Multilayer metal medium metamaterial wave absorber and 3D printing manufacturing method thereof

Abstract

The invention provides a multilayer metal medium metamaterial wave absorber and a 3D printing manufacturing method thereof.The multilayer metal medium metamaterial wave absorber comprises a plurality of structural units arranged in rows and columns, and each structural unit comprises a metal base and a plurality of hollow square ring-shaped metal-medium composite layers stacked up and down; the metal-medium composite layers are sequentially and vertically stacked on the metal base according to the side length sequence, and the sizes of the metal-medium composite layers are sequentially decreased from bottom to top. Compared with the prior art, the multi-layer metal medium metamaterial wave absorber has a high-efficiency wave absorbing effect in an ultra-wide frequency band; and the medium material and size can be flexibly selected, and the 3D printing additive manufacturing technology is utilized for manufacturing, so that the processing difficulty and the manufacturing cost are reduced.

Description

Technical Field

[0001] The present invention relates to the field of novel artificial electromagnetic materials, and in particular to a multilayer metal dielectric metamaterial absorber and a 3D printing manufacturing method thereof. Background Art

[0002] Electromagnetic wave absorption technology has been widely used in the civil and military fields. As a modern absorbing material, metamaterial absorbers have the advantages of simple structure and high absorption rate. They can flexibly control electromagnetic waves, which has led to the rapid development of related technologies in the field of electromagnetic wave absorption. The development of technology and the complexity of application scenarios have also put forward higher requirements on the performance of metamaterial absorbers in terms of working frequency, bandwidth, oblique incidence performance, etc.

[0003] In recent years, new artificial electromagnetic performance designs have emerged in the structure of metamaterial absorbers. Based on the electromagnetic properties of the material itself, multi-layer absorbers with different equivalent electromagnetic parameters designed for different working frequencies can achieve broadband absorption. With the expansion of the absorption bandwidth and the improvement of the impedance matching requirements of multi-layer complex interfaces, the complexity of metamaterial microstructures, spatial topological structures, materials, and appearances has also posed challenges to the production of metamaterial absorbers. Traditional mechanical processing and manual assembly methods have reduced the processing accuracy of absorbers to a certain extent. Complex structures are difficult to process, and the adhesives used will affect the absorbing performance of the absorber. The preparation costs of microelectronic etching and printed circuit board processes are high, making it difficult to put them into large-scale use.

[0004] Therefore, a new technical solution is needed to solve the above problems. Summary of the invention

[0005] In order to solve the problems caused by the prior art, the present invention provides a multi-layer metal dielectric metamaterial absorber, which can achieve high-efficiency wave absorption in an ultra-wide frequency band; the design and production method of the multi-layer metal dielectric metamaterial absorber can flexibly select dielectric materials and sizes to achieve absorption of electromagnetic waves of specific frequencies;

[0006] The present invention provides a 3D printing manufacturing method for the above-mentioned multi-layer metal dielectric metamaterial absorber, which uses 3D printing additive manufacturing technology to reduce processing difficulty and production cost.

[0007] In order to achieve the above-mentioned purpose, the multilayer metal dielectric metamaterial absorber proposed in the present invention can adopt the following technical solutions:

[0008] A multilayer metal dielectric metamaterial absorber, comprising a plurality of structural units arranged in rows; wherein each of the structural units comprises a metal base and a plurality of metal-dielectric composite layers in the shape of hollow square rings stacked up and down, wherein the metal-dielectric composite layers are stacked vertically on the metal base in order of side lengths, and the side length of each metal-dielectric composite layer is smaller than the metal-dielectric composite layer stacked below it; the metal bases of the structural units are arranged in a rectangular array to form the multilayer metal dielectric metamaterial absorber.

[0009] Furthermore, the metal-dielectric composite layer includes a metal layer and a dielectric layer, and the metal layer is vertically stacked on the upper surface of the dielectric layer; the cross-sectional shapes of the metal layer and the dielectric layer are both hollow square rings, the material of the metal layer is a low-conductivity metal with a conductivity of 5S / m, and the thickness of the metal layer and the thickness of the dielectric layer are both 0.6 mm;

[0010] The cross-sectional shape of the metal base is a square; the side length of the metal base is greater than any metal-dielectric composite layer; the thickness of the metal base is greater than the skin depth of the material and the material of the metal base has an electrical conductivity of 6.3×10 7 S / m metallic silver.

