Infrared and radar compatible double-stealth metamaterial structure and preparation method thereof

Abstract

The invention discloses an infrared and radar compatible double stealth metamaterial structure and a preparation method thereof, and belongs to the technical field of stealth function materials. The structure comprises an infrared stealth layer, a spacing layer and a radar wave-absorbing body which are arranged from top to bottom, the infrared stealth layer is a metal patch array; the radar wave absorber is composed of a patterned top resonance layer, an intermediate dielectric loss layer and a bottom metal reflection layer. The top resonance layer comprises an open square ring and a *-shaped structure which are arranged in a nested manner, and a lumped resistor is loaded at an opening; the spacing layer is a low-dielectric-constant foam board. Through the design of the multi-layer composite structure, the principle contradiction between infrared high reflection and radar high absorption is successfully solved, the radar wave absorption rate of the structure at the frequency band of 6.5-12.5 GHz is higher than 90%, the infrared emissivity of the structure at the frequency band of 8-14 microns is lower than 0.35, meanwhile, the structure has the advantages of being insensitive to angles, light in weight and easy to process, and the application range is wide. The stealth requirements of platforms such as unmanned aerial vehicles are particularly met.

Description

Technical Field

[0001] This invention relates to the field of stealth functional materials technology, specifically to an infrared and radar compatible dual stealth metamaterial structure and its preparation method. Background Technology

[0002] An ideal stealth system for unmanned aerial vehicles (UAVs) needs to be able to cope with both radar and infrared, the two most important and common detection methods, that is, to achieve dual stealth that is compatible with both infrared and radar.

[0003] To achieve infrared stealth, equipment surfaces must possess high reflectivity and low emissivity to maximize the reflection of ambient heat radiation and suppress the escape of their own infrared signals. Radar stealth, on the other hand, requires equipment surfaces with low reflectivity and high absorptivity to minimize the reflection of incident radar waves, absorbing and dissipating their energy. Therefore, infrared stealth and radar stealth exhibit an inherent and fundamental contradiction in their physical principles, posing a significant technical obstacle to achieving compatibility between the two.

[0004] Currently, existing drone stealth technologies mainly rely on shape optimization and functional material coatings, but they have many limitations in achieving infrared and radar-compatible stealth: Traditional single-function materials struggle to reconcile these physical contradictions. For instance, radar-absorbing coatings (such as ferrites and iron carbonyl) widely used for radar stealth often exhibit high infrared emissivity due to their high absorption characteristics, which is detrimental to infrared stealth. Conversely, metal-based high-reflectivity coatings used to reduce infrared emissivity strongly reflect radar waves, leading to a sharp decline in radar stealth performance. Furthermore, some existing composite stealth structures are often complex in design or can only achieve limited compatible stealth effects within narrow frequency bands and specific incident angles, failing to meet the practical demands of modern wide-band, all-around detection. When applied to UAVs, their broadband absorption performance and low infrared emissivity are often mutually exclusive.

[0005] Traditional microwave absorbing coatings exhibit unstable performance and insufficient durability under varying temperature and humidity conditions. Furthermore, these materials are often dense and rigid, which can easily create gaps or add excessive weight and volume when applied to the curved surfaces of drones, severely impacting the aerodynamic performance and maneuverability of the drones.

[0006] Therefore, there is an urgent need in this field for a new solution that is simple in structure, low in cost, stable in performance, and easy to manufacture, which can fundamentally break through the technical bottleneck of the mutual constraints between infrared and radar stealth, and provide a truly effective infrared and radar compatible dual stealth capability for drones, especially small drones. Summary of the Invention

[0007] To solve the above technical problems in the prior art, the present invention provides a dual-stealth metamaterial structure compatible with infrared and radar, comprising an infrared stealth layer, a spacer layer, and a radar absorber arranged from top to bottom; the infrared stealth layer is a metal patch array; The radar absorber is a three-layer composite structure, comprising a patterned top resonance layer, an intermediate dielectric loss layer, and a bottom metal reflection layer; the top resonance layer contains mutually coupled circular resonance units and cross-shaped resonance units, and at least some of the resonance units are connected with resistive elements; the dielectric constant of the spacer layer is lower than that of the dielectric loss layer.

[0008] The circular resonance unit is an open square ring, and the cross-shaped resonance unit is a "rice" shaped structure; the resistive element is a lumped resistor, arranged at the opening of the open square ring, with a resistance value of 100 Ω.

