Wave-absorbing metamaterial

Abstract

The embodiment of the invention provides a wave-absorbing metamaterial, which comprises a first wave-absorbing prepreg layer, two second wave-absorbing prepreg layers, a third wave-absorbing prepreg layer, a first metamaterial layer and a second metamaterial layer, the first wave-absorbing prepreg layer, the second wave-absorbing prepreg layer, the first metamaterial layer, the second wave-absorbing prepreg layer, the third wave-absorbing prepreg layer and the second metamaterial layer are sequentially stacked together. According to the wave-absorbing metamaterial disclosed by the invention, the wave-absorbing frequency band is widened by utilizing superposition and coupling effects of wave-absorbing frequency bands of different wave-absorbing bodies comprising the wave-absorbing prepreg (namely the first wave-absorbing prepreg layer, the second wave-absorbing prepreg layer and the third wave-absorbing prepreg layer) and the metamaterial layer (namely the first metamaterial layer and the second metamaterial layer); therefore, wide-frequency-band and large-angle strong absorption is realized.

Description

Technical Field

[0001] This invention relates to the field of metamaterials, and more specifically, to a microwave absorbing metamaterial. Background Technology

[0002] With the rapid development of various new radar detection technologies, "detection equals destruction" has become one of the key characteristics of modern warfare. Stealth performance is a crucial design indicator for the survivability of modern fighter jets. The development of stealth technology began in the 1940s, and Lockheed started research on low-observable aircraft technology in the late 1950s. In 1973, the United States first raised the need to develop stealth technology. Since the 1980s, foreign-developed fighter jets have widely adopted stealth technology, greatly enhancing their survivability.

[0003] Currently, the applications of electromagnetic absorbing materials have far exceeded the scope of stealth and anti-stealth, countermeasures and countermeasures. Their demand in civilian fields such as radio communication, electromagnetic compatibility, microwave radiation protection, information security, and new energy development and utilization is becoming increasingly urgent. Whether in military applications for stealth or in civilian fields such as electromagnetic radiation protection, ideal electromagnetic absorbing materials should possess characteristics such as wide operating frequency band, strong absorption, and thin thickness. However, existing absorbing structures and materials struggle to simultaneously meet these requirements. Summary of the Invention

[0004] This invention proposes a microwave absorbing metamaterial that solves the technical problem of how to broaden the microwave absorption bandwidth by utilizing the superposition and coupling effect of different microwave absorbing frequency bands, including microwave absorbing prepreg and metamaterial layers, to achieve wide-band, large-angle strong absorption.

[0005] This invention provides a microwave absorbing metamaterial, comprising: a first microwave absorbing prepreg layer, two second microwave absorbing prepreg layers, a third microwave absorbing prepreg layer, a first metamaterial layer, and a second metamaterial layer, wherein the first microwave absorbing prepreg layer, the second microwave absorbing prepreg layer, the first metamaterial layer, the second microwave absorbing prepreg layer, the third microwave absorbing prepreg layer, and the second metamaterial layer are sequentially stacked together.

[0006] The beneficial effects of this invention are as follows:

[0007] The microwave absorbing metamaterial of this invention adopts an integrated design scheme of metamaterial microstructure (i.e., first metamaterial layer and second metamaterial layer) and microwave absorbing prepreg. While ensuring mechanical and toughness properties through the first microwave absorbing prepreg layer, two second microwave absorbing prepreg layers and two third microwave absorbing prepreg layers, the microwave absorbing frequency band is broadened by the superposition and coupling effect of different microwave absorbing frequency bands of the microwave absorbing prepreg layers (i.e., first microwave absorbing prepreg layer, second microwave absorbing prepreg layer, and third microwave absorbing prepreg layer) and metamaterial layers (i.e., first metamaterial layer and second metamaterial layer). This can comprehensively improve the microwave absorption effect, thereby achieving wide-band, large-angle strong absorption. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the structure of the microwave absorbing metamaterial according to an embodiment of the present invention.

