Light and small full-polarization SAR satellite system based on reflecting surface system

Abstract

The invention provides a light and small full-polarization SAR satellite system based on a reflector system. The light and small full-polarization SAR satellite system comprises a comprehensive electronic cabin, a load cabin, a supporting cabin, an antenna unfolding mechanism, a multi-polarization phased array feed source and a reflector antenna. The reflector antenna is a bifocus ellipsoid parabolic reflector, the azimuth focus and the distance focus of the reflector antenna do not coincide, and the multi-polarization phased array feed source is located at the azimuth focus. The multi-polarization phased array feed source comprises N dual-polarization radiation units which are arranged in a row in the longitudinal direction and penetrate through the top face of a feed source shell from the interior of the feed source shell, and each dual-polarization radiation unit comprises a horn radiation port, a V-polarization radio frequency connection port and an H-polarization radio frequency connection port; and N dual-channel T / R assemblies. According to the SAR satellite system, the bifocus ellipsoid paraboloid is adopted to be matched with the multi-polarization phased array feed source, so that the full-polarization function is achieved, and meanwhile the scanning and shaping capacity is achieved in the distance direction.

Description

Technical Field

[0001] The present application belongs to the technical field of synthetic aperture radar (SAR) satellites, and generally relates to a lightweight and small fully polarized SAR satellite system based on a reflector antenna. Background Art

[0002] Spaceborne synthetic aperture radar (SAR) has the advantages of all-day and all-weather imaging, has a certain ability to penetrate the ground and forest vegetation, and can provide different polarization information, achieving high-resolution and wide-bandwidth observation capabilities. It is currently a major means of realizing microwave remote sensing observations of the earth.

[0003] Lightweight and small SAR satellites based on reflector antennas are an important development direction in the SAR satellite field. Compared with flat-panel phased array SAR satellites, reflector SAR satellites have the advantages of light weight and small size. While reducing the cost of satellite development, they also reduce the satellite's requirements for the rocket's envelope size and carrying capacity, thereby reducing launch costs.

[0004] At present, the reflector antenna SAR satellites in the existing technology all adopt a fixed multi-beam feed + parabolic reflector antenna system, which can only achieve single polarization function, and cannot achieve dual polarization and full polarization functions. Summary of the invention

[0005] In view of the problems in the prior art, the present invention proposes a lightweight and small fully polarized SAR satellite system based on a reflective surface system, which can not only realize the full polarization function, but also has scanning and shaping capabilities along the range direction.

[0006] The present application provides a light and small fully polarized SAR satellite system based on a reflector system. The SAR antenna includes an integrated electronic cabin, a payload cabin, a support cabin, an antenna deployment mechanism, a multi-polarization phased array feed, and a reflector antenna. The reflector antenna and the multi-polarization phased array feed are connected to the support cabin through the antenna deployment mechanism.

[0007] Among them, the payload cabin is located on one side of the integrated electronic cabin and is used to carry SAR payloads;

[0008] Wherein, the support cabin is fixed to one side of the payload cabin, and is used to support the antenna deployment mechanism and connect the antenna deployment mechanism to the payload cabin;

[0009] Among them, the antenna deployment mechanism is fixed on the supporting cabin, and is used to deploy the reflector antenna and the multi-polarization phased array feed in orbit, while ensuring that the reflector antenna has a compact structure in the folded state; wherein the reflector antenna is a dual-focus ellipsoidal parabola reflector, and the dual-focus ellipsoidal parabola reflector is a dual-focus ellipsoidal parabola, and the dual-focus ellipsoidal parabola reflector has an azimuth focus in the azimuth direction and a range focus in the range direction, and the azimuth focus and the range focus do not overlap. After the reflector antenna is deployed in orbit, the antenna deployment mechanism makes the multi-polarization phased array feed located at the azimuth focus.

[0010] Wherein, the multi-polarization phased array feed is fixedly connected to the antenna deployment mechanism, and the multi-polarization phased array feed includes:

[0011] A feed housing having a top surface, a first longitudinal side wall and a second longitudinal side wall opposite to each other;

[0012] N dual-polarization radiating units are arranged in a row in the longitudinal direction and penetrate through the top surface of the feed housing from the inside of the feed housing, and the dual-polarization radiating units include a horn radiation port, a V-polarization radio frequency connection port, and an H-polarization radio frequency connection port;

[0013] N dual-channel T / R components, each dual-channel T / R component has a V channel and an H channel, wherein N / 2 dual-channel T / R components are V-polarized dual-channel T / R components, which are located on the inner wall of the first longitudinal side wall of the feed housing; and the other N / 2 dual-channel T / R components are H-polarized dual-channel T / R components, which are located on the inner wall of the second longitudinal side wall of the feed housing;

[0014] 2N RF connectors are used to respectively connect the N dual-channel T / R components to the V-polarized RF connection port and the H-polarized RF connection port of the dual-polarized radiating unit.

