A wave-absorbing structure and a wave-absorbing material

Abstract

The application discloses a wave-absorbing structure and a wave-absorbing material, wherein the wave-absorbing structure comprises a medium layer, a first resistance layer and a substrate layer which are sequentially stacked from top to bottom; the medium layer comprises a first sub-medium layer and a second sub-medium layer which are sequentially stacked from top to bottom, and the first sub-medium layer is provided with a mounting hole; a second resistance layer is arranged in the mounting hole, and the upper surface of the second resistance layer is an incident surface of electromagnetic waves. By sequentially stacking the medium layer, the first resistance layer and the substrate layer from top to bottom, a multi-layer composite wave-absorbing structure is formed, so that the electromagnetic waves are incident from the second resistance layer and multiple interferences occur between the second resistance layer, the medium layer and the first resistance layer, and the electromagnetic waves are consumed through the absorption and reflection of the resistance layer and the substrate layer, thereby improving the overall wave-absorbing efficiency; meanwhile, the impedance compensation of the medium layer to the wave-absorbing structure is utilized, so that a wider wave-absorbing bandwidth under the condition of oblique incidence of electromagnetic waves is realized.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing materials technology, and in particular to a wave absorbing structure and wave absorbing material. Background Technology

[0002] Microwave-absorbing materials are functional materials that can absorb electromagnetic waves and dissipate electromagnetic energy, converting electromagnetic wave energy into heat or other forms of energy for dissipation. However, current research on the performance of microwave-absorbing materials usually focuses on low reflectivity, which makes it difficult to effectively dissipate the energy of electromagnetic waves during multiple reflections and transmissions, resulting in poor absorption performance. In addition, when electromagnetic waves are incident at large angles, the performance of microwave-absorbing materials will significantly decrease due to impedance mismatch, narrowing the absorption bandwidth and failing to meet the application requirements of wideband and high-efficiency microwave absorption. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a microwave absorbing structure and a microwave absorbing material.

[0004] In a first aspect, the present invention provides a microwave absorbing structure comprising a dielectric layer, a first resistive layer, and a substrate layer stacked sequentially from top to bottom;

[0005] The dielectric layer includes a first sub-dielectric layer and a second sub-dielectric layer stacked from top to bottom. The first sub-dielectric layer has a mounting hole, and a second resistive layer is disposed in the mounting hole. The upper surface of the second resistive layer is the incident surface of the electromagnetic wave.

[0006] In some embodiments of the present invention, the sheet resistance of the first resistive layer is 10-100 Ω / □, and the sheet resistance of the second resistive layer is 50-250 Ω / □.

[0007] In some embodiments of the present invention, the inner diameter of the first sub-dielectric layer is smaller than the inner diameter of the second sub-dielectric layer, the shape of the projection of the first sub-dielectric layer on the horizontal plane is a square with a side length of 0.1-10 mm, and the cross-section of the second sub-dielectric layer is a square with a side length of 5-15 mm.

[0008] The thickness of the second resistive layer, the thickness of the first sub-dielectric layer, and the depth of the mounting hole are all the same, ranging from 0.1 to 1.5 mm.

[0009] The thickness of the first resistive layer is 0.1-0.5 mm.

[0010] In some embodiments of the present invention, the relative permittivity of the dielectric layer is 1.0-5.0, and the thickness of the dielectric layer is 0.2-10 mm.

[0011] In some embodiments of the present invention, the second resistive layer is filled into the mounting hole by mechanical injection of conductive paste;

[0012] The first resistive layer is formed by screen printing the conductive paste onto the lower surface of the dielectric layer or the upper surface of the substrate layer.

[0013] In some embodiments of the present invention, the second sub-dielectric layer, the first resistive layer and the substrate layer have the same projection shape on the horizontal plane, and are all squares with a side length of 5-15mm.

[0014] In some embodiments of the present invention, the material of the dielectric layer includes one or more of the following: quartz fiber, basalt fiber, glass fiber, high boron fiber, cyanate ester resin, epoxy resin, polyimide, and polymethyl methacrylate.

[0015] The material of the first resistive layer includes one or more of the following: carbon nanotubes, graphene, carbon nanoparticles, carbon fibers, silver nanowires, zinc oxide, zinc tin oxide, and indium tin oxide.

[0016] The material of the second resistive layer includes one or more of the following: carbon nanotubes, graphene, carbon nanoparticles, carbon fibers, silver nanowires, zinc oxide, zinc tin oxide, and indium tin oxide.