[0010] Figure 2 yes Figure 1 A schematic diagram of the structure of the first metamaterial layer in the microwave absorbing metamaterial.

[0011] Figure 3 yes Figure 1 A schematic diagram of the structure of the second metamaterial layer in the microwave absorbing metamaterial.

[0012] Figure 4 yes Figure 1 The diagram shows a comparison of the vertical incident reflectivity of the microwave absorbing metamaterial (i.e., the new scheme) and the traditional microwave absorbing prepreg (i.e., the original scheme).

[0013] Figure 5 yes Figure 1 The diagram shows a comparison of the reflectivity of the microwave absorbing metamaterial (i.e., the new scheme) and the traditional microwave absorbing prepreg (i.e., the original scheme) under 30-degree oblique incidence in TE and TM modes. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0015] Figure 1A schematic diagram of the structure of a microwave absorbing metamaterial 100 according to an embodiment of the present invention is shown. The microwave absorbing metamaterial 100 is a broadband, extremely low scattering microwave absorbing metamaterial. The microwave absorbing metamaterial 100 includes a first microwave absorbing prepreg layer 11, two second microwave absorbing prepreg layers 13 and 15, a third microwave absorbing prepreg layer 16, a first metamaterial layer 14, and a second metamaterial layer 18.

[0016] The first absorbing prepreg layer 11, the second absorbing prepreg layer 13, the first metamaterial layer 14, the second absorbing prepreg layer 15, the third absorbing prepreg layer 16, and the second metamaterial layer 18 are stacked together in sequence to form the absorbing metamaterial 100. In this way, the absorbing metamaterial 100 can achieve broadband and large-angle strong absorption.

[0017] Furthermore, the microwave absorbing metamaterial 100 also includes another third microwave absorbing prepreg layer 19. The first microwave absorbing prepreg layer 11, the second microwave absorbing prepreg layer 13, the first metamaterial layer 14, the second microwave absorbing prepreg layer 15, the third microwave absorbing prepreg layer 16, the second metamaterial layer 18, and the third microwave absorbing prepreg layer 19 are sequentially stacked together to form the microwave absorbing metamaterial 100. In this way, the microwave absorbing metamaterial 100 can also achieve broadband, large-angle strong absorption.

[0018] The thicknesses of the first microwave absorbing prepreg layer 11, the second microwave absorbing prepreg layer 13, the first metamaterial layer 14, the second microwave absorbing prepreg layer 15, the third microwave absorbing prepreg layer 16, the second metamaterial layer 18, and the third microwave absorbing prepreg layer 19, which are stacked together in sequence, are 1 mm, 0.88 mm, 0.05 mm, 0.22 mm, 1.35 mm, 0.05 mm, and 0.81 mm, respectively. The two second microwave absorbing prepreg layers 13 and 15 are bonded to the first metamaterial layer 14 with an adhesive film, and the two third microwave absorbing prepreg layers 16 and 19 are bonded to the second metamaterial layer 18 with an adhesive film; the thickness of the adhesive film is 0.1 mm.

[0019] In this embodiment of the invention, the first microwave absorbing prepreg layer 11, the two second microwave absorbing prepreg layers 13 and 15, and the two third microwave absorbing prepreg layers 16 and 19 are all obtained by making a microwave absorbing material containing resin and microwave absorbing agent into a film and hot-pressing and impregnating the film with fibers.

[0020] The contents of resin, fiber and microwave absorbing agent in the first, second and third microwave absorbing prepreg layers are different, and the microwave absorbing prepreg layers target different microwave absorbing frequency bands.

[0021] Preferably, the first microwave absorbing prepreg layer 11, the two second microwave absorbing prepreg layers 13 and 15, and the two third microwave absorbing prepreg layers 16 and 19 are all obtained by forming a film from a microwave absorbing material containing epoxy resin and a magnetic microwave absorbing agent, and then hot-pressing and impregnating the film with quartz fibers. The magnetic microwave absorbing agent includes, but is not limited to, carbon-based iron powder.

