Nonmetal three-dimensional spiral broadband wave-absorbing metamaterial as well as preparation method and application thereof

Abstract

The invention relates to the field of microwave absorbing metamaterials, in particular to a nonmetal three-dimensional spiral broadband wave-absorbing metamaterial and a preparation method and application thereof. The microwave absorption metamaterial is a rectangular array of non-metal spiral metamaterial units, each non-metal spiral metamaterial unit comprises a planar substrate and n spiral columns, n is an integer larger than or equal to 1, the n spiral columns are arranged on the surface of the planar substrate in a rectangular array mode, and n is an integer larger than or equal to 2. Or the n spiral columns are arranged in a rectangular array after rotating at the same or different angles on the surface of the planar substrate, and the tops of the spiral columns are cut into planes; the metamaterial can realize an effective wave absorbing bandwidth exceeding 32 GHz in a frequency band of 2-40 GHz. The wave-absorbing composite material constructs a three-dimensional spiral metamaterial structure and has multiple wave-absorbing mechanisms. The metamaterial can be used for designing and manufacturing high-performance stealth structures such as stealth aircrafts, missiles and radars, and has good application prospects in the fields of aerospace and land weapon equipment development.

Description

Technical Field

[0001] The present invention relates to the field of microwave-absorbing metamaterials, and particularly to a non-metallic three-dimensional spiral broadband microwave-absorbing metamaterial, a preparation method thereof, and an application thereof. Background Art

[0002] In the fields of electronic communication and radar stealth, researchers use microwave-absorbing materials to absorb electromagnetic waves, thereby reducing electromagnetic interference and the radar detectability of military equipment. Traditional microwave-absorbing coatings usually strongly rely on the quarter-wavelength interference effect to loss electromagnetic waves, so the effective absorption bandwidth (reflectivity less than -10 dB) is relatively narrow, and it is difficult to achieve broadband microwave absorption. Metamaterials are artificially designed and manufactured sub-wavelength scale lattice structures, and their electromagnetic properties can be regulated by adjusting the geometric parameters of the unit structure. As a new type of microwave-absorbing material, the microwave-absorbing structure of metamaterials has the advantages of thin thickness and wide absorption bandwidth compared with traditional microwave-absorbing coatings and sandwich structures, and has broad application prospects in the field of microwave absorption.

[0003] In various designs of microwave-absorbing metamaterials, chiral microwave-absorbing metamaterials mostly use metals to form spiral structures, which generate induced currents under the action of incident electromagnetic waves, and enhance electromagnetic absorption through ohmic loss. For example, the invention patent with the application number CN201910095823.X and the name of "A Chiral Microwave-Absorbing Metamaterial and a Preparation Method Thereof" discloses a metal spring spiral microwave-absorbing structure, in which metal springs with different outer diameters are coaxially nested perpendicular to the dielectric substrate and distributed in a two-dimensional array, achieving a microwave-absorbing bandwidth of 27.68 GHz in the frequency range of 1 - 40 GHz, but the effective bandwidth in the frequency band of 8 - 18 GHz is only about 5 GHz. The forming method is to mill the dielectric plate and manually assemble the metal springs. For another example, the application number is 202010084836.X, and the name is "A Bionic Microwave-Absorbing Metamaterial Inspired by the Spiral Structure of Beetle Carapace and Adapted to Multiple Waves and Multi-Functions", which uses a high-entropy alloy and an elastic foam matrix to prepare a spiral structure formed by twisting and stacking multiple unit layers, and enhances the microwave-absorbing performance by using the dynamic conversion from linearly polarized waves to circularly polarized waves. When the rotation angle is 15°, a microwave-absorbing bandwidth of 12.96 - 18 GHz is achieved.

[0004] Although the above-mentioned metal spiral metamaterials have certain microwave-absorbing properties, there are still some deficiencies. 1. The resistivity of metals is relatively small, and the induced current only exists on the surface of the metal, resulting in limited electromagnetic loss. 2. The microwave-absorbing mechanism is single, and only relies on the resistance loss generated by the induced current to absorb electromagnetic waves. 3. The microwave-absorbing bandwidth needs to be further broadened. 4. The structure forming method involves process flows such as machining of dielectric materials and assembly of spiral structures and dielectric materials, and the manufacturing process is relatively cumbersome, making it difficult to achieve integrated precise and rapid forming. Summary of the Invention

[0005] The present invention aims to overcome the deficiencies of the prior art and provides a non-metallic three-dimensional spiral broadband absorbing metamaterial.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows: a non-metallic three-dimensional spiral broadband absorbing metamaterial, the broadband absorbing metamaterial is a rectangular array of non-metallic spiral metamaterial units, the non-metallic spiral metamaterial unit includes a planar substrate and n spiral columns, where n is an integer greater than 1, and the n spiral columns are arranged in a rectangular array on the surface of the planar substrate, or the n spiral columns are arranged in a rectangular array on the surface of the planar substrate after rotating at the same or different angles, and the top of the spiral column is cut into a plane; the broadband absorbing metamaterial achieves an effective absorption bandwidth of more than 32 GHz in the frequency band of 2 - 40 GHz.

