A method for optimizing the design of a satellite stealth configuration

Abstract

The present invention discloses an optimized design method for satellite stealth configurations, belonging to the field of satellite stealth design. Based on the existing multi-faceted stealth satellite with a regular hexagon bottom surface, the present invention optimizes the configuration by changing the number of sides of the regular polygon bottom surface. The present invention includes multi-faceted cones with regular pentagon, regular hexagon, regular octagon, regular dodecagon, and regular hexadecagon bottom surfaces respectively; through the RCS comparison simulation of the five stealth configurations in the optimization method, it is obtained that the arithmetic mean of the configuration RCS first decreases and then increases with the increase of the number of sides of the polygon. When the bottom surface is a regular octagon, the arithmetic mean of the RCS reaches the minimum, that is, the satellite stealth effect is the best. Compared with the prior art, the arithmetic mean of the circumferential RCS of the satellite stealth configuration of the present invention has decreased by 6.95 dBsm, and the decrease amplitude has reached 34.42%, and the stealth performance is better.

Description

Technical Field

[0001] The present invention relates to the field of satellite configuration design, in particular to the optimal design of stealth configurations for microsatellites, and specifically to a method for optimizing the stealth configuration of a satellite. Background Art

[0002] Stealth satellites play a crucial role in future space offensive and defensive operations. In response to the different threats faced by satellites under different detection systems, satellite stealth technologies can be divided into radar stealth, radio frequency stealth, visible light stealth, and infrared stealth. Among them, one of the main threats to satellites comes from radar. Designing and optimizing the stealth configuration of satellites can further reduce the target RCS and improve the stealth ability of satellites.

[0003] Perhaps due to reasons of confidentiality, there is relatively little research on the field of satellite stealth at home and abroad, and it is even rarer to optimize the stealth configuration of existing stealth satellites. In 1990, the first satellite of the US Misty Program (Misty-1) was successfully launched. There was a conical inflatable cover under the cylindrical satellite body. When the radar waves emitted from the ground irradiated the conical inflatable cover, they would be refracted in other directions, greatly suppressing the echo energy. At the same time, this was also the world's first stealth satellite in orbit. Zheng Kan proposed 3 stealth microsatellite configurations based on the design idea of multi-faceted surfaces and obtained the conclusion that the multi-faceted pyramid had better stealth effects through RCS comparison simulations. Zhu Dongjun et al. proposed a satellite configuration that took into account both radar stealth and optical stealth. Its peak optical cross-sectional area (OCS) was only 0.082 m 2 and it was not easily monitored and identified by optical detection systems.

[0004] The existing stealth satellite Tianxun-1 (with a regular hexagon as the bottom surface) has carried out verification means such as RCS numerical calculation, ground stealth performance test of the prototype satellite, and in-orbit operation test of the regular satellite, which have confirmed its low radar target characteristics. However, the stealth configuration of Tianxun-1 is not the optimal configuration, and the configuration can be further optimized on its basis to further reduce the satellite RCS. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method for optimizing the stealth configuration of a satellite, obtaining a better configuration, further reducing the arithmetic mean of RCS in the key angular domain and the omnidirectional angular domain, optimizing the bottom surface of the initial configuration, that is, Tianxun-1 with a regular hexagon as the bottom surface, that is, starting from reducing and increasing the number of sides of the regular polygon to optimize the configuration, and obtaining multi-faceted pyramids with regular pentagons, regular hexagons, regular octagons, regular dodecagons, and regular hexadecagons as the bottom surfaces, which have better stealth performance. The multi-faceted pyramids of the present invention improve the stealth ability of satellites and provide a technical reference for the stealth design and optimization of future microsatellites.

[0006] The present invention is implemented as follows:

[0007] A method for optimizing the design of a satellite stealth configuration, characterized in that the satellite stealth configuration is a multi-faceted pyramid with a three-section geometric body structure, and the multi-faceted pyramid is successively a multi-edged pyramid, a multi-edged frustum, and a multi-edged prism from top to bottom; the multi-faceted pyramid is a regular octagonal three-section body, that is, the bottom surface of the multi-faceted pyramid is a regular octagon.