[0009] The material of the bottom metal reflection layer is copper, with a thickness not less than 0.018 mm; the material of the dielectric loss layer is FR-4 epoxy glass cloth board.

[0010] The top resonance layer adopts a square metal patch array structure, and square patches are made of copper with a conductivity of 5.8×10 7 S / m and an emissivity less than 0.1; the dielectric layer adopts F4B with a dielectric constant ε r of 2.2 and an emissivity less than 0.9. The width w of the square copper patch is 0.6 mm, the gap width g between patches is 0.1 mm, and the thickness is 0.018 mm. According to the formula calculation, the metal area filling rate of this structure is 73.5% at this time, and the corresponding infrared emissivity is 0.316.

[0011] The spacer layer is a foam dielectric board, with a dielectric constant of 1.03 and a thickness of 2.7 mm to 4.5 mm.

[0012] The open square ring and the "rice" shaped structure have the following structural parameters: the outer side length of the open square ring: 9 mm; the unit structure period: 14 mm; the line width of the open square ring: 0.1 mm; the opening width of the open square ring: 1.4 mm; the arm length of the "rice" shaped structure: 8 mm; the arm width of the "rice" shaped structure: 0.8 mm.

[0013] The radar wave absorption rate of the structure is higher than 90% within the frequency range of 6.5 GHz to 12.5 GHz, and the emissivity within the infrared band range of 8 μm to 14 μm is lower than 0.35.

[0014] On the other hand, the present invention provides an unmanned aerial vehicle, at least part of whose surface is covered with the above-mentioned dual-stealth metamaterial structure compatible with infrared and radar.

[0015] The method for constructing an infrared and radar compatible dual stealth metamaterial structure includes the following steps: S1: preparing the radar absorber; S2: providing the infrared stealth layer and the spacer layer; S3: sequentially combining the infrared stealth layer, the spacer layer, and the radar absorber to form the dual stealth metamaterial structure.

[0016] This invention provides a method for verifying the performance of the infrared and radar compatible dual stealth metamaterial structure. The method includes: using the bow-shaped frame method combined with a vector network analyzer to test its radar wave absorption performance; and using an infrared thermal imager to test its infrared radiation performance.

[0017] The present invention has the following advantages over the prior art: This invention fundamentally resolves the inherent contradiction between infrared and radar stealth principles, achieving high-performance, compatible stealth. Through an innovative "functional separation-structural integration" design, it combines an infrared stealth layer responsible for high reflectivity / low emission with a broadband radar absorber responsible for high absorption / low reflectivity via a spacer layer. This provides an independent implementation path for these two conflicting stealth mechanisms in terms of physical structure. This fundamentally overcomes the inherent limitation of traditional single-material stealth systems that cannot reconcile conflicting principles, making it possible to simultaneously achieve low infrared emissivity and high radar absorption within the same structure.

[0018] On the other hand, this invention possesses excellent broadband radar absorption performance and angle insensitivity, resulting in stronger environmental adaptability. Through the nested design of the "open square ring" and "rice" shaped structure in the top resonant layer, along with the synergistic effect of lumped resistance, efficient capture and dissipation of electromagnetic energy are achieved, thereby obtaining a radar absorption band as wide as 6.5-12.5 GHz. Simultaneously, this metamaterial structure is insensitive to the incident angle of electromagnetic waves, ensuring stable stealth performance of the UAV under different attitudes. Furthermore, based on PCB technology and a stable material system, the structure's performance is less affected by environmental changes, and its durability is far superior to traditional coatings.

[0019] This invention features a simple, lightweight, and easily manufactured structure, making it highly adaptable to various platforms and economical. The core radar absorber can be manufactured on a large scale and at low cost using mature printed circuit board technology. The entire composite structure is clearly layered, using readily available and common materials, avoiding the use of expensive or special absorbing agents. The overall structure is thin and lightweight, and the addition of low-density foam spacers significantly reduces weight, perfectly meeting the stringent payload and maneuverability requirements of small UAVs. This structure can be manufactured as a rigid sheet or adapted for curved surfaces by selecting flexible substrates, exhibiting extremely high platform applicability and industrialization potential. Attached Figure Description