[0022] like Figure 2 As shown, in this embodiment of the invention, the first metamaterial layer 14 includes a substrate and six first conductive geometric structures 140 and two conductive geometric structures 240 disposed on the substrate. The six first conductive geometric structures 140 are all identical and are connected end to end in sequence to form an approximately ring structure, and a gap is formed at the center of the approximately ring structure; the second conductive geometric structure 240 is disposed in the gap.

[0023] Each first conductive geometry 140 includes, sequentially connected end-to-end, a straight segment 141 at the beginning, a first convex curved segment 142, a second concave curved segment 144, a curved segment 145 in the shape of a rectangular wave, a third convex curved segment 146, a fourth concave curved segment 148, and a straight segment 149 at the end. The shapes of the first convex curved segment 142 and the third convex curved segment 146 are the same as the shape of a rectangular wave in the positive half-cycle, and the shapes of the second concave curved segment 144 and the fourth concave curved segment 148 are the same as the shape of a rectangular wave in the negative half-cycle. The second conductive geometry 240 includes a single-ring structure in the shape of a regular hexagon.

[0024] Specifically, the linewidth d1 of the first conductive geometry 140 is 0.05 mm, the lengths of the high-level continuous line segments and the low-level continuous line segments of the rectangular wave-shaped curve segment 145 are both 0.3167 mm, the lengths of the high-level continuous line segments of the first convex curve segment 142 and the third convex curve segment 146 are both 0.3167 mm, and the lengths of the low-level continuous line segments of the second concave curve segment 144 and the fourth concave curve segment 148 are both 0.3167 mm; the linewidth d2 of the regular hexagonal single-ring structure in the second conductive geometry 240 is 0.1732 mm.

[0025] As shown in Figure 3, the second metamaterial layer 18 includes a substrate and a third conductive geometry 180 disposed on the substrate.

[0026] In this embodiment of the invention, the third conductive geometry 180 includes a regular hexagonal single-ring structure. In the stacked structure of the microwave absorbing metamaterial 100, the regular hexagonal single-ring structure in the third conductive geometry 180 is located inside the regular hexagonal single-ring structure in the second conductive geometry 240, and the side length of the regular hexagonal single-ring structure in the third conductive geometry 180 is smaller than the side length of the regular hexagonal single-ring structure in the second conductive geometry 240.

[0027] Specifically, the linewidth d3 of the single-ring structure of the regular hexagon in the third conductive geometry 180 is 0.1732 mm.

[0028] In other optional embodiments, the first metamaterial layer includes a substrate and four first conductive geometric structures and two conductive geometric structures disposed on the substrate. The four first conductive geometric structures are all identical and are connected end to end in sequence to form an approximately ring structure, and a gap is formed at the center of the approximately ring structure; the second conductive geometric structure is disposed in the gap.

[0029] Each first conductive geometry includes a first straight line segment, a first convex curve segment, a second concave curve segment, a rectangular wave-shaped curve segment, a third convex curve segment, a fourth concave curve segment, and a last straight line segment connected end to end in sequence; the shapes of the first and third convex curve segments are the same as the shape of the rectangular wave in the positive half-cycle, and the shapes of the second and fourth concave curve segments are the same as the shape of the rectangular wave in the negative half-cycle; the second conductive geometry includes a single-ring structure of a regular quadrilateral.

[0030] In other optional embodiments, the second metamaterial layer includes a substrate and a third conductive geometry disposed on the substrate, the third conductive geometry including a single-ring structure of a regular quadrilateral; in the stacked structure of the microwave absorbing metamaterial, the single-ring structure of the regular quadrilateral in the third conductive geometry is located inside the single-ring structure of the regular quadrilateral in the second conductive geometry; the side length of the single-ring structure of the regular quadrilateral in the third conductive geometry is smaller than the side length of the single-ring structure of the regular quadrilateral in the second conductive geometry.