[0008] Furthermore, the bottom surface of the multi-faceted pyramid can also be a regular pentagon, a regular hexagon, a regular dodecagon, or a regular hexadecagon, and the bottom polygons are all within the circular envelope of the same diameter; the height of the first section of the multi-faceted pyramid is 262 mm, the height of the second section is 374 mm, and the height of the third section is 185 mm.

[0009] Furthermore, the stealth performance of the multi-faceted pyramid with different bottom surfaces is different. When the number of sides of the regular polygon at the bottom of the multi-faceted pyramid changes, the size and inclination angle of each facet of the satellite will also change accordingly, which will cause the backscattering radar cross-section of the satellite to change, that is, the stealth performance of the satellite changes.

[0010] Furthermore, the stealth performance of the satellite is measured by the RCS value; through the RCS comparison simulation of satellites with multi-faceted pyramids of regular pentagons, regular hexagons, regular octagons, regular dodecagons, and regular hexadecagons in the X-band, the arithmetic mean of the RCS in the key angular domain and the omnidirectional angular domain is statistically calculated. The key angular domain is selected as the ±60° angular domain centered at the tip of the satellite; the circumferential RCS mean value of the regular pentagon is -16.19 dBsm, and the key angular domain RCS mean value is -32.28 dBsm; the circumferential RCS mean value of the regular hexagon is -20.19 dBsm, and the key angular domain RCS mean value is -20.19 dBsm; the circumferential RCS mean value of the regular octagon is -27.14 dBsm, and the key angular domain RCS mean value is -24.03 dBsm; the circumferential RCS mean value of the regular dodecagon is -23.65 dBsm, and the key angular domain RCS mean value is -15.26 dBsm; the circumferential RCS mean value of the regular hexadecagon is -21.94 dBsm, and the key angular domain RCS mean value is -11.75 dBsm.

[0011] Furthermore, the electromagnetic scattering mechanisms of the multi-faceted pyramids with regular pentagons, regular hexagons, regular octagons, regular dodecagons, and regular hexadecagons at the bottom are all the same, including specular reflection, edge diffraction, and tip scattering; different configurations of the multi-faceted pyramids result in different facet areas and oblique angles, which lead to different scattering fields and RCSs.

[0012] The optimization method of the method for optimizing the design of a satellite stealth configuration according to the present invention is as follows:

[0013] Step 1: Obtain different satellite stealth configurations by changing the shape of the polygon on the bottom surface of Tianxun-1 stealth satellite with a regular hexagon bottom surface; iterating downward the number of sides of the regular hexagon can obtain a regular pentagon, and iterating upward can obtain regular octagons, dodecagons, and hexadecagons, and thus five different multi-faceted stealth satellites are obtained;

[0014] Step 2: For the scattering characteristics of this type of multi-faceted stealth satellite, adopt a hybrid solution method of physical optics method and equivalent electromagnetic current method to solve the RCS of the multi-faceted stealth satellite;

[0015] The described physical optics method (PO) is applicable to solving the scattering characteristics of the target in the optical region. Starting from the Stratton-Chu scattering field integral equation, through the tangent plane approximation method, it is assumed that the target surface current value is equal to the current value when the target is an ideal smooth plane at the integral surface element, and based on this, the physical optics current is integrated to obtain the far-field scattering field of the target; the square root of the RCS of the surface element obtained according to the tangent plane approximation is:

[0016]

[0017] In the formula: n represents the normal vector at the integral surface element, k is the number of incident electromagnetic waves, j is the imaginary unit, S is the area of the small surface element, e r and h i are respectively the electric field unit vector of the receiving antenna and the magnetic field unit vector of the transmitting antenna, and i and s respectively represent the unit vectors of the incident direction and the scattering direction of the electromagnetic wave.

