Lattice element sequence structure wave-absorbing metamaterial and preparation method thereof

Abstract

The invention relates to the technical field of wave-absorbing metamaterials, in particular to a lattice element sequential wave-absorbing metamaterial and a preparation method thereof.The wave-absorbing metamaterial comprises a substrate and a lattice structure layer, and the lattice structure layer is formed by arranging a plurality of structure units on the surface of the substrate in a periodic array mode; each structural unit is formed by arranging a plurality of dot matrix elements; the dot matrix elements are sheet-shaped magnetic dot matrix elements. The wave absorbing crest of the dot matrix superstructure moves towards high frequency, and RLlt; and the effective absorption bandwidth of-10dB is improved. The wave-absorbing strength and bandwidth are improved, and the problem that an existing homogeneous wave-absorbing coating is difficult to have the characteristics of small thickness and light weight while the bandwidth is improved is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of absorbing metamaterials, and in particular to a lattice primitive sequence structure absorbing metamaterial and a preparation method thereof. Background Art

[0002] With the continuous upgrading of the electronic information industry and detection methods, the application of electromagnetic waves is becoming more and more extensive, but the electromagnetic pollution and safety issues that come with it are also becoming increasingly severe. Electromagnetic pollution is mainly manifested in electromagnetic interference to equipment and health hazards to organisms. For example, in the surrounding environment, a large amount of radiated electromagnetic waves will not only cause varying degrees of interference to electronic equipment, but in severe cases even cause system disorders or paralysis. At the same time, electromagnetic radiation will also cause thermal and non-thermal effects on organisms, affecting immune function, visual system and other aspects, thus posing a potential threat to human health.

[0003] In order to meet this challenge, the application of absorbing materials is particularly important. Absorbing materials refer to materials that can absorb or significantly reduce the electromagnetic wave energy received on their surface, thereby reducing electromagnetic interference. In the military and civilian fields, the development of high-performance absorbing materials with light weight, thin thickness, wide absorption frequency band and strong absorbing ability has become a research hotspot.

[0004] However, for homogeneous absorbing coatings, due to the limitations of intrinsic physical properties, they are subject to many restrictions in improving absorption bandwidth, reducing coating thickness, reducing weight, etc. According to the Planck-Lozanov limit theory, Δλ / d<16μ s / |lnρ0|, when the material of the homogeneous absorbing coating is determined, its magnetic permeability and reflection coefficient are determined at the same time. This means that if you want to increase the absorption bandwidth, you often need to increase the thickness of the coating at the same time to meet the effective absorption of electromagnetic waves. However, this will make it difficult for the homogeneous absorbing coating to have the characteristics of thin thickness and light weight while increasing the bandwidth. Summary of the invention

[0005] In order to solve the problem that the current homogeneous absorbing coating is difficult to have the characteristics of thin thickness and light weight while improving the bandwidth, the purpose of the present invention is to provide a multi-band compatible absorbing metamaterial with a lattice element structure and a preparation method thereof.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] The first aspect of the present invention provides a lattice primitive sequence structure absorbing metamaterial, comprising a substrate and a lattice structure layer, wherein the lattice structure layer is composed of a plurality of structural units arranged in a periodic array on the surface of the substrate; each of the structural units is composed of a plurality of lattice primitives arranged;

[0008] Each of the structural units is composed of a plurality of lattice primitives arranged in an arrangement; the lattice primitives are sheet-shaped magnetic lattice primitives.

[0009] Preferably, the thickness of the lattice element is 1.8 mm to 2 mm.

[0010] Preferably, the lattice primitives include grid lattice primitives and face-centered lattice primitives; the number of the face-centered lattice primitives is 0 or 1;

[0011] The connection lines of multiple grid lattice primitives on each of the structural units form a regular polygonal grid; the face-centered lattice primitive is arranged at the center of the regular polygonal grid.

[0012] Preferably, the lattice structure layer is composed of a plurality of structural units arranged in a periodic array on the surface of the substrate in a co-edge manner; and the arrangement composition structure of the lattice primitives on each of the structural units is the same.

[0013] Further preferably, the structural unit includes a first structural unit, a second structural unit, a third structural unit and a fourth structural unit;

[0014] The first structural unit is a tetragonal lattice composed of four grid lattice primitives arranged in an arrangement;

[0015] The second structural unit is a face-centered tetragonal lattice composed of four grid lattice primitives and one face-centered lattice primitive;

[0016] The third structural unit is a hexagonal lattice composed of 6 grid lattice primitives;

[0017] The fourth structural unit is a face-centered hexagonal lattice composed of 6 grid lattice primitives and 1 face-centered lattice primitive.