[0017] In some embodiments of the present invention, the substrate layer includes a plurality of first liner units and second liner units that are alternately stacked in sequence;

[0018] Both the first liner unit and the second liner unit are carbon fiber fabric composite materials, and the first liner unit and the second liner unit are prepared by autoclave molding process to form the substrate layer.

[0019] In some embodiments of the present invention, the first liner unit includes a first carbon fiber reinforcement and a first resin matrix, wherein the first carbon fiber reinforcement is disposed within the first resin matrix;

[0020] The second liner unit includes a second carbon fiber reinforcement and a second resin matrix, wherein the second carbon fiber reinforcement is disposed within the second resin matrix;

[0021] The layup direction between the first carbon fiber reinforcement in the first liner unit and the second carbon fiber reinforcement in the second liner unit is 45°.

[0022] A second aspect of the present invention also provides a microwave absorbing material comprising M×N microwave absorbing structures as described in any of the first aspects above, wherein each of the microwave absorbing structures is arranged in a periodic, densely packed, rectangular pattern in a two-dimensional plane, wherein M > 10 and N > 10.

[0023] The microwave absorbing structure and microwave absorbing material provided by this invention have at least the following advantages:

[0024] The absorbing structure provided by this invention forms a multi-layered composite absorbing structure by sequentially stacking a dielectric layer, a first resistive layer, and a substrate layer from top to bottom. This allows electromagnetic waves to interfere multiple times between the second resistive layer, the dielectric layer, and the first resistive layer after being incident on the second resistive layer. The electromagnetic waves are then consumed by the absorption and reflection effects of the resistive layer and the substrate layer, thereby improving the overall absorbing efficiency. At the same time, by utilizing the impedance compensation of the absorbing structure by the dielectric layer, a wider absorbing bandwidth is achieved under the oblique incidence state of the electromagnetic waves. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0026] Figure 1 A schematic diagram of the exploded structure of the microwave absorbing structure provided in an exemplary embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the absorbing structure provided in an exemplary embodiment of the present invention;

[0028] Figure 3 A top view of an absorbing structure provided in an exemplary embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the substrate layer provided in an exemplary embodiment of the present invention;

[0030] Figure 5 A schematic diagram of the structure of a microwave absorbing material provided in an exemplary embodiment of the present invention;

[0031] Figure 6 A graph showing the variation of reflectivity with frequency when an electromagnetic wave is incident at a perpendicular angle, provided as an exemplary embodiment of the present invention;

[0032] Figure 7 The graph shows the variation of absorption performance of electromagnetic waves with frequency at different incident angles, as provided in an exemplary embodiment of the present invention.

[0033] The following labels are shown in the attached diagram:

[0034] 1. Dielectric layer; 110. First sub-dielectric layer; 111. Mounting hole; 120. Second sub-dielectric layer;

[0035] 2. First resistive layer;

[0036] 3. Substrate layer; 310. First liner unit; 311. First carbon fiber reinforcement; 312. First resin matrix; 320. Second liner unit; 321. Second carbon fiber reinforcement; 322. Second resin matrix;

[0037] 4. Second resistive layer. Detailed Implementation

[0038] 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 a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0039] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] Today, the problem of electromagnetic radiation pollution is no longer limited to stealth technology for military equipment. The electromagnetic interference it causes can also lead to signal disconnection and weakening in industrial and civilian equipment, and even cause serious damage to the human body that is exposed to strong electromagnetic radiation for a long time. Therefore, the technology to weaken or even eliminate electromagnetic radiation has become a hot issue of concern to society and the scientific community.

[0041] Microwave-absorbing materials are functional materials that can absorb electromagnetic waves and dissipate electromagnetic energy, converting electromagnetic wave energy into heat or other forms of energy for dissipation. However, current research on the performance of microwave-absorbing materials usually focuses on low reflectivity, which makes it difficult to effectively dissipate the energy of electromagnetic waves during multiple reflections and transmissions, resulting in poor absorption performance. In addition, when electromagnetic waves are incident at large angles, the performance of microwave-absorbing materials will significantly decrease due to impedance mismatch, narrowing the absorption bandwidth and failing to meet the application requirements of wideband and high-efficiency microwave absorption.

[0042] The following is combined Figures 1-7 The embodiments of the present invention will be further described below.

