A wave-absorbing metamaterial based on tree-branch fractal structure and preparation method thereof

Abstract

The present invention relates to an absorbing metamaterial based on a branch fractal structure and a preparation method thereof, wherein the absorbing metamaterial comprises: a plurality of absorber structure units arranged in an array; each absorber structure unit comprises an absorbing layer and a metal bottom plate layer, the absorbing layer being located on the metal bottom plate layer; the absorbing layer comprises a branch fractal structure and a ring structure, the ring structure being located outside the branch fractal structure; the branch fractal structure is formed by a plurality of branch branches rotating around the junction point of the plurality of branch branches at a target angle for replication; each branch branch comprises a plurality of level structures connected in sequence, and the length, width and height of each level branch in the plurality of level structures change in a gradient as the number of levels increases. The absorbing metamaterial increases the number of interfaces of the absorber structure by combining gradient change and rotation angle, so that the incident electromagnetic wave is reflected and refracted multiple times at each interface, thereby realizing large-scale loss of the electromagnetic wave.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic wave absorption, and in particular relates to a wave absorbing metamaterial based on a tree branch fractal structure and a preparation method thereof. Background Art

[0002] With the rapid development of detection and identification technology in the military field, modern warfare has entered a new form of warfare based on rapid reconnaissance and precision strikes, and the threat of reconnaissance and strikes on military targets is becoming increasingly serious. At the same time, in social production and life, equipment based on electromagnetic wave technology is more widely used, and the impact of various electromagnetic wave radiation on the environment is increasing. Therefore, both stealth absorption in the military field and electromagnetic shielding attenuation in the civilian field require the support of high-efficiency absorbing materials.

[0003] There are two basic conditions that need to be met for absorbing electromagnetic waves: impedance matching and attenuation. Traditional absorbing materials mainly optimize their absorbing performance by adjusting the properties of the components of the material itself. Most materials are usually complex in design, difficult to mass produce, and have a narrow effective bandwidth, making it difficult to meet broadband absorbing requirements.

[0004] Metamaterial structures are artificial structures with precisely adjustable electromagnetic properties, which are composed of periodic or non-periodic arrangements of sub-wavelength-scale unit structures. They exhibit electromagnetic characteristics opposite to those of conventional materials. Metamaterial absorbers, as an important branch of metamaterial applications, have attracted extensive attention from researchers. At present, how to achieve absorbing metamaterials that can achieve large-scale loss of electromagnetic waves is an urgent problem to be solved. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a wave-absorbing metamaterial based on a dendrite fractal structure and a preparation method thereof. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0006] The embodiment of the present invention provides a wave-absorbing metamaterial based on a tree-branch fractal structure, comprising:

[0007] A plurality of absorber structure units arranged in an array; each of the absorber structure units comprises an absorbing layer and a metal bottom plate layer, wherein the absorbing layer is located on the metal bottom plate layer;

[0008] The wave absorbing layer comprises a branch fractal structure and a circular ring structure, wherein the circular ring structure is located outside the branch fractal structure;

[0009] The tree branch fractal structure is formed by rotating a plurality of branch branches around the junction point of the plurality of branch branches by a target angle and replicating them;

[0010] Each of the branch branches includes a plurality of levels of structures connected in sequence, and the length, width and height of each level of branches in the plurality of levels of structures change in a gradient as the number of levels increases.

[0011] In one embodiment of the present invention, the target angle is 45°.

[0012] In one embodiment of the present invention, the tree branch fractal structure is a rotationally symmetrical structure, and the rotation angle of the rotationally symmetrical structure includes 90°.

[0013] In one embodiment of the present invention, the number of the branch branches is 8.

[0014] In one embodiment of the present invention, each level of branches in each branch tree branch forms a V-shaped structure, and the included angle of the V-shaped structure is 45°.

[0015] In one embodiment of the present invention, the several levels of structures include a primary structure, a secondary structure and a tertiary structure, wherein:

[0016] The primary structure, the secondary structure, and the tertiary structure are connected in sequence from inside to outside;

[0017] The length, width and height of each branch in the primary structure, the secondary structure and the tertiary structure all change in a gradient as the number of levels increases.

