Broadband wave-absorbing metamaterial with umbrella-like polyhedral structure and application of broadband wave-absorbing metamaterial

Abstract

The invention discloses a broadband wave-absorbing metamaterial of an umbrella-like polyhedral structure and application of the broadband wave-absorbing metamaterial, and belongs to the technical field of electromagnetic metamaterials. The broadband wave-absorbing metamaterial with the umbrella-like polyhedral structure comprises a substrate layer and an umbrella-like polyhedral structure layer, the bottom surface of the umbrella-like polyhedral structure layer is connected with the substrate layer; the umbrella-like polyhedral structure layer is a hemisphere-like body formed by connecting a plurality of gradient layers, and the bottom surface of the hemisphere-like body is a regular polygon; and the surface of each gradient layer is formed by splicing a plurality of similar trapezoids or similar triangles with the same size. The umbrella-like polyhedral structure and the gradient gradient structure are combined, the highly symmetrical structure design is adopted, the broadband wave absorbing performance can be shown in the microwave band, wave absorbing performance regulation and control and 100% effective wave absorbing in the full frequency band of 12.00-40.00 GHz can be achieved through parameter adjustment, the wave absorbing performance has polarization insensitivity, and high wave absorbing stability is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic metamaterials, and in particular to a broadband wave-absorbing metamaterial with an umbrella-shaped polyhedron structure and applications thereof. Background Art

[0002] With the rapid development of modern technology, electromagnetic radiation is ubiquitous. From the stealth requirements of military equipment to the electromagnetic compatibility of civilian electronic equipment, higher demands are being placed on absorbing materials. Traditional absorbing materials often suffer from deficiencies such as insufficient absorption performance and heavy structures when faced with complex operating conditions such as low frequencies, wide bandwidths, and multi-angle incidence, making them unable to meet current technological demands. However, electromagnetic metamaterials, with their unique artificial microstructure design, can overcome the physical limitations of traditional materials, achieving precise control and efficient absorption of electromagnetic waves, opening up a new path to solving many electromagnetic challenges.

[0003] Traditional absorbing materials such as ferrites, metal micropowders, and ceramics have gradually exposed numerous drawbacks when dealing with complex electromagnetic environments. While ferrite absorbers offer acceptable absorption performance, their bandwidth is narrow, typically limiting their effectiveness within a specific frequency band. This makes them inadequate for cross-band electromagnetic interference suppression, as required in modern communication systems. Metal micropowder absorbers have a high density, which not only increases the weight of equipment but also has poor resistance to oxidation, acid, and alkali, limiting their service life in harsh environments. For example, the use of such materials in shipborne electronic equipment exposed to long-term corrosion from seawater mist presents a severe challenge. Dielectric absorbers such as ceramics, whose absorption mechanism relies primarily on polarization relaxation loss, are ineffective at absorbing low-frequency electromagnetic waves, making them ineffective in addressing electromagnetic pollution in industrial environments with strong low-frequency electromagnetic radiation. As electronic equipment continues to miniaturize and increase in frequency, traditional absorbers, due to their inherent limitations, are increasingly struggling to achieve both lightweight and efficient absorption performance, hindering further improvements in electromagnetic compatibility and stability.

