Method for reducing RCS (radar cross section) of low-scattering metal support

Abstract

The invention discloses a method for reducing RCS (radar cross section) of a low-scattering metal support. The RCS of the metal support is reduced by combining three different wave-absorbing materials and loading the wave-absorbing materials on the outer surface of the low-scattering metal support in different modes. The three wave-absorbing materials are respectively a wave-absorbing coating, a metamaterial and a hard wave-absorbing material. According to the invention, multiple wave absorbing materials are loaded on the low-scattering metal support, so that the low-frequency RCS performance of the low-scattering metal support can be effectively optimized, the coupling scattering between the support and the target is reduced, and the test requirements of more invisible targets can be met; the wave-absorbing material structure adopted by the method is light in weight, easy to process, transport, mount and maintain and relatively low in cost, and the mechanical property of the metal bracket is not influenced; the method is easy to implement, high in operability and capable of being used for upgrading and optimizing an existing low-scattering metal support.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic measurement, and in particular to a method for reducing RCS of a low-scattering metal bracket. Background Art

[0002] The low-scattering metal bracket is an important component of the support system in the compact field test system. Its main function is to support the target under test within the quiet zone and enable the target to rotate and pitch, etc., to simulate the state of the target under test during actual work.

[0003] Low-scattering metal brackets represent the cutting-edge development level of current support technology. Almost all advanced RCS (Radar Cross Section) test sites are equipped with low-scattering metal brackets. However, low-scattering metal brackets still have various defects, such as the difficulty in reducing the scattering level of low-frequency bands of low-scattering metal brackets, and the strong coupling scattering between targets and brackets that is difficult to eliminate with currently commonly used post-processing technologies such as background cancellation.

[0004] At present, accurate RCS measurement requires that the background level be more than 20dB lower than the target's RCS level, which places high demands on the low-frequency (especially P-band) low RCS characteristics of metal brackets. The RCS performance of traditional low-scattering metal brackets composed of single-curvature or double-curvature olive cross-sections is difficult to meet the test requirements of stealth targets. Patent document CN106125051 A discloses a low-scattering metal bracket with a special shape, which has little optimization on the low-scattering characteristics of the low-scattering metal bracket. The bracket RCS value in the frequency range of 8Ghz~18GHz is not significantly optimized compared to the tilted bracket, and the P-band (0.3Ghz~1GHz) optimization will only be smaller, which cannot meet the current test requirements. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for reducing the RCS of a low-scattering metal bracket, by combining and loading three different absorbing materials on the outer surface of the low-scattering metal bracket to reduce the RCS of the metal bracket; the three different absorbing materials are specifically an absorbing coating layer, a metamaterial layer, and a hard absorbing material layer.

[0006] Furthermore, the absorbing paint layer is configured to absorb the specular reflection generated after the electromagnetic wave is irradiated to the low-scattering metal bracket; the absorbing paint layer adopts a magnetic absorbing material, and the absorbent in the magnetic absorbing material mainly includes: ferrite absorbent and carbonyl iron powder absorbent.

[0007] Furthermore, the metamaterial layer is configured to reduce creeping waves and edge scattering generated when electromagnetic waves are irradiated onto a low-scattering metal bracket; the metamaterial layer is composed of a flexible dielectric substrate and a conductive material printed thereon, and the conductive material includes: metal powder, graphite, and carbon powder.

[0008] Furthermore, the metamaterial layer is a multi-layer structure. Except for the first layer which is arranged at the edge of the support, each subsequent layer is arranged at the edge of the previous layer, and the pattern of the conductive material printed on each layer is different.

[0009] Furthermore, the hard absorbing material layer is configured to support the metamaterial layer and perform preliminary absorption of electromagnetic waves; wherein the hard absorbing material layer is connected by alternating mortise and tenon joints.

[0010] Furthermore, the overall shape of the hard absorbing material is oval, teardrop or date-core shaped.