[0043] To address the aforementioned technical problems, this invention provides an absorbing structure and absorbing material. The absorbing structure comprises a multi-layered composite absorbing structure formed by sequentially stacking a dielectric layer, a first resistive layer, and a substrate layer from top to bottom. This allows electromagnetic waves incident through the second resistive layer to undergo multiple interferences between the second resistive layer, the dielectric layer, and the first resistive layer, resulting in the electromagnetic waves being absorbed and reflected by the resistive and substrate layers, thus improving the overall absorption efficiency. Furthermore, by utilizing the impedance compensation of the dielectric layer for the absorbing structure, a wider absorption bandwidth is achieved under oblique incidence of electromagnetic waves.

[0044] An exemplary embodiment of the present invention provides a wave-absorbing structure, such as Figure 1 and Figure 2 As shown, the structure includes a dielectric layer 1, a first resistive layer 2, and a substrate layer 3 stacked sequentially from top to bottom. It can be understood that along the thickness direction of the absorbing structure, from the upper surface to the lower surface, the dielectric layer 1, the first resistive layer 2, and the substrate layer 3 are stacked sequentially. That is, the first resistive layer 2 is disposed on the upper surface of the substrate layer 3, and the dielectric layer 1 is disposed on the upper surface of the first resistive layer 2. It should be noted that "upper" and "lower" here are for ease of description only and do not constitute a limitation on the absorbing structure. The dielectric layer 1 includes a first sub-dielectric layer 1101 and a second sub-dielectric layer 1201 stacked sequentially from top to bottom. The first sub-dielectric layer 1101 and the second sub-dielectric layer 1201 can be separate structures or integrally formed structures. The first sub-dielectric layer 1101 has a mounting hole 111, and a second resistive layer 4 is disposed within the mounting hole 111. The upper surface of the second resistive layer 4 is the incident surface of the electromagnetic wave, and the lower surface of the second resistive layer 4 is attached to the upper surface of the second sub-dielectric layer 1201. The dielectric layer 1 can be formed using an autoclave molding process. For example, the second resistive layer 4 is shaped into a circle that fits the mounting hole 111. The circle has uniformity and symmetry, facilitating the filling of the second resistive layer 4 into the dielectric layer 1. Simultaneously, it allows the electromagnetic wave to more uniformly irradiate the surface of the second resistive layer 4, thereby improving the electromagnetic wave reception efficiency, reducing electromagnetic wave reflection and scattering on the resistive layer surface, and enabling more electromagnetic wave energy to be effectively absorbed by the second resistive layer 4. Thus, by stacking the dielectric layer 1, the first resistive layer 2, and the substrate layer 3 sequentially from top to bottom, a multi-layered composite absorbing structure is formed. This allows electromagnetic waves to interfere multiple times between the second resistive layer 4, the dielectric layer 1, and the first resistive layer 2 after being incident on the second resistive layer 4. The electromagnetic waves are then consumed by the absorption and reflection of the resistive layer and the substrate layer 3, thereby improving the overall absorption efficiency. At the same time, by utilizing the impedance compensation of the absorbing structure by the dielectric layer 1, a wider absorption bandwidth is achieved under the oblique incidence state of the electromagnetic waves.

[0045] In some embodiments of the present invention, reference is made to... Figure 1 , Figure 2 and Figure 3 The sheet resistance of the first resistive layer 2 is 10-100 Ω / □, and the sheet resistance of the second resistive layer 4 is 50-250 Ω / □. After electromagnetic waves enter the absorbing material, their energy is first dissipated in the second resistive layer 4, converting it into heat energy. Then, any undissipated electromagnetic waves are further dissipated in the first resistive layer 2. This synergistic effect helps improve the overall absorption efficiency. Resistive layers with different resistance values ​​can be optimized for electromagnetic waves of different frequencies, enabling effective dissipation over a wide frequency range.