[0004] With the deep cross-fertilization of science and technology, absorbing metamaterials are entering a new stage of multidisciplinary collaborative innovation. On the one hand, the close integration of multidisciplinary knowledge, including materials science, physics, and electromagnetics, is deepening the understanding of the interaction between microscopic particles and electromagnetic waves. This allows for precise manipulation of the electromagnetic parameters of materials at the microscopic level, providing theoretical support for the design of metamaterial structures with unique electromagnetic responses. On the other hand, the rapid development of computer science and engineering has made it possible to optimize metamaterial designs through numerical simulations and artificial intelligence algorithms. Finite element analysis software is used to simulate the electromagnetic properties of metamaterials under different operating conditions, significantly shortening R&D cycles and reducing costs. Machine learning algorithms are leveraging hidden patterns within massive amounts of data to intelligently predict the relationship between metamaterial structural parameters and absorbing properties, accelerating the development of high-performance absorbing metamaterials and promoting their widespread application in complex electromagnetic systems such as 5G communication base stations and satellites. One of the key challenges facing the field of electromagnetic metamaterials is how to fabricate broadband absorbing metamaterials with superior performance to meet the needs of modern communications and other electromagnetic-related systems, addressing the narrow bandwidth, poor low-frequency electromagnetic wave absorption, and insufficiently stable absorbing performance of traditional absorbing materials. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a broadband absorbing metamaterial with an umbrella-shaped polyhedron structure and its application, so as to solve the problems of traditional absorbing materials such as narrow frequency band, poor low-frequency electromagnetic wave absorption effect, and insufficient stability of absorbing performance.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] The first object of the present invention is to provide a broadband wave-absorbing metamaterial having an umbrella-like polyhedron structure, comprising a base layer and an umbrella-like polyhedron structure layer;

[0008] The bottom surface of the umbrella-shaped polyhedron structure layer is connected to the base layer;

[0009] The umbrella-shaped polyhedron structure layer is a semi-sphere-like shape formed by connecting several gradient layers, and the bottom surface of the semi-sphere-like shape is a regular polygon;

[0010] The surface of each gradient layer is composed of several trapezoidal or triangular shapes of the same size.

[0011] The beneficial effects of the present invention are as follows: the present invention combines an umbrella-shaped polyhedron structure with a gradient structure and adopts a highly symmetrical structural design, which can exhibit broadband wave absorption performance in the microwave band. By adjusting and optimizing parameters, the wave absorption performance can be regulated and 100% effective wave absorption can be achieved in the entire frequency band of 12.00-40.00GHz. The wave absorption performance is polarization-insensitive, and stable wave absorption can be achieved within a wide range of incident angles. It has high wave absorption stability, and the hollow metamaterial structure can also significantly reduce the weight of the material.

[0012] Furthermore, the length of the sides of the regular polygonal base of the umbrella-like polyhedron structure layer is 5-12;

[0013] The number of trapezoidal or triangular shapes on the surface of each gradient layer is 5-12;

[0014] The number of gradient layers of the umbrella-shaped polyhedron structure layer is 5-12.

[0015] Furthermore, the number of faces on the surface of the umbrella-shaped polyhedron structure layer is 25-144.

[0016] Furthermore, the base layer is a square flat plate;

[0017] The diameter of the bottom circumscribed circle of the umbrella-like polyhedron structure layer is equal to the side length of the base layer;

[0018] The height of the umbrella-shaped polyhedron structure layer is half the side length of the base layer.

[0019] Furthermore, the side length of the base layer is 5-20 mm, and the thickness is 0.5-2 mm.

[0020] Furthermore, the length of the sides of the regular polygonal base of the umbrella-like polyhedron structure layer is 6;

[0021] The number of trapezoidal or triangular shapes on the surface of each gradient layer is 6;

[0022] The number of gradient layers of the umbrella-shaped polyhedron structure layer is 6.

[0023] Furthermore, the number of faces on the surface of the umbrella-shaped polyhedron structure layer is 36.

[0024] Furthermore, a broadband absorbing metamaterial with an umbrella-like polyhedron structure is produced by 3D printing using a SiBOC ceramic precursor as a raw material and pyrolyzing it at 1000-1200°C.

[0025] The beneficial effect of adopting the above-mentioned further technical solution is: by using 3D printed SiBOC ceramics as the preparation raw material, the present invention can achieve high-precision preparation of fully dense and complex structures through the DLP 3D printing process, which is fast, efficient and low-cost.

[0026] A second object of the present invention is to provide an array of broadband absorbing metamaterials with an umbrella-like polyhedron structure, which is made by connecting and arranging a plurality of the above-mentioned broadband absorbing metamaterials with an umbrella-like polyhedron structure as unit units.