[0018] In one embodiment of the present invention, the primary structure includes a main branch, the secondary structure includes a first branch and a second branch, and the tertiary structure includes a third branch, a fourth branch, a fifth branch and a sixth branch, wherein:

[0019] The first branch and the second branch are both connected to the end of the main branch, and the length, width and height of the first branch and the second branch are gradiently changed relative to the length, width and height of the main branch;

[0020] The third branch and the fourth branch are both connected to the end of the first branch, the fifth branch and the sixth branch are both connected to the end of the second branch, and the length, width and height of the third branch, the fourth branch, the fifth branch and the sixth branch vary gradually relative to the length, width and height of the first branch and the second branch.

[0021] In one embodiment of the present invention, the length, width and height of each branch in the primary structure, the secondary structure and the tertiary structure decrease with increasing levels at different gradient ratios.

[0022] Another embodiment of the present invention provides a method for preparing a wave-absorbing metamaterial based on a dendrite fractal structure, which is used to prepare the wave-absorbing metamaterial based on a dendrite fractal structure as described in the above embodiment, comprising the steps of:

[0023] S1. preparing a composite wire material of a polymer matrix material and an absorbent material;

[0024] S2. designing a wave absorbing layer structure in a wave absorbing metamaterial based on a dendrite fractal structure according to the electromagnetic parameters of the composite wire;

[0025] S3. Construct the absorbing layer using a fused deposition 3D printing method.

[0026] In one embodiment of the present invention, the polymer matrix material includes any one of polylactic acid, acrylonitrile-butadiene-styrene copolymer, and polyetheretherketone, and the absorber material includes any one of conductive polymers, graphene, metal magnetic particles, derivatives of metal magnetic particles, and carbon-based absorbing materials.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The absorbing metamaterial of the present invention adopts a tree branch fractal structure, which is formed by rotating a number of branch branches, and each of the branch branches adopts a gradient change structure. By combining the gradient change and the rotation angle, the number of interfaces of the absorber structure is increased, so that the incident electromagnetic wave is reflected and refracted multiple times at each interface, thereby achieving large-scale loss of electromagnetic waves.

[0029] 2. The wave-absorbing metamaterial of the present invention adopts a tree-branch fractal structure. Compared with the traditional flat plate structure, on the basis of improving the effective bandwidth at the same thickness, its mass can be significantly reduced through gradient structure design, thereby achieving the design goal of lightweight and broadband.

[0030] 3. The wave-absorbing metamaterial of the present invention adopts a centrally symmetrical and rotationally symmetrical design and is insensitive to polarization and angle changes.

[0031] 4. The preparation method of the absorbing metamaterial of the present invention is combined with the fused deposition 3D printing technology to accurately control the size and surface accuracy of the metamaterial absorbing structure, thereby improving the material utilization rate. The process method is simple and can realize large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a wave-absorbing metamaterial based on a tree-branch fractal structure provided by an embodiment of the present invention;

[0033] Figure 2 A schematic structural diagram of an absorber structure unit in an absorber metamaterial based on a dendrite fractal structure provided by an embodiment of the present invention;

[0034] Figure 3 A top view of an absorber structure unit in an absorber metamaterial based on a dendrite fractal structure provided by an embodiment of the present invention;

[0035] Figure 4 A side view of an absorber structure unit in an absorber metamaterial based on a dendrite fractal structure provided by an embodiment of the present invention;

[0036] Figure 5 A diagram showing the simulation results of the reflection coefficient of a wave-absorbing metamaterial provided by an embodiment of the present invention when a TE polarized wave is incident;

[0037] Figure 6 A diagram showing the calculation results of the absorption rate of a wave-absorbing metamaterial provided in an embodiment of the present invention when a TE polarized wave is incident;

[0038] Figure 7 A diagram showing the simulation results of the reflection coefficient of a wave-absorbing metamaterial provided by an embodiment of the present invention when a TM polarized wave is incident;

[0039] Figure 8 A diagram showing the calculation results of the absorption rate of a wave-absorbing metamaterial provided in an embodiment of the present invention when a TM polarized wave is incident. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0041] Embodiment 1

[0042] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 , Figure 1 A schematic diagram of the structure of a wave-absorbing metamaterial based on a tree-branch fractal structure provided by an embodiment of the present invention, Figure 2 A schematic diagram of a structure of an absorber structure unit in an absorber metamaterial based on a dendrite fractal structure provided by an embodiment of the present invention, Figure 3 A top view of an absorber structure unit in an absorber metamaterial based on a dendrite fractal structure provided by an embodiment of the present invention, Figure 4 A side view of an absorber structure unit in an absorbing metamaterial based on a dendrite fractal structure provided in an embodiment of the present invention.