[0018] PO has a high solution accuracy for specular reflection, but the solution effect for scattering problems at edges and tips is not ideal; therefore, the equivalent electromagnetic current method is used to solve and calculate the edge diffraction and tip scattering of the satellite. The square root of the RCS of the surface element based on the equivalent electromagnetic current theory is:

[0019]

[0020] In the formula: t is the direction of the edge unit vector, θ is the angle including the incident direction i and t, is the incident electric field strength, is the incident magnetic field strength, Z0 is the free space impedance, r t is the position vector in the middle of the edge, and l is the vector of the edge;

[0021] At this time, the total RCS superposition equation of the satellite is:

[0022]

[0023] Step 3: Post-process the satellite RCS data obtained by using the hybrid method, i.e., PO+ECM, calculate the circumferential RCS mean value and the RCS mean value in the key angular region, and conduct a comparative analysis. It is not difficult to find from the simulation results that the stealth performance of the satellite first increases and then decreases as the number of sides of the satellite bottom polygon increases. The best stealth configuration appears when the bottom surface is a regular octagon, which proves the effectiveness of this optimization method. By changing the satellite configuration, the RCS mean value of the stealth satellite can be reduced, and the satellite stealth performance can be further improved, that is, a satellite configuration with better stealth effect can be obtained by iterating the number of sides of the satellite bottom polygon.

[0024] The beneficial effects of the present invention compared with the prior art are as follows: A new stealth configuration is obtained by further optimizing the existing satellite configuration. The omnidirectional RCS mean value and the RCS mean value in the key angular region are respectively lower than those of the original design (Tianxun-1) by 6.95 dBsm and 3.12 dBsm, and the reduction amplitudes reach 34.42% and 14.92%, respectively, and the stealth performance has been significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a three-segment multi-faceted stealth configuration with a regular pentagon bottom surface in the satellite configuration optimization method of the present invention;

[0026] Figure 2 It is a three-segment multi-faceted stealth configuration with a regular hexagon bottom surface in the satellite configuration optimization method of the present invention;

[0027] Figure 3 It is a three-segment multi-faceted stealth configuration with a regular octagon bottom surface in the satellite configuration optimization method of the present invention;

[0028] Figure 4 It is a three-segment multi-faceted stealth configuration with a regular dodecagon bottom surface in the satellite configuration optimization method of the present invention;

[0029] Figure 5 It is a three-segment multi-faceted stealth configuration with a regular hexadecagon bottom surface in the satellite configuration optimization method of the present invention;

[0030] Figure 6 It is a RCS comparison simulation of five stealth satellite configurations of the present invention at the center frequency point (10 GHz) of the X band;

[0031] Figure 7 It is a flow chart of the satellite configuration optimization method of the present invention;

[0032] Figure 8 It is a satellite stealth configuration obtained by a satellite stealth configuration optimization design method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] To make the objectives, technical solutions, and effects of the present invention clearer and more definite, the following further describes the present invention in conjunction with simulation examples and drawings to facilitate a better understanding of the significant improvement in the stealth performance of the optimized configuration in the present invention. It should be noted that the specific implementations described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] An optimized design method for a satellite stealth configuration disclosed by the present invention, the optimization method being:

[0035] Step 1: Obtain several different configurations of satellite stealth configurations by changing the shape of the bottom polygon of the Tianxun-1 stealth satellite. By iteratively decreasing the number of sides of a regular hexagon, a regular pentagon can be obtained, and by iteratively increasing the number of sides, a regular octagon, a regular dodecagon, and a regular hexadecagon can be obtained, thereby obtaining five different multi-faceted stealth satellites.

[0036] Step 2: For the scattering characteristics of this type of multi-faceted stealth satellite, a hybrid solution method of physical optics method + equivalent electromagnetic current method is adopted, which can not only accurately solve the RCS of the multi-faceted stealth satellite but also significantly reduce the computer memory requirements and save the time spent on RCS numerical calculations.

[0037] The physical optics method (PO) is mainly applicable to solving the scattering characteristics of a target in the optical region. Starting from the Stratton-Chu scattering field integral equation, by using the tangent plane approximation method, it is assumed that the target surface current value is equal to the current value when the target is an ideal smooth plane at the integral surface element, and based on this, the physical optics current is integrated to obtain the far-field scattering field of the target. The square root of the RCS of the surface element obtained according to the tangent plane approximation is:

[0038]

[0039] In the formula: n represents the normal vector at the integral surface element, k is the number of incident electromagnetic waves, j is the imaginary unit, S is the area of the small surface element, e r and h i are the electric field unit vector of the receiving antenna and the magnetic field unit vector of the transmitting antenna respectively, and i and s represent the unit vectors of the incident direction and the scattering direction of the electromagnetic wave respectively.

