-metal feed array support structure, such as high processing and assembly accuracy, low production cost and convenient operation, are fully reflected.

[0024] (2) This invention adopts a novel all-metal multi-beam feed support structure with aluminum alloy as the main material. Based on the thermal stress problem mentioned above, it innovatively proposes a thermally decoupled connection design. It adopts a mounting base with a unidirectional weak stiffness design arranged in a concentric circle radiation direction on the bottom plate of the feed support structure, with the projection point of the feed array phase center on the mounting surface as the center. The weak stiffness direction is a parallelogram "π" shaped structure. The instability of the structure can achieve slight structural deformation under high and low temperature environments, which restricts the overall deformation position of the feed array to the mounting base between the feed array and the satellite compartment. This avoids the thermal stress of the high-stiffness design feed array being randomly released to a certain weak stiffness point, affecting the feed pointing or causing fatigue stress damage to the components. At the same time, the all-metal feed array support structure has the advantages of high processing and assembly accuracy, low production cost, and convenient operation, which can effectively improve the economic benefits and working efficiency of the spaceborne multi-beam antenna feed. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the all-metal feed array and its support structure of the present invention;

[0026] 1—Feeding component; 2—Waveguide assembly; 3—Support structure

[0027] Figure 2 This is a schematic diagram of the feed array support structure of the present invention and its exploded view;

[0028] 4—Front panel; 5—Rear panel; 6—First side panel; 7—Second side panel; 8—Base plate; 9—Mounting base

[0029] Figure 3These are schematic diagrams of two different forms of unidirectional weak stiffness mounting base installation structures according to the present invention;

[0030] 91—First mounting base; 92—Second mounting base

[0031] Figure 4 This is a schematic diagram of the concentric pyrolysis coupling layout of the titanium alloy unidirectional weak stiffness mounting base of the present invention, with the phase center as the center of the circle.

[0032] Figure 5 This is a schematic diagram of the thermal stress relief grooves for two types of titanium alloy mounting bases of the present invention;

[0033] Figure 6 This is a schematic diagram showing the high-precision shaft hole fit between the feed horn and the front panel of the present invention. Detailed Implementation

[0034] The invention will now be further described with reference to the accompanying drawings.

[0035] like Figure 1 , Figure 2 As shown, this invention provides a multi-beam antenna feed support structure based on all-metal materials. The feed components 1 of the feed array (including feed horn, orthogonal mode coupler, etc.) and waveguide assembly 2 are supported by a support structure 3 (including front panel 4, rear panel 5, first side panel 6, second side panel 7, and base plate 8, as shown). Figure 2 As shown, the components are assembled into a whole. All of the above materials are aluminum alloy, and the mounting base 9 at the bottom of the base plate 8 is made of titanium alloy, providing a connection interface for the satellite cabin panel with carbon fiber honeycomb sandwich structure.

[0036] Both the support structure 3 and the power supply component 1 are made of aluminum alloy, and all components have the same coefficient of thermal expansion. Therefore, the connection thermal stress problem caused by the difference in the coefficient of thermal expansion of the materials between the power supply component 1 and the support structure 3 has been solved.

[0037] like Figure 6 As shown, the front panel 4 and the feed speaker are positioned using a high-precision shaft hole fit (H7 / g7). The purpose is to provide different pointing angle installation accuracy for dozens of feed components 1. High-precision milling can meet the high-precision structural size requirements. At the same time, the same aluminum alloy material can effectively avoid the thin-walled speaker extrusion fatigue damage caused by the change in shaft hole fit size under high and low temperature conditions.

[0038] The all-aluminum alloy support structure 3 assembles the front panel 4, rear panel 5, first side panel 6, second side panel 7, and base plate 8 together by screwing. The base plate 8 is installed at the bottom of the support frame structure formed by the front panel 4, rear panel 5, first side panel 6, and second side panel 7. The flat panel parts can also achieve high machining accuracy through conventional milling. The good part dimensional accuracy also brings high assembly accuracy. During the assembly process, the first side panel 6 and second side panel 7 can be left uninstalled, which can provide more operating space for the operator. In addition to the main load-bearing screw connection parts, the five panels are designed with a large number of light-reducing cavities. The wall thickness is set at 2mm to 2.5mm, and the weight index is comparable to that of carbon fiber aluminum honeycomb sandwich support structures of the same scale for multi-beam applications.