[0027] The third object of the present invention is to provide the application of the broadband absorbing metamaterial with the above-mentioned umbrella-shaped polyhedron structure or the broadband absorbing metamaterial array with the umbrella-shaped polyhedron structure in military equipment, 5G communication base stations or satellite equipment.

[0028] The present invention has the following beneficial effects:

[0029] (1) The broadband absorbing metamaterial with an umbrella-like polyhedron structure designed in the present invention exhibits significant broadband absorbing performance in the microwave band. Computer simulation results show that the structure can achieve selective absorbing performance regulation and 100% effective absorbing performance in the entire frequency band of 12.00 to 40.00 GHz by simply adjusting the characteristic parameters.

[0030] (2) The metamaterial structure designed in the present invention is a highly symmetrical umbrella-shaped polyhedron structure, so its wave absorbing performance is polarization-insensitive and can achieve stable wave absorption within a wide range of incident angles, with high wave absorbing stability.

[0031] (3) The dielectric material used in the present invention is derived from 3D-printed SiBOC ceramics. This material can be produced with high precision using the DLP 3D printing process to create fully dense, complex SiBOC ceramics with high speed, high efficiency, and low cost. The effective absorption bandwidth of this material can be significantly expanded through the preparation of absorbing metamaterials. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The intrinsic dielectric constant of SiBOC ceramics pyrolyzed at 900-1000℃ is shown in Figure 1, where A is the real part and B is the imaginary part.

[0033] Figure 2 The loss tangent diagram of SiBOC ceramics pyrolyzed at 900-1000℃;

[0034] Figure 3 Schematic diagram of the structure of the umbrella-shaped 36-sided absorbing metamaterial, where a is the overall structure diagram, b is the top view, and c is the cross-sectional view;

[0035] Figure 4 This is a diagram showing the wave absorption performance of the umbrella-shaped 36-hedron wave absorbing metamaterial optimized for the Ku band in Example 1;

[0036] Figure 5 Schematic diagram of the structure of the umbrella-shaped 36-hedron absorbing metamaterial array in Example 1;

[0037] Figure 6 This is a graph showing the electromagnetic wave dissipation power distribution at different frequencies of the umbrella-shaped 36-hedron absorbing metamaterial array in Example 1;

[0038] Figure 7 This is a graph showing the wave absorption performance of the umbrella-shaped 36-hedron wave absorbing metamaterial optimized for the K band in Example 2;

[0039] Figure 8This is a graph showing the absorbing performance of the umbrella-shaped 36-hedron absorbing metamaterial optimized for the full frequency range of Ku, K, and Ka in Example 3;

[0040] Among them, in the figure, 1 is the base layer, 2 is the umbrella-shaped polyhedron structure layer, 21 is the trapezoid, and 22 is the triangle. DETAILED DESCRIPTION

[0041] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not intended to limit the scope of the invention. In the embodiments, if specific conditions are not specified, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0042] When designing absorbing metamaterials, the choice of materials is crucial. Taking dielectric materials as an example, different dielectric materials have different dielectric constants and loss tangent values. Dielectrics with high dielectric constants can enhance electric field confinement, change the propagation characteristics of electromagnetic waves, and guide them to develop in a direction that is conducive to absorption; dielectrics with larger loss tangents can convert more electrical energy into heat energy and directly consume electromagnetic wave energy. In the following embodiments, the present invention uses the intrinsic dielectric constant of 3D printed SiBOC ceramics with independent intellectual property rights (preparation method see patent CN202210496894.2) as the basic design parameter, such as Figure 1 As shown in Figure 3, it can be seen that with the increase of pyrolysis temperature, both the real and imaginary parts of the intrinsic dielectric constant of SiBOC ceramics increase significantly.

[0043] The loss tangent of SiBOC ceramics at three pyrolysis temperatures is further calculated, as follows: Figure 2 As shown in the figure, it can be seen that the sample pyrolyzed at 1100°C has the largest loss tangent, so the dielectric constant of this sample is selected as the basic design parameter. The SiBOC ceramics used in the following examples are all this ceramic, and the pyrolysis temperature is 1100°C.