[0007] As a further limitation of the technical solution of the present invention, the non-metallic spiral metamaterial unit includes four spiral columns, and the four spiral columns are arranged in an array after rotating 90° in sequence on the surface of the planar substrate.

[0008] As a further limitation of the technical solution of the present invention, the diameter d of the column cross-section of the spiral column is 5 mm, the diameter D of the spiral coil is 14 mm, the pitch N of the spiral is 10 mm, the number of turns M of the spiral is 1, the thickness t of the planar substrate 1 is 0.5 mm, and the side length P of the planar substrate 1 is 40 mm.

[0009] The present invention also provides a preparation method for the above non-metallic three-dimensional spiral broadband absorbing metamaterial. The absorbing agent pellets and the low-dielectric resin pellets are extruded by a screw extruder to obtain an absorbing composite material wire, and the absorbing composite material wire is transported to a fused deposition FDM printing device. The wire is heated and extruded in the print head and then deposited on the printed planar substrate, and after cooling, a non-metallic spiral broadband absorbing metamaterial is obtained.

[0010] The present invention also provides a preparation method for the above non-metallic three-dimensional spiral broadband absorbing metamaterial. Using the absorbing agent powder and the low-dielectric resin powder as raw materials, the non-metallic spiral broadband absorbing metamaterial is manufactured by adopting the selective laser sintering SLS process.

[0011] The present invention also provides a preparation method for the above non-metallic three-dimensional spiral broadband absorbing metamaterial. Using the absorbing agent powder, the low-dielectric resin powder, and the binder as raw materials, the non-metallic spiral broadband absorbing metamaterial is manufactured by adopting the powder bonding and forming 3DP process.

[0012] The present invention adopts a 3D printing integrated forming method to manufacture the non-metallic spiral broadband absorbing metamaterial structure. The above 3D printing process does not involve the assembly of unit structures, there is no manual manufacturing participation, and the whole process is a digital and automated manufacturing process.

[0013] As a further limitation of the technical solution of the present invention, the low-dielectric resin is one of thermoplastic resins such as acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), polylactic acid (PLA), and polycarbonate (PC).

[0014] As a further limitation of the technical solution of the present invention, the wave-absorbing agent is carbon-based powder and fiber, metal powder, or ferrite powder.

[0015] As a further limitation of the technical solution of the present invention, the carbon-based powder and fiber are carbon nanotubes, graphene, carbon fiber, or carbon black; the metal powder is iron powder, cobalt powder, nickel powder, aluminum powder, or copper powder; the ferrite powder is carbonyl iron or magnetite powder.

[0016] The present invention also provides an application of the above-mentioned non-metallic three-dimensional spiral broadband wave-absorbing metamaterial in the preparation of stealth structures for stealth aircraft, missiles, or radars.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention can solve the problem of small induction current distribution area. The principle is as follows: A three-dimensional spiral metamaterial structure is constructed using a wave-absorbing composite material, and the electromagnetic parameters of the wave-absorbing composite material satisfy: the tangent of the dielectric loss angle or the tangent of the magnetic loss angle is greater than 0.2 in the frequency band of 8-18 GHz, and the resistivity is in the range of 0.1-1000 S / m. The resistivity of this type of wave-absorbing composite material is higher than that of metal, and the skin effect is extremely weak. Therefore, induction currents exist simultaneously on the surface and inside of the three-dimensional spiral metamaterial structure constructed with it, and the distribution area of the induction current becomes larger, which helps to enhance the resistive loss and improve the wave-absorbing performance.

[0018] The present invention can also solve the problem of single wave-absorbing mechanism of metal spiral metamaterials. The principle is as follows: The three-dimensional spiral metamaterial structure constructed with a wave-absorbing composite material has multiple wave-absorbing mechanisms, including resistive loss caused by induction current, local electrical resonance, local magnetic resonance, etc.

