A spaceborne lightweight low-profile deployable SAR antenna array

Abstract

This invention discloses a spaceborne lightweight, low-profile, deployable SAR antenna array, comprising four deployable antenna sub-plates. Each sub-plate has a mounting plate as its main load-bearing structure, with radiating elements, feed line elements, and various active devices arranged on its front and back sides, respectively. The mounting plate is directly connected to the satellite deployment mechanism, eliminating the traditional adapter frame and reducing the cross-sectional thickness by 45%. The mounting plate adopts an aluminum alloy shell-honeycomb-cover plate adhesive molding structure, which significantly simplifies the process and reduces costs compared to carbon fiber mounting plates. The array devices adopt a high-density integration layout along the range direction with a 180° rotational symmetry at the center, reducing the types of cables by 50% and significantly improving integration and electrical assembly efficiency. The four sub-plates are folded and stacked during launch and unfolded into a planar array after entering orbit. This invention solves the problems of large cross-section, complex manufacturing process, and high cost of existing spaceborne SAR antennas, and is particularly suitable for commercial micro SAR satellite platforms.

Description

Technical Field

[0001] This invention relates to the field of microwave antenna technology, specifically to a spaceborne lightweight, low-profile deployable SAR antenna array, which is particularly suitable for commercial micro SAR satellite platforms. Background Technology

[0002] In recent years, synthetic aperture radar (SAR) satellites have been widely used in remote sensing mapping, disaster monitoring, ocean observation, and military reconnaissance. With the rapid development of commercial spaceflight, large-scale construction of commercial SAR satellite constellations has begun both domestically and internationally. Commercial space companies such as Finland's ICEYE and the United States' Capella have launched dozens of commercial SAR satellites, and China has planned to launch more than 200 commercial SAR satellites. Commercial SAR satellites mostly use microsatellite platforms and are launched in a multi-satellite launch configuration, placing extremely stringent requirements on antenna weight, profile thickness, manufacturing cost, and production cycle.

[0003] Traditional medium-to-large-sized spaceborne SAR antennas typically use carbon fiber composite materials as mounting plates. While carbon fiber materials offer advantages such as high specific stiffness and strength, they also suffer from complex molding processes, long production cycles, and high manufacturing costs, making it difficult to meet the low-cost, mass production requirements of commercial satellites. Furthermore, in traditional antenna architectures, the active array needs to be mounted on a separate carbon fiber frame before being connected to the satellite deployment mechanism. This transition structure significantly increases the cross-sectional thickness of the antenna array, resulting in a large envelope size when the antenna is folded up, making it difficult to meet the strict envelope size limitations of multi-satellite launches.

[0004] Furthermore, the dispersed arrangement of electronic components in traditional spaceborne antenna arrays results in a large feed network area, numerous cable types, and low electrical assembly efficiency, further increasing the antenna's weight and cost. With the large-scale construction of commercial SAR satellite constellations, existing antenna architectures can no longer meet the application requirements of low cost, short cycle time, low profile, and lightweight design, necessitating the development of new SAR antenna arrays suitable for commercial microsatellite platforms. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a spaceborne lightweight, low-profile deployable SAR antenna array. This solves the technical problems of existing spaceborne SAR antennas, such as large profile thickness, complex mounting plate forming process, long production cycle, high manufacturing cost, and low array integration. It also meets the application requirements of commercial micro SAR satellites for multi-satellite launch and mass production.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a spaceborne lightweight low-profile deployable SAR antenna array, comprising four antenna sub-boards, namely -X outer board, -X inner board, +X inner board, and +X outer board; each sub-board includes a mounting plate, a radiating element, a feed line element, a TR assembly, a power module, a delay module, a beam control unit, a power divider assembly, a high-frequency cable network, and a low-frequency cable network. The radiating element and the feed line element are disposed on one side of the mounting plate. The TR assembly, power module, delay module, beam control unit, power divider assembly, high-frequency cable network, and low-frequency cable network are disposed on the other side of the mounting plate. The cable network is located on the other side of the mounting plate; the mounting plate, as the main load-bearing structure of the antenna, is directly connected to the satellite's deployment mechanism; the mounting plate is formed by hot-pressing and bonding an aluminum alloy shell-honeycomb-cover plate structure; the TR components on the sub-board are integrated with high density along the distance, and the remaining electronic components are arranged around the TR components, and the TR components, power modules, delay modules, and wave control units are arranged in a 180° rotational symmetry relative to the center of the sub-board; the four sub-boards are connected to the satellite through clamping seats and deployment drive components, and have a retracted state, a half-deployed state, and a fully deployed state.