[0040] PO has a high solution accuracy for specular reflection, but the solution effect for scattering problems at edges and tips is not ideal. Therefore, the equivalent electromagnetic current method is used to solve the edge diffraction and tip scattering of the satellite. The square root of the RCS of the surface element based on the equivalent electromagnetic current theory is:

[0041]

[0042] In the formula: t is the direction of the edge unit vector, θ is the angle including the incident direction i and t, is the incident electric field strength, is the incident magnetic field strength, Z0 is the free space impedance, r t is the position vector in the middle of the edge, and l is the vector of the edge.

[0043] At this time, the total RCS superposition equation of the satellite is:

[0044]

[0045] Step 3: Post-process the satellite RCS data obtained by using the hybrid method (PO+ECM), calculate the circumferential RCS mean value and the RCS mean value in the key angular region, and conduct a comparative analysis. It is not difficult to find from the simulation results that the stealth performance of the satellite first increases and then decreases as the number of sides of the polygon at the bottom of the satellite increases, and the best stealth configuration appears when the bottom is an octagon. This proves the effectiveness of the present optimization method. By changing the satellite configuration, the RCS mean value of the stealth satellite can be reduced, and the stealth performance of the satellite can be further improved, that is, a satellite configuration with better stealth effect can be obtained by iterating the number of sides of the polygon at the bottom of the satellite.

[0046] The stealth configuration of the satellite obtained by the above method is a multi-faceted pyramid with a three-section geometric structure, as Figures 1 to 5 shown. The multi-faceted pyramid is successively a multi-edge pyramid (1), a multi-edge frustum (2), and a multi-edge prism (3) from top to bottom; the bottom of the multi-faceted pyramid is a regular pentagon, a regular hexagon, an octagon, a dodecagon, and a hexadecagon, and the bottom polygons are all within the circular envelope of the same diameter; the heights corresponding to the three sections of the geometric body of the multi-faceted pyramid are the same, the height of the first section is 262 mm, the height of the second section is 374 mm, and the height of the third section is 185 mm.

[0047] The stealth shapes of the five stealth satellites of the present invention are relatively similar, but the specific RCS distributions are significantly different. By changing the shape of the regular polygon at the bottom, the surface area, quantity, and inclination angle of the inclined surface of the pyramid, frustum, and prism are changed, thereby changing the backscattering radar cross section.

[0048] The stealth performance of the satellite is measured by RCS. To verify the configuration optimization method, Figure 6 the circumferential RCS distribution and RCS comparison diagrams of all satellites in the configuration optimization method at the center frequency point of the X band (10 GHz) are given.

[0049] The RCS distributions of configurations other than the regular pentagon are symmetrically distributed with a symmetry center at 180°. At 180°, all configurations have a maximum scattering wave peak, which exactly corresponds to the strong specular reflection of the polygonal base. Except for the obvious main lobe at the center, there are 3 symmetric scattering wave peaks on each side, and they gradually approach both sides as the number of sides of the polygon increases. This is because the different numbers of sides of the bottom polygon result in different areas and oblique angles of each prism surface, thus affecting the total RCS of the satellite. Specifically, Figure 6 (a) shows the RCS simulation results of the five-edge three-section configuration. Since it is not a centrosymmetric structure, its RCS curve is not symmetrically distributed along 180°. The main lobe appears at 180°. In addition, there are also two strong scattering wave peaks in the angular range near 270°. Except for the main lobe, the RCS in the remaining angular ranges is basically below 20 dB, and the overall stealth effect is very poor. Figure 6 (b) to Figure 6 (e) have similar scattering characteristics. There is a strong scattering wave peak at 180°, which corresponds to the case where the radar wave is vertically incident on the polygonal base. The RCS in the remaining angular ranges is at a relatively low level. Among them, Figure 6 (b) Except for the main lobe, the RCS in the remaining angular ranges is basically below -5 dB, and the stealth effect is good; Figure 6 (c) In most angular ranges, the RCS is at an extremely low level, reaching below -40 dB. Except for the main lobe, the RCS in the remaining angular ranges is basically below 0 dB, and the stealth effect is good; In figure (d), except for the main lobe, the RCS in the remaining angular ranges is basically below 5 dB; In figure (e), except for the main lobe, the RCS in the remaining angular ranges is basically below 15 dB, and the stealth effect is poor. Figure 6 (f) From the RCS comparison simulation, it can be seen that the overall RCS of Tianxun-1, the regular octagon, and the regular dodecagon is relatively low, while the overall RCS of the regular pentagon and the regular hexadecagon is relatively high.