[0019] The present invention can also solve the problem of narrow wave-absorbing bandwidth. The present invention achieves an effective wave-absorbing bandwidth of more than 32 GHz in the frequency band of 2-40 GHz, and the bandwidth is greater than the effective wave-absorbing bandwidth of the reported metal spiral metamaterials.

[0020] The method of the present invention can solve the problems of cumbersome process, low precision, and low efficiency caused by step-by-step manufacturing and manual assembly in the manufacturing process of metal spiral metamaterials. The principle lies in: The present invention uses a 3D printing integrated forming method to manufacture the non-metallic spiral broadband wave-absorbing metamaterial structure. The 3D printing process does not involve the assembly of unit structures, there is no manual manufacturing participation, and the whole process is a digital and automated manufacturing process.

[0021] The present invention can be used for designing and manufacturing high-performance stealth structures such as stealth aircraft, missiles, and radars, improving the survivability and combat penetration ability of weaponry and equipment, and having good application prospects in the fields of aerospace and land weaponry and equipment research and development. At the same time, in civil fields such as information and communication technology and medical technology, this invention also has certain application potential. Description of the Drawings

[0022] Figure 1 is a perspective view of the non-metallic spiral metamaterial unit structure of the present invention.

[0023] Figure 2 is a top view of the non-metallic spiral metamaterial unit structure of the present invention.

[0024] Figure 3 is a left view of the non-metallic spiral metamaterial unit structure of the present invention.

[0025] Figure 4 is a schematic diagram of the spiral column in the non-metallic spiral metamaterial unit structure of the present invention.

[0026] Figure 5 is a simulation diagram of the surface current distribution of the non-metallic three-dimensional spiral broadband absorbing metamaterial in Example 1.

[0027] Figure 6 is a simulation diagram of the internal current distribution of the non-metallic three-dimensional spiral broadband absorbing metamaterial structure in Example 1.

[0028] Figure 7 is a simulation diagram of the electric field distribution of the non-metallic three-dimensional spiral broadband absorbing metamaterial structure in Example 1.

[0029] Figure 8 is a simulation diagram of the magnetic field distribution of the non-metallic three-dimensional spiral broadband absorbing metamaterial structure in Example 1.

[0030] Figure 9 is a physical diagram of the printed sample of the non-metallic three-dimensional spiral broadband absorbing metamaterial in Example 2.

[0031] Figure 10 is the reflectivity-frequency curve measured experimentally for the non-metallic three-dimensional spiral broadband absorbing metamaterial in Example 2.

[0032] The markings in the figures are as follows: 1 - planar substrate, 2 - spiral column. Detailed Embodiments

[0033] The present invention will be further described below in conjunction with specific embodiments. Example 1

[0034] Regarding the non-metallic three-dimensional spiral broadband absorbing metamaterial and its preparation method in the 2 - 40 GHz frequency band.

[0035] The non-metallic spiral metamaterial unit of the non-metallic three-dimensional spiral broadband absorbing metamaterial is as follows Figures 1-3 shown. Figures 1-3 They are the perspective view, top view, and left view of the metamaterial unit structure respectively.

[0036] Figure 1 As shown, the non-metallic spiral metamaterial unit structure is composed of 4 spiral columns 2 and a planar substrate 1. The 4 spiral columns 2 are sequentially rotated by 90° and arranged in an array on the upper surface of the planar substrate. The planar substrate 1 is a square thin plate with side length P and thickness t. The cross-sectional diameter d of the spiral column 2 is 5 mm, the diameter D of the spiral coil is 14 mm, the spiral pitch N is 10 mm, the number of turns M is 1, the thickness t of the square planar substrate is 0.5 mm, and the side length P of the substrate is 40 mm.

[0037] Using carbon nanotubes (CNT) and ABS resin as raw materials, a CNT / ABS composite wire with a diameter of 1.7 - 1.8 mm is prepared by a screw extrusion process. The loss tangent value of this composite material in the 8 - 18 GHz frequency band is 0.8 - 1.2, and the conductivity is 0.31 S / m. Then, a non-metallic three-dimensional spiral broadband absorbing metamaterial structure is manufactured by 3D printing in an integrated forming manner.