[0018] Further preferably, the length of the connection between two adjacent grid lattice primitives in the first structural unit is equal to the length of the connection between two adjacent grid lattice primitives in the second structural unit; the length of the connection between two adjacent grid lattice primitives in the third structural unit is equal to the length of the connection between two adjacent grid lattice primitives in the fourth structural unit.

[0019] Further preferably, the lattice element is obtained by grinding and mixing carbonyl iron and a matrix material and then cold pressing; the matrix material is resin or paraffin; and the mass ratio of carbonyl iron to matrix material is 6 to 7:1.

[0020] Preferably, the cold press forming conditions are: the pressing pressure is 4.8 MPa to 5 MPa, and the holding time is 2 min to 3 min.

[0021] Preferably, the substrate comprises a dielectric layer and a metal matrix layer; the dielectric layer is arranged on one side surface of the metal matrix layer, and the lattice structure layer is arranged on one side surface of the dielectric layer.

[0022] Preferably, the material of the dielectric layer is FR-4, polyurethane or polyimide; the dielectric constant of the dielectric layer is 4.4; and the material of the metal matrix layer is aluminum, copper or iron.

[0023] Preferably, the thickness ratio of the lattice structure layer, the dielectric layer and the metal matrix layer is 1.8 to 2:1:1.5.

[0024] The second aspect of the present invention provides a method for preparing the lattice primitive structure absorbing metamaterial according to the first aspect, comprising the following steps:

[0025] The carbonyl iron and the matrix material are mixed and ground, and then cold pressed to prepare a lattice element;

[0026] The dot matrix elements are attached to the surface of the substrate to form a structural unit; the operation is repeated for multiple times to form a dot matrix structural layer by arranging the dot matrix elements in a periodic array on the surface of the substrate.

[0027] Beneficial effects of the present invention:

[0028] 1. The present invention regulates the overall effective electromagnetic parameters of the material by designing the sub-wavelength-scale shape on the lattice structure layer, thereby changing the overall effective refractive index of the material, ultimately affecting the transmission path and propagation mode of electromagnetic waves inside the material, and improving the absorption and loss capacity of electromagnetic waves. The designed lattice structure layer is used to change the strength and direction of the magnetic field above to achieve the purpose of better absorption of electromagnetic waves; electromagnetic waves may propagate in the lattice structure layer perpendicular to the thickness direction, which is equivalent to increasing the effective thickness and improving the absorption and loss capacity of electromagnetic waves.

[0029] 2. The present invention achieves absorption and loss of electromagnetic waves by changing the shape, size, arrangement and other factors of the primitives in the lattice superstructure. This metamaterial has a stronger electromagnetic wave loss capability and can effectively absorb and lose electromagnetic waves, thereby protecting electronic devices from interference and damage from electromagnetic waves.

[0030] 3. The present invention uses carbonyl iron electromagnetic primitives for lattice arrangement to prepare a discontinuous superstructure. The discontinuous structure achieves effective loss of incident electromagnetic wave energy through multiple mechanisms such as magnetic resonance, electromagnetic coupling, and electromagnetic wave interference between primitives, thereby significantly broadening the absorption frequency band and improving the absorption performance. The introduction of this lattice superstructure design is expected to enable the material to break through its inherent intrinsic property limitations and bring new physical performance to the structure.

[0031] 4. The maximum absorption intensity of the lattice metamaterial of the present invention is as high as -41dB in the frequency band of 2GHz to 18GHz, the effective absorption bandwidth can reach 6.4GHz, and RL<-10dB. It is expected to be used in aircraft, military vehicles, electronic equipment, microwave darkrooms and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of a lattice primitive sequence absorbing metamaterial provided by the first embodiment of the present invention.

[0033] Figure 2 It is a schematic structural diagram of a lattice primitive sequence absorbing metamaterial provided by the second embodiment of the present invention.

[0034] Figure 3 It is a schematic structural diagram of a lattice primitive sequence absorbing metamaterial provided by the third embodiment of the present invention.

[0035] Figure 4 It is a schematic structural diagram of a lattice primitive order absorbing metamaterial provided by the fourth embodiment of the present invention.

[0036] Figure 5 It is a schematic diagram of four structural units provided by the present invention. Among them, Figure a is a schematic diagram of the first structural unit; Figure b is a schematic diagram of the second structural unit; Figure c is a schematic diagram of the third structural unit; Figure d is a schematic diagram of the fourth structural unit.

[0037] Figure 6 It is a schematic cross-sectional view of a lattice element structured absorbing metamaterial provided in one embodiment of the present invention.

[0038] Figure 7 It is a schematic diagram of the structure of a lattice primitive provided in one embodiment of the present invention.

[0039] Figure 8 The following are SEM images of carbonyl iron. Figure a is a SEM image of carbonyl iron particles at a scale of 0.5 μm; Figures b to d are SEM images of carbonyl iron particles at a scale of 5 μm dispersed in different positions in paraffin.