[0011] The 3D printing manufacturing method of the multilayer metal dielectric metamaterial absorber provided by the present invention can adopt the following technical scheme, including the following steps:

[0012] Step 1, determining the overall thickness of the multi-layer metal dielectric metamaterial absorber structure unit and the side length range of the metal-dielectric composite layer in the structure unit according to the highest operating frequency and the lowest operating frequency of the actual absorbing requirements; further determining the material, the number of layers of the metal-dielectric composite layer in the multi-layer metal dielectric metamaterial absorber structure unit and the side length of each metal-dielectric layer;

[0013] Step 2, building a model, using computer-aided modeling software to build a three-dimensional model of the multi-layer metal dielectric metamaterial absorber, using slicing software to process the model, and selecting a corresponding molding method according to the settings of the 3D printer;

[0014] Step 3, 3D printing, printing two-dimensional sheets layer by layer on the raw material according to the working path, and after printing, vertically stacking the two-dimensional sheets layer by layer to form the multi-layer metal dielectric metamaterial absorber.

[0015] Furthermore, in step 1, the overall thickness of the structural unit of the multi-layer metal dielectric metamaterial absorber is less than one tenth of the longest operating wavelength.

[0016] Furthermore, in step 1, according to formulas (1) and (2), the side length of the metal-dielectric composite layer in the structural unit of the multi-layer metal-dielectric metamaterial absorber within a given operating frequency range is calculated, and the optimization is continuously iterated according to the design results;

[0017] For a single metal-dielectric composite layer with a side length of w, the effective electromagnetic wave frequency absorbed is:

[0018]

[0019] Where c is the speed of light, ε′ r and μ′ r They represent the real part of the dielectric constant and the real part of the magnetic permeability of the medium, respectively, and w is the side length of the metal-dielectric composite layer;

[0020] For a total of N l For multiple metal-dielectric composite layers, the absorbing frequency of the i-th layer is:

[0021]

[0022] Furthermore, relative bandwidth FB is used as a quality evaluation index; the relative bandwidth is the ratio of the signal bandwidth to the center frequency, expressed as:

[0023]

[0024] In the formula, f min is the minimum frequency and f of the band with coefficients greater than 90% max is the maximum frequency of the band with coefficients greater than 90%, f c is the center frequency.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The present invention provides a multi-layer metal dielectric metamaterial absorber, which can achieve high-efficiency wave absorbing effect in an ultra-wide frequency band; the multi-layer metal dielectric metamaterial absorber can flexibly select dielectric materials and sizes to achieve absorption of electromagnetic waves of specific frequencies.

[0027] The method for manufacturing the above-mentioned multi-layer metal dielectric metamaterial absorber can be manufactured using 3D printing additive manufacturing technology, thereby reducing processing difficulty and manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A model diagram of a multi-layer metal dielectric metamaterial absorber structure unit according to an embodiment.

[0029] Figure 2 Graph showing the reflection coefficient of a multilayer metal dielectric metamaterial absorber structure unit according to an embodiment.

[0030] Figure 3 Graph showing reflection coefficients of a multilayer metal dielectric metamaterial absorber structure unit at different polarization angles of incidence.

[0031] Figure 4 Graphs showing the wave absorption rates of the multilayer metal dielectric metamaterial absorber structure unit at different incident angles of the embodiment.

[0032] Figure 5 This is a sample of a multi-layer metal dielectric metamaterial absorber made using 3D printing additive manufacturing technology. DETAILED DESCRIPTION

[0033] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0034] like Figure 1 As shown in FIG. 1 , a structural unit of the multilayer metal dielectric metamaterial absorber of the present invention, the dark part is made of metal, including the metal base and the metal layer in the metal-dielectric composite layer, and the light part is the dielectric layer in the metal-dielectric composite layer. Figure 1 The structural unit of a multi-layer metal dielectric metamaterial absorber includes N l (N l = 14) stacked metal-dielectric composite layers and a metal base; the metal-dielectric composite layer includes a dielectric layer and a metal layer, and the cross-section is a hollow square ring. All metal-dielectric composite layers are stacked on the upper surface of the metal base in the order of side length, and the metal-dielectric composite layer at the bottom has a larger side length. The thickness of the metal base is d 1mm, and the thickness of each dielectric layer is t d and the metal layer thickness t m The metal base is made of 0.6mm and has a conductivity of 6.3×10 7 The metal layer is made of low-conductivity metal with a conductivity of 5 S / M, and the dielectric layer is made of polylactic acid with a relative dielectric constant of 3 and a loss tangent of 0.025. Each multi-layer metal dielectric metamaterial absorber structure unit is made using a 3D printing process.