[0031] like Figure 4 and Figure 5 As shown, compared with the traditional microwave absorbing prepreg scheme (i.e., the original scheme, which specifically includes a first microwave absorbing prepreg, a second microwave absorbing prepreg, and a third microwave absorbing prepreg stacked sequentially, with thicknesses of 1 mm, 1.3 mm, and 2.4 mm respectively), the microwave absorbing metamaterial 100 of the present invention (i.e., the new scheme) adopts a design scheme that integrates the metamaterial microstructure (i.e., the first metamaterial layer and the second metamaterial layer) with the microwave absorbing prepreg. While ensuring the mechanical and toughness properties of the original scheme, it utilizes the superposition and coupling effect of the absorption frequency bands of different microwave absorbers (i.e., the first microwave absorbing prepreg layer, the second microwave absorbing prepreg layer, the third microwave absorbing prepreg layer, the first metamaterial layer, and the second metamaterial layer) to broaden the microwave absorption frequency band. The new solution of the microwave absorbing metamaterial 100 described in this invention, without changing the thickness and the microwave absorbing substrate, widens the microwave absorbing bandwidth and comprehensively improves the microwave absorbing effect of the original traditional microwave absorbing prepreg solution (i.e., the original solution).

[0032] like Figure 4 and Figure 5 As shown, the absorbing metamaterial 100 exhibits high absorption of electromagnetic waves in the 1.3–12 GHz frequency band; the high absorption refers to the absorption effect of "less than -3 dB" in the frequency range of 1.3–12 GHz, that is, the absorbing metamaterial 100 of the present invention achieves wide-band, large-angle strong absorption.

[0033] In summary, it is difficult to achieve the aforementioned excellent wave absorption effect at low frequencies with a single absorbing material at such a low thickness. The absorbing metamaterial 100 of this invention has a total thickness of 4.76 mm and achieves wide-band, large-angle strong absorption in the frequency range of 1.3 to 12 GHz. Traditional absorbing rubber materials have poor temperature resistance and mechanical load-bearing capacity. At the same time, the absorbing metamaterial 100 of this invention is a fiber prepreg composite material, which can be produced and laid according to the product design shape. After molding and curing, it has the advantages of high temperature resistance and strong mechanical load-bearing capacity.

[0034] The microwave absorbing metamaterial 100 of this invention is designed with a hexagonal unit structure. While ensuring that the microwave absorption and transmission performance and the miniaturized unit size are not affected, the polarization stability of the structure's frequency response characteristics and the electromagnetic wave oblique incidence conditions (such as...) are improved. Figure 5 The angular stability under 30-degree oblique incidence (as shown); by precisely changing the topology, geometric parameters and arrangement of the microstructure units, the macroscopic electromagnetic properties of the material are adjusted so that the equivalent permittivity and equivalent permeability are equal, satisfying the impedance matching condition, so that all electromagnetic waves enter the metamaterial, and the electromagnetic waves that have entered the material are completely absorbed through electric resonance / magnetic resonance, thus achieving the absorption characteristics of a specific frequency band.

[0035] The absorbing metamaterial 100 described in this invention utilizes integrated absorbing metamaterial technology to achieve a multi-functional integrated design for low-bandwidth stealth. Furthermore, because the design of metamaterials is independent of the aircraft's physical shape, metamaterials have the advantage of being able to achieve synergistic design with aerodynamic performance, enabling low-bandwidth stealth performance for modern equipment while also meeting the high-precision detection and communication requirements of radar antennas. This has significant practical value in fields such as aircraft stealth and camouflage, high-performance radar antennas, and novel communication systems.