[0050] To specifically analyze the stealth performance of the satellite configuration in the optimization method, the arithmetic mean of the RCS distribution curve is used as a reference index. Starting from the circumferential RCS, it is not difficult to find that as the number of edges of the regular polygon at the bottom of the satellite increases, the circumferential RCS mean first decreases and then increases. That is, the configuration of Tianxun-1 can be further optimized to improve its radar stealth performance. The best stealth configuration should be a three-section body with eight regular edges (an eight-edge prism + an eight-edge frustum + an eight-edge pyramid). Select 0-60° as the key angular domain, which is also the main radar wave irradiation angular domain. It can be found that the ranking of the stealth effects of the configurations changes within the key angular domain. The configuration with the smallest RCS mean is the three-section body with five regular edges, followed by the three-section body with eight regular edges. When the regular pentagon is removed, the stealth performance of the four configurations still shows the characteristic of first increasing and then decreasing. This is mainly because the regular pentagon is not a highly symmetric geometric body, and its RCS distribution characteristics do not show a regular symmetric distribution like the other four configurations. Although the three-section body with five regular edges has the best effect within the key angular domain, the omnidirectional stealth ability of the satellite will be particularly important under the future space-air-ground integrated radar surveillance system. Therefore, considering comprehensively, the three-section body with eight regular edges should be selected as the best stealth configuration.

[0051] Based on the existing stealth satellite, a three-section body with eight regular edges is obtained through a stealth configuration optimization design method. Its circumferential and RCS means within the key angular domain are respectively 6.95 dBsm and 3.12 dBsm lower than the original design (Tianxun-1), and the decrease amplitudes reach 34.42% and 14.92%. Specifically, as shown in Table 1.

[0052] Table 1 Comparison of RCS means of stealth configurations

[0053]

[0054] As can be seen from the above table: The stealth effect of the regular pentagon is the worst, and its RCS mean is 4 dBsm higher than that of the original design. This configuration is not considered. The circumferential RCSs of the other three configurations all decrease to varying degrees. The circumferential RCS mean of the regular octagon is 6.95 dBsm lower than that of Tianxun-1. The circumferential RCS means of the regular dodecagon and the regular hexadecagon are respectively 3.46 dBsm and 1.75 dBsm lower than that of Tianxun-1, and the reduction amplitudes are relatively small. From the above analysis, it is not difficult to conclude that the stealth performance of a stealth satellite with a multi-faceted cone will first increase and then decrease as the number of edges of the regular polygon at the bottom increases; when the bottom is a regular octagon, the configuration stealth performance reaches the optimal.

[0055] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements can still be made, and these improvements should also be regarded as the protection scope of the present invention.