[0020] Figure 1This is a three-dimensional view of the infrared and radar compatible dual stealth metamaterial structure of the present invention; Figure 2 These are 3D views (left) and top views (right) of the infrared layer of the infrared and radar compatible dual stealth metamaterial structure of this invention. Figure 3 These are 3D views (left) and top views (right) of the broadband radar absorber unit structure of the infrared and radar compatible dual stealth metamaterial structure of the present invention. Figure 4 This is a 3D view (left) and a top view (right) of the infrared layer of a dual-band radar absorber unit structure. Figure 5 It is the absorption curve of a dual-band radar absorber in the range of 8~16GHz; Figure 6 The influence of structural parameters on the absorption characteristics of broadband radar absorbers: (a) absorption curves corresponding to different lumped resistances R; (b) absorption curves corresponding to different dielectric layer thicknesses t; (c) absorption curves corresponding to different arm widths b of the "rice" shaped structure. Figure 7 Absorption curves of infrared and radar compatible dual stealth metamaterial structures. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention.

[0022] This invention provides an infrared and radar compatible dual-stealth metamaterial structure, such as... Figure 1 As shown, it includes, from top to bottom, an infrared stealth layer 1, a spacer layer 2, and a radar absorber 3; the infrared stealth layer 1 is a metal patch array, such as... Figure 2 As shown, a square metal patch array structure 11 is adopted, and copper is used to make the square patch array; the dielectric layer 12 has a dielectric constant ε r The F4B has an emissivity of 2.2 and less than 0.9. The square copper patch has a width w = 0.6 mm, a patch gap width g = 0.1 mm, and a thickness of 0.018 mm. According to the formula, the metal area fill rate of this structure is 73.5%, and the corresponding infrared emissivity is 0.316. The spacer layer is a foam dielectric board with a dielectric constant of 1.03 and a thickness of 2.7 mm to 4.5 mm.

[0023] The radar absorber 3 has a three-layer composite structure, such as Figure 3As shown, it includes a patterned top resonant layer 31, an intermediate dielectric loss layer 32, and a bottom metal reflection layer 33; the top resonant layer 31 includes mutually coupled annular resonant units and cross-shaped resonant units, and resistive elements are connected to at least some of the resonant units, with a single resistance value of 100 Ω; the dielectric constant of the spacer layer 2 is lower than that of the dielectric loss layer 32. The annular resonant unit is an open square ring 313, and the cross-shaped resonant unit is a "cross" structure 311; the resistive element is a lumped resistor 312, which is arranged at the opening of the open square ring. The top resonant layer 31 and the bottom metal reflection layer 33 are made of copper, with a thickness not less than 0.018 mm; the dielectric loss layer 32 is made of FR-4 epoxy glass cloth board. The open square ring 313 and the "cross" structure 311 have the following structural parameters: outer side length of the open square ring: 9 mm; unit structure period: 14 mm; line width of the open square ring: 0.1 mm; opening width of the open square ring: 1.4 mm; arm length of the "cross" structure: 8 mm; arm width of the "cross" structure: 0.8 mm. The radar wave absorption rate of the structure is higher than 90% in the frequency range of 6.5 GHz to 12.5 GHz, and the emissivity is lower than 0.35 in the infrared band range of 8 μm to 14 μm.

[0024] An unmanned aerial vehicle has the infrared and radar compatible dual stealth metamaterial structure of the present invention adhered to at least part of the surface of a traditional unmanned aerial vehicle.

[0025] A method for preparing the infrared and radar compatible dual stealth metamaterial structure of the present invention includes the steps: S1: preparing the radar absorber 3; S2: providing the infrared stealth layer 1 and the spacer layer 2; S3: sequentially laminating the infrared stealth layer 1, the spacer layer 2, and the radar absorber 3 to form the dual stealth metamaterial structure.

[0026] On the other hand, the present invention provides a method for verifying the performance of the infrared and radar compatible dual stealth metamaterial structure. The method includes: using the bow-tie method in combination with a vector network analyzer to test its radar wave absorption performance; using an infrared thermal imager to test its infrared radiation performance.

[0027] Embodiment 1

[0028] This embodiment provides an infrared and radar compatible dual stealth material structure, and its core lies in solving the problem that the infrared and radar stealth principles are contrary through a multi-layer composite structure.