[0040] Fig. 9 This is a schematic diagram of the hysteresis loop of carbonyl iron.

[0041] Fig.10 It is a schematic diagram of electromagnetic parameters of carbonyl iron. Among them, (a) is the complex dielectric constant; (b) is the complex magnetic permeability. ε′ represents the real part of the complex dielectric constant; ε″ represents the imaginary part of the complex dielectric constant; μ′ represents the real part of the complex magnetic permeability; μ″ represents the imaginary part of the complex magnetic permeability.

[0042] Fig.11It is a schematic diagram of reflection loss curves of the lattice primitive structure absorbing metamaterial provided by Examples 1 to 4 and the flat sample provided by Comparative Example 1.

[0043] In the figure, 1, lattice structure layer; 11, structural unit; 111, first structural unit; 112, second structural unit; 113, third structural unit; 114, fourth structural unit; 12, lattice element; 121, grid lattice element; 122, face-centered lattice element; 2, dielectric layer; 3, metal matrix layer. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0046] Electromagnetic metamaterials introduce new resonance and coupling mechanisms into the coating by designing a special geometric structure of the coating, so that the electromagnetic metamaterials exhibit electromagnetic properties far beyond the material itself. When the scale of the structural design in the electromagnetic metamaterial is below the working wavelength, the structural system can be used as an equivalent medium. By adjusting its structural characteristics, its equivalent electromagnetic parameters can be changed, and even some lossless materials can obtain significant wave absorption performance.

[0047] In order to overcome the absorption bandwidth limitation and reduce the coating thickness and weight, the present invention designs and prepares a topological lattice superstructure absorbing material with a carbonyl iron absorber. The topological lattice system can achieve the purpose of regulating electromagnetic transmission by simulating a microscopic atomic array. So far, topological lattice arrays have not been reported in the application of deep subwavelength scale electromagnetic materials in the GHz frequency band. The present invention patterns deep subwavelength lattice primitives onto a specific lattice to manufacture absorbing metamaterials. Since the structural scale is much smaller than the working wavelength, it can be designed at the deep subwavelength scale and described by macroscopic effective properties. When an electromagnetic wave is incident on the lattice structure, the carbonyl iron lattice causes the electromagnetic wave to scatter spatially and vibrate topologically, and reacts to the spatial electromagnetic field. These electromagnetic coupling effects increase the electromagnetic wave loss mechanism, thereby improving the absorption intensity and bandwidth. At the same time, the large number of gaps between the lattices can reduce the overall weight of the metamaterial, which is conducive to the lightweight of the absorbing material.

[0048] The present invention aims to break through the Planck-Rozanov limit of absorbing materials, so as to improve the absorbing bandwidth without increasing the thickness and weight of the material. Based on the topological lattice in the microscopic atomic lattice, the present invention provides a lattice absorbing metamaterial with a simple structure, flexible production and adjustable frequency band. The lattice superstructure used can cause the incident electromagnetic wave to produce spatial scattering and topological vibration, so that the superstructure has both intrinsic loss and structural loss two absorbing mechanisms, and its application frequency band can be controllably adjusted according to the lattice shape and period size. The lattice absorbing metamaterial of the present invention realizes the C, X, K U Effectively compatible stealth in three bands.

[0049] An embodiment of the present invention provides a lattice element sequenced absorbing metamaterial, comprising a substrate and a lattice structure layer 1, wherein the lattice structure layer 1 is composed of a plurality of structural units 11 arranged in a periodic array on the substrate surface; each structural unit 11 is composed of a plurality of lattice elements 12 arranged in an array; the lattice element 12 is a sheet-like magnetic lattice element, preferably a circular sheet-like magnetic lattice element.

[0050] In one embodiment of the present invention, a structural unit is designed to form a lattice superstructure. By designing the shape of the structural unit of the subwavelength ruler of the lattice superstructure, the effective electromagnetic parameters of the whole material are precisely controlled, so that the effective refractive index of the whole material changes, thereby affecting the transmission path and propagation mode of electromagnetic waves inside the material, and improving the absorption and loss capacity of the absorbing metamaterial to electromagnetic waves. In one embodiment of the present invention, the intensity and direction of the magnetic field above the lattice superstructure are controlled by the lattice superstructure to further optimize the absorption effect of electromagnetic waves. Electromagnetic waves may propagate perpendicular to the thickness direction inside the lattice superstructure. This characteristic is equivalent to increasing the effective thickness of the material, thereby enhancing the absorption and loss effect of electromagnetic waves. Compared with traditional flat coatings, the lattice superstructure designed in one embodiment of the present invention has significant advantages. Compared with homogeneous coatings, the absorption peak of the lattice superstructure designed in one embodiment of the present invention moves to high frequency, and the effective absorption bandwidth of RL<-10dB is improved. Both the absorption intensity and bandwidth are improved. The maximum absorption intensity of the lattice superstructure sample designed in one embodiment of the present invention can reach -41dB, and the effective absorption bandwidth is as high as 6.4GHz, which is 2.7 times the absorption bandwidth of the flat coating. Therefore, while improving the bandwidth, it can also have the characteristics of thin thickness and light weight. In a preferred embodiment, the thickness of the lattice element 12 is H = 1.8 ~ 2mm; the outer diameter of the lattice element 12 is D = 10mm, such as Figure 7 .