[0043] like Figure 1 As shown, the wave-absorbing metamaterial based on the tree-branch fractal structure includes a plurality of wave-absorbing body structural units arranged in an array.

[0044] like Figure 2As shown, each absorber structure unit includes an absorbing layer 1 and a metal bottom plate layer 2, wherein the absorbing layer 1 is located on the metal bottom plate layer 2. The absorbing layer 1 includes a branch fractal structure 11 and a ring structure 12, wherein the ring structure 12 is located outside the branch fractal structure 11, and the branch fractal structure 11 is formed by rotating a plurality of branch branches 110 around the junction point of the plurality of branch branches 110 by a target angle and replicating, and each of the branch branches 110 includes a plurality of level structures connected in sequence, and the length, width, and height of each level branch in the plurality of level structures change in a gradient manner as the number of levels increases.

[0045] Specifically, the branch fractal structure 11 includes a plurality of branch branches 110, and the plurality of branch branches 110 are connected to the same connection point, and the structure of each branch branch 110 is the same. In other words, the branch fractal structure 11 is a centrally symmetrical structure.

[0046] Specifically, each branch branch 110 is formed by a multi-level structure, and branches are added on the basis of the upper branch to form a lower structure. Therefore, as the number of levels increases, the number of branches in each level of structure gradually increases. As the number of branches in the branch branch 110 increases, the length, width, and height of each level of branch change in a gradient; but in each level of structure, the length, width, and height of the branch are the same. Further, as the number of branches in the branch branch 110 increases, the length, width, and height of each level of branch change in a gradient with different gradient ratios.

[0047] It should be noted that the gradient change in this embodiment includes a gradient increase or a gradient decrease. Preferably, the gradient change is a gradient decrease.

[0048] In a specific embodiment, the target angle is 45°, that is, the tree branch fractal structure 11 is formed by a plurality of branch branches 110 being replicated by rotating 45° around the junction of the branches.

[0049] In a specific embodiment, each branch of each branch branch 110 forms a V-shaped structure. It can be understood that each level of structure in each branch branch 110 includes multiple branches, and each level of structure forms a V-shaped structure. Specifically, the angle of the V-shaped structure is 45°.

[0050] In a specific embodiment, the branch fractal structure 11 is a rotationally symmetrical structure, and the rotation angle of the rotationally symmetrical structure includes 90°. That is, after the branch fractal structure 11 is rotated 90°, it completely overlaps with the initial branch fractal structure 11. At this time, the number of branch branches 110 is a multiple of 4, for example, the number of branch branches 110 is 4, 8, 12, etc.

[0051] In a specific embodiment, the number of branch branches 110 is eight.

[0052] In a specific embodiment, the number of levels of the plurality of structures is 3, namely, a primary structure 111, a secondary structure 112 and a tertiary structure 113, wherein the primary structure 111, the secondary structure 112 and the tertiary structure 113 are sequentially connected from the inside to the outside, and the length, width and height of the branches in the primary structure 111, the secondary structure 112 and the tertiary structure 113 all change in a gradient manner with the increase of the number of levels.

[0053] In this embodiment, the primary structure 111 includes a main branch, and a V-shaped structure is formed between the multiple main branches, and the angle θ1 of the V-shaped structure is 45°; the secondary structure 112 includes a first branch 1121 and a second branch 1122 connected to the end of the main branch, the first branch 1121 and the second branch 1122 form a V-shaped structure, and the angle θ2 of the V-shaped structure is 45°; the tertiary structure 113 includes a third branch 1131 and a fourth branch 1132 connected to the end of the first branch 1121, and a fifth branch 1133 and a sixth branch 1134 connected to the end of the second branch 1122, the third branch 1131 and the fourth branch 1132 form a V-shaped structure, the fifth branch 1133 and the sixth branch 1134 form a V-shaped structure, and the angle θ3 of the V-shaped structure is 45°.

[0054] Further, the length, width and height of the first branch 1121 and the second branch 1122 are the same, and have a gradient change relationship with the length, width and height of the main branch. The length, width and height of the third branch 1131, the fourth branch 1132, the fifth branch 1133, and the sixth branch 1134 are the same, and have a gradient change relationship with the length, width and height of the first branch 1121 or the second branch 1122.