[0029] See the appendix Figure 1, the dual-stealth metamaterial structure is a layered composite from top to bottom, specifically including an infrared stealth layer 1, a spacer layer 2, and a radar absorber 3. The infrared stealth layer 1 is a square metal patch array; the spacer layer 2 is a foam dielectric plate with a dielectric constant of 1.03 and a thickness of 2.7 mm to 4.5 mm; the radar absorber 3 is a three-layer composite structure, including a patterned top resonant layer 31, an intermediate dielectric loss layer 32, and a bottom metal reflection layer 33.

[0030] See the appendix Figure 2 , the infrared stealth layer 1 is a square metal patch array 11, whose metal filling ratio is optimized, and copper is selected to make the square patch array; the dielectric layer 12 uses F4B with a dielectric constant ε r of 2.2 and an emissivity less than 0.9. The width w of the square copper patch is 0.6 mm, the patch gap width g is 0.1 mm, and the thickness is 0.018 mm. According to the calculation formula of the infrared emissivity ε of the periodic patch array: (1)

[0031] In the formula, ε is the emissivity of the periodic patch array, εm and εd are the emissivities of the metal and the dielectric plate respectively, fm is the metal part filling ratio (metal area / total area), and a metal material with a high filling ratio can obtain a lower infrared emissivity. The calculated infrared emissivity of this structure at this time is 0.316. In addition, the radar wave frequency of 4 - 16 GHz is much smaller than the resonance frequency of 169 GHz of this infrared stealth layer, so it can pass through this infrared stealth layer and be incident on the broadband radar absorber.

[0032] As shown in the appendix Figure 3 , the top resonant layer 31 uses copper metal, with a relative permeability of 1.0 and a conductivity of 5.8×10 7 S / m, and a thickness of 0.018 mm. This resonant layer is composed of mutually coupled circular resonant units 313 and cross-shaped resonant units 311. More specifically, the circular resonant unit is an open square ring, and the cross-shaped resonant unit is a "rice" character structure. To achieve broadband absorption, a lumped resistor 312 with a single resistance value of 100Ω is loaded at the opening of the open square ring as a resistive element.

[0033] The intermediate dielectric loss layer 32 is made of a high-loss material, FR-4 epoxy glass cloth board, with a dielectric constant of 4.3, a loss tangent value of 0.025, and a thickness of 4 mm. The bottom metal reflection layer 33 is made of copper, with a thickness not less than 0.018 mm, greater than the skin depth of radar waves, to ensure that the transmittance T(ω) tends to 0 and reflect all transmitted electromagnetic waves back to the dielectric loss layer for secondary absorption. The spacer layer 2 is located between the infrared stealth layer 1 and the radar absorber 3. The low dielectric constant characteristic of this spacer layer is crucial for achieving impedance matching of the overall structure and is the key to solving the contradiction between high infrared reflection and high radar absorption.

[0034] As Figure 4 shown is the structure of a dual-band radar absorber unit, where the yellow area represents copper, and the blue area is the intermediate dielectric layer made of a high-loss material, FR-4, with a dielectric constant of 4.3 and a thickness t5 = 6 mm. The top layer is a resonant structure composed of an open square loop and a "cross" structure. After simulation optimization, the parameters of the dual-band radar absorber unit structure are: the side length of the unit structure d = 14 mm, the outer side length of the square loop a = 9 mm, the width of the square loop g = 1 mm, the opening width of the square loop n = 1.4 mm, the arm length of the "cross" structure m = 8 mm, and the arm width of the "cross" structure b = 0.8 mm. The absorption rate of this dual-band radar absorber for electromagnetic waves from 8 to 16 GHz is as Figure 5 shown, and the absorption rates at 9.21 GHz and 14.65 GHz are 99.6% and 99.9% respectively.

[0035] The main performance parameters of a broadband absorber include the bandwidth of the absorption band, relative bandwidth, absorption rate, and device thickness, etc. The bandwidth of the absorption band generally refers to the frequency difference between the frequencies where the absorption rates on both sides reach more than 90%, denoted by Δf. The wider the bandwidth, the better the broadband absorption performance. The relative bandwidth RB can be calculated from the bandwidth: (2)

[0036] In the formula, fmax and fmin are the frequencies corresponding to the absorption rate equal to 90%, f0 represents the center resonance frequency, and Q represents the quality factor. The center resonance frequency f0 satisfies the relationship with the equivalent inductance L and equivalent capacitance C: (3)