[0038] In the CST Microwave studio simulation software, the surface current distribution, internal current distribution, electric field distribution, and magnetic field distribution of the non-metallic three-dimensional spiral broadband absorbing metamaterial are simulated. The simulation results are respectively as Figure 5 , 6 , 7, and 8 shown. As Figure 5 shown, there is an induced current on the surface of the structure; Figure 6 shown, there is an induced current inside the structure, which indicates that compared with the metal spiral metamaterial, the distribution range of the induced current of the present invention is wider. Figure 7 shown, there is a local electric field resonance enhancement region on the surface of the structure; as Figure 8 shown, there is a local magnetic field resonance enhancement region on the surface of the structure, indicating that compared with the metal spiral metamaterial, the types of wave absorption mechanisms of the present invention increase. Example 2

[0039] A non-metallic three-dimensional spiral broadband absorbing metamaterial array structure containing 4.5×4.5 unit structures (the unit structure is the same as the non-metallic spiral metamaterial unit structure in Example 1) is manufactured by the FDM printing process. ABS material is used to print the support columns. The physical diagram of the sample is as Figure 9 shown. The bow method is used to measure the reflectivity of the above sample in the 2 - 40 GHz frequency band. The test results are as Figure 10 shown, and the effective absorption bandwidth is 33.7 GHz (3.5 - 5.1 GHz, 7.9 - 40 GHz).

Claims

1. A non-metallic three-dimensional spiral broadband absorbing metamaterial, characterized in that, The broadband absorbing metamaterial is a rectangular array of non-metallic spiral metamaterial units. The non-metallic spiral metamaterial unit includes a planar substrate (1) and n spiral columns (2), where n is an integer greater than 1. The n spiral columns (2) are arranged in a rectangular array on the surface of the planar substrate (1), or the n spiral columns (2) are arranged in a rectangular array after being rotated at the same or different angles on the surface of the planar substrate (1). The top of the spiral column (2) is cut into a plane. The broadband absorbing metamaterial achieves an effective absorption bandwidth of more than 32 GHz in the frequency band of 2 - 40 GHz.

2. The non-metallic three-dimensional spiral broadband absorbing metamaterial according to claim 1, wherein The non-metallic spiral metamaterial unit includes four spiral columns (2), and the four spiral columns (2) are arranged in an array after being rotated by 90° in sequence on the surface of the planar substrate (1).

3. The non-metallic three-dimensional spiral microwave absorption metamaterial according to claim 2, characterized in that, The diameter d of the column cross-section of the spiral column (2) is 5 mm, the diameter D of the spiral coil is 14 mm, the pitch N of the spiral is 10 mm, the number of turns M of the spiral is 1, the thickness t of the planar substrate (1) is 0.5 mm, and the side length P of the planar substrate (1) is 40 mm.

4. The preparation method of a non-metallic three-dimensional spiral broadband absorbing metamaterial according to claim 1, characterized in that, The absorbing agent pellets and low-dielectric resin pellets are extruded into an absorbing composite material wire through a screw extruder. The absorbing composite material wire is transported to a fused deposition FDM printing device. The wire is heated and extruded in the print head and then deposited on the planar substrate. After cooling, a non-metallic spiral broadband absorbing metamaterial is obtained.

5. The preparation method of a non-metallic three-dimensional spiral broadband absorbing metamaterial according to claim 1, characterized in that, Using absorbing agent powder and low-dielectric resin powder as raw materials, a non-metallic spiral broadband absorbing metamaterial is manufactured by selective laser sintering SLS process.

6. The preparation method of a non-metallic three-dimensional spiral broadband absorbing metamaterial according to claim 1, wherein, Using absorbing agent powder, low-dielectric resin powder, and binder as raw materials, a non-metallic spiral broadband absorbing metamaterial is manufactured by powder bonding and forming 3DP process.

7. A method for preparing a non-metallic three-dimensional spiral broadband absorbing metamaterial according to any one of claims 4-6, characterized in that, The low-dielectric resin is one of acrylonitrile-butadiene-styrene copolymer, polyamide, polylactic acid, polycarbonate, and thermoplastic resin.

8. A method for preparing a non-metallic three-dimensional spiral broadband absorbing metamaterial according to any one of claims 4-6, characterized in that, The absorbing agent is carbon-based powder and fiber, metal powder, or ferrite powder.

9. The preparation method of a non-metallic three-dimensional spiral broadband absorbing metamaterial according to claim 8, characterized in that, The carbon-based powder and fiber are carbon nanotubes, graphene, carbon fiber, or carbon black; the metal powder is iron powder, cobalt powder, nickel powder, aluminum powder, or copper powder; the ferrite powder is carbonyl iron or iron oxide powder.

10. An application of a non-metallic three-dimensional spiral broadband absorbing metamaterial as described in any one of claims 1 - 3 in the preparation of stealth structures for stealth aircraft, missiles, or radars.

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