[0051] In a preferred embodiment, the lattice element 12 is made by grinding and mixing spherical carbonyl iron and a matrix material, and then cold pressing; the matrix material is resin or paraffin; the mass ratio of carbonyl iron to the matrix material is 6 to 7:1. Preferably, the cold pressing conditions are: the pressing pressure is 4.8 MPa to 5 MPa, and the holding time is 2 min to 3 min. During the cold pressing process, in order to prevent the lattice element 12 from sticking to the wall, a small amount of lubricating oil is applied to the mold wall before pressing to facilitate demolding.

[0052] The disc-shaped magnetic lattice element is made of carbonyl iron. In one embodiment of the present invention, scanning electron microscope analysis, hysteresis loop analysis and electromagnetic parameter analysis are performed on the carbonyl iron.

[0053] Scanning electron microscope morphology of carbonyl iron, such as Figure 8 As shown. Figure 8 It can be seen that the microscopic morphology of carbonyl iron powder is spherical particles with an "onion-like" structure, and the diameter of the particles ranges from 0.5μm to 3.5μm.

[0054] The hysteresis loop of carbonyl iron, such as Fig. 9 As shown. Fig. 9 The results show that carbonyl iron has the characteristics of high saturation magnetization and low coercive force, showing typical soft magnetic properties and good comprehensive magnetic properties.

[0055] Electromagnetic parameters of carbonyl iron, such as Fig.10 As shown. Fig.10 It can be seen that the dielectric loss capacity of carbonyl iron is relatively weak, and the magnetic loss capacity is relatively strong, so carbonyl iron has better magnetic loss performance.

[0056] From the above analysis, it can be seen that carbonyl iron has corresponding electromagnetic loss to the incident electromagnetic wave, thus generating eddy current loss. Carbonyl iron is formed into a disc-shaped magnetic lattice unit by cold pressing, and then the disc-shaped magnetic lattice unit is arranged in a lattice to prepare a discontinuous lattice superstructure. This discontinuous lattice superstructure will lose the energy of the incident electromagnetic wave through magnetic resonance, electromagnetic coupling, electromagnetic wave interference and other effects between the disc-shaped magnetic lattice units, thereby broadening the wave absorption frequency band and improving the wave absorption performance.

[0057] In a preferred embodiment, the substrate includes a dielectric layer 2 and a metal matrix layer 3; the dielectric layer 2 is disposed on one side surface of the metal matrix layer 3, and the lattice structure layer 1 is disposed on one side surface of the dielectric layer 2. Figure 6 An embodiment of the present invention is mainly assembled from a lattice structure layer 1, a dielectric layer 2 and a metal matrix layer 3. The lattice structure layer 1 is composed of structural units 11 distributed in a periodic array on the plane of the dielectric layer 2. Each structural unit is composed of different arrangements of lattice elements, and the arrangement of the lattice elements of each structural unit is consistent.

[0058] Preferably, the material of the dielectric layer 2 is FR-4, polyurethane or polyimide; the dielectric constant of the dielectric layer 2 is 4.4; the material of the metal matrix layer 3 is aluminum, copper or iron. Among them, FR-4 is an epoxy glass cloth laminate; the material of the metal matrix layer 3 is preferably a conductive metal. Preferably, the thickness ratio of the lattice structure layer 1, the dielectric layer 2 and the metal matrix layer 3 is 1.8 to 2:1:1.5. Preferably, the thickness of the lattice element 12 is 1.8 mm to 2 mm; the thickness of the dielectric layer 2 is 1 mm; and the thickness of the metal matrix layer 3 is 1.5 mm.

[0059] According to the electromagnetic loss characteristics of the dot array, a dot array element structure absorbing metamaterial is designed, such as Figure 6 The absorbing metamaterial includes three layers from top to bottom, namely, a lattice structure layer 1, a dielectric layer 2, and a metal matrix layer 3. The lattice structure layer of the absorbing metamaterial has four different arrangements, such as Figure 5 , the arrangement modes of the lattice primitives 12 are tetragonal lattice, face-centered tetragonal lattice, hexagonal lattice and face-centered hexagonal lattice. The lattice primitives 12 include grid lattice primitives 121 and face-centered lattice primitives 122; the number of face-centered lattice primitives 122 is 0 or 1; the connection lines of multiple grid lattice primitives 121 on each structural unit 11 form a regular polygonal grid; the face-centered lattice primitives 122 are arranged at the center of the regular polygonal grid.