[0037] According to the above analysis, the smaller the quality factor Q, the wider the relative bandwidth. Therefore, reducing its quality factor Q can broaden its absorption bandwidth. When a metamaterial radar absorber is working, it can be equivalent to an RLC resonator. Therefore, its quality factor Q can be expressed in terms of its equivalent resistance R, equivalent capacitance C, and equivalent inductance L as: (4)

[0038] According to Formulas (3) and (4), it can be analyzed that changing L, R, and C can all change the quality factor, thereby achieving the purpose of changing the relative bandwidth. However, changing L and C will also change the center resonance frequency. Therefore, increasing the equivalent resistance R can not only broaden the relative bandwidth but also does not affect the center resonance frequency. In this paper, the absorption bandwidth of the absorber is broadened by adding a lumped resistor to the resonance layer. In addition, adjusting the structural parameters can also regulate the equivalent inductance L and the equivalent capacitance C.

[0039] Therefore, when designing a broadband radar absorber in the present invention, it is selected to add a lumped resistor R on the basis of the Figure 4 shown dual-band radar absorber, and at the same time optimize each structural parameter to obtain a broadband radar absorber with the best absorption performance. Through the analysis of the corresponding absorption curves under different structural parameters in the simulation results, it is obtained that the change of the resistance value of the lumped resistor added at the opening of the square loop, the thickness of the dielectric layer, and the width of the square loop patch has an obvious impact on the absorption performance. The simulation results are as Figure 6 shown.

[0040] According to the simulation results, the resistance value of a single lumped resistor is finally determined to be 100 Ω, which can successfully expand the absorption frequency band from discrete dual-frequency points to a continuous broadband. The specific structural parameters are as follows: The thickness t1 of the dielectric substrate is 0.1 mm, the thickness t2 of the foam board is 2.7 mm, the thickness t3 of the dielectric layer is 4 mm, the thickness t of the bottom reflection layer is 0.018 mm, the outer side length a of the square loop is 9 mm, the side length d of the unit structure is 14 mm, the width h of the square loop is 0.1 mm, the opening width n of the square loop is 1.4 mm, the width w of the metal patch is 0.6 mm, the arm length m of the "cross" structure is 8 mm, the arm length m of the "cross" structure is 8 mm, and the arm width b of the "cross" structure is 0.8 mm. The optimized parameters can make the infrared emissivity lower than 0.35 and the radar absorption rate above 90% at 6.5 - 12.5 GHz.

[0041] After simulation tests, as Figure 7 shown, for the embodiment with the above structure and parameters, the radar wave absorption rate in the frequency range of 6.5 GHz to 12.5 GHz is higher than 90%. The absorption bandwidth of this infrared and radar compatible dual-stealth metamaterial structure is 12.5 GHz - 6.5 GHz = 6 GHz, the center frequency is 9.5 GHz, and the relative bandwidth is 0.63. The infrared emissivity in the infrared band range of 8 μm to 14 μm is lower than 0.35, and the dual stealth of infrared and radar is successfully achieved.

[0042] Embodiment 2

[0043] This embodiment provides a method for fabricating the above dual-stealth metamaterial structure, and the specific steps are as follows: S1: The radar absorber 3 is fabricated using the conventional printed circuit board (PCB) process. Specifically, on a dielectric substrate with a thickness of 0.1 mm, a top resonance layer 31 composed of nested split-ring resonators and "rice" - shaped structures is formed through a patterning process, and a lumped resistor is welded at the opening of the split-ring resonator. Subsequently, an FR-4 board is laminated thereon as the dielectric loss layer 32. Finally, a copper foil is coated on the lower surface of the FR-4 board as the bottom metal reflection layer 33. S2: The infrared stealth layer 1 and the spacer layer 2 are provided. The infrared stealth layer 1 can also be obtained by fabricating a square metal patch array through the PCB process. The spacer layer 2 is a preformed foam board with a thickness of 2.7 mm. S3: The infrared stealth layer 1, the spacer layer 2, and the radar absorber 3 are laminated in sequence and compounded by gluing or hot pressing to form a complete dual-stealth metamaterial structure. S4: When this structure needs to be attached to a curved surface such as a UAV model, due to the geometric difference between the curved surface and the planar sample, fitting gaps will inevitably occur. At this time, conductive pastes such as silver paste can be used to fill the gaps between the samples to ensure the continuity of electrical performance.

