An encoded metamaterial wave absorber with compression load bearing and broadband wave absorption

Abstract

The application discloses an encoding metamaterial wave-absorbing body with compression resistance and broadband wave-absorbing capability, comprising: a frame formed by three-dimensional printing of insulating material, which is in a periodic grid structure and has a plurality of array-arranged and mutually independent cavities; and a plurality of wave-absorbing material blocks made of magnetic wave-absorbing composite material and detachably filled in the cavities; the wave-absorbing material blocks at least include first-type blocks with three-dimensional convex structures and second-type blocks with three-dimensional concave structures, and the two types of blocks are complementary in space; the first-type blocks constitute first encoding units, the second-type blocks constitute second encoding units, and the two types of blocks are combined to constitute third encoding units, and the three types of encoding units have different wave-absorbing frequency response characteristics; the plurality of wave-absorbing material blocks are selectively arranged in the cavities according to a preset encoding scheme, and the wave-absorbing performance is reconfigured by physically replacing the arrangement mode. The application realizes an absorption efficiency of more than 90% in a 2-18 GHz frequency band, the frame has a compression strength of not less than 4 MPa, and has the advantages of broadband wave-absorbing capability, compression resistance and performance reconfigurability, and can be applied to the fields of aircraft skin, warship radar shielding and electromagnetic protection of electronic equipment.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorption and electromagnetic compatibility, and specifically relates to a coded metamaterial absorber with compressive strength and broadband absorption. Background Technology

[0002] With the rapid development of electronic information technology and the continuous expansion of its application scenarios, electromagnetic waves are increasingly widely used in wireless communication, radar detection, electronic warfare, and other fields. However, the electromagnetic waves radiated by electronic devices during operation not only cause electromagnetic interference to surrounding equipment, leading to performance degradation or even failure, but may also pose potential hazards to human health. Therefore, how to effectively absorb and shield electromagnetic waves has become a key technical problem that urgently needs to be solved in fields such as electromagnetic compatibility, radar stealth, and microwave anechoic chambers.

[0003] Microwave absorbing materials are one of the important means to solve the above problems. Microwave absorbing materials are mainly divided into two categories: traditional coating-type microwave absorbing materials and structural microwave absorbing metamaterials. Coating-type microwave absorbing materials are usually composed of magnetic or dielectric loss fillers and a matrix. They have the advantage of simple preparation process, but their absorption frequency band is narrow, making it difficult to achieve broadband and efficient absorption. In addition, their structure is simple and their functions are limited, making it difficult to adapt to the complex and ever-changing electromagnetic environment requirements.

[0004] In recent years, metamaterials have attracted widespread attention due to their extraordinary ability to manipulate electromagnetic waves. Metamaterials are artificial composite materials composed of periodically arranged subwavelength structural units. By designing the shape, size, and arrangement of these structural units, electromagnetic properties not found in natural materials can be achieved, such as negative refraction, perfect absorption, and electromagnetic cloaking. In the field of microwave absorption, researchers have attempted to apply metamaterials to the design of microwave absorbers. By introducing resistive films, lumped elements, or multilayer structures, they have effectively improved the microwave absorption performance of absorbers and broadened the absorption bandwidth. However, existing metamaterial microwave absorption structures still have the following shortcomings:

[0005] First, most existing metamaterial absorbers are monolithic, fixed structures, meaning their absorption performance is fixed after fabrication and cannot be flexibly adjusted or reconfigured according to actual application needs. When the electromagnetic environment changes or selective absorption for different frequency bands is required, new absorbers must be redesigned and fabricated, resulting in high costs and poor adaptability.

[0006] Second, existing metamaterial wave absorbers typically employ two-dimensional planar structures or honeycomb structures. While they possess certain wave absorption properties, their mechanical load-bearing capacity is relatively weak, making it difficult for them to function effectively in application scenarios that require both structural support and electromagnetic wave absorption.

[0007] Third, the absorption frequency range of existing metamaterial absorbers is limited, especially the absorption performance in the low frequency band is poor, making it difficult to achieve ultra-wideband effective absorption from the S-band to the Ku-band.

[0008] To address the aforementioned issues, while existing technologies have proposed some tunable metamaterial solutions, such as continuously controlling the electromagnetic response of metamaterial units through temperature or electric fields, these solutions typically require complex control devices such as external power supplies, heaters, or piezoelectric elements. They are characterized by high system integration and high cost, and the control method is continuously adjustable rather than discretely reconfigurable, making it difficult to achieve flexible switching across multiple frequency bands and modes.