[0060] like Figures 1 to 4 In a preferred embodiment, the lattice structure layer 1 is composed of a plurality of structural units 11 arranged in a periodic array on the surface of the substrate in a co-edge manner; and the arrangement and composition structure of the lattice primitives 12 on each structural unit 11 are the same. Specifically, the arrangement of the lattice primitives 12 of each structural unit 11 on the lattice structure layer 1 is consistent. Among them, the structural units 11 are arranged in a periodic array on the surface of the dielectric layer in a co-edge manner of a regular polygonal grid.

[0061] like Figures 1 to 4 The structural unit 11 includes a first structural unit 111, a second structural unit 112, a third structural unit 113 and a fourth structural unit 114; and the lattice structure layer 1 randomly selects any one of the four structural units to arrange them in a periodic array on the surface of the dielectric layer. Among them, the first structural unit 111 is composed of 4 grid lattice primitives 121 arranged to form a tetragonal lattice; the second structural unit 112 is composed of 4 grid lattice primitives 121 and 1 face-centered lattice primitive 122 arranged to form a face-centered tetragonal lattice; the third structural unit 113 is composed of 6 grid lattice primitives 121 arranged to form a hexagonal lattice; the fourth structural unit 114 is composed of 6 grid lattice primitives 121 and 1 face-centered lattice primitive 122 arranged to form a face-centered hexagonal lattice.

[0062] In a preferred embodiment, the length of the connection between two adjacent grid dot matrix primitives 121 in the first structural unit 111 is equal to the length of the connection between two adjacent grid dot matrix primitives 121 in the second structural unit 112; the length of the connection between two adjacent grid dot matrix primitives 121 in the third structural unit 113 is equal to the length of the connection between two adjacent grid dot matrix primitives 121 in the fourth structural unit 114. In the embodiment of the present invention, there are four arrangements of the dot matrix primitives on the structural unit, such as Figure 5 , the arrangement modes are tetragonal lattice, face-centered tetragonal lattice, hexagonal lattice and face-centered hexagonal lattice; the structural units on the lattice structure layer are selected from any one of the above four arrangement modes.

[0063] The grid lattice primitives in the tetragonal lattice are connected to form a square grid, and the grid lattice primitives in the tetragonal lattice structure occupy the four corners of the square grid, and the side length of the square grid is 28 mm. The grid lattice primitives in the face-centered tetragonal lattice are connected to form a square grid, and the four grid lattice primitives in the face-centered tetragonal lattice structure occupy the four corners of the square grid, and the face-centered lattice primitive is located at the center of the square grid, and the side length of the square grid is 28 mm.

[0064] Connect the grid lattice primitives in the hexagonal lattice to form a regular hexagonal grid. The grid lattice primitives in the hexagonal lattice structure occupy the hexagonal positions of the regular hexagonal grid, and the side length of the regular hexagonal grid is 15mm. Connect the grid lattice primitives in the face-centered hexagonal lattice to form a regular hexagonal grid. The grid lattice primitives in the face-centered hexagonal lattice structure occupy the hexagonal positions of the regular hexagonal grid, and the face-centered lattice primitives are located at the center of the regular hexagonal grid. The side length of the regular hexagonal grid is 15mm. Figure 7 The diameter of the disc-shaped magnetic dot matrix element is D=10mm and the thickness is H=2mm.

[0065] In one embodiment of the present invention, the shape of the disc-shaped magnetic element in the lattice superstructure is designed to be sub-wavelength scale, and the overall effective electromagnetic parameters of the material are regulated, so that the overall effective refractive index of the material changes, which ultimately affects the transmission path and propagation mode of electromagnetic waves inside the material, and improves the absorption and loss capacity of electromagnetic waves. In addition, a patterned lattice structure layer 1 is formed by using disc-shaped magnetic lattice elements to be distributed in a two-dimensional plane periodic array. Thus, by changing the intensity and direction of the magnetic field above the lattice superstructure, the purpose of better absorption of electromagnetic waves is achieved; the electromagnetic waves propagate inside the lattice superstructure in a direction perpendicular to the thickness, which is equivalent to increasing the effective thickness and improving the absorption and loss capacity of electromagnetic waves.

[0066] The specific preparation process of the lattice primitive sequence structure absorbing metamaterial is described below.