[0015] According to at least one embodiment of the present application, the distance to the focus is closer to the bifocal ellipsoidal parabola reflector.

[0016] According to at least one embodiment of the present application, the phased array feed is pushed forward toward the focus relative to the distance of the dual-focal ellipsoidal parabola reflector.

[0017] According to at least one embodiment of the present application, a multi-polarization phased array feed is used to realize multiple polarization modes, including a single polarization mode, a dual polarization mode, and a full polarization mode.

[0018] According to at least one embodiment of the present application, the horn radiation port is located outside the feed housing, and the V-polarized RF connection port and the H-polarized RF connection port are located inside the feed housing.

[0019] According to at least one embodiment of the present application, N is an integer greater than or equal to 2.

[0020] According to at least one embodiment of the present application, the RF connector has a right-angle bending connection structure, a first port and a second port, the first port is used to connect to a dual-channel T / R component, and the second port is connected to a V-polarized RF connection port or an H-polarized RF connection port of a dual-polarized radiating unit through an RF cable.

[0021] According to at least one embodiment of the present application, the interior of the RF connector is completely filled with a medium, eliminating the cavity structure inside the RF connector.

[0022] According to at least one embodiment of the present application, the dual-focal point ellipsoidal parabola reflector SAR antenna has an aperture of 9.10 m×3.75 m and an azimuth focal length of 4 m.

[0023] According to at least one embodiment of the present application, the dual-polarization radiation unit is implemented by a horn antenna unit, and an orthogonal mode coupler is provided at the lower end of the horn radiation port of the dual-polarization radiation unit.

[0024] The present invention adopts a new SAR antenna imaging system of multi-polarization phased array feed plus dual-focus ellipsoidal parabolic reflector, which can realize the full polarization function of SAR satellite, greatly improve the system reliability, and at the same time take into account the light weight of the whole satellite, small satellite envelope size, and good mechanical properties of the whole satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following will further explain the above characteristics, technical features, advantages and implementation methods of the present application in a clear and understandable manner through the description of the preferred embodiments and in combination with the accompanying drawings. The following drawings are only intended to illustrate and explain the present application, and do not limit the scope of the present application. Among them:

[0026] Figure 1 It is a schematic diagram of the structure of the SAR satellite of the present invention when the reflector and the feed are deployed;

[0027] Figure 2 It is a schematic diagram of the structure of the SAR satellite of the present invention when the reflector and the feed source are retracted;

[0028] Figure 3 is a schematic diagram of a SAR antenna system of the present invention;

[0029] Figure 4 It is a schematic diagram of the external structure of the phased array feed source of the present invention;

[0030] Figure 5 It is a schematic diagram of the internal structure of the phased array feed of the present invention;

[0031] Figure 6 It is a schematic diagram of the structure of the radiation unit of the present invention;

[0032] Figure 7This is a schematic diagram of the full dielectric filling structure of the high-power connector of the present invention;

[0033] Figure 8 It is a side view of the dual-focus ellipsoidal parabola antenna reflector of the present invention. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described with reference to the accompanying drawings.

[0035] like Figure 1 and Figure 2 As shown, the SAR satellite based on the multi-polarization phased array feed and the reflector antenna provided by the present application includes: an integrated electronic cabin 6; a payload cabin 3; a support cabin 4; an antenna deployment mechanism 5; a multi-polarization phased array feed 1, whose structure is as shown in FIG. Figure 4 and Figure 5 As shown; the reflector antenna 2 is a double-focus ellipsoidal parabolic reflector, and its structure is as follows Figure 3 and Figure 8 shown.

[0036] The payload cabin 3 is located on one side of the integrated electronic cabin 6 and is used to carry the SAR payload; the payload cabin 3 has a smaller lateral (i.e., Z direction in the figure) dimension than the integrated electronic cabin 6, thereby forming accommodating spaces on both lateral sides of the payload cabin 3; the payload cabin 3 is asymmetrically (i.e., not centered) arranged relative to the integrated electronic cabin 6, so that the accommodating space on the left side (-Z direction) is smaller than the accommodating space on the right side (Z direction).

[0037] The support cabin 4 is fixed to one side of the load cabin 3, and is used to support the antenna deployment mechanism 5 and connect the antenna deployment mechanism 5 to the load cabin 3. The support cabin 4 is a trapezoidal body, having a top surface 41 and an inclined surface 42 inclined relative to the load cabin 3.