[0009] Therefore, there is an urgent need to develop a novel metamaterial absorber that combines broadband absorption performance, good compressive strength, and reconfigurable absorption performance to meet the pressing demand for multifunctional and tunable absorbing materials in complex electromagnetic environments. Summary of the Invention

[0010] The present invention aims to solve the technical problems existing in the prior art, such as fixed and non-reconfigurable absorption performance of metamaterial absorbers, weak mechanical load-bearing capacity, and limited absorption frequency band coverage, and provides a coded metamaterial absorber with compressive load-bearing capacity and broadband absorption.

[0011] To achieve the above objectives, the present invention provides a coded metamaterial absorber with compressive strength and broadband absorption, comprising:

[0012] A frame is integrally formed from insulating material through 3D printing. The frame has a periodic grid structure and multiple arrayed and independent cavities inside. The frame is used to provide compressive load-bearing support.

[0013] Multiple microwave absorbing material blocks are detachably filled in the cavity, and the microwave absorbing material blocks are made of magnetic microwave absorbing composite material;

[0014] The microwave absorbing material block includes at least the following:

[0015] The first type of block has a three-dimensional convex structure;

[0016] The second type of block has a three-dimensional concave structure, which is spatially complementary to the three-dimensional convex structure of the first type of block.

[0017] The first type of block constitutes a first coding unit on its own, the second type of block constitutes a second coding unit on its own, and the first type of block and the second type of block are combined to form a third coding unit;

[0018] The first coding unit, the second coding unit, and the third coding unit each have different absorption frequency response characteristics;

[0019] The multiple absorbing material blocks are selectively arranged in multiple cavities of the frame according to a preset coding scheme, with the first coding unit, the second coding unit, and the third coding unit arranged in a specific order. By physically changing the arrangement of the absorbing material blocks, the absorbing performance of the metamaterial absorber can be reconstructed.

[0020] Furthermore, the frame is made of polylactic acid.

[0021] Furthermore, the magnetic microwave absorbing composite material is a carbonyl iron powder / thermoplastic polyurethane composite.

[0022] Furthermore, the first coding unit composed of the first type of block alone is used to achieve broadband absorption, the second coding unit composed of the second type of block alone is used to achieve high-frequency strong absorption, and the third coding unit composed of the first type of block and the second type of block combined is used to achieve low-frequency strong absorption.

[0023] Furthermore, the three-dimensional convex structure of the first type of block includes a base and a protrusion, and the three-dimensional concave structure of the second type of block includes a base and a recess, wherein the shape and size of the protrusion and the recess match.

[0024] Furthermore, the total height of the first type of block and the second type of block is 5 mm, the side length of the base is 19 mm, the side length of the protrusion and the recess is 13.5 mm, and the height of the protrusion and the recess is 4 mm.

[0025] Furthermore, the frame is a square hollow grid structure with a wall thickness of 0.5 mm, a height of 6 mm, a side length of 20 mm for each grid, and a side length of 19 mm for the internal cavity of the grid; the compressive strength of the frame is not less than 4 MPa.

[0026] Furthermore, the coded metamaterial absorber also includes a metal backing, which is disposed on the back of the frame and the absorber block.

[0027] The present invention also provides a method for reconstructing the performance of a coded metamaterial absorber, applied to the coded metamaterial absorber described in any of the above claims, comprising:

[0028] A frame is provided, which is integrally formed by 3D printing of insulating material. The frame has a periodic grid structure and multiple arrayed and independent cavities are formed inside.

[0029] Provides a variety of microwave absorbing material blocks including at least a first type of block and a second type of block, wherein the first type of block has a three-dimensional convex structure, the second type of block has a three-dimensional concave structure that is complementary to the three-dimensional convex structure, the first type of block alone constitutes a first coding unit, the second type of block alone constitutes a second coding unit, and the first type of block and the second type of block combined constitute a third coding unit;

[0030] Based on the target absorption performance, a coding scheme is determined, wherein the coding scheme defines the arrangement of the first coding unit, the second coding unit, and the third coding unit in the plurality of cavities;

[0031] According to the coding scheme, the various absorbing material blocks are detachably filled into the cavity, and the absorbing performance of the metamaterial absorber is reconstructed by physically changing the arrangement of the absorbing material blocks.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The coded metamaterial absorber provided by this invention possesses compressive strength and broadband absorption capabilities. A 3D-printed frame provides compressive support, while three coding units are constructed from magnetic absorbing composite material blocks with three-dimensional convex and concave structures. Each coding unit exhibits different absorption frequency response characteristics. By selectively arranging these coding units within the frame's cavities according to a preset coding scheme, and by physically changing the arrangement of the absorbing material blocks, the absorption performance can be reconstructed, thus overcoming the limitation of existing metamaterial absorbers having fixed and unreconfigurable performance.