[0044] Example 1:

[0045] A kind of umbrella-shaped 36-sided absorbing metamaterial optimized for Ku band (12-18GHz) (structure diagram as shown in the figure) Figure 3 As shown), it includes the following structure:

[0046] The super-absorbing material comprises a base layer 1 and an umbrella-shaped polyhedron structure layer 2;

[0047] The base layer 1 is a square flat plate with a side length 2r of 11 mm and a thickness a of 0.9 mm, 1.1 mm, 1.3 mm or 1.5 mm;

[0048] The bottom surface of the umbrella-shaped polyhedron structure layer 2 is a regular hexagon, connected to the base layer 1, and the diameter of the circumscribed circle of the regular hexagon is equal to the side length 2r of the base layer 1;

[0049] The umbrella-like polyhedron structure layer 2 is a hollow hemispherical structure formed by connecting six gradient layers. The bottom surface of the hemispherical structure is a regular hexagon. The height of the hemispherical structure is equal to half the side length of the base layer 1, which is r = 5.5 mm. Starting from the bottom gradient layer of the hemispherical structure, the bottom edge of the bottom gradient layer (the first layer) is the regular hexagonal bottom edge of the umbrella-like 36-hedron structure layer, and the top edge is the bottom edge of the second gradient layer. And so on. The top of the top layer (the sixth layer) is the vertex of the umbrella-like polyhedron structure layer 2, which is also the vertex of the hemispherical circumscribed circle.

[0050] The surfaces of the gradient layers from the first to the fifth layers are respectively composed of six equal-sized trapezoidal shapes 21, and the surface of the gradient layer of the sixth layer is composed of six equal-sized triangles 22, which together constitute the 36 faces of the umbrella-shaped polyhedron structure layer 2.

[0051] Among the six gradient layers, the straight-line distance from the bottom edge to the fixed edge or vertex of each layer is equal.

[0052] The method for preparing the aforementioned umbrella-shaped 36-hedron absorbing metamaterial optimized for the Ku band comprises the following steps:

[0053] According to Figure 3 The structure of the umbrella-shaped 36-sided absorbing metamaterial shown in FIG1 is modeled, and then a green body is prepared by 3D printing using SiBOC ceramic as a raw material. Finally, the green body is pyrolyzed at 1100°C to obtain the umbrella-shaped 36-sided absorbing metamaterial.

[0054] The essence of the numerical analysis method of the electromagnetic field is the process of converting the discretized Maxwell equations into a computer program for numerical solution. The CST Studio Suite simulation software based on the finite integration method is used to perform numerical simulation of the electromagnetic response characteristics of metamaterials, structural design and parameter optimization. In the electromagnetic simulation calculation settings, the periodic unit method is selected to simulate and calculate only one unit structure of the metamaterial. This method can greatly simplify the calculation process and shorten the calculation time. The periodic boundary condition (PBC) is used to simulate the infinite absorbing metamaterial array structure. The calculation method selects the frequency domain finite element method, the boundary is Unit Cell, and the Floquet port excitation. Because the actual test and calculation RC process are based on the metal backplane model, Z can be min The boundary conditions are set to electrical boundary to simulate the metal layer, at Z max An excitation port is set on the upper surface. Under this condition, the simulation calculation results only need to focus on S 11 parameter.

[0055] The absorbing performance of the umbrella-shaped 36-sided absorbing metamaterial prepared in this embodiment was simulated and analyzed by the above method. The results are as follows: Figure 4 shown.

[0056] The optimal parameters of the absorbing metamaterial unit structure optimized for the Ku band (12-18 GHz) are r = 5.5 mm, a = 0.9 mm. In the 12-40 GHz band, the minimum reflection coefficient RC of the designed metamaterial is min = -46.79dB. Two absorption peaks are clearly visible in the figure. The effective absorption bandwidth (EAB) at the low-frequency end exceeds the entire Ku-band (12-22.80GHz), demonstrating the effectiveness of targeted optimization. Combined with the absorption peak at the high-frequency end, the umbrella-shaped 36-hedron absorbing metamaterial EAB reaches up to 16.87GHz (12-22.80, 27.71-33.78GHz) under these parameters, covering the entire Ku-band and 59.93% of the 12-40GHz range.