[0038] The antenna deployment mechanism 5 is fixed on the support cabin 4 and is used to deploy the reflector antenna 2 and the multi-polarization phased array feed source 1 on track. Figure 1 As shown, the reflector antenna 2 is ensured to be compact in structure in the folded state. The antenna deployment mechanism 5 includes a plurality of support rods connected in an interlaced manner, one end of the antenna deployment mechanism 5 is connected to the top surface 41 and the inclined surface 42 of the support cabin 4, and the other end is connected to the reflector antenna 2 and the multi-polarization phased array feed source 1. In the folded state, the reflector antenna 2 is folded into the accommodation space on the left side of the load cabin 3 (-Z direction), and the multi-polarization phased array feed source 1 is folded into the accommodation space on the right side of the load cabin 3 (Z direction).

[0039] Among them, the multi-polarization phased array feed 1 can realize multiple polarization modes, including single polarization mode, dual polarization mode, and full polarization mode, such as Figure 2 and Figure 3As shown, the multi-polarization phased array feed source 1 is fixedly connected to the antenna deployment mechanism 5, and the multi-polarization phased array feed source 1 includes:

[0040] The feed housing 11 has a top surface 111, two opposite longitudinal side walls 112 and two opposite transverse side walls 113;

[0041] N dual-polarization radiating units 12 (in this embodiment, there are 16 dual-polarization radiating units) are arranged in a row in the longitudinal direction and penetrate through the top surface 111 of the feed housing 11 from the inside of the feed housing 11. The dual-polarization radiating unit is implemented by a horn antenna unit. Figure 4 A single dual-polarization radiating unit is shown, which has a low cross-polarization horn structure. The single dual-polarization radiating unit includes a horn radiation port 121, a first polarization RF connection port 12V (a V-polarization RF connection port in this embodiment), and a second polarization RF connection port 12H (an H-polarization RF connection port in this embodiment). The horn radiation port 121 is located outside the feed housing 11, and the first polarization port V and the second polarization port H are located inside the feed housing 11. The lower end of the horn radiation port also has an orthogonal mode coupler (not shown in the figure). Under the condition of sharing one dual-polarization radiating unit, H orthogonal polarization and V orthogonal polarization are realized independently of each other to realize the dual polarization function;

[0042] N dual-channel T / R components (in this embodiment, there are 16 dual-channel T / R components), each dual-channel T / R component has a V channel and an H channel, of which N / 2 (in this embodiment, 8) dual-channel T / R components are V-polarized dual-channel T / R components 13V, and the other N / 2 (in this embodiment, 8) dual-channel T / R components are H-polarized dual-channel T / R components 13H. The 8 V-polarized dual-channel T / R components are located on the inner wall of one longitudinal side wall 112 of the feed housing 11, and the 8 H-polarized dual-channel T / R components are located on the inner wall of the other longitudinal side wall 112 of the feed housing 11. Figure 3 As shown, 8 H-polarized dual-channel T / R components 13H are shown on the inner wall of the longitudinal side wall 112. The dual-channel T / R components are independently configured inside the two opposite side walls of the feed housing 11 according to H polarization and V polarization, so that the SAR satellite system can flexibly choose to work in H single polarization mode, V single polarization mode, H dual polarization mode, V dual polarization mode and full polarization mode as needed. The dual-channel T / R components use S-band gallium nitride power devices with an output power of more than 200W. Gallium nitride power devices have the advantages of high output power, strong radiation resistance and high temperature operation;

[0043] 2N RF connectors 14 are used to connect the V channel and the H channel of the dual-channel T / R component 13 to the RF connection ports 12V and 12H of the dual-polarization radiation unit respectively. Figure 5As shown, the RF connector 14 has a right-angle bending connection structure 143, a first port 141 and a second port 142. Figure 4 As shown, the first port 141 is used to connect to the dual-channel T / R component 13, and the second port 142 is connected to the RF connection ports 12V and 12H of the dual-polarization radiation unit through a RF cable.

[0044] In this embodiment, the RF connector 14 has a right-angle bending connection structure 143 , and the first port 141 and the second port 142 are oriented perpendicular to each other.

[0045] In this embodiment, 16 dual-channel T / R components with an output power of not less than 200W are directly arranged in the multi-polarization phased array feed. 16 dual-polarization radiating units are used, each of which directly carries the high-power output of the dual-channel T / R component. The interior of the high-power RF connector 14 (especially at the right-angle bending connection structure 143 of the RF connector 14) is completely filled with a medium 144, eliminating the internal cavity structure of the RF connector 14, and enhancing the anti-micro-discharge performance of the high-power RF connector 14.