[0034] This invention employs a complementary design of absorbing material blocks with convex and concave structures. The coding unit composed of the first type of block alone can achieve broadband absorption, the coding unit composed of the second type of block alone can achieve strong high-frequency absorption, and the coding unit composed of the combination of the first and second types of blocks can achieve strong low-frequency absorption. Through the flexible combination of the three coding units, an absorption efficiency of over 90% can be achieved in the 2-18 GHz frequency band, exhibiting excellent broadband absorption performance.

[0035] This invention employs a 3D-printed frame structure with a compressive strength of not less than 4 MPa, possessing excellent compressive load-bearing capacity. It can simultaneously meet the dual functional requirements of structural support and electromagnetic wave absorption, and can be widely applied in application scenarios that require both structural strength and electromagnetic protection, such as aircraft skin, ship radar shielding, and electronic equipment enclosures.

[0036] This invention reconstructs the absorption performance by physically changing the arrangement of the absorbing material blocks. It does not require complex control devices such as external power supplies, heaters, or piezoelectric elements. It has the advantages of simple structure, convenient operation, and low cost. The absorption performance can be flexibly adjusted according to actual application needs to adapt to complex and ever-changing electromagnetic environments. Attached Figure Description

[0037] Figure 1 A schematic diagram of the structure of the coded metamaterial absorber with compressive strength and broadband absorption provided by the present invention;

[0038] Figure 2 An exploded view of the structure of the frame and the microwave absorbing material block provided by the present invention;

[0039] Figure 3 This is a schematic diagram of the coding arrangement of the coded metamaterial absorber provided by the present invention;

[0040] Figure 4 A comparison of reflection loss curves for three single coding units provided by the present invention;

[0041] Figure 5 A reflection loss curve of the first coding unit and the second coding unit mixed and encoded in different proportions according to the present invention;

[0042] Figure 6 A reflection loss curve of the second and third coding units mixed and encoded in different proportions according to the present invention;

[0043] Figure 7 A reflection loss curve of the first coding unit and the third coding unit mixed and encoded in different proportions, provided by the present invention;

[0044] Figure 8 The reflection loss curves of the first, second, and third coding units mixed encoding provided by the present invention;

[0045] Figure 9 Stress-strain curves of the frame provided for this invention;

[0046] Figure 10 A comparison of measured reflection loss curves of the absorber under different coding schemes provided by this invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0048] Example 1: Preparation of microwave absorbing material block

[0049] This embodiment provides a method for preparing a microwave absorbing material block, used to prepare a first type of block with a three-dimensional convex structure and a second type of block with a three-dimensional concave structure, the specific structures as follows: Figure 1 and 2 As shown.

[0050] First, thermoplastic polyurethane (TPU) was selected as the matrix material. TPU is a multiphase block copolymer composed of diisocyanate, polyol, and chain extender, possessing certain flexibility, transparency, and environmental resistance, and can be plasticized by heating. Spherical micron-sized carbonyl iron powder was selected as the magnetic microwave absorbing filler. Acetone and cyclohexanone were selected as solvents for the TPU.