[0011] Furthermore, the method of loading three different absorbing materials on the outer surface of the low-scattering metal bracket specifically includes the following steps: S1. Spraying the configured magnetic absorbing material on the surface of the metal bracket through a spray gun; S2. After spraying, placing the metal bracket on a tooling rack for surface drying; S3. Adding a metamaterial layer to the front and rear edges of the metal bracket after surface drying; S4. Adding a surrounding structure made of hard absorbing material to the periphery of the metal bracket.

[0012] Furthermore, in the step S1, the thickness of the magnetic absorbing material sprayed is in the range of 0.1 mm to 5 mm.

[0013] Furthermore, in the step S4, the installation method of the surrounding structure is to connect it using a mortise and tenon structure.

[0014] The present invention provides a method for reducing the RCS of a low-scattering metal bracket, which has the following beneficial effects: The present invention can effectively optimize the low-frequency RCS performance of the low-scattering metal bracket by loading a variety of absorbing materials on the low-scattering metal bracket, reduce the coupling scattering between the bracket and the target, and meet the testing needs of more stealth targets; the absorbing material structure used is light in weight, easy to process, transport, install and maintain, and has a relatively low cost, and will not affect the mechanical properties of the metal bracket itself; it is simple to implement and has strong operability, and can be configured as an upgrade and optimization of the existing low-scattering metal bracket. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of the result of loading the absorbing coating layer and the metamaterial layer on the bracket provided by the present invention; Figure 2 A schematic diagram of the result of loading a hard absorbing material layer provided by the present invention; Figure 3 A schematic diagram of the mortise and tenon wave-absorbing edge structure of the hard wave-absorbing material provided by the present invention; Figure 4 A schematic diagram of the region supporting the metamaterial provided by the present invention; Figure 5 The RCS simulation effect diagram of the P band of the embodiment provided by the present invention (HH polarization); Figure 6 This is a diagram of the RCS simulation effect of the P band of the embodiment provided by the present invention (VV polarization). DETAILED DESCRIPTION

[0017] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0018] The following is a detailed description of the implementation method of the present invention in conjunction with the accompanying drawings. Only some embodiments are described, not all embodiments. For the purpose of clarity, representations and descriptions that are not related to the present invention are omitted in the drawings and descriptions.

[0019] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below. Obviously, the implementation cases described are part of the embodiments of the present invention, not all of the embodiments, and cannot be understood as limiting the scope of the implementation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0020] like Figure 1 , Figure 2 As shown, the present invention provides a method for reducing the RCS of a low-scattering metal bracket, by combining three different absorbing materials and loading them on the outer surface of the low-scattering metal bracket to reduce the RCS of the metal bracket; the three different absorbing materials are specifically an absorbing coating layer, a metamaterial layer, and a hard absorbing material layer.

[0021] Among them, the absorbing paint layer is configured to absorb the specular reflection generated after the electromagnetic wave is irradiated to the low-scattering metal bracket; the absorbing paint layer adopts magnetic absorbing material, and the absorbent in the magnetic absorbing material mainly includes: ferrite absorbent and carbonyl iron powder absorbent.

[0022] The metamaterial layer is configured to reduce creeping waves and edge scattering generated by electromagnetic waves irradiating the low-scattering metal bracket; the metamaterial layer is specifically composed of a flexible dielectric substrate and a conductive material printed thereon, and the conductive material includes: metal powder (such as silver powder, copper powder), graphite, and carbon powder. The metamaterial layer is a multi-layer structure. Except for the first layer set at the edge of the bracket, each subsequent layer is set at the edge of the previous layer. The pattern of the conductive material printed on each layer is different, that is, the equivalent resistance, capacitance, inductance and other parameters of each layer are different.

[0023] The hard absorbing material layer is configured to support the metamaterial layer and perform preliminary absorption of electromagnetic waves; the hard absorbing material layer is connected by alternating mortise and tenon joints.

[0024] The overall shape of the hard absorbing material is egg-shaped, teardrop-shaped or date-shaped.

[0025] The method of loading three different absorbing materials on the outer surface of a low-scattering metal bracket specifically includes the following steps: S1. Spraying the configured magnetic absorbing material on the surface of the metal bracket through a spray gun; S2. After spraying, placing the metal bracket on a fixture rack for surface drying; S3. Adding a metamaterial layer to the front and rear edges of the metal bracket after surface drying; S4. Adding a surrounding structure made of hard absorbing material to the periphery of the metal bracket.