[0067] The method for preparing a lattice primitive structure wave absorbing metamaterial comprises the following steps:

[0068] Step 1, paraffin is selected as the matrix material, carbonyl iron and paraffin are fully ground and mixed in a mass ratio of 7:1, and then the ground material is placed in a mold. To ensure the smooth progress of subsequent operations, an appropriate amount of release agent is applied to the inner wall of the mold. The release agent is a common release agent for cold pressing technology, which can be purchased directly. For example, the release agent can be edible oil. Using cold pressing technology, the material is pressed at a constant pressure of 5MPa, and the pressure is maintained for 3 minutes to ensure that the material is formed, and a disc-shaped magnetic lattice element with a diameter of 10mm and a thickness of 2mm is prepared. Of course, in other embodiments, resin can also be selected as the matrix material.

[0069] Step 2, prepare a sufficient number of disc-shaped magnetic lattice elements according to the method of step 1.

[0070] Step 3, select an aluminum plate as the metal matrix layer, the thickness of the aluminum plate is 1.5 mm, and the plane size is 200 mm×200 mm. Clean the surface of the aluminum plate and place it at the bottom layer.

[0071] FR-4 is selected as the dielectric layer, the thickness of the dielectric layer is 1 mm, and the plane size is the same as the sheet size of the metal matrix layer. The surface of the dielectric layer is cleaned and covered on the metal matrix layer as an intermediate layer.

[0072] Step 4: Arrange the disk-shaped magnetic lattice primitives according to the pre-designed lattice superstructure, and attach the disk-shaped magnetic lattice primitives to the surface of FR-4 to form a structural unit 11; repeat the operation multiple times to form a lattice structure layer 1 in a periodic array arrangement on the surface of FR-4. Finally, the corresponding lattice primitive sequence structure absorbing metamaterial is prepared.

[0073] The technical solution of the present invention is described in detail below through specific examples. In the following examples, the methods described are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0074] In the following embodiments, magnetic permeability, referred to as μ s . Reflection coefficient, referred to as ρ0. Absorption bandwidth, referred to as Δλ. Coating thickness, referred to as d. Carbonyl iron, referred to as CIP.

[0075] Example 1

[0076] A tetragonal lattice superstructure, such as Figure 6 , including three layers from top to bottom, namely, a lattice structure layer 1, a dielectric layer 2 and a metal matrix layer 3.

[0077] The lattice structure layer 1 is composed of a plurality of structural units 11 arranged in a periodic array on the surface of the substrate; each structural unit 11 is composed of a plurality of lattice primitives 12 arranged; the lattice primitives 12 are disc-shaped magnetic lattice primitives. The disc-shaped magnetic lattice primitives are prepared by adding carbonyl iron and paraffin in a mass ratio of 7:1 into an agate mortar for sufficient grinding, and then cold pressing is used to prepare the disc-shaped magnetic lattice primitives. The process parameters of cold pressing are a pressing pressure of 5MPa and a holding time of 3min. After pressing, a disc-shaped magnetic lattice primitive with a diameter of 10mm and a thickness of 2mm is obtained. In order to prevent the disc-shaped magnetic lattice primitive from sticking to the wall, a small amount of release agent is applied to the mold wall before pressing to facilitate demolding.

[0078] The material of the dielectric layer is FR-4, with a thickness of 1 mm and a plane size of 200 mm × 200 mm. The material of the metal matrix layer is aluminum plate, with a thickness of 1.5 mm and a plane size of 200 mm × 200 mm.

[0079] like Figure 1 The dot matrix element 12 includes a grid dot matrix element 121. The dot matrix element 12 is arranged in a square dot matrix, and the structural unit 11 is a first structural unit 111. The first structural unit 111 is a square dot matrix composed of four grid dot matrix elements 121. The grid dot matrix elements in the square dot matrix are connected to form a square grid. The grid dot matrix elements in the square dot matrix structure occupy the four corners of the square grid respectively, and the side length of the square grid is 28 mm.

[0080] Example 2

[0081] A face-centered tetragonal lattice superstructure, which differs from Example 1 in that: Figure 2 , the lattice primitive 12 includes a grid lattice primitive 121 and a face-centered lattice primitive 122, and the number of the face-centered lattice primitive 122 is 1. The arrangement of the lattice primitive 12 is a face-centered tetragonal lattice, and the structural unit 11 is a second structural unit 112, and the second structural unit 112 is a face-centered tetragonal lattice composed of 4 grid lattice primitives 121 and 1 face-centered lattice primitive 122. The grid lattice primitives in the face-centered tetragonal lattice are connected to form a square grid, and the 4 grid lattice primitives in the face-centered tetragonal lattice structure occupy the four corners of the square grid respectively, and the face-centered lattice primitive is located at the center of the square grid, and the side length of the square grid is 28 mm.