[0057] A method for preparing an umbrella-shaped 36-hedron absorbing metamaterial array comprises the following steps:

[0058] According to electromagnetic simulation theory, the smaller the size, the higher the resonant frequency. By fine-tuning the unit size, the absorbing frequency band can be accurately located to meet the needs of different frequency band application scenarios such as millimeter waves and radar stealth. In terms of arrangement, close arrangement can enhance the interaction between units and achieve collaborative absorption. In terms of structural characteristics, the design of the symmetry axis can reduce the sensitivity of the metamaterial to the incident angle of electromagnetic waves. According to the relevant parameters of the umbrella-shaped 36-sided absorbing metamaterial prepared in this embodiment, the design of the umbrella-shaped 36-sided absorbing metamaterial array is carried out, such as Figure 5 As shown in the figure, the array is composed of 8×8 umbrella-shaped 36-sided absorbing metamaterials connected and arranged. Figure 5 The structure shown in the figure was modeled, and the green body was prepared by 3D printing using SiBOC ceramic as the raw material. Finally, an umbrella-shaped 36-hedron absorbing metamaterial array was obtained by pyrolysis at 1100°C.

[0059] By using genetic algorithms in CST Studio suite electromagnetic simulation software to perform a large number of numerical simulations and setting energy flux density monitors at different frequencies, the ability of the metamaterial structure to dissipate electromagnetic waves at different positions at the corresponding frequencies can be obtained, such as Figure 6As shown, the metamaterial exhibits distinct responses and dissipation characteristics at different locations for different frequencies of electromagnetic waves. At low frequencies, the high dissipation region is primarily located at the contact points between the umbrella-shaped 36-hedron structure and the underlying planar structure, as well as on the faces of the polyhedron. However, as the frequency increases, the high dissipation region shifts to the edges and tips of the unit cell structure, consistent with the general pattern of how metamaterial characteristic shapes respond to electromagnetic waves.

[0060] Example 2:

[0061] A kind of umbrella-shaped 36-sided absorbing metamaterial optimized for K-band (18-28GHz) (structure diagram as shown) Figure 3 As shown), it includes the following structure:

[0062] The super-absorbing material comprises a base layer 1 and an umbrella-shaped polyhedron structure layer 2;

[0063] The base layer 1 is a square flat plate with a side length 2r of 8 mm and a thickness a of 0.9 mm, 1.1 mm, 1.3 mm or 1.5 mm;

[0064] The bottom surface of the umbrella-shaped polyhedron structure layer 2 is a regular hexagon, connected to the base layer 1, and the diameter of the circumscribed circle of the regular hexagon is equal to the side length 2r of the base layer 1;

[0065] The umbrella-like polyhedron structure layer 2 is a hollow hemispherical structure formed by connecting six gradient layers. The bottom surface of the hemispherical structure is a regular hexagon. The height of the hemispherical structure is equal to half the side length of the base layer 1, which is r = 4.0 mm. Starting from the bottom gradient layer of the hemispherical structure, the bottom edge of the bottom gradient layer (the first layer) is the regular hexagonal bottom edge of the umbrella-like 36-hedron structure layer, and the top edge is the bottom edge of the second gradient layer. Similarly, the top of the top layer (the sixth layer) is the vertex of the umbrella-like polyhedron structure layer 2, which is also the vertex of the hemispherical circumscribed circle.

[0066] The surfaces of the gradient layers from the first to the fifth layers are respectively composed of six equal-sized trapezoidal shapes 21, and the surface of the gradient layer of the sixth layer is composed of six equal-sized triangles 22, which together constitute the 36 faces of the umbrella-shaped polyhedron structure layer 2.

[0067] Among the six gradient layers, the straight-line distance from the bottom edge to the fixed edge or vertex of each layer is equal.