[0051] Generally, the higher the proportion of absorber in a composite material, the higher its electromagnetic parameters (relative permittivity and permeability). According to the quarter-wavelength theory, for microwave absorbers of the same thickness, the absorption peak shifts to lower frequencies as the electromagnetic parameters of the material increase. Therefore, to achieve ultra-wideband microwave absorption, convex and concave structures employ different magnetic powder / polyurethane mass ratios. Convex structures are prepared using a higher mass ratio composite to cover broadband absorption at lower frequencies; concave structures use a lower mass ratio, which is more conducive to generating absorption peaks at higher frequencies for high-frequency electromagnetic wave absorption. The selection of different mass ratios provides the foundation for subsequent ultra-wideband absorption and efficient encoding and reconstruction performance. Based on this, samples with varying mass ratios were prepared, and the optimal range of ratios was determined through simulation screening and optimization. When the mass ratio of carbonyl iron powder to polyurethane is 5.2-7.8:1, the convex structure is beneficial for achieving effective absorption over a wide frequency range covering lower frequencies. A mass ratio of 6.4:1 is preferred for simulation and experimentation in this embodiment. When the mass ratio of carbonyl iron powder to polyurethane is 2.0-3.3:1, the concave structure is beneficial for generating absorption peaks at high frequencies to achieve effective absorption of high-frequency electromagnetic waves. A mass ratio of 2.6:1 is preferred for simulation and experimentation.

[0052] Thermoplastic polyurethane and solvent were stirred in a mixer. After the thermoplastic polyurethane was fully dissolved, carbonyl iron powder was added at a mass ratio of 6.4:1. The mixture was stirred until it reached a slightly viscous consistency. The mixed slurry was then coated onto a plate covered with a centrifugal membrane and dried to obtain carbonyl iron powder / thermoplastic polyurethane composite flakes.

[0053] The dried carbonyl iron powder / thermoplastic polyurethane composite sheet was placed into a mold and hot-pressed on a flat vulcanizing machine. After demolding, two types of sheets with thicknesses of 1 mm and 4 mm were obtained. The composite sheets of 4 mm and 1 mm thicknesses were molded using square dies with side lengths of a2=13.5 mm and a1=19 mm, respectively. A rectangular block with a side length of a2=13.5 mm was joined to a block with a side length of a1=19 mm to obtain a first type of block with a three-dimensional convex structure. The total height of the first type of block is h1=5 mm, the base side length is a1=19 mm, the side length of the protrusion is a2=13.5 mm, and the height of the protrusion is h2=4 mm.

[0054] Using the same preparation method, the mass ratio of carbonyl iron powder to thermoplastic polyurethane was adjusted to 2.6:1. A second type of block with a three-dimensional concave structure was prepared according to the above steps. The total height of the second type of block was h1=5 mm, the base side length was a1=19 mm, the concave side length was a2=13.5 mm, and the concave height was h2=4 mm. The concave part and the protrusion of the first type of block formed a complementary match in space.

[0055] Example 2: Framework Preparation

[0056] This embodiment provides a method for preparing a frame. Polylactic acid (PLA) is selected as the molding material for the frame. PLA is a biodegradable thermoplastic made from renewable resources such as corn starch or sugarcane. Its low melting point and glass transition temperature make it easy to 3D print and highly efficient in molding.

[0057] A 3D printer is used to print polylactic acid (PLA) material into a square hollow mesh structure, forming a frame. This frame has a periodic mesh structure with multiple arrayed and independent cavities inside. Figure 2 As shown, the side length of a single cell in the frame is p = 20 mm, the side length of a single cavity is 19 mm, the unit wall thickness is w = 0.5 mm, and the height is h = 6 mm. The frame is used to provide compressive load support, and its compressive strength, as tested by a universal testing machine, is not less than 4 MPa (see...). Figure 9 ).

[0058] Example 3: Assembly of a coded metamaterial absorber

[0059] This embodiment provides a method for assembling a coded metamaterial absorber.

[0060] The first type of block obtained in Example 1 is used as the first coding unit and named "1"; the second type of block is used as the second coding unit and named "-1"; the combination of the first type of block and the second type of block is used as the third coding unit and named "0". The first coding unit is used to achieve broadband absorption, the second coding unit is used to achieve high-frequency strong absorption, and the third coding unit is used to achieve low-frequency strong absorption.

[0061] like Figure 3 As shown, the three types of coding units are detachably filled into multiple cavities of the frame prepared in Example 2 according to a preset coding scheme. Specifically, the coding scheme can be determined according to the target absorption performance, and the coding scheme defines the arrangement of the three types of coding units in multiple cavities. By filling the cavities with the absorbing material blocks according to the determined coding scheme, a coded metamaterial absorber can be obtained. A metal backing is provided on the back of the frame and the absorbing material blocks to form a complete absorber.

[0062] Example 4: Wave absorption performance test of a single coding unit

[0063] This embodiment simulates the absorption performance of coded metamaterial absorbers filled with a single coding unit.