[0046] like Figure 1 As shown, the SAR satellite system based on the multi-polarization phased array feed and the reflector antenna provided by the present application also includes a dual-focus ellipsoidal parabola reflector 2. The dual-focus ellipsoidal parabola reflector 2 is a dual-focus ellipsoidal parabola, which cooperates with the multi-polarization phased array feed 1 to realize the full polarization function and the range scanning function.

[0047] Figure 1 1 shows a side view of the bifocal ellipsoidal parabolic reflector 2, Figure 6 FIG. 2 shows a front view of the bifocal ellipsoidal parabolic reflector 2. Figure 1 and Figure 6 As shown, the bifocal ellipsoidal parabola reflector 2 is a bifocal ellipsoidal parabola, which has a Figure 6 The focal length in the Y direction is f1, and the focus in the azimuth direction is p1; Figure 6 The focal length in the X direction is f2, and the focus upward is p2.

[0048] After the reflector antenna is deployed in orbit, the antenna deployment mechanism 5 places the phased array feed 1 at the azimuth focus p1 of the dual-focal ellipsoidal parabola reflector 2, and uses the focusing ability of the reflector to improve the antenna beam gain. The phased array feed 1 is pushed forward relative to the distance focus p2 of the dual-focal ellipsoidal parabola reflector 2 (i.e., closer to the dual-focal ellipsoidal parabola reflector 2 relative to the distance focus p2), increasing the range beam scanning angle, thereby using the phase scanning capability of the phased array feed 1 to achieve flexible shaping of the range beam.

[0049] The SAR satellite system in the prior art usually adopts a standard parabolic frame antenna, but this antenna form cannot meet the application requirements of a beam-scanning SAR antenna formed with a phased array feed. In response to this problem, the present invention proposes a dual-focus ellipsoidal parabolic reflector, whose focal length in the range direction is different from that in the azimuth direction, and the focal point in the azimuth direction does not overlap with the focal point in the range direction. The present invention realizes the full polarization function and range scanning capability of the SAR satellite by adopting a new SAR antenna imaging system of a multi-polarization phased array feed + dual-focus ellipsoidal parabolic reflector.

[0050] The existing SAR satellite system using a fixed multi-beam feed and a parabolic reflector antenna system usually adopts a method of realizing centralized high-power amplification in the SAR satellite cabin, and then transmitting it to the fixed multi-beam feed outside the cabin through a long-distance waveguide, which has a large insertion loss and low system reliability. In view of this problem, in the SAR satellite system based on a multi-polarization phased array feed and a reflector antenna provided by the present invention, the dual-channel T / R components of the multi-polarization phased array feed are independently configured according to H polarization and V polarization. Compared with the centralized high-power power amplification method adopted by the SAR satellite on orbit, the technical solution adopted by the present invention has been improved in redundant design, and the system reliability is greatly improved. In addition, the present invention adopts multiple dual-polarization radiation units, and multiple high-output power (in this embodiment, the output power is not less than 200W) dual-channel T / R components are directly arranged on the multi-polarization phased array feed. Compared with the method of first realizing centralized high-power amplification in the SAR satellite cabin and then transmitting it to the fixed multi-beam feed outside the cabin through a long-distance waveguide in the prior art, the present application can reduce the insertion loss generated during the long-distance transmission of concentrated power.

[0051] Compared with the fixed multi-beam feed in the prior art, the multi-polarization phased array feed used in the present application can realize wave position control by controlling the amplitude and phase of small signals through wave control codes, which can reduce the insertion loss on the high-power link in the transmission link and greatly improve the reliability of the system.

[0052] For high-output dual-channel T / R components, the present invention also proposes a high-power connector in a fully dielectric-filled state, whose peak power against micro-discharge can reach above 1000W. This greatly improves the product's ability to withstand micro-discharge, eliminates the cavity structure inside the connector, and avoids the dielectric micro-discharge mechanism.

[0053] According to a preferred embodiment of the present application, the dual-focal point ellipsoidal parabola reflector 2 has an aperture of 9.10m×3.75m and an azimuth focal length of 4m, which ensures the best focal diameter ratio, thereby achieving the highest reflector aperture efficiency and maximum gain. The dual-focal point ellipsoidal parabola reflector antenna of this aperture size is the largest size currently in orbit for SAR satellites. The weight of the SAR antenna reflector can be as low as 76kg, the weight of the phased array feed can be as low as 66kg, and the weight of the deployment mechanism can be as low as 46kg. Considering the total weight of the cable and thermal control SAR antenna of 199kg, compared with the flat-panel phased array antenna, the weight is only about one-third of that of the flat-panel phased array antenna.