[0055] In a specific embodiment, the length, width and height of each branch in the primary structure 111, the secondary structure 112 and the tertiary structure 113 decrease with increasing levels at different gradient ratios.

[0056] Specifically, the length, width and height of the main branch in the primary structure 111 are L, H and W respectively, the length gradient ratio is k, the width gradient ratio is m, the height gradient ratio is t, the height of the outer ring 2 is H and the width is D, then the length of the first branch 1121 and the second branch 1122 in the secondary structure 112 is L2=k*L, the width is W2=m*W, and the height is H2=t*H, and the length of the third branch 1131, the fourth branch 1132, the fifth branch 1133 and the sixth branch 1134 in the tertiary structure 113 is L3=k*k*L, the width is W3=m*m*W, and the height is H3=t*t*H. Among them, 0<k<1, 0<m<1, 0<t<1.

[0057] The absorbing metamaterial of this embodiment adopts a tree branch fractal structure, which is formed by rotating a number of branch branches, and each of the branch branches adopts a gradient change structure. By combining the gradient change and the rotation angle, the number of interfaces of the absorber structure is increased, so that the incident electromagnetic wave is reflected and refracted multiple times at each interface, thereby achieving large-scale loss of electromagnetic waves.

[0058] The absorbing metamaterial of this embodiment adopts a tree-branch fractal structure. Compared with the traditional flat plate structure, on the basis of improving the effective bandwidth at the same thickness, its mass can be significantly reduced through gradient structure design, thereby achieving the design goal of lightweight and broadband.

[0059] The wave-absorbing metamaterial of this embodiment adopts a centrally symmetrical and rotationally symmetrical design and is insensitive to polarization and angle changes.

[0060] Embodiment 2

[0061] On the basis of Example 1, this embodiment provides a method for preparing a wave-absorbing metamaterial based on a dendrite fractal structure, which is used to prepare the wave-absorbing metamaterial described in Example 1, comprising the steps of:

[0062] S1. Prepare composite wires of polymer matrix materials and absorbent materials.

[0063] Specifically, after the polymer matrix material and the absorbent material are uniformly mixed in a certain proportion, the composite wire is prepared by melt extrusion process. The polymer matrix material includes any one of polylactic acid (PLA), acrylonitrile-butadiene-styrene (ABS), polyetheretherketone, etc.; the absorbent material includes any one of conductive polymer, graphene, metal magnetic particles, metal magnetic particle derivatives, carbon-based absorbent materials, and carbon-based absorbent materials include carbon nanotubes, carbon fibers, carbon black, etc.

[0064] S2. Designing a wave-absorbing layer structure in a wave-absorbing metamaterial based on a dendrite fractal structure according to the electromagnetic parameters of the composite wire.

[0065] Specifically, the dielectric constant and magnetic permeability of the composite wire are detected to obtain the electromagnetic parameters of the composite wire; based on the electromagnetic parameters of the composite wire obtained by the test, the CST software is used to design the absorbing layer structure in the absorbing metamaterial based on the tree branch fractal structure.

[0066] In this embodiment, the parameter scanning module in the CST electromagnetic analysis software can be used to change the size structure of the metamaterial absorber structure unit, thereby exciting different resonance modes, achieving multi-resonance goals, and improving its broadband wave absorption capability.

[0067] S3. Construct the absorbing layer using a fused deposition 3D printing method.

[0068] Specifically, the designed absorbing layer material is constructed by using a fused deposition 3D printing method, and the absorbing layer material is placed on a metal base layer to obtain an absorbing metamaterial based on a tree branch fractal structure.

[0069] In this embodiment, 3D printing technology has the advantages of being suitable for processing large, complex and difficult-to-process material components, short design cycle, and high material utilization rate. Therefore, the use of 3D printing technology to prepare metamaterials can be used as an effective way to break through the bottleneck of preparing complex metamaterial structures. The preparation method of the absorbing metamaterial in this embodiment combines the fused deposition 3D printing technology to accurately control the size and surface accuracy of the metamaterial absorbing structure, improve the material utilization rate, and the process method is simple, which can achieve large-scale production.

[0070] Embodiment 3

[0071] On the basis of the first embodiment, this embodiment prepares a wave-absorbing metamaterial based on a dendrite fractal structure and simulates the wave-absorbing metamaterial to illustrate the performance of the wave-absorbing metamaterial.