[0007] Furthermore, in the folded state, the -X outer plate and -X inner plate, and the +X outer plate and +X inner plate are respectively stacked in double layers and pressed onto the satellite by the clamping seat; in the semi-deployed state, the deployment drive assembly drives the -X outer plate and +X outer plate to deploy synchronously to both sides; in the fully deployed state, the four sub-plates form a complete antenna array on the same plane and enter the working state.

[0008] Furthermore, the housing of the mounting plate is precision milled from a single piece of aluminum plate. Bosses are machined on the housing at the mounting positions that connect to the satellite deployment mechanism and at the mounting positions of various electronic components, and threaded holes are provided on the bosses. Reinforcing ribs are machined on the main force transmission path of the housing. The cavity formed after milling and removing material from the remaining areas of the housing is filled with aluminum honeycomb core and then bonded to the cover plate.

[0009] Furthermore, both the shell and the cover are made of aluminum alloy and the surface is treated with phosphoric acid anodizing; the adhesive surfaces of the shell and the cover are bonded with adhesive film, and the gaps are filled with expanding foam; the wall thickness of both the shell and the cover is 0.5 mm, and the thickness of the reinforcing rib is 1 mm.

[0010] Furthermore, each active module consists of 4 TR components, 1 power module, 1 delay module, and 1 wave control unit. A single daughterboard has 4 active modules, with the active modules arranged diagonally being 180° rotationally symmetrical with respect to the center of the daughterboard.

[0011] Furthermore, the SMP RF connectors on the TR component and delay module are blindly interconnected with the SMP RF interfaces on the feeder unit and radiating unit through double female connectors, forming an RF signal path; the low-frequency pins on the TR component, delay module and wave control unit are vertically blindly interconnected with the low-frequency socket on the feeder unit, forming a low-frequency signal path; corresponding connector vias are provided on the mounting plate, and the blind connection adopts clearance fit to meet the installation tolerance requirements.

[0012] Furthermore, the radiating unit is formed by precision milling after cavity welding, with a cavity wall thickness of 0.5mm, and the radiating unit and cable assembly are integrated and installed as a whole; the feeder unit adopts a high-low frequency mixed pressure plate structure.

[0013] Furthermore, the radiation unit, feeder unit, TR component, power module, delay module, beam control unit, and power divider are all mounted on the mounting plate using fasteners; the high-frequency cable network and low-frequency cable network are interconnected with each electronic device and then fixed to the mounting plate using bindings.

[0014] Compared with the prior art, the present invention has the following significant advantages: 1. Low profile design: The present invention adopts an architecture in which the mounting plate is directly connected to the satellite deployment mechanism, eliminating the carbon fiber adapter frame of the traditional antenna. Compared with the traditional architecture, the antenna profile thickness is reduced by 45%, which greatly reduces the envelope size of the antenna in the retracted state. It is more suitable for the multi-satellite launch mode and can significantly reduce the launch cost.

[0015] 2. Low cost and short cycle time: The mounting plate of this invention adopts an aluminum alloy shell-honeycomb-cover plate adhesive molding structure. While meeting the requirements of rigidity and lightweight, it greatly simplifies the molding process compared with the traditional carbon fiber mounting plate, shortens the production cycle by 60%, and reduces the manufacturing cost by 50%, making it particularly suitable for the mass production needs of commercial satellites.

[0016] 3. High integration design: The present invention adopts an array layout with 180° rotational symmetry from the high-density integration center. On the one hand, it minimizes the connection distance between the TR components and the feeder network, reduces the area of ​​the feeder network, and improves the array integration. On the other hand, the rotational symmetry design makes the length and shape of the high-frequency cables completely consistent, reduces the types of cables by 50%, significantly reduces cable costs, and greatly improves electrical assembly efficiency and reduces assembly error rate.

[0017] 4. Vertical blind mating interconnect: This invention adopts a blind mating interconnect structure of radio frequency and low frequency connectors, realizing cable-free vertical interconnection of devices on both sides of the mounting board, further reducing the cross-sectional thickness, reducing the use of adapter cables, improving integration and assembly efficiency, and improving interconnection reliability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the SAR antenna array in the retracted state of the present invention; Figure 2 This is a schematic diagram of the SAR antenna array in its semi-deployed state according to the present invention; Figure 3 This is a schematic diagram of the SAR antenna array of the present invention in its fully deployed state; Figure 4 This is a schematic diagram of the front (radiating surface) structure of a single antenna sub-board of the present invention; Figure 5 This is a schematic diagram of the back (device side) structure of a single antenna sub-board of the present invention; Figure 6 This is a schematic diagram of the device layout of the antenna sub-board of the present invention; Figure 7 This is an exploded view of the overall structure of the mounting plate of the present invention; Figure 8 This is a schematic diagram of the shell structure of the present invention; Figure 9 This is a schematic diagram of the shell reinforcing rib structure of the present invention; Figure 10 This is a schematic diagram of the radio frequency blind mating connection structure of the present invention; Figure 11 This is a schematic diagram of the low-frequency blind mating connection structure of the present invention.