[0039] A thermal decoupling design is adopted between the feed array support structure 3 and the satellite compartment panel. Since both the feed array 1 and its support structure 3 are made of aluminum alloy (thermal expansion coefficient 24e-6), while the satellite compartment panel is a carbon fiber-aluminum honeycomb sandwich structure (thermal expansion coefficient 2-3e-6), there is an order-of-magnitude difference in their thermal expansion coefficients. Without a reasonable thermal decoupling design, the large-sized multi-beam feed array base plate will generate significant thermal stress, which could potentially cause shear failure of the embedded parts in the compartment panel, leading to product failure. The principle of the thermal decoupling design is as follows: A unidirectional weak stiffness design mounting base 9 is set between the base plate 8 of the feed array support structure 3 and the satellite compartment panel. This base includes a horizontal plate and support lugs. The support lugs are arranged parallel to each other on both sides of the horizontal plate, forming a parallelogram-shaped "π" structure with the weak stiffness direction being a parallelogram. The ends of the support lugs and the horizontal plate are respectively... Screw holes are provided, and the weak stiffness direction of the mounting base 9 is arranged radially in a concentric circle with the projection point 10 of the feed array phase center on the mounting surface as the center. Under high-altitude and low-temperature conditions, the parallelogram structure of the mounting base 9, due to its structural shape instability, can achieve slight structural deformation in the radial direction, limiting the overall deformation of the feed array 1 relative to the satellite module to the mounting base 9. Simultaneously, this invention sets the feed phase center, a sensitive parameter affecting the feed pointing error, at the center of the radially arranged mounting base 9. When the unidirectional weak stiffness mounting base 9 deforms, the feed array phase center is at the center of the deformation circle, thus the positional change is minimal, greatly reducing the pointing deviation caused by thermal deformation. The base plate 8 has several spokes arranged radially along the radial direction with the projection point 10 as the center, connecting to the frame of the base plate 8.

[0040] Except for the weak stiffness direction of the radiation direction centered on the phase center, where the mounting base 9 is set as a parallelogram, the other directions still provide greater stiffness due to the larger equivalent thickness. In the design, the first-order fundamental frequency of the feed array 1 can also be increased by increasing the number of mounting bases 9. In this embodiment, the first-order fundamental frequencies of the feed components in the X, Y, and Z directions are 145.73Hz / X direction, 163.82Hz / Y direction, and 91.89Hz / Z direction, respectively, which meet the requirements that the first-order frequencies of the satellite feed are higher than 30Hz in the X and Y directions and higher than 60Hz in the Z direction, thus avoiding the structural strength risk caused by the main frequency resonance of the satellite structure.

[0041] The mounting base 9 is made of titanium alloy of grade TC4-R. The purpose of choosing titanium alloy is as follows: the interface between the feed array 1 and the satellite compartment, that is, the mounting base 9, is the part with the greatest stress in the launch mechanical environment of the feed array, and titanium alloy has a yield strength close to that of steel, which can meet the design requirements of high stress; secondly, titanium alloy has good elasticity, which is suitable for the application requirements of long-term weak elastic strain in orbit; at the same time, titanium alloy has the advantages of low density and light weight, so it has become the preferred material for the mounting base.

[0042] like Figures 3-5 As shown, the mounting base plate 8 of the feed array support structure 3 is relatively low in height from the satellite compartment panel. In this embodiment, the height of the mounting base plate 8 is 42mm, thus limiting the operating space. To meet the operating space requirements when the mounting base 9 is screwed onto the satellite compartment panel, two different types of parallelogram mounting bases are designed: the first mounting base 91 and the second mounting base 92. All mounting interfaces are arranged on the outer perimeter of the base plate 8, providing sufficient installation space for the feed array and its support structure on the satellite compartment panel. The mounting base 9 itself is also designed with stress relief grooves 93 to reduce thermal coupling deformation, which can further reduce the thermal coupling shear stress between the mounting base 9 and the embedded parts of the satellite compartment panel. The support lugs of the first mounting base 91 are located on the short side of the horizontal plate, and stress relief grooves 93 are opened at the center of the two short sides of the horizontal plate. The support lugs of the second mounting base 92 are located on the long side of the horizontal plate, and stress relief grooves 93 are connected to the center points of the two long sides of the horizontal plate. Stress relief grooves 93 are also opened at the center points of the ends of the two support lugs.