[0035] As an optimal implementation, the overall size of the multi-layer metal dielectric metamaterial absorber is 248 mm×248 mm, and is composed of 16×16 multi-layer metal dielectric metamaterial absorber structural units distributed in an array.

[0036] In this embodiment, it is required to design an absorbing structure that is polarization insensitive and has wide-angle incidence performance within an ultra-wide frequency band of 1.5-40 GHz, and is manufactured based on 3D printing additive manufacturing technology. The multi-layer metal dielectric metamaterial absorber structure unit includes N l (N l = 14) stacked metal-dielectric composite layers and a metal base. The design and production steps are as follows:

[0037] (1) Design a metal base. The metamaterial absorber absorbs the electromagnetic wave energy incident on its surface and converts it into heat energy through material loss. According to the absorption theory, the absorption rate A(ω) of the absorber can be expressed as:

[0038] A(ω)=1-R(ω)-T(ω)=1-|S 11 | 2 -|S 12 | 2 (1)

[0039] Where R(ω) is the reflectivity, T(ω) is the transmittance, S 11 is the incident reflection coefficient, S 12 is the transmission coefficient. To improve the wave absorption effect, the incident reflection coefficient and the transmission coefficient should be as small as possible, that is, S 11 →0,S 12 →0. For the transmission coefficient S 12 , consider using a metal base with a thickness greater than the skin depth to prevent electromagnetic waves from passing through the metamaterial absorber, making the transmission coefficient S 12 =0, ensuring the wave absorbing performance.

[0040] Specifically, in this embodiment, the metal base is made of metallic silver with an electrical conductivity of 6.3×10 7 S / m and a thickness of 1 mm.

[0041] (2) Design the metal-dielectric composite layer. Use the metal base to design the transmission coefficient S 12 While ensuring the absorbing effect of the absorber, the present invention further considers designing the incident reflection coefficient S 11 To further ensure the wave absorption effect. To ensure the smallest possible incident reflection coefficient S 11 The absorber structure needs to be able to consume as many electromagnetic waves as possible, so a stacked metal-dielectric composite layer is introduced. The metal-dielectric composite layer includes a dielectric layer and a metal layer, both of which have hollow square ring cross-sections. The metal-dielectric composite layer is placed on the upper surface of the metal base described in step 1, while satisfying the minimum S 11 With S 12 requirements to ensure the absorbing performance.

[0042] The metal-dielectric composite layer is specifically designed as follows:

[0043] Metal layers and dielectric layers with the same geometric structure and a certain thickness are stacked to achieve the effect of absorbing electromagnetic waves of a specific frequency. For a metal-dielectric composite layer with a side length of w, the effective electromagnetic wave frequency absorbed is:

[0044]

[0045] Where c is the speed of light, ε′ r and μ′ r Respectively represent the real part of the dielectric constant and the real part of the magnetic permeability of the medium, and w is the side length of the metal-dielectric composite layer. The absorption frequency is also affected by the magnetic permeability and dielectric constant of the medium, and the magnetic permeability and dielectric constant of the medium are determined by the specific material of the medium.

[0046] Specifically, in this embodiment, the thickness of each dielectric layer and metal layer is 0.6 mm, the material of the metal layer is a low conductivity metal with a conductivity of 5 S / m, and the material of the dielectric layer is polylactic acid (POLYLACTIC ACID) with a relative dielectric constant of 3 and a loss tangent of 0.025.