[0068] The method for preparing the aforementioned umbrella-shaped 36-hedron absorbing metamaterial optimized for the Ku band comprises the following steps:

[0069] According to Figure 3The structure of the umbrella-shaped 36-sided absorbing metamaterial shown in FIG1 is modeled, and then a green body is prepared by 3D printing using SiBOC ceramic as a raw material. Finally, the green body is pyrolyzed at 1100°C to obtain the umbrella-shaped 36-sided absorbing metamaterial.

[0070] The absorbing performance of the prepared umbrella-shaped 36-sided absorbing metamaterial was simulated and calculated by the method in Example 1. The results are as follows: Figure 7 shown.

[0071] The optimal parameters of the absorbing metamaterial unit structure optimized for the K band (18-28 GHz) are r = 4.0 mm, a = 0.9 mm (with maximum absorption bandwidth), and a = 1.5 (with minimum reflection coefficient). In the 12-40 GHz band, when a = 1.5 mm, the designed metamaterial can achieve the minimum reflection coefficient RC min = -54.38dB. The figure clearly shows that there are still two absorption peaks. When a = 0.9mm, the effective absorption bandwidth (EAB) at the low-frequency end exceeds the entire K-band (14.13-30.82GHz), demonstrating the effectiveness of targeted optimization. Combined with the absorption peak at the high-frequency end, the umbrella-shaped 36-hedron absorbing metamaterial EAB reaches a maximum of 16.87GHz (14.13-30.82, 38.09-40.00GHz) under these parameters, covering the entire K-band and 66.43% of the 12-40GHz range.

[0072] Example 3:

[0073] An umbrella-shaped 36-sided absorbing metamaterial optimized for Ku, K and Ka full-frequency absorption (structure diagram as shown in the figure) Figure 3 As shown), it includes the following structure:

[0074] The super-absorbing material comprises a base layer 1 and an umbrella-shaped polyhedron structure layer 2;

[0075] The base layer 1 is a square flat plate with a side length 2r of 9 mm and a thickness a of 0.9 mm, 1.1 mm, 1.3 mm or 1.5 mm;

[0076] The bottom surface of the umbrella-shaped polyhedron structure layer 2 is a regular hexagon, connected to the base layer 1, and the diameter of the circumscribed circle of the regular hexagon is equal to the side length 2r of the base layer 1;

[0077] The umbrella-like polyhedron structure layer 2 is a hollow hemispherical structure formed by connecting six gradient layers. The bottom surface of the hemispherical structure is a regular hexagon. The height of the hemispherical structure is equal to half the side length of the base layer 1, which is r = 4.5 mm. Starting from the bottom gradient layer of the hemispherical structure, the bottom edge of the bottom gradient layer (the first layer) is the regular hexagonal bottom edge of the umbrella-like 36-hedron structure layer, and the top edge is the bottom edge of the second gradient layer. Similarly, the top of the top layer (the sixth layer) is the vertex of the umbrella-like polyhedron structure layer 2, which is also the vertex of the hemispherical circumscribed circle.

[0078] The surfaces of the gradient layers from the first to the fifth layers are respectively composed of six equal-sized trapezoidal shapes 21, and the surface of the gradient layer of the sixth layer is composed of six equal-sized triangles 22, which together constitute the 36 faces of the umbrella-shaped polyhedron structure layer 2.

[0079] Among the six gradient layers, the straight-line distance from the bottom edge to the fixed edge or vertex of each layer is equal.

[0080] The method for preparing the aforementioned umbrella-shaped 36-hedron absorbing metamaterial optimized for the Ku band comprises the following steps:

[0081] According to Figure 3 The structure of the umbrella-shaped 36-sided absorbing metamaterial shown in FIG1 is modeled, and then a green body is prepared by 3D printing using SiBOC ceramic as a raw material. Finally, the green body is pyrolyzed at 1100°C to obtain the umbrella-shaped 36-sided absorbing metamaterial.

[0082] The absorbing performance of the prepared umbrella-shaped 36-sided absorbing metamaterial was simulated and calculated by the method in Example 1. The results are as follows: Figure 8 shown.