[0046] In some embodiments of the present invention, reference is made to... Figure 1 , Figure 2 and Figure 3 The inner diameter of the first sub-dielectric layer 1101 is smaller than the inner diameter of the second sub-dielectric layer 1201. The shape of the projection of the first sub-dielectric layer 1101 onto the horizontal plane is a square with a side length of 0.1-10 mm, and the cross-section of the second sub-dielectric layer 1201 is a square with a side length of 5-15 mm. The thickness of the second resistive layer 4, the thickness of the first sub-dielectric layer 1101, and the depth of the mounting hole 111 are the same, all being 0.1-1.5 mm. The thickness of the first resistive layer 2 is 0.1-0.5 mm. For example, referring to... Figure 2 and Figure 3 The second resistive layer 4 and the mounting hole 111 have the same diameter, both 5mm. The side length of the first sub-dielectric layer 1101 is 8mm, and the side length of the second sub-dielectric layer 1201 is 10mm. The thickness of the second resistive layer 4, the thickness of the first sub-dielectric layer 1101, and the depth of the mounting hole 111 are all 1mm. The thickness of the second sub-dielectric layer 1201 is 5mm, and the thickness of the first resistive layer 2 is 0.2mm. When the inner diameter of the first sub-dielectric layer 1101 is smaller than the inner diameter of the second sub-dielectric layer 1201, this stepped structure design is more conducive to the absorption of electromagnetic waves. Dielectric layers 1 of different sizes can produce different responses to electromagnetic waves of different frequencies, thereby broadening the absorption bandwidth or improving the absorption efficiency. The difference in inner diameter can also affect the impedance matching between dielectric layers 1, which helps to reduce the reflection of electromagnetic waves and further improve the absorption performance.

[0047] In some embodiments of the present invention, reference is made to... Figure 1 , Figure 2 and Figure 3 The dielectric layer 1 has a relative permittivity of 1.0-5.0 and a thickness of 0.2-10 mm. In this embodiment, the dielectric layer 1 has a thickness of 6 mm, a relative permittivity of 3.5, and a loss tangent of 0.0031. Thus, the parameter design of the dielectric layer 1 enables the entire absorbing structure to have better absorption, reflection, or transmission performance within a specific frequency band, achieving high-performance electromagnetic absorption.

[0048] In some embodiments of the present invention, reference is made to... Figure 1 , Figure 2 and Figure 3 The second resistive layer 4 is filled into the mounting hole 111 by mechanical injection of conductive paste. Mechanical injection can quickly and evenly fill the mounting hole 111 with conductive paste, improve production efficiency, ensure good filling of conductive paste in the mounting hole 111, avoid the generation of defects such as voids and bubbles, thereby improving the conductivity and stability of the resistive layer.

[0049] The first resistive layer 2 is formed by screen printing conductive paste onto the lower surface of the dielectric layer 1 or the upper surface of the substrate layer 3. In this embodiment, the first resistive layer 2 is formed by screen printing conductive paste onto the lower surface of the dielectric layer 1. Of course, in other embodiments, the first resistive layer 2 can also be formed by screen printing conductive paste onto the upper surface of the substrate layer 3. In this way, the conductive paste has good fluidity and plasticity, and can be printed with various complex patterns and shapes. The conductive paste adheres tightly to the dielectric layer 1 or the substrate layer 3 through screen printing, forming a robust and reliable resistive layer, ensuring the stability and durability of the resistive layer during long-term use, thereby improving the overall reliability of the absorbing structure.

[0050] In some embodiments of the present invention, reference is made to... Figure 1 , Figure 2 and Figure 3 The second sub-dielectric layer 1201, the first resistive layer 2, and the substrate layer 3 all have the same projected shape on the horizontal plane, and are all squares with a side length of 5-15 mm. In this embodiment, the projected shape of the second sub-dielectric layer 1201, the first resistive layer 2, and the substrate layer 3 on the horizontal plane is a square with a side length of 10 mm. Setting the second sub-dielectric layer 1201, the first resistive layer 2, and the substrate layer 3 to have the same projected shape and size makes it easier to align and assemble these three layers during the design and manufacturing process, simplifying the production process, reducing manufacturing difficulty, and improving production efficiency. The same shape and size help ensure tight adhesion and uniform distribution between the layers, enhancing the overall stability and reliability of the absorbing structure.

[0051] In some embodiments of the present invention, reference is made to... Figure 1 , Figure 2 and Figure 3The dielectric layer 1 is made of one or more of the following materials: quartz fiber, basalt fiber, glass fiber, high boron fiber, cyanate ester resin, epoxy resin, polyimide, and polymethyl methacrylate. The first resistive layer 2 is made of one or more of the following materials: carbon nanotubes, graphene, carbon nanoparticles, carbon fibers, silver nanowires, zinc oxide, zinc tin oxide, and indium tin oxide. The second resistive layer 4 is made of one or more of the following materials: carbon nanotubes, graphene, carbon nanoparticles, carbon fibers, silver nanowires, zinc oxide, zinc tin oxide, and indium tin oxide. It is understood that the materials of the first resistive layer 2 and the second resistive layer 4 can be the same or different. Carbon-based materials such as carbon nanotubes, graphene, and carbon fibers, as well as metallic materials such as silver nanowires, have high conductivity and can effectively convert electromagnetic wave energy into heat energy or other forms of energy, thereby improving wave absorption performance and reducing the overall weight of the wave absorption structure. The dielectric layer 1 is made of materials such as quartz fiber and glass fiber. These materials also have good electromagnetic wave transmission performance and can be used as wave-transmitting materials, which helps to optimize the electromagnetic wave absorption performance of the wave-absorbing structure. By selecting different dielectric layer 1 materials, the electromagnetic parameters such as dielectric constant and magnetic permeability of the wave-absorbing structure can be adjusted, thereby optimizing its wave-absorbing performance.