[0036] In the microwave absorbing metamaterial 100 described in this invention, the metamaterial achieves specific electromagnetic functions not possessed by traditional materials in nature through the design, fabrication, and composite of artificial microstructures and substrate materials. The tunability and reconfigurability of the metamaterial make it highly suitable for application in the stealth design of multi-functional aperture structures at the leading edge of aircraft. Through ordered structural design at key physical scales, the metamaterial possesses dielectric constant, permeability, and other properties that are difficult to match by conventional materials. This allows for the designability of various electromagnetic wave characteristics, such as reflection, transmission, absorption, deflection, and diffraction, across different electromagnetic spectrum bands. Its broader designability of electromagnetic parameters compensates for the shortcomings of traditional stealth materials and expands the design direction of traditional stealth technology.

[0037] In the microwave absorbing metamaterial 100 described in this invention, a multi-layer complementary structure is used to broaden the microwave absorption bandwidth. By combining different electromagnetic structural metamaterial microstructures, the microwave absorption bandwidth is broadened by utilizing the superposition and coupling effect of the microwave absorption frequency bands of different absorbers. Microstructure units with excellent microwave absorption performance are selected, and a multi-layer combination structure with gradually varying microstructure unit sizes is designed. The microwave absorption bandwidth is broadened by utilizing the superposition effect of the microwave absorption frequency bands of each layer. Microstructure units with excellent impedance matching performance and microwave absorption performance are selected respectively, and a structural combination design of impedance matching layer—high loss layer—metal reflective layer is adopted to guide electromagnetic waves into the interior of the material and generate high attenuation to achieve the microwave absorption effect.

[0038] The absorbing metamaterial 100 described in this invention can be applied to the stealth design of aircraft edge structures. All low-scattering advanced aircraft platforms can use this technology to improve the stealth performance of aircraft edge structures, thereby improving the survivability and penetration capability of advanced aircraft platforms.

[0039] The absorbing metamaterial 100 (i.e., the low-bandwidth absorbing metamaterial scheme) described in this invention has the advantage of enabling the coordinated design of aircraft edge structures and aerodynamic performance to achieve the stealth performance of modern equipment. It has great practical value in fields such as new stealth radar radomes, aviation stealth structural components, electromagnetic compatibility, and communication equipment.

[0040] The most challenging aspect of conceiving the microwave absorbing metamaterial 100 of this invention is combining different electromagnetically structured metamaterial microstructures. This involves selecting microstructures and substrate materials with specific electrical properties based on requirements, and using equivalent medium theory or equivalent circuit methods to make a preliminary selection of the microstructure parameter range, determining the topology and key parameter ranges. Then, large-scale optimization design methods are employed to repeatedly design metamaterial microstructures under various given incident angles, with targeted optimizations. After completing a series of individual microstructure designs, the arrangement of the microstructures is further designed, i.e., a metamaterial array design to achieve a non-uniform and effective arrangement. Through comprehensive algorithm optimization of various dimensional parameters and arrangement rules of the microstructures (such as array form, spacing range, etc.), the electromagnetic wave modulation capability of the metamaterial plate is meticulously adjusted and controlled, achieving the design goal of an integrated microwave absorbing scheme for the metamaterial.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microwave absorbing metamaterial, characterized in that, include: The first microwave absorbing prepreg layer, two second microwave absorbing prepreg layers, a third microwave absorbing prepreg layer, a first metamaterial layer, and a second metamaterial layer are stacked together in sequence.

2. The microwave absorbing metamaterial according to claim 1, characterized in that, It also includes another third microwave absorbing prepreg layer, wherein the first microwave absorbing prepreg layer, the second microwave absorbing prepreg layer, the first metamaterial layer, the second microwave absorbing prepreg layer, the third microwave absorbing prepreg layer, the second metamaterial layer and the third microwave absorbing prepreg layer are stacked together in sequence.

3. The microwave absorbing metamaterial according to claim 2, characterized in that, Both second microwave absorbing prepreg layers are bonded to the first metamaterial layer via adhesive film, and both third microwave absorbing prepreg layers are bonded to the second metamaterial layer via adhesive film.