[0019] Explanation of reference numerals in the attached diagram: 11-Satellite body, 12-Pressure seat, 13-Outer X panel, 14-Inner X panel, 15-Inner +X panel, 16-Outer +X panel, 17-Deployment drive assembly, 21-Radiation unit, 22-Feeder unit, 24-Mounting plate, 231-TR assembly, 232-Power module, 233-Delay module, 234-Wavelength control unit, 235-Power divider assembly, 236-High-frequency cable network, 237-Low-frequency cable network, 41-Housing, 42-Honeycomb core, 43-Cover plate, 51-SMP RF connector (TR / delay side), 52-SMP RF connector (feeder / radiation side), 53-Dual female connector, 54-Low-frequency socket (feeder side), 55-CY181 low-frequency pin (device side). Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1-3As shown, the present invention discloses a spaceborne lightweight low-profile deployable SAR antenna array, which is mainly used in commercial micro SAR satellite platforms. The entire antenna array consists of four antenna sub-boards with identical structure and composition, namely -X outer board 13, -X inner board 14, +X inner board 15 and +X outer board 16. The four sub-plates are directly connected to the satellite body 11 via the clamping seat 12 and the deployment drive assembly 17. The entire antenna has three working states: During the satellite assembly, transportation and launch stages, the antenna is in the retracted state. At this time, the -X outer plate 13 is stacked on the outside of the -X inner plate 14, and the +X outer plate 16 is stacked on the outside of the +X inner plate 15, forming a double-layer stacked structure. The clamping seat 12 achieves reliable clamping, minimizing the launch envelope size and improving the carrying capacity of multiple satellites launched by a single rocket. After the satellite enters orbit, the clamping seat is unlocked, and the deployment drive assembly 17 provides deployment power, driving the -X outer plate 13 and the +X outer plate 16 to deploy synchronously in the -X and +X directions, respectively, entering the semi-deployed state. When the outer plates are fully deployed, the four sub-plates are in the same plane, forming a complete planar antenna array. The antenna enters the fully deployed state and can begin normal SAR imaging work.

[0022] like Figure 4-5 As shown, the single antenna sub-board adopts a two-sided layout. The front side (+Z side, i.e., the radiating surface facing space) is equipped with radiating element 21 and feed line unit 22, while the back side (-Z side, i.e., the device side facing the satellite) is equipped with TR component 231, power module 232, delay module 233, wave control unit 234, power divider assembly 235, high-frequency cable network 236, and low-frequency cable network 237. The mounting plate 24, as the main load-bearing structure of the entire sub-board, not only provides a high-precision mounting reference for all electronic components, but also directly connects to the satellite's deployment drive assembly 17 and clamping seat 12, eliminating the independent adapter frame structure in the traditional antenna architecture and fundamentally reducing the antenna's cross-sectional thickness.

[0023] All electronic components on the front and back are secured to the mounting plate 24 with stainless steel fasteners. After the high-frequency cable network 236 and low-frequency cable network 237 complete the electrical connection between the components, they are secured to the back of the mounting plate with high-temperature resistant cable ties. The low-frequency cable network includes cables that connect across the sub-boards, used to provide power supply and transmit beam control signals between the four sub-boards.

[0024] The radiating element 21, which serves as the radiating front end of the antenna, is formed by precision milling after welding an aluminum alloy cavity. The cavity wall thickness is only 0.5mm, achieving a lightweight design while ensuring structural strength. To further reduce the profile thickness and improve integration, the radiating unit 21 and the matching cable assembly are installed in an integrated manner, reducing the use of separate connectors.

[0025] The feeder unit 22 serves as a signal distribution network for antenna RF power supply and low-frequency control. It adopts a high-low frequency mixed-voltage printed circuit board process, which realizes the functions of RF power supply network and low-frequency control network simultaneously with the fewest printed circuit board layers. This greatly reduces the use of separate cables, reduces the size and weight of the feeder network, and improves the integration.