[0052] In some embodiments of the present invention, reference is made to... Figure 4 The substrate layer 3 comprises multiple alternating layers of first liner units 310 and second liner units 320. Both the first liner units 310 and the second liner units 320 are carbon fiber fabric composite materials. The first liner units 310 and the second liner units 320 are fabricated using an autoclave molding process to form the substrate layer 3. The substrate layer 3 uses carbon fiber composite materials, which possess extremely high tensile strength and modulus, enabling the substrate layer 3 to withstand large mechanical loads while maintaining good shape stability. Compared to traditional metal materials, carbon fiber composite materials have a lower density, resulting in a lighter substrate layer 3, which contributes to the lightweight design of the microwave absorbing structure.

[0053] In some embodiments of the present invention, reference is made to... Figure 4 The first liner unit 310 includes a first carbon fiber reinforcement 311 and a first resin matrix 312, with the first carbon fiber reinforcement 311 embedded within the first resin matrix 312. The second liner unit 320 includes a second carbon fiber reinforcement 321 and a second resin matrix 322, with the second carbon fiber reinforcement 321 embedded within the second resin matrix 322. The layup angle between the first carbon fiber reinforcement 311 in adjacent first liner units 310 and the second carbon fiber reinforcement 321 in adjacent second liner units 320 is 45°. (Refer to...) Figure 4Multiple first carbon fiber reinforcements 311 are woven into a mesh and then inserted into the first resin matrix 312. Multiple second carbon fiber reinforcements 321 are woven into a mesh and then inserted into the second resin matrix 322. The angle between the weaving direction of the first carbon fiber reinforcements 311 and the weaving direction of the second carbon fiber reinforcements 321 is 45°. The 45° layup can effectively improve the shear resistance of the composite material, thereby increasing the overall stability of the substrate layer 3. Under stress, the 45° layup intersection angle can make the stress more evenly distributed, reduce the possibility of stress concentration, and thus avoid the material from being damaged due to excessive local stress.

[0054] A second aspect of the present invention also provides a microwave absorbing material, referring to... Figure 5 The absorbing material comprises M×N absorbing structures as described in any of the above embodiments, wherein the absorbing structures are arranged in a periodic, close-packed pattern of M×N rectangles in a two-dimensional plane, where M > 10 and N > 10. For example, the absorbing material comprises 15*15 absorbing structures, each of which is arranged in a periodic, close-packed pattern of 15*15 rectangles in a two-dimensional plane. Through this periodic close-packing, the absorbing material can form a continuous absorbing layer over a larger area, thereby more effectively absorbing and dissipating electromagnetic waves, ensuring that electromagnetic waves are reflected and absorbed multiple times during propagation, improving the overall absorbing performance of the material. The periodically arranged absorbing structures can form specific electromagnetic resonance modes, which helps to absorb electromagnetic waves over a wider frequency band. Furthermore, the periodically close-packed absorbing structures are easier to standardize and mass-produce during manufacturing, ensuring consistent performance for each absorbing structure and contributing to improved overall stability and reliability of the absorbing material.

[0055] In this embodiment, a simulation experiment of the microwave absorbing material provided by the present invention is conducted using commercial electromagnetic simulation software, with reference to... Figure 6 When electromagnetic waves are incident perpendicularly, the reflectivity of the absorbing material in this embodiment is less than -10dB in the frequency band range of 19.9GHz to 24.7GHz, less than -10dB in the frequency band range of 20.6GHz to 21.4GHz, and achieves a minimum reflectivity of -34.8dB at a frequency of 20.9GHz.