[0082] Example 3

[0083] A hexagonal lattice superstructure, which differs from Example 1 in that: Figure 3, the lattice primitives 12 include grid lattice primitives 121. The arrangement of the lattice primitives 12 is a hexagonal lattice, and the structural unit 11 is a third structural unit 113, and the third structural unit 113 is a hexagonal lattice composed of 6 grid lattice primitives 121. The grid lattice primitives in the hexagonal lattice are connected to form a regular hexagonal grid, and the grid lattice primitives in the hexagonal lattice structure occupy the hexagonal positions of the regular hexagonal grid, and the side length of the regular hexagonal grid is 15 mm.

[0084] Example 4

[0085] A face-centered hexagonal lattice superstructure, which is different from Example 1 in that: Figure 4 , the lattice primitive 12 includes a grid lattice primitive 121 and a face-centered lattice primitive 122, and the number of the face-centered lattice primitive 122 is 1. The arrangement of the lattice primitive 12 is a face-centered hexagonal lattice, and the structural unit 11 is a fourth structural unit 114, and the fourth structural unit 114 is composed of 6 grid lattice primitives 121 and 1 face-centered lattice primitive 122 arranged to form a face-centered hexagonal lattice. Among them, the grid lattice primitives in the face-centered hexagonal lattice are connected to form a regular hexagonal grid, and the grid lattice primitives in the face-centered hexagonal lattice structure occupy the hexagonal positions of the regular hexagonal grid respectively, and the face-centered lattice primitive is located at the center of the regular hexagonal grid, and the side length of the regular hexagonal grid is 15 mm.

[0086] Comparative Example 1

[0087] A flat-plate absorbing superstructure comprises three layers from top to bottom, namely a flat-plate coating, a dielectric layer 2 and a metal matrix layer 3.

[0088] The flat plate coating is made by mixing carbonyl iron and paraffin in a mass ratio of 7:1. After stirring and shaking, the mixture is evenly spread on the dielectric layer. The coating thickness is 2 mm and the plane size is 200 mm×200 mm.

[0089] The material of the dielectric layer is FR-4, with a thickness of 1 mm and a plane size of 200 mm × 200 mm. The material of the metal matrix layer is aluminum plate, with a thickness of 1.5 mm and a plane size of 200 mm × 200 mm.

[0090] The reflection loss of the absorbing metamaterial prepared in the above embodiment under the incident electromagnetic wave of 2GHz to 18GHz is analyzed as follows: Fig.11 shown.

[0091] Depend on Fig.11It can be seen that, from the perspective of the matching frequency of the absorption peak, the peak frequency of the flat-plate absorbing superstructure of Comparative Example 1 is 5 GHz; the peak frequency of the face-centered tetragonal lattice superstructure of Example 2 is 7.5 GHz; the peak frequencies of the tetragonal lattice superstructure of Example 1, the hexagonal lattice superstructure of Example 3, and the face-centered hexagonal lattice superstructure of Example 4 are all above 8 GHz.

[0092] In terms of peak value, the peak value of the tetragonal lattice superstructure of Example 1 is -41dB, which is lower than the lattice superstructures of Examples 2 to 4 and the flat sample of Comparative Example 1. The peak values ​​of the lattice superstructures of Examples 2 to 4 are all higher than the flat sample of Comparative Example 1 and lower than -10dB.

[0093] In terms of effective absorption bandwidth, the effective absorption bandwidth of the face-centered tetragonal lattice superstructure of Example 2 is twice that of the flat sample of Example 1. The effective absorption bandwidths of the tetragonal lattice superstructure of Example 1, the hexagonal lattice superstructure of Example 3, and the face-centered hexagonal lattice superstructure of Example 4 are all more than twice that of the flat sample of Example 1.

[0094] In terms of comprehensive peak value and effective absorption bandwidth, the tetragonal lattice superstructure of Example 1 has relatively good absorption performance, with a maximum absorption intensity of -41dB and an effective absorption bandwidth of 6.4GHz, which is 2.7 times the absorption bandwidth of the flat sample of Example 1.

[0095] In summary, the lattice primitive order absorbing metamaterial prepared in the embodiment of the present invention regulates the overall effective electromagnetic parameters of the material through the sub-wavelength scale shape design, thereby changing the overall effective refractive index of the material, ultimately affecting the transmission path and propagation mode of electromagnetic waves inside the material, and improving the absorption and loss capacity of electromagnetic waves. In addition, the lattice superstructure may achieve the purpose of better absorption of electromagnetic waves by changing the intensity and direction of the magnetic field above it; electromagnetic waves may propagate in the lattice superstructure in a direction perpendicular to the thickness, which is equivalent to increasing the effective absorbing thickness and improving the absorption and loss capacity of electromagnetic waves.