[0026] In the step S1, the thickness of the magnetic absorbing material sprayed is in the range of 0.9 mm to 1 mm; and in the step S4, the surrounding structure is installed by connecting with a mortise and tenon structure.

[0027] Embodiment: A low-scattering metal bracket loaded with multiple absorbing materials, the main feature of which is that the scattering level of the low-scattering metal bracket is reduced by combining absorbing coatings, metamaterials and hard absorbing materials.

[0028] First, a designed broadband absorbing paint is sprayed on the outer surface of the low-scattering metal bracket. The absorbing paint is a magnetic absorbing material, and its absorbent is mainly ferrite absorber and carbonyl iron powder absorber. It mainly attenuates the electromagnetic waves entering the coating through the magnetic loss of the absorbing paint absorber, absorbs the radiation energy of the electromagnetic waves, and then converts the energy of the electromagnetic waves into heat energy through coupling. The main function of the absorbing paint is to absorb the specular reflection generated by the electromagnetic waves irradiating the low-scattering metal bracket.

[0029] The low-scattering metal bracket as a supporting structure belongs to the low RCS radar target, and the impact of the non-specular scattering it produces is also very important. The creeping wave and edge scattering generated by the electromagnetic wave irradiating the low-scattering metal bracket are reduced by loading metamaterials. The metamaterial needs to be loaded on the front and rear edges of the low-scattering metal bracket and ensure that it is parallel to the direction of the incident electromagnetic wave. The metamaterial is composed of a flexible dielectric substrate and a conductive material printed on it. It is a periodic absorbing structure that focuses on using artificial structures to gather the incident electromagnetic field and then absorbs the gathered energy through dielectric loss. The metamaterial on the edge of the bracket can be a multi-layer structure. Except for the first layer set at the edge of the bracket, each subsequent layer is set at the edge of the previous layer. The materials of the metamaterials in different layers are the same, but the periodic patterns of the corresponding areas are different, that is, the amount of material used in each layer area is different, and the equivalent resistance, capacitance, inductance and other parameters of each layer are different, so as to achieve multi-peak broadband absorption.

[0030] Finally, since the metamaterial is a flexible dielectric substrate and the loading length on the front and back sides of the low-scattering metal bracket is relatively long, in order to ensure that it is parallel to the direction of the incident electromagnetic wave, it needs to be supported by supporting materials. The present invention loads an absorbing edge support made of hard absorbing material on the periphery of the low-scattering metal bracket. The electromagnetic parameters of the hard absorbing material are relatively small, and the shape needs to be designed into a low-scattering shape. It can be designed into an egg-shaped, water-drop-shaped, or a jujube-shaped shape to ensure that its own scattering is smaller than the scattering of the low-scattering metal bracket and does not affect the low-scattering metal bracket. Its main function is to achieve the support of the metamaterial on both sides of the low-scattering metal bracket, and at the same time, it can perform a preliminary absorption of electromagnetic waves to further reduce the scattering of the bracket itself. The hard absorbing material adopts alternating mortise and tenon connections, which can achieve direct and tight connection of components, while reducing the use of glue, avoiding the excessive scattering of the hard absorbing material itself and affecting the low-scattering metal bracket. Figure 3 , Figure 4 shown.

[0031] The specific operation steps are to stir the prepared magnetic absorbing paint evenly with a stirring rod, and then filter the paint into the spray gun with a clean filter screen, and complete the spraying in 4-5 times, with a spraying interval of 20min-40min, and spray the surface evenly with a spraying thickness of 0.9mm~1mm. After spraying, place it on a tooling rack to dry on the surface. Then add metamaterials to the front and back edges. The metamaterial in the embodiment is a resistor in the equivalent circuit. The metamaterial has a layer of metal edge overlapped on the front and back edges of the low-scattering metal bracket, and then the resistance of each layer gradually changes from the bracket to the outside. Finally, in order to support the metamaterials at the front and back edges, a circle of surrounding edge structure made of a teardrop-shaped, hard absorbing material with very small electromagnetic parameters is loaded on the periphery of the bracket. The installation method of the surrounding edge structure uses a mortise and tenon structure for connection.