[0072] The preparation method of the wave-absorbing metamaterial based on the dendrite fractal structure comprises the following steps:

[0073] S1. Prepare composite wires of polymer matrix materials and absorbent materials.

[0074] Specifically, ABS and conductive black were uniformly mixed in a mass ratio of 1:7, and a uniform wire material with a wire diameter of 1.75 mm was prepared by a wire extruder.

[0075] S2. Designing the structure of the wave absorbing layer 1 in the wave absorbing metamaterial based on the dendrite fractal structure according to the electromagnetic parameters of the composite wire.

[0076] Specifically, Figure 1-4 As shown, the metal bottom plate layer 2 is used as a substrate, and an absorbing layer is established on the substrate.

[0077] Furthermore, the structure of the absorbing layer 1 is specifically as follows: the length, width and height of each branch in each level of the structure are respectively changed with respect to the length, width and height of each branch in the primary structure. The length, width and height of the main branch in the primary structure 111 are L1=8mm, W1=3.6mm, H1=7mm, respectively, and the gradient ratios are k=0.9, m=0.5, t=0.6, respectively; the height of the outer ring 2 is H=7mm, and the width is D=2mm; then the lengths of each branch in the secondary structure 112 and the tertiary structure 113 are L2=t*L1=4.8mm, L3=t*t*L1=2.88mm, respectively, the widths are W2=m*W1=1.8mm, W3=m*m*W1=0.9mm, respectively, and the heights are H2=k*H1=6.3mm, H3=k*k*H1=5.67mm, respectively. The top view of the designed structure is as shown in Figure 3 As shown, the perspective view is Figure 4 The designed metamaterial structure is modeled using commercial electromagnetic field simulation software (CST MICROWAVE STUDIO2020). The unit structure is arranged in a periodic manner, and the array is as follows: Figure 1 As shown in the figure, the periodic structure is modeled perpendicular to the Z axis. Periodic boundary conditions are set in the X and Y directions, and open boundary conditions are set in the Z direction. The incident electromagnetic wave is set as a plane wave perpendicular to the incident plane. Due to the blocking of electromagnetic waves by the metal material on the back, the absorber has no transmission (S 21 =0), so according to the formula A(ω)=1-R(ω)-T(ω)=1-|S 11 | 2 -|S 21 | 2 , (where R(ω) is the reflectivity and T(ω) is the transmittance) it can be obtained that the absorption rate of the metamaterial is A(ω)=1-R(ω)=1-|S 11 | 2 .

[0078] S3. Construct the absorbing layer using a fused deposition 3D printing method.

[0079] Specifically, the fused deposition 3D printing technology FDM is used to perform physical printing and preparation of the printed metamaterial structure to obtain an absorbing metamaterial based on a tree branch fractal structure.

[0080] The above-obtained wave-absorbing metamaterial based on the branch fractal structure is simulated, and the simulation results are as follows: Figures 5 to 8 As shown, Figure 5 A simulation result diagram of the reflection coefficient of a wave-absorbing metamaterial provided in an embodiment of the present invention when a TE polarized wave is incident. Figure 6 A graph showing the calculation result of the absorption rate of a wave-absorbing metamaterial provided in an embodiment of the present invention when a TE polarized wave is incident. Figure 7A simulation result diagram of the reflection coefficient of a wave-absorbing metamaterial provided by an embodiment of the present invention when a TM polarized wave is incident. Figure 8 A diagram showing the calculation results of the absorption rate of a wave-absorbing metamaterial provided in an embodiment of the present invention when a TM polarized wave is incident.

[0081] Figure 5 It can be seen from the figure that the absorbing metamaterial array structure of the present invention satisfies the S11 curve in the frequency range of 5 GHz to 40 GHz and always keeps below -10 dB under the TE wave incident condition. Figure 6 It can be seen that within the frequency range of 5 GHz to 40 GHz, the absorption rate can reach almost 90% or more, indicating that the absorbing metamaterial proposed in this embodiment can achieve broadband electromagnetic wave absorption under the condition of TE polarized wave incidence within the range of 5 GHz to 40 GHz, and has good wave absorption characteristics. Figure 7 It can be seen that the absorbing metamaterial array structure of this embodiment satisfies the return loss S11 curve in the frequency range of 5 GHz to 40 GHz under the condition of TM wave incidence and always remains below -10 dB. Figure 8 It can be seen that within the frequency range of 5 GHz to 40 GHz, the absorption rate can reach more than 90%, indicating that the absorbing metamaterial of this embodiment can achieve broadband electromagnetic wave absorption under the condition of TM polarized wave incidence within the frequency range of 5 GHz to 40 GHz, and has good absorbing characteristics.