[0044] Example 3

[0045] This embodiment provides a method for verifying the performance of the above dual-stealth metamaterial structure, and the steps are as follows: Using the bow-tie method, in a microwave anechoic chamber, in cooperation with a vector network analyzer and horn antennas, the reflection and absorption of electromagnetic waves by the structure are measured, so as to accurately calculate its radar wave absorption rate in the frequency band of 6.5 GHz to 12.5 GHz.

[0046] An infrared thermal imager (such as FLIR ONE PRO) with a working band of 8 - 14 μm is used to measure the thermal radiation characteristics of the surface of the structure. By comparing with its background environment, its low infrared emissivity performance is verified, and its infrared stealth effect is confirmed.

[0047] The present invention provides an infrared and radar compatible dual-stealth structure based on metamaterials. Through the multi-layer composite design of an infrared stealth layer, a low-dielectric constant spacer layer, and a broadband radar absorber, the principle contradiction between high infrared reflectivity and high radar absorption is successfully solved structurally. The structure is scientifically designed with clear parameters and can be fabricated through a mature PCB process, having excellent stealth performance (the radar wave absorption rate in the range of 6.5 - 12.5 GHz is higher than 90%, and the infrared emissivity in the range of 8 μm - 14 μm is lower than 0.35), good angular insensitivity, lightweight, and low cost and other significant advantages. The present invention not only provides an effective dual-stealth solution for equipment such as UAVs, but also has important significance for promoting the application and development of metamaterials in the field of compatible stealth.

[0048] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An infrared and radar compatible dual-stealth metamaterial structure, characterized in that, It includes an infrared stealth layer (1), a spacer layer (2), and a radar absorber (3) arranged from top to bottom; the infrared stealth layer (1) is a metal patch array; The radar absorber (3) is a three-layer composite structure, including a patterned top resonance layer (31), an intermediate dielectric loss layer (32), and a bottom metal reflection layer (33); the top resonance layer (31) contains mutually coupled ring resonance units and cross-shaped resonance units, and at least some of the resonance units are connected with resistive elements; the dielectric constant of the spacer layer (2) is lower than the dielectric constant of the dielectric loss layer (32).

2. The infrared and radar compatible dual stealth metamaterial structure according to claim 1, characterized in that, The ring resonance unit is an open square ring, and the cross-shaped resonance unit is a "rice" character structure; the resistive element is a lumped resistor, which is arranged at the opening of the open square ring.

3. The infrared and radar compatible dual stealth metamaterial structure according to claim 1 or 2, characterized in that, The materials of the top resonance layer (31) and the bottom metal reflection layer (33) are copper, and the thickness is not less than 0.018 mm; the material of the dielectric loss layer (32) is FR-4 epoxy glass cloth board.

4. The infrared and radar compatible dual stealth metamaterial structure according to claim 1, characterized in that, The spacer layer (2) is a foam dielectric board, its dielectric constant is 1.03, and the thickness is 2.7 mm to 4.5 mm.

5. The infrared and radar compatible dual stealth metamaterial structure according to claim 2, characterized in that, The open square ring and the "rice" character structure have the following structural parameters: outer side length of the open square ring: 9 mm; unit structure period: 14 mm; line width of the open square ring: 0.1 mm; opening width of the open square ring: 1.4 mm; arm length of the "rice" character structure: 8 mm; arm width of the "rice" character structure: 0.8 mm.

6. The infrared and radar compatible dual stealth metamaterial structure according to claim 1, characterized in that, The radar wave absorption rate of the structure is higher than 90% within the frequency range of 6.5 GHz to 12.5 GHz, and the emissivity within the infrared band range of 8 μm to 14 μm is lower than 0.

35.

7. A drone, characterized in that, At least part of its surface is covered with the infrared and radar compatible dual-stealth metamaterial structure according to any one of claims 1 to 6.

8. A method for preparing an infrared and radar-compatible dual stealth metamaterial structure as described in any one of claims 1 to 6, characterized in that, It includes steps: S1: Prepare the radar absorber (3); S2: Provide the infrared stealth layer (1) and the spacer layer (2); S3: Composite the infrared stealth layer (1), the spacer layer (2), and the radar absorber (3) in sequence to form the dual-stealth metamaterial structure.

9. A method for verifying the performance of an infrared and radar-compatible dual stealth metamaterial structure as described in any one of claims 1 to 6, characterized in that, The method includes: adopting the bow-tie method and combining with a vector network analyzer to test its radar wave absorption performance; adopting an infrared thermal imager to test its infrared radiation performance.

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