[0064] By filling the entire cavity with the first coding unit (convex structure block), effective absorption was achieved in the 2.3-17 GHz frequency band, with a reflection loss coefficient of less than -10 dB, exhibiting broadband absorption characteristics.

[0065] The entire cavity was filled with the second coding unit (concave structure block), which achieved strong absorption at high frequencies. The absorption peak frequency was 15.3 GHz, and the reflection loss coefficient reached below -25dB, demonstrating strong high-frequency absorption characteristics.

[0066] By filling the entire cavity with the third coding unit (a combination of convex and concave structures), strong absorption is achieved at low frequencies, with an absorption peak frequency of 2.1 GHz and a reflection loss coefficient below -20dB, demonstrating strong low-frequency absorption characteristics.

[0067] like Figure 4 As shown, the three coding units have different absorption frequency response characteristics, which provides a basis for achieving ultra-wideband absorption performance after hybrid coding.

[0068] Example 5: Wave absorption performance test of hybrid coding

[0069] This embodiment simulates the absorption performance of the coded metamaterial absorber of the hybrid-filled coded unit, taking a 2×2 coded region as an example.

[0070] The first and second coding units are mixed and filled in ratios of 1:3, 2:2, and 3:1, and the resulting performance curves are shown below. Figure 5 As shown. The performance curves obtained by mixing and filling the second and third coding units in ratios of 1:3, 2:2, and 3:1 are shown below. Figure 6 As shown. The performance curves obtained by mixing and filling the first and third coding units in ratios of 1:3, 2:2, and 3:1 are shown below. Figure 7 As shown in the figure, the results indicate that the metamaterial absorber exhibits different absorption properties under different coding schemes. It can maintain broadband absorption while showing strong absorption peaks at different frequencies, allowing for strong absorption at specific target frequencies. The performance curve changes with the proportion of elements, and generally conforms to the rule that the larger the proportion, the closer the curve is to the performance curve when all elements are of that type. This is beneficial for directional metamaterial reconstruction according to requirements.

[0071] Encoding the first, second, and third coding units using a 5:1:3 hybrid coding scheme, the resulting metamaterial absorber achieved an absorption efficiency exceeding 90% in the ultra-wideband range of 2-18 GHz, with reflection loss coefficients all less than -10 dB. Figure 8 As shown, this coded metamaterial absorber possesses excellent ultra-wideband microwave absorption performance.

[0072] Example 6: Frame compressive bearing capacity test

[0073] This embodiment tests the compressive load-bearing capacity of the frame.

[0074] The frame prepared in Example 2 was subjected to compression testing using a universal testing machine, and the results were as follows: Figure 9 The stress-strain curves are shown. Test results indicate that the frame has a maximum compressive strength of 4.1 MPa, demonstrating good compressive bearing capacity and meeting the application requirements for both structural support and electromagnetic wave absorption.

[0075] Example 7: Performance Verification of Coding Reconstruction

[0076] This embodiment experimentally verifies the performance reconstruction capability of the coded metamaterial absorber.

[0077] The prepared coded metamaterial absorber sample was placed in an arch-bridge method testing system, and reflection loss was measured using a vector network analyzer. First, the absorption performance under an initial single coding scheme (e.g., filling all first coding units) was tested to obtain the reflection loss curve. Then, following the method described in Example 5... Figure 8The simulation used the same hybrid coding scheme (i.e., the first, second, and third coding units were arranged in a 5:1:3 ratio). The absorbing material blocks were rearranged and reassembled before the absorption performance was tested. The experimental results are as follows: Figure 10 As shown, the measured reflection loss curve under this coding scheme is similar to... Figure 8 The simulation results are highly consistent, proving the feasibility of reconstructing the performance of the absorber of this invention and the correctness of the simulation results. By physically changing the arrangement of the absorber material blocks, this metamaterial absorber can exhibit absorber performance corresponding to different coding schemes, realizing flexible reconstruction of absorber performance. The entire process does not require complex control devices such as external power supplies, heaters, or piezoelectric elements.