[0082] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A wave-absorbing metamaterial based on a tree-branch fractal structure, characterized in that: include: A plurality of absorber structural units arranged in an array; Each of the absorber structure units comprises an absorbing layer (1) and a metal bottom plate layer (2), wherein the absorbing layer (1) is located on the metal bottom plate layer (2); the absorbing layer (1) is constructed by using a fused deposition 3D printing method; The wave absorbing layer (1) comprises a branch fractal structure (11) and a circular ring structure (12), wherein the circular ring structure (12) is located outside the branch fractal structure (11); The tree branch fractal structure (11) is formed by replicating a plurality of branch branches (110) by rotating a target angle around a connection point of the plurality of branch branches (110); Each of the branch branches (110) comprises a plurality of sequentially connected level structures, wherein the length, width and height of each level of the branch in the plurality of level structures change in a gradient as the number of levels increases; The plurality of structures include a primary structure (111), a secondary structure (112) and a tertiary structure (113), wherein the primary structure (111), the secondary structure (112) and the tertiary structure (113) are sequentially connected from the inside to the outside; the length, width and height of each branch in the primary structure (111), the secondary structure (112) and the tertiary structure (113) all change in a gradient as the number of levels increases; The primary structure (111) includes a main branch, the secondary structure (112) includes a first branch (1121) and a second branch (1122), and the tertiary structure (113) includes a third branch (1131), a fourth branch (1132), a fifth branch (1133) and a sixth branch (1134), wherein the first branch (1121) and the second branch (1122) are both connected to the end of the main branch, and the length, width and height of the first branch (1121) and the second branch (1122) are relatively large relative to the main branch. The length, width and height of the branches change in a gradient; the third branch (1131) and the fourth branch (1132) are both connected to the end of the first branch (1121), the fifth branch (1133) and the sixth branch are both connected to the end of the second branch, and the length, width and height of the third branch (1131), the fourth branch (1132), the fifth branch (1133) and the sixth branch (1134) change in a gradient relative to the length, width and height of the first branch (1121) and the second branch (1122).

2. The wave-absorbing metamaterial based on the dendrite fractal structure according to claim 1, characterized in that: The target angle is 45°.

3. The wave-absorbing metamaterial based on the dendrite fractal structure according to claim 1, characterized in that: The tree branch fractal structure (11) is a rotationally symmetrical structure, and the rotation angle of the rotationally symmetrical structure includes 90°.

4. The wave-absorbing metamaterial based on the dendrite fractal structure according to claim 1, characterized in that: The number of the branch branches (110) is 8.

5. The wave-absorbing metamaterial based on the dendrite fractal structure according to claim 1, characterized in that: Each level of branches in each branch tree branch (110) forms a V-shaped structure, and the included angle of the V-shaped structure is 45°.

6. The wave-absorbing metamaterial based on the dendrite fractal structure according to claim 1, characterized in that: The length, width and height of each branch in the primary structure (111), the secondary structure (112) and the tertiary structure (113) decrease with increasing number of levels at different gradient ratios.

7. A method for preparing a wave-absorbing metamaterial based on a dendrite fractal structure, characterized in that: The method for preparing the wave-absorbing metamaterial based on the dendrite fractal structure as claimed in any one of claims 1 to 6 comprises the following steps: S1. preparing a composite wire material of a polymer matrix material and an absorbent material; S2. designing a wave absorbing layer structure in a wave absorbing metamaterial based on a dendrite fractal structure according to the electromagnetic parameters of the composite wire; S3. Construct the absorbing layer using a fused deposition 3D printing method.

8. The method for preparing the wave-absorbing metamaterial based on the dendrite fractal structure according to claim 7, characterized in that: The polymer matrix material includes any one of polylactic acid, acrylonitrile-butadiene-styrene copolymer, and polyetheretherketone, and the absorber material includes any one of conductive polymer, graphene, metal magnetic particles, derivatives of metal magnetic particles, and carbon-based absorbing materials.

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