[0083] The optimal parameters of the absorbing metamaterial unit structure optimized for Ku, K, and Ka full-frequency absorption are r = 4.0mm, a = 1.3mm (with maximum absorption bandwidth), and a = 0.9 (with minimum reflection coefficient). In the 12-40GHz band, when a = 0.9mm, the designed metamaterial can achieve the minimum reflection coefficient RC min =-52.36dB. It can be clearly seen from the figure that there are still two absorption peaks. When a = 1.3mm, the effective absorption bandwidth EAB of the umbrella-shaped 36-hedron absorbing metamaterial covers the entire Ku, K and Ka bands (12.00~40.00GHz), demonstrating the excellent performance of this structure in ultra-wideband absorption.

[0084] 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 in the scope of protection of the present invention.

Claims

1. A broadband absorbing metamaterial with an umbrella-like polyhedron structure, characterized in that: It comprises a base layer (1) and an umbrella-shaped polyhedron structure layer (2); The bottom surface of the umbrella-shaped polyhedron structure layer (2) is connected to the base layer (1); The umbrella-shaped polyhedron structure layer (2) is a semi-sphere-like body formed by connecting a plurality of gradient layers, and the bottom surface of the semi-sphere-like body is a regular polygon; The surface of each gradient layer is formed by splicing a number of trapezoidal (21) or triangular (22) shapes of the same size.

2. The broadband absorbing metamaterial with an umbrella-like polyhedron structure according to claim 1, characterized in that: The length of the regular polygonal bottom surface of the umbrella-shaped polyhedron structure layer (2) is 5-12; The number of trapezoidal shapes (21) or triangle shapes (22) on the surface of each gradient layer is 5-12; The number of gradient layers of the umbrella-shaped polyhedron structure layer (2) is 5-12.

3. The broadband absorbing metamaterial with an umbrella-like polyhedron structure according to claim 2, characterized in that: The number of faces on the surface of the umbrella-shaped polyhedron structure layer (2) is 25-144.

4. The broadband absorbing metamaterial with an umbrella-like polyhedron structure according to claim 1, characterized in that: The base layer (1) is a square flat plate; The diameter of the bottom circumscribed circle of the umbrella-shaped polyhedron structure layer (2) is equal to the side length of the base layer (1); The height of the umbrella-shaped polyhedron structure layer (2) is half the side length of the base layer (1).

5. The broadband absorbing metamaterial with an umbrella-like polyhedron structure according to claim 4, characterized in that: The base layer (1) has a side length of 5-20 mm and a thickness of 0.5-2 mm.

6. The broadband absorbing metamaterial with an umbrella-like polyhedron structure according to claim 2, characterized in that: The length of the sides of the regular polygonal bottom surface of the umbrella-shaped polyhedron structure layer (2) is 6; The number of trapezoidal (21) or triangle (22) shapes on the surface of each gradient layer is 6; The number of gradient layers of the umbrella-shaped polyhedron structure layer (2) is 6.

7. The broadband absorbing metamaterial with an umbrella-like polyhedron structure according to claim 6, characterized in that: The number of faces on the surface of the umbrella-shaped polyhedron structure layer (2) is 36.

8. The broadband microwave-absorbing metamaterial with an umbrella-like polyhedron structure according to claim 1, characterized in that: The broadband wave-absorbing metamaterial with an umbrella-like polyhedron structure is prepared by 3D printing using a SiBOC ceramic precursor as a raw material and pyrolyzing it at 1000-1200°C.

9. A broadband absorbing metamaterial array with an umbrella-like polyhedron structure, characterized in that: The broadband wave-absorbing metamaterial with an umbrella-like polyhedron structure as claimed in any one of claims 1 to 8 is prepared by connecting and arranging individual units.

10. Use of the broadband absorbing metamaterial with an umbrella-like polyhedron structure according to any one of claims 1 to 8 or the broadband absorbing metamaterial array with an umbrella-like polyhedron structure according to claim 9 in military equipment, 5G communication base stations, or satellite equipment.

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