[0078] In summary, the coded metamaterial absorber provided by this invention, possessing both compressive strength and broadband absorption, utilizes a 3D-printed frame for compressive support. Three coding units are constructed from absorber material blocks with three-dimensional convex and concave structures, each with different absorption frequency response characteristics. By selectively arranging these coding units within the frame's cavity according to a preset coding scheme, and by physically changing the arrangement of the absorber material blocks, the absorption performance can be reconstructed. This achieves an absorption efficiency exceeding 90% in the 2-18 GHz frequency band, while maintaining a frame compressive strength of at least 4 MPa. This coded metamaterial absorber combines broadband absorption, compressive strength, and reconfigurable performance, making it widely applicable in scenarios requiring both structural strength and electromagnetic protection, such as aircraft skin, ship radar shielding, and electronic equipment enclosures, demonstrating broad application prospects.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coded metamaterial microwave absorber with compressive strength and broadband absorption, characterized in that, include: A frame is integrally formed from insulating material through 3D printing. The frame has a periodic grid structure and multiple arrayed and independent cavities inside. The frame is used to provide compressive load-bearing support. Multiple microwave absorbing material blocks are detachably filled in the cavity, and the microwave absorbing material blocks are made of magnetic microwave absorbing composite material; The microwave absorbing material block includes at least the following: The first type of block has a three-dimensional convex structure; The second type of block has a three-dimensional concave structure, which is spatially complementary to the three-dimensional convex structure of the first type of block. The first type of block constitutes a first coding unit on its own, the second type of block constitutes a second coding unit on its own, and the first type of block and the second type of block are combined to form a third coding unit; The first coding unit, the second coding unit, and the third coding unit each have different absorption frequency response characteristics; wherein, the first coding unit composed of the first type of block alone is used to achieve broadband absorption, the second coding unit composed of the second type of block alone is used to achieve high-frequency strong absorption, and the third coding unit composed of the first type of block and the second type of block combined is used to achieve low-frequency strong absorption. The multiple absorbing material blocks are selectively arranged in multiple cavities of the frame according to a preset coding scheme, with the first coding unit, the second coding unit, and the third coding unit arranged in a specific order. By physically changing the arrangement of the absorbing material blocks, the absorbing performance of the metamaterial absorber can be reconstructed.

2. The coded metamaterial absorber according to claim 1, characterized in that, The frame is made of polylactic acid.

3. The coded metamaterial absorber according to claim 1, characterized in that, The magnetic microwave absorbing composite material is a carbonyl iron powder / thermoplastic polyurethane composite; the mass ratio of carbonyl iron powder to thermoplastic polyurethane in the first type of block is 6.4:1, and the mass ratio of carbonyl iron powder to thermoplastic polyurethane in the second type of block is 2.6:

1.

4. The coded metamaterial absorber according to claim 1, characterized in that, The first type of block has a three-dimensional convex structure including a base and a protrusion, and the second type of block has a three-dimensional concave structure including a base and a recess, wherein the protrusion and the recess match in shape and size.

5. The coded metamaterial absorber according to claim 4, characterized in that, The total height of the first type of block and the second type of block is 5 mm, the side length of the base is 19 mm, the side length of the protrusion and the recess is 13.5 mm, and the height of the protrusion and the recess is 4 mm.

6. The coded metamaterial absorber according to claim 1, characterized in that, The frame has a wall thickness of 0.5 mm, a height of 6 mm, a side length of 20 mm for each grid, and a side length of 19 mm for the internal cavity of the grid; the compressive strength of the frame is not less than 4 MPa.

7. The coded metamaterial absorber according to claim 1, characterized in that, It also includes a metal backing, which is disposed on the back of the frame and the microwave absorbing material block.

8. A method for reconstructing the performance of a coded metamaterial absorber, applied to the coded metamaterial absorber according to any one of claims 1 to 7, characterized in that, include: A frame is provided, which is integrally formed by 3D printing of insulating material. The frame has a periodic grid structure and multiple arrayed and independent cavities are formed inside. Provides a variety of microwave absorbing material blocks including at least a first type of block and a second type of block, wherein the first type of block has a three-dimensional convex structure, the second type of block has a three-dimensional concave structure that is complementary to the three-dimensional convex structure, the first type of block alone constitutes a first coding unit, the second type of block alone constitutes a second coding unit, and the first type of block and the second type of block combined constitute a third coding unit; Based on the target absorption performance, a coding scheme is determined, wherein the coding scheme defines the arrangement of the first coding unit, the second coding unit, and the third coding unit in the plurality of cavities; According to the coding scheme, the various absorbing material blocks are detachably filled into the cavity, and the absorbing performance of the metamaterial absorber is reconstructed by physically changing the arrangement of the absorbing material blocks.

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