[0026] The TR component 231, as the core active device of the antenna, adopts a multi-channel integrated design. It integrates functional units such as a multi-functional chip, power amplifier, ring isolator, and beam control circuit. It can realize power amplification of the transmitted signal and low-noise amplification of the received signal, and at the same time, it can achieve beam scanning function in conjunction with the delay module.

[0027] like Figure 6 As shown, the electronic components on the back of the sub-board adopt a high-density integrated layout in the distance direction combined with a 180° rotational symmetry at the center: the TR component 231 is arranged in a high density along the distance direction (i.e., the vertical direction of the azimuth), and the power module 232, delay module 233, wave control unit 234 and other supporting components are closely arranged on both sides of the TR component, which minimizes the connection distance between the TR component and the feeder network, reduces the area of ​​the feeder unit 22, and improves the array integration.

[0028] In this embodiment, every four TR components 231, paired with one power module 232, one delay module 233, and one wave control unit 234, constitute a standard active module. A total of four active modules are arranged on a single daughterboard. Active modules 1 and 3, located diagonally, are rotationally symmetrical about 180° with respect to the geometric center of the daughterboard. Similarly, active modules 2 and 4 are also rotationally symmetrical about 180° with respect to the geometric center of the daughterboard. This rotationally symmetrical layout ensures that the length and bending shape of the high-frequency cables at symmetrical positions are completely consistent, reducing the variety of high-frequency cables by 50%. This not only lowers cable costs but also significantly improves electrical assembly efficiency, reduces assembly error rates, and facilitates mass production.

[0029] The entire daughterboard adopts an integrated electromechanical and thermal design. Before all components are installed, thermally conductive silicone rubber is coated on the mounting surface. The mounting plate 24 also serves as a heat dissipation structure, which quickly conducts away the heat generated by the active components to ensure that the components operate within a suitable temperature range.

[0030] like Figure 7-9 As shown, the mounting plate 24 adopts a lightweight sandwich structure of aluminum alloy shell-honeycomb-cover plate, mainly composed of three parts: shell 41, aluminum honeycomb core 42, and cover plate 43, which are formed in one piece by hot pressing and bonding process. Both shell 41 and cover plate 43 are made of 6061 high-strength aluminum alloy material, and the surface is treated with phosphate anodizing to improve corrosion resistance and bonding strength; the honeycomb core 42 adopts aluminum-based perforated honeycomb core material, which provides sufficient shear strength and ventilation and heat dissipation capacity while ensuring lightweight.

[0031] During the adhesive bonding process, the mating surfaces of the housing 41 and the cover plate 43 are bonded using a high-strength structural adhesive film, and the assembly gaps are filled with expanding foam to ensure the connection strength and sealing of the entire structure, preventing moisture and particles from the space environment from entering the interior of the structure. The molded mounting plate has a wall thickness of only 0.5mm and excellent flatness, with a flatness accuracy of up to 0.1mm / m, meeting the high-precision installation requirements of various components.

[0032] To ensure the rigidity and strength of the mounting plate while maintaining a lightweight design, the housing 41 is formed by CNC precision milling from a single piece of aluminum plate. Local bosses are machined at the connection points with the unfolding mechanism and at the mounting positions of various electronic components. These bosses are machined with stainless steel wire threaded holes to ensure connection strength after multiple disassemblies and reassemblies. 1mm thick reinforcing ribs are machined along the main force transmission paths, and all component mounting bosses are placed near these ribs to form a reasonable force transmission path and improve overall rigidity. All other non-mounting areas of the housing are milled to create cavities filled with aluminum honeycomb core 42, minimizing weight while maintaining rigidity. High-precision through-holes are designed on the mounting plate 24 corresponding to the connector positions, allowing RF and low-frequency connectors to pass through and enabling vertical interconnection of components on both sides.

[0033] like Figure 10-11 As shown, the components on both sides of the mounting plate are vertically interconnected using a blind-mating method, eliminating the need for adapter cables, further reducing the cross-sectional thickness and signal transmission loss. Regarding the RF signal path, the SMP RF connectors 51 on the TR component 231 and delay module 233, and the SMP RF connectors 52 on the feeder unit 22 and radiating unit 21, are blind-mated using standard SMP dual-female connectors 53 to complete the vertical transmission of RF signals, covering the X-band operating frequency. In terms of the low-frequency signal path, the CY181 low-frequency pins 55 on the TR component 231, delay module 233, and wave control unit 234 are vertically blind-mated with the low-frequency sockets 54 on the feeder unit 22 to complete the transmission of low-frequency control signals and power signals. All blind-mating connections adopt a small-clearance fit design to compensate for the machining tolerances and assembly tolerances of each component, ensuring the reliability and consistency of the connection.