Claims

1. A method for optimizing the stealth configuration of a satellite, characterized in that, Step 1. Obtain satellite stealth configurations with different configurations by changing the shape of the bottom polygon of Tianxun-1 stealth satellite with a regular hexagon bottom; the satellite stealth configuration is a multi-faceted pyramid with a three-section geometric body structure, and the multi-faceted pyramid is successively a multi-edged pyramid, a multi-edged frustum, and a multi-edged prism from top to bottom; the height of the first section of the multi-faceted pyramid is 262 mm, the height of the second section is 374 mm, and the height of the third section is 185 mm; By iteratively decreasing the number of sides of the regular hexagon at the bottom of Tianxun-1 stealth satellite, a regular pentagon can be obtained, and by iteratively increasing the number of sides, a regular octagon, a regular dodecagon, and a regular hexadecagon can be obtained. The bottom polygons are all within a circular envelope of the same diameter, and five different multi-faceted stealth satellites are thus obtained; that is, the stealth configurations of multi-faceted pyramid satellites with regular pentagon, regular hexagon, regular octagon, regular dodecagon, and regular hexadecagon bottoms; Step 2. For the scattering characteristics of this type of multi-faceted stealth satellite, use a hybrid solution method of Physical Optics (PO) and Equivalent Electromagnetic Current Method (ECM) to solve the RCS of the multi-faceted stealth satellite; The Physical Optics method is applicable to solving the scattering characteristics of the target in the optical region. Starting from the Stratton-Chu scattering field integral equation, by the tangent plane approximation method, it is assumed that the target surface current value is equal to the current value when the target is an ideal smooth plane at the integration surface element, and based on this, the physical optics current is integrated to obtain the far-field scattering field of the target; the square root of the RCS of the surface element obtained according to the tangent plane approximation is: Where: n represents the normal vector at the integration surface element, k is the number of incident electromagnetic waves, j is the imaginary unit, S is the area of the small surface element, e r and h i are respectively the electric field unit vector of the receiving antenna and the magnetic field unit vector of the transmitting antenna, and i and s respectively represent the unit vectors of the incident direction and the scattering direction of the electromagnetic wave; PO has a high solution accuracy for specular reflection, but the solution effect for scattering problems at edges and tips is not ideal; therefore, the equivalent electromagnetic current method is used to solve and calculate the edge diffraction and tip scattering of the satellite. The square root of the RCS of the surface element based on the equivalent electromagnetic current theory is: where: t is the direction of the edge unit vector, θ is the angle including the incident direction i and t, is the incident electric field strength, is the incident magnetic field strength, Z0 is the free space impedance, r t is the position vector in the middle of the edge, l is the vector of the edge; At this time, the total RCS superposition equation of the satellite is: Step 3. Post-process the satellite RCS data obtained by using the hybrid method, i.e., PO+ECM, calculate the omnidirectional angular domain RCS mean value and the RCS mean value in the key angular domain and conduct a comparative analysis; it is not difficult to find from the simulation results that the stealth performance of the satellite first increases and then decreases as the number of sides of the bottom polygon of the satellite increases. The best stealth configuration appears when the bottom is a regular octagon, which proves the effectiveness of this optimization method. By changing the satellite configuration, the RCS mean value of the stealth satellite can be reduced, and the satellite stealth performance can be further improved, that is, by iteratively changing the number of sides of the satellite bottom polygon, a satellite configuration with better stealth effect can be obtained; The stealth performances of multi-faceted pyramids with different bottoms are different. When the number of sides of the regular polygon at the bottom of the multi-faceted pyramid changes, the size and inclination angle of each facet of the satellite will also change accordingly, which will cause the change of the rearward radar cross section of the satellite, that is, the change of the satellite stealth performance.

2. The method for optimizing the stealth configuration of a satellite according to claim 1, characterized in that, The stealth performance of the satellite is measured by the RCS value; through the RCS comparison simulation of satellites with multi-faceted pyramids of regular pentagons, regular hexagons, regular octagons, regular dodecagons, and regular hexadecagons in the X-band, the arithmetic mean of the RCS in the key angular range and the omnidirectional angular range is statistically calculated. The key angular range is selected as the ±60° angular range centered at the tip of the satellite; the omnidirectional angular range RCS mean value of the regular pentagon is -16.19 dBsm, and the key angular range RCS mean value is -32.28 dBsm; the omnidirectional angular range RCS mean value of the regular hexagon is -20.19 dBsm, and the key angular range RCS mean value is -20.19 dBsm; the omnidirectional angular range RCS mean value of the regular octagon is -27.14 dBsm, and the key angular range RCS mean value is -24.03 dBsm; the omnidirectional angular range RCS mean value of the regular dodecagon is -23.65 dBsm, and the key angular range RCS mean value is -15.26 dBsm; the omnidirectional angular range RCS mean value of the regular hexadecagon is -21.94 dBsm, and the key angular range RCS mean value is -11.75 dBsm.

3. The method for optimizing the stealth configuration of a satellite according to claim 1, characterized in that, The electromagnetic scattering mechanisms of the multi-faceted pyramids with regular pentagons, regular hexagons, regular octagons, regular dodecagons, and regular hexadecagons as the bottom surfaces are all the same, including specular reflection, edge diffraction, and tip scattering; different configurations of the multi-faceted pyramids result in different facet areas and oblique angles, leading to different scattering fields and RCSs.

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