[0056] Reference Figure 7When electromagnetic waves are incident perpendicularly, the absorbing material of this embodiment achieves an absorption effect of over 90% in the 19.9GHz–24.7GHz frequency band and over 99% in the 20.6GHz–21.4GHz frequency band. When the electromagnetic wave incident angle is 30°, the absorbing material of this embodiment achieves an absorption effect of over 90% in the 20.2GHz–25.2GHz frequency band and over 99% in the 23.3GHz–24.0GHz frequency band. As the electromagnetic wave incident angle increases, the absorption peak gradually shifts to higher frequencies. Furthermore, the high-frequency absorption effect of the absorbing material is better when the electromagnetic wave is incident obliquely than when it is incident perpendicularly. Even when the electromagnetic wave incident angle is 45°, the absorbing material of this embodiment still achieves an absorption effect of over 90% in the 21.6GHz–26.2GHz frequency band.

[0057] The simulation results above show that the absorbing material can achieve a reflectivity of less than -10dB in the range of 19.9GHz to 24.7GHz, which has a significant absorption effect. At the same time, it can still maintain more than 90% absorption in a wide frequency band when electromagnetic waves are obliquely incident, which shows good absorption stability.

[0058] The above-described contents can be implemented individually or in various combinations, and these variations are all within the protection scope of this invention.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wave-absorbing structure, characterized in that, The medium layer, the first resistance layer and the substrate layer are sequentially stacked from top to bottom. The medium layer comprises a first sub-medium layer and a second sub-medium layer stacked from top to bottom, the first sub-medium layer is provided with a mounting hole, and the second resistance layer is arranged in the mounting hole, and the upper surface of the second resistance layer is an incident surface of electromagnetic waves. The inner diameter of the first sub-medium layer is smaller than the inner diameter of the second sub-medium layer to form a stepped structure to facilitate the absorption of electromagnetic waves of different frequencies. The second resistance layer is filled with conductive paste in the mounting hole by mechanical perfusion. The substrate layer comprises a plurality of first and second lining units which are alternately and sequentially stacked. The first lining unit comprises a first carbon fiber reinforcement and a first resin matrix, and the first carbon fiber reinforcement is arranged in the first resin matrix. The second lining unit comprises a second carbon fiber reinforcement and a second resin matrix, and the second carbon fiber reinforcement is arranged in the second resin matrix. The included angle between the first carbon fiber reinforcement in the first lining unit and the second carbon fiber reinforcement in the second lining unit is 45°.

2. The wave-absorbing structure according to claim 1, characterized in that, The surface resistance of the first resistance layer is 10-100 Ω / □, and the surface resistance of the second resistance layer is 50-250 Ω / □.

3. The wave-absorbing structure according to claim 1, characterized in that, The projection of the first sub-medium layer on the horizontal plane is a square with a side length of 0.1-10 mm, and the cross section of the second sub-medium layer is a square with a side length of 5-15 mm. The thickness of the second resistance layer, the thickness of the first sub-medium layer and the hole depth of the mounting hole are the same, and are all 0.1-1.5 mm. The thickness of the first resistance layer is 0.1-0.5 mm.

4. The wave-absorbing structure of claim 1, wherein, The relative dielectric constant of the medium layer is 1.0-5.0, and the thickness of the medium layer is 0.2-10 mm.

5. The wave-absorbing structure of claim 1, wherein The first resistance layer is printed on the lower surface of the medium layer or the upper surface of the substrate layer by screen printing.

6. The wave-absorbing structure of claim 1, wherein, The projection of the second sub-medium layer, the first resistance layer and the substrate layer on the horizontal plane is the same, and is a square with a side length of 5-15 mm.

7. The wave-absorbing structure of claim 1, wherein, The material of the medium layer comprises one or more of quartz fiber, basalt fiber, glass fiber, high boron fiber, cyanate ester resin, epoxy resin, polyimide and polymethyl methacrylate. The material of the first resistance layer comprises one or more of carbon nanotube, graphene, carbon nanoparticles, carbon fiber, silver nanowire, zinc oxide, zinc tin oxide and indium tin oxide. The material of the second resistance layer comprises one or more of carbon nanotube, graphene, carbon nanoparticles, carbon fiber, silver nanowire, zinc oxide, zinc tin oxide and indium tin oxide.

8. The wave-absorbing structure of claim 1, wherein The first lining unit and the second lining unit are carbon fiber fabric composites, and the first lining unit and the second lining unit are prepared by a hot press tank forming process to form the substrate layer.

9. A wave-absorbing material, characterized by, The wave-absorbing material comprises M×N wave-absorbing structures as claimed in any one of claims 1-8, wherein each wave-absorbing structure is arranged in a M×N rectangular periodic close-packed array in a two-dimensional plane, and M>10 and N>10.

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