[0043] When the antenna is in orbit, the feed array achieves thermal stress decoupling between the metal feed array and the carbon fiber structure satellite module through slight deformation of the first mounting base 91 and the second mounting base 92 under the base plate 8 in the direction of weak stiffness.

[0044] The unidirectional weak stiffness mounting base 9 used in this invention is designed with a concentric circle radiation direction centered on the phase center of the feed array. Other similar radial structures, such as the I-shaped structure, are also protected by this invention.

[0045] The application of this invention is not limited to the design of large-scale feed array support for multi-beam antennas. Other dual-feed and multi-feed support structure designs in the C, Ku, and Ka bands can also be carried out with reference to this invention and are also protected by this invention.

[0046] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0047] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A thermally decoupled metal support structure for a satellite-borne multi-beam antenna feed array, characterized by: It comprises a front panel (4), a back panel (5), a first side panel (6), a second side panel (7), a bottom plate (8) and mounting bases (9); the bottom plate (8) is mounted at the bottom of the support frame structure surrounded by the front panel (4), the back panel (5), the first side panel (6) and the second side panel (7); a plurality of mounting bases (9) are installed on the lower surface of the frame of the bottom plate (8) in a radial manner with the projection point (10) of the phase center of the feed array on the bottom plate (8) as the center.

2. The pyrolytic decoupled feed array support structure of claim 1, wherein, The materials of the front panel (4), the back panel (5), the first side panel (6), the second side panel (7) and the bottom plate (8) are aluminum alloy materials, and a plurality of lightening cavities are arranged in the front panel (4), the back panel (5), the first side panel (6), the second side panel (7) and the bottom plate (8).

3. The pyrolytic decoupled feed array support structure of claim 1, wherein, The front panel (4) is positioned with the feed horn of the feed component (1) by shaft hole cooperation, and the precision is H7 / g7.

4. The pyrolytic decoupled feed array support structure of claim 1, wherein, The material of the mounting base (9) is titanium alloy.

5. The pyrolytic decoupled feed array support structure of claim 4, wherein, The mounting base (9) comprises a horizontal plate and support lugs, the support lugs are arranged on both sides of the horizontal plate, screw holes are arranged on the ends of the support lugs and the horizontal plate respectively, and the bottom plate (8) and the satellite cabin plate are connected.

6. The pyrolytic decoupled feed array support structure of claim 5, wherein, The mounting base (9) comprises a first mounting base (91) and a second mounting base (92); the support lugs of the first mounting base (91) are arranged in the short edge direction of the horizontal plate; and the support lugs of the second mounting base (92) are arranged in the long edge direction of the horizontal plate.

7. The pyrolytic decoupled feed array support structure of claim 6, wherein, The first mounting base (91) is provided with stress release grooves (93) at the centers of the two short edges of the horizontal plate respectively.

8. The pyrolytic decoupled feed array support structure of claim 6, wherein, The stress release grooves (93) of the second mounting base (92) are connected to the center points of the two long edges of the horizontal plate, and stress release grooves (93) are also arranged at the center points of the ends of the two support lugs.

9. The pyrolytic decoupled feed array support structure of claim 8, wherein, When the mounting base (9) is installed, each mounting base (9) is in the shape of π on the section along the radiation direction of the feed array.

10. The pyrolytic decoupled feed array support structure of claim 1, wherein, The bottom plate (8) is provided with a plurality of spokes connected to the frame of the bottom plate (8) in a radial manner along the radial direction with the projection point (10) of the phase center of the feed array on the bottom plate (8) as the center.

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