[0034] The antenna array in this embodiment has undergone actual environmental testing and on-orbit verification. Compared with traditional carbon fiber frame-connected spaceborne SAR antennas, it has a 45% reduction in profile thickness, a 30% reduction in weight, a 60% reduction in production cycle, and a 50% reduction in manufacturing cost. At the same time, it reduces the types of high-frequency cables by 50% and improves electrical assembly efficiency by more than double. It is particularly suitable for the low-cost, mass production needs of commercial micro SAR satellites and has good application prospects.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A spaceborne lightweight low-profile deployable SAR antenna array, comprising multiple antenna sub-boards, each sub-board including a mounting plate, a radiating element, a feed line element, a TR assembly, a power module, a delay module, a beam control unit, a power divider assembly, a high-frequency cable network, and a low-frequency cable network, wherein the radiating element and the feed line element are disposed on one side of the mounting plate, and the TR assembly, power module, delay module, beam control unit, power divider assembly, high-frequency cable network, and low-frequency cable network are disposed on the other side of the mounting plate, characterized in that: The antenna sub-board consists of four parts: -X outer board, -X inner board, +X inner board, and +X outer board. The mounting plate serves as the main load-bearing structure of the antenna and is directly connected to the satellite's deployment mechanism. The TR component on the sub-board is integrated along the distance direction, and the remaining electronic components are arranged around the TR component. The TR component, power module, delay module, and wave control unit are arranged in a 180° rotational symmetry relative to the center of the sub-board. The four sub-boards are connected to the satellite through a clamping seat and a deployment drive assembly, and have a retracted state, a half-deployed state, and a fully deployed state.

2. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 1, characterized in that: In the folded state, the -X outer plate and -X inner plate, and the +X outer plate and +X inner plate are respectively stacked in double layers and assembled onto the satellite by clamping seats; in the semi-deployed state, the deployment drive assembly drives the -X outer plate and +X outer plate to deploy synchronously to both sides; in the fully deployed state, the four sub-plates form a complete antenna array on the same plane and enter the working state.

3. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 1, characterized in that: The housing of the mounting plate is precision milled from a single piece of aluminum plate. Bosses are machined on the housing at the mounting positions that connect to the satellite deployment mechanism and at the mounting positions of various electronic components. Threaded holes are provided on the bosses. Reinforcing ribs are machined on the main force transmission path of the housing. The cavities formed after milling and removing material from the remaining areas of the housing are filled with aluminum honeycomb cores and then bonded to the cover plate.

4. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 3, characterized in that: The mounting plate adopts a shell-honeycomb-cover structure and is hot-pressed and bonded together. Both the shell and the cover are made of aluminum alloy and the surface is treated with phosphoric acid anodizing. The bonding surface between the shell and the cover is bonded with adhesive film, and the gaps are filled with expanding foam. The wall thickness of both the shell and the cover is 0.5 mm, and the thickness of the reinforcing rib is 1 mm.

5. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 1, characterized in that: Each active module consists of 4 TR components, 1 power module, 1 delay module, and 1 wave control unit. There are 4 active modules on a single daughterboard, with the active modules arranged diagonally symmetrically with respect to the center of the daughterboard at 180°.

6. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 1, characterized in that: The SMP RF connectors on the TR component and delay module are blindly connected to the SMP RF interfaces on the feeder unit and radiating unit through double female connectors, forming an RF signal path.

7. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 6, characterized in that: The low-frequency pins on the TR component, delay module, and wave control unit are vertically blind-mated with the low-frequency sockets on the feeder unit to form a low-frequency signal path; corresponding connector vias are provided on the mounting plate, and the blind-mating connection adopts clearance fit to meet the installation tolerance requirements.

8. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 1, characterized in that: The radiating unit is formed by precision milling after cavity welding, with a cavity wall thickness of 0.5mm. The radiating unit and the cable assembly are integrated and installed as a whole. The feeder unit adopts a high-low frequency mixed pressure plate structure.

9. The spaceborne lightweight low-profile deployable SAR antenna array according to claim 1, characterized in that: The radiation unit, feeder unit, TR component, power module, delay module, beam control unit, and power divider are all mounted on the mounting plate using fasteners; the high-frequency cable network and low-frequency cable network are interconnected with each electronic device and then fixed to the mounting plate using bindings.

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