[0096] The structural unit used in the embodiment of the present invention is novel in design. Compared with other metamaterial structures, it can achieve absorption and loss of electromagnetic waves by changing the shape, size, arrangement and other factors of the element in the lattice metastructure. This metamaterial has a stronger electromagnetic wave loss capacity and can effectively absorb and lose electromagnetic waves, thereby protecting electronic equipment from interference and damage from electromagnetic waves.

[0097] The embodiment of the present invention uses carbonyl iron electromagnetic primitives for lattice arrangement to prepare a discontinuous superstructure. The discontinuous structure achieves effective loss of incident electromagnetic wave energy through multiple mechanisms such as magnetic resonance, electromagnetic coupling, and electromagnetic wave interference between primitives, thereby significantly broadening the absorption frequency band and improving the absorption performance. The introduction of this lattice superstructure design is expected to enable the material to break through its inherent intrinsic property limitations and bring new physical performance to the structure.

[0098] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A lattice element structure absorbing metamaterial, characterized in that: It comprises a substrate and a lattice structure layer (1), wherein the lattice structure layer (1) is composed of a plurality of structural units (11) arranged in a periodic array on the surface of the substrate; Each of the structural units (11) is composed of a plurality of arranged lattice primitives (12); the lattice primitives (12) are sheet-shaped magnetic lattice primitives.

2. The lattice element structured wave absorbing metamaterial according to claim 1, characterized in that: The thickness of the lattice element (12) is 1.8 mm to 2 mm.

3. The lattice element structured wave absorbing metamaterial according to claim 1, characterized in that: The lattice primitives (12) include grid lattice primitives (121) and face-centered lattice primitives (122); the number of the face-centered lattice primitives (122) is 0 or 1; The connection lines of the plurality of grid lattice primitives (121) on each of the structural units (11) form a regular polygonal grid; the face-centered lattice primitive (122) is arranged at the center of the regular polygonal grid.

4. The lattice element structured wave absorbing metamaterial according to claim 3, characterized in that: The lattice structure layer (1) is composed of a plurality of structure units (11) arranged in a periodic array on the surface of the substrate in a co-edge manner; and the arrangement and composition structure of the lattice primitives (12) on each of the structure units (11) are the same.

5. The lattice element structured absorbing metamaterial according to claim 3, characterized in that: The structural unit (11) comprises a first structural unit (111), a second structural unit (112), a third structural unit (113) and a fourth structural unit (114); The first structural unit (111) is composed of four grid lattice primitives (121) arranged to form a square lattice; The second structural unit (112) is composed of four grid lattice primitives (121) and one face-centered lattice primitive (122) arranged to form a face-centered tetragonal lattice; The third structural unit (113) is composed of six grid lattice primitives (121) arranged to form a hexagonal lattice; The fourth structural unit (114) is composed of six grid lattice primitives (121) and one face-centered lattice primitive (122) arranged to form a face-centered hexagonal lattice.

6. The lattice element structured wave absorbing metamaterial according to claim 5, characterized in that: The length of a line connecting two adjacent grid lattice primitives (121) in the first structural unit (111) is equal to the length of a line connecting two adjacent grid lattice primitives (121) in the second structural unit (112); and the length of a line connecting two adjacent grid lattice primitives (121) in the third structural unit (113) is equal to the length of a line connecting two adjacent grid lattice primitives (121) in the fourth structural unit (114).

7. The lattice element structured wave absorbing metamaterial according to claim 1, characterized in that: The lattice element (12) is obtained by grinding and mixing carbonyl iron and a matrix material and then cold pressing the mixture; the matrix material is resin or paraffin; and the mass ratio of carbonyl iron to the matrix material is 6 to 7:

1.

8. The lattice primitive order absorbing metamaterial according to claim 1, characterized in that: The substrate comprises a dielectric layer (2) and a metal matrix layer (3); the metal matrix layer (3) is arranged on one side surface of the dielectric layer (2), and the lattice structure layer (1) is arranged on the other side surface of the dielectric layer (2).

9. The lattice element structured wave absorbing metamaterial according to claim 1, characterized in that: The material of the dielectric layer (2) is FR-4, polyurethane or polyimide; the dielectric constant of the dielectric layer (2) is 4.4; and the material of the metal matrix layer (3) is aluminum, copper or iron.

10. A method for preparing the lattice primitive structure absorbing metamaterial according to claim 7, comprising the following steps: The carbonyl iron and the matrix material are mixed and ground, and then cold pressed to prepare a lattice element (12); The lattice primitives (12) are attached to the surface of the substrate to form a structural unit (11); the operation is repeated multiple times to form a lattice structural layer (1) arranged in a periodic array on the surface of the substrate.

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