[0032] like Figure 5 , Figure 6As shown in the figure, the results show that after loading a variety of absorbing materials, the RCS performance of the low-scattering metal bracket has been greatly optimized, and the P-band RCS performance is lower than -30dBsm, which can meet the test requirements of more targets. Among them, the horizontal axis is the frequency, 0.3GHz-1GHz, and the main optimized frequency range; the vertical axis is the RCS (radar cross section) value. The smaller the RCS, the smaller the bracket scattering and the better the stealth performance. Figure 5 , Figure 6 The HH polarization and VV polarization mentioned in the figure represent horizontal polarization and vertical polarization respectively, which are two polarization modes of electromagnetic waves and correspond to the vibration direction of the electric field vector.

[0033] The present invention can effectively optimize the low-frequency RCS performance of the low-scattering metal bracket by loading a variety of absorbing materials on the low-scattering metal bracket, reduce the coupling scattering between the bracket and the target, and meet the testing needs of more stealth targets; the absorbing material structure used is light in weight, easy to process, transport, install and maintain, and has a relatively low cost, and will not affect the mechanical properties of the metal bracket itself; it is simple to implement and has strong operability, and can be used for upgrading and optimizing existing low-scattering metal brackets.

[0034] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for reducing the RCS of a low-scattering metal bracket, characterized in that: The RCS of the metal bracket is reduced by combining and loading three different absorbing materials on the outer surface of the low-scattering metal bracket; the three different absorbing materials are specifically an absorbing coating layer, a metamaterial layer, and a hard absorbing material layer.

2. The method for reducing the RCS of a low-scattering metal stent according to claim 1, characterized in that: The absorbing paint layer is configured to absorb the specular reflection generated after the electromagnetic wave irradiates the low-scattering metal bracket; the absorbing paint layer adopts magnetic absorbing material, and the absorbent in the magnetic absorbing material mainly includes: ferrite absorbent and carbonyl iron powder absorbent.

3. The method for reducing the RCS of a low-scattering metal stent according to claim 1, characterized in that: The metamaterial layer is configured to reduce creeping waves and edge scattering generated when electromagnetic waves are irradiated onto a low-scattering metal support; The metamaterial layer is composed of a flexible dielectric substrate and a conductive material printed thereon, wherein the conductive material includes metal powder, graphite, and carbon powder.

4. The method for reducing the RCS of a low-scattering metal stent according to claim 3, characterized in that: The metamaterial layer is a multi-layer structure. Except for the first layer arranged at the edge of the bracket, each subsequent layer is arranged at the edge of the previous layer, and the pattern printed on the conductive material on each layer is different.

5. The method for reducing the RCS of a low-scattering metal stent according to claim 1, characterized in that: The hard absorbing material layer is configured to support the metamaterial layer and perform preliminary absorption of electromagnetic waves; wherein the hard absorbing material layer is connected by alternating mortise and tenon joints.

6. The method for reducing the RCS of a low-scattering metal stent according to claim 1, characterized in that: The hard absorbing material has an overall shape of an egg, a water drop or a date core.

7. The method for reducing the RCS of a low-scattering metal stent according to claim 1, characterized in that: The method of loading three different absorbing materials on the outer surface of a low-scattering metal bracket specifically includes the following steps: S1. Spraying the configured magnetic absorbing material on the surface of the metal bracket through a spray gun; S2. After spraying, placing the metal bracket on a fixture rack for surface drying; S3. Adding a metamaterial layer to the front and rear edges of the metal bracket after surface drying; S4. Adding a surrounding structure made of hard absorbing material to the periphery of the metal bracket.

8. The method for reducing the RCS of a low-scattering metal stent according to claim 7, characterized in that: The thickness of the magnetic absorbing material sprayed in step S1 is in the range of 0.1 mm to 5 mm.

9. The method for reducing the RCS of a low-scattering metal stent according to claim 7, characterized in that: The installation method of the surrounding structure in step S4 is to connect it using a mortise and tenon structure.

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