4. The microwave absorbing metamaterial according to claim 2, characterized in that, The first microwave absorbing prepreg layer, the two second microwave absorbing prepreg layers, and the two third microwave absorbing prepreg layers are all obtained by making a microwave absorbing material containing resin and microwave absorbing agent into a film and hot-pressing and impregnating the film with fiber. The contents of resin, fiber and microwave absorbing agent in the first, second and third microwave absorbing prepreg layers are different; the first, second and third microwave absorbing prepreg layers target different microwave absorbing frequency bands.

5. The microwave absorbing metamaterial according to claim 4, characterized in that, The first, second, and third microwave absorbing prepreg layers are all obtained by making a film from a microwave absorbing material containing epoxy resin and magnetic microwave absorbing agent, and by hot pressing and impregnating the film with quartz fiber.

6. The microwave absorbing metamaterial according to claim 2, characterized in that, The first metamaterial layer includes a substrate and six first conductive geometric structures and a second conductive geometric structure disposed on the substrate. The six first conductive geometric structures are all identical and are connected end to end to form an approximately ring structure, with a gap formed at the center of the approximately ring structure; the second conductive geometric structure is disposed within the gap. Each first conductive geometry includes a first straight line segment, a first convex curve segment, a second concave curve segment, a rectangular wave-shaped curve segment, a third convex curve segment, a fourth concave curve segment, and a last straight line segment connected end to end in sequence; the shapes of the first and third convex curve segments are the same as the shape of the rectangular wave in the positive half-cycle, and the shapes of the second and fourth concave curve segments are the same as the shape of the rectangular wave in the negative half-cycle; the second conductive geometry includes a single-ring structure in the shape of a regular hexagon.

7. The microwave absorbing metamaterial according to claim 6, characterized in that, The second metamaterial layer includes a substrate and a third conductive geometric structure disposed on the substrate. The third conductive geometric structure includes a regular hexagonal single-ring structure. In the stacked structure of the microwave absorbing metamaterial, the regular hexagonal single-ring structure in the third conductive geometric structure is located inside the regular hexagonal single-ring structure in the second conductive geometric structure. The side length of the single-ring structure of the regular hexagon in the third conductive geometry is less than the side length of the single-ring structure of the regular hexagon in the second conductive geometry.

8. The microwave absorbing metamaterial according to claim 2, characterized in that, The first metamaterial layer includes a substrate and four first conductive geometric structures and a second conductive geometric structure disposed on the substrate. The four first conductive geometric structures are all identical and are connected end to end to form an approximately ring structure, with a gap formed at the center of the approximately ring structure; the second conductive geometric structure is disposed within the gap. Each first conductive geometry includes a first straight line segment, a first convex curve segment, a second concave curve segment, a rectangular wave-shaped curve segment, a third convex curve segment, a fourth concave curve segment, and a last straight line segment connected end to end in sequence; the shapes of the first and third convex curve segments are the same as the shape of the rectangular wave in the positive half-cycle, and the shapes of the second and fourth concave curve segments are the same as the shape of the rectangular wave in the negative half-cycle; the second conductive geometry includes a single-ring structure of a regular quadrilateral.

9. The microwave absorbing metamaterial according to claim 8, characterized in that, The second metamaterial layer includes a substrate and a third conductive geometric structure disposed on the substrate. The third conductive geometric structure includes a regular quadrilateral single-ring structure. In the stacked structure of the microwave absorbing metamaterial, the regular quadrilateral single-ring structure in the third conductive geometric structure is located inside the regular quadrilateral single-ring structure in the second conductive geometric structure. The side length of the single-ring structure of the regular quadrilateral in the third conductive geometry is less than the side length of the single-ring structure of the regular quadrilateral in the second conductive geometry.

10. The microwave absorbing metamaterial according to claim 2, characterized in that, The aforementioned absorbing metamaterial exhibits high absorption of electromagnetic waves in the 1.3–12 GHz frequency band.

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