[0054] In order to achieve light mass of the entire satellite and small satellite envelope size, this application adopts a reasonable satellite configuration layout, designs an asymmetric payload cabin and a trapezoidal support cabin, designs a phased array feed and reflector antenna deployment mechanism, meets the on-orbit deployment requirements of large-aperture reflector antennas, and at the same time ensures that the large-aperture reflector antenna has a compact structure in the folded state, ensures that the mechanical properties of the entire satellite are good, and can adapt to the mechanical environment during the launch of the carrier rocket.

[0055] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0056] The above description is only an illustrative embodiment of the present application and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by any technician in the field without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. A light and small fully polarized SAR satellite system based on a reflector system, comprising an integrated electronic cabin, a payload cabin, a support cabin, an antenna deployment mechanism, a multi-polarization phased array feed, and a reflector antenna. The reflector antenna and the multi-polarization phased array feed are connected to the support cabin through the antenna deployment mechanism. in, The payload bay is located on one side of the integrated electronics bay and is used to carry SAR payloads; Wherein, the support cabin is fixed to one side of the payload cabin, and is used to support the antenna deployment mechanism and connect the antenna deployment mechanism to the payload cabin; The antenna deployment mechanism is fixed on the support cabin, which is used to deploy the reflector antenna and the multi-polarization phased array feed in orbit, while ensuring that the reflector antenna is compact in structure when folded. Wherein, the reflector antenna is a dual-focus ellipsoidal parabola reflector, the dual-focus ellipsoidal parabola reflector is a dual-focus ellipsoidal parabola, the dual-focus ellipsoidal parabola reflector has an azimuth focus in the azimuth direction and a distance focus in the distance direction, the azimuth focus and the distance focus do not overlap, and after the reflector antenna is deployed in orbit, the antenna deployment mechanism causes the multi-polarization phased array feed to be located at the azimuth focus; Wherein, the multi-polarization phased array feed is fixedly connected to the antenna deployment mechanism, and the multi-polarization phased array feed includes: A feed housing having a top surface, a first longitudinal side wall and a second longitudinal side wall opposite to each other; N dual-polarization radiating units are arranged in a row in the longitudinal direction and penetrate through the top surface of the feed housing from the inside of the feed housing, and the dual-polarization radiating units include a horn radiation port, a V-polarization radio frequency connection port, and an H-polarization radio frequency connection port; N dual-channel T / R components, each dual-channel T / R component has a V channel and an H channel, wherein N / 2 dual-channel T / R components are V-polarized dual-channel T / R components, which are located on the inner wall of the first longitudinal side wall of the feed housing; and the other N / 2 dual-channel T / R components are H-polarized dual-channel T / R components, which are located on the inner wall of the second longitudinal side wall of the feed housing; 2N RF connectors are used to respectively connect the V channels and H channels of the N dual-channel T / R components to the V polarization RF connection port and the H polarization RF connection port of the dual-polarization radiating unit.

2. The system according to claim 1, wherein: The distance to the focus is closer to the bifocal ellipsoidal parabolic reflector.

3. The system according to claim 1, wherein: The phased array feed is pushed forward toward the focal point relative to the distance of the dual-focal ellipsoidal parabolic reflector.

4. The system according to claim 1, wherein: Multi-polarization phased array feed is used to realize multiple polarization modes, including single polarization mode, dual polarization mode, and full polarization mode.

5. The system according to claim 1, wherein: The horn radiation port is located outside the feed source housing, and the V-polarized radio frequency connection port and the H-polarized radio frequency connection port are located inside the feed source housing.

6. The system according to claim 1, wherein: N is an integer greater than or equal to 2.

7. The system according to claim 1, wherein: The RF connector has a right-angle bending connection structure, a first port and a second port. The first port is used to connect to a dual-channel T / R component, and the second port is connected to a V-polarized RF connection port or an H-polarized RF connection port of a dual-polarized radiating unit through an RF cable.

8. The system according to claim 7, wherein: The interior of the RF connector is completely filled with dielectric, eliminating the cavity structure inside the RF connector.

9. The system according to claim 1, wherein: The double-focus ellipsoidal parabolic reflector has an aperture of 9.10m×3.75m and an azimuth focal length of 4m.

10. The system according to claim 1, wherein: The dual-polarization radiation unit is realized by a horn antenna unit, and an orthogonal mode coupler is arranged at the lower end of the horn radiation port of the dual-polarization radiation unit.

Images