[0047] (3) Multiple metal-dielectric composite layers are stacked. The multi-layer metal-dielectric metamaterial absorber needs to absorb electromagnetic waves within a specific bandwidth. The traditional single-layer metal-dielectric composite layer and the metal base are not sufficient to meet the requirements. The multi-layer metal-dielectric metamaterial absorber of the present invention is stacked with metal-dielectric composite layers with different side lengths to maximize the absorber's ability to consume electromagnetic waves. Multiple metal-dielectric composite layers of different sizes and the same material are stacked up and down to form a multi-layer metal-dielectric metamaterial absorber structural unit. Each metal-dielectric composite layer absorbs electromagnetic waves of different frequencies. Designing the side lengths of different layers of metal-dielectric composite layers can achieve the absorption of broadband electromagnetic waves by the multi-layer metal-dielectric metamaterial absorber. Specifically, for a total of N l For multiple metal-dielectric composite layers, the absorbing frequency of the i-th layer is:

[0048]

[0049] The superposition of multiple metal-dielectric composite layers enables the multi-layer metal dielectric metamaterial absorber of the present invention to absorb electromagnetic waves at different frequency points, thereby generating a wider effective absorption bandwidth. The lowest frequency and the highest frequency of the effective absorption bandwidth of the multi-layer metal dielectric metamaterial absorber are defined as the working low frequency point f1 and the working high frequency point f2, respectively. According to step 1 and formula (3), the working low frequency point and the working high frequency point are respectively determined by the maximum side length w1 and the minimum side length w2 of the metal-dielectric composite layer. Specifically, f1 and Can be expressed as:

[0050]

[0051] In order to accurately evaluate the absorbing performance of broadband absorbers, relative bandwidth FB is used as a quality indicator. Specifically, relative bandwidth is the ratio of signal bandwidth to center frequency, expressed as:

[0052]

[0053] In the formula, f min and f max is the extreme frequency of the band where the absorption coefficient is greater than 90%, f c is the center frequency. So far, the modeling of the relationship between the geometric structure, physical properties and absorbing performance of the structural unit of the multi-layer metal dielectric metamaterial absorber has been completed. In actual use, the side length of the metal-dielectric composite layer and the material of the medium used are adjusted according to the actual absorbing frequency requirements to achieve the absorbing effect of the multi-layer metal dielectric metamaterial absorber for the expected absorbing frequency.

[0054] Specifically, the multi-layer metal dielectric unit structure is modeled, simulated and optimized in CST. l (N l =14) stacked metal-dielectric composite layers and a metal base; the metal-dielectric composite layer includes a dielectric layer and a metal layer, and the cross-section is a hollow square ring. All metal-dielectric composite layers are stacked on the upper surface of the metal base in the order of side length, and the metal-dielectric composite layer at the bottom has a larger side length.

[0055] Specifically, if Figure 1 As shown, in this embodiment, the metal base period p is selected to be 15.5 mm, and the side length of the metal base is the unit period length of the array structure. The side lengths of different metal-dielectric composite layers are w1, w2, w3, w4, w5, w6, w7, w8, w9, w 10 ,w 11 ,w 12 ,w 13 ,w 14 , where the side length is from w1 to w 14 The design of the structural unit of the multi-layer metal-dielectric metamaterial absorber is based on the multi-layer metal-dielectric composite layer, and its corresponding side lengths w1, w2, w3, w4, w5, w6, w7, w8, w9, w1 are calculated according to the working center frequency of a single metal-dielectric composite layer. 10 ,w 11 ,w 12 ,w 13 ,w 14The higher the frequency, the smaller the side length of the metal-dielectric composite layer, and vice versa, that is, the entire three-dimensional structure gradually becomes larger from top to bottom.

[0056] The bottom layer is defined as the first layer, and the top layer is defined as the fourteenth layer; the side lengths of each layer are optimized according to numerical software simulation: the side length of the first metal-dielectric layer is w1 = 15 mm, the side length of the second metal-dielectric layer is w2 = 12.5 mm, the side length of the third metal-dielectric layer is w3 = 10.7 mm, the side length of the fourth metal-dielectric layer is w4 = 9.375 mm, the side length of the fifth metal-dielectric layer is w5 = 8.33 mm, the side length of the sixth metal-dielectric layer is w6 = 7.5 mm, the side length of the seventh metal-dielectric layer is w7 = 6.82 mm, the side length of the eighth metal-dielectric layer is w8 = 6.25 mm, the side length of the ninth metal-dielectric layer is w9 = 5.77 mm, the side length of the tenth metal-dielectric layer is w 10 =5.36mm, the side length of the eleventh metal-dielectric layer is w 11 =5mm, the side length of the twelfth metal-dielectric layer is w 12 =4.69mm, the side length of the thirteenth metal-dielectric layer w 13 =4.41mm, the side length of the fourteenth metal-dielectric layer w 14 =4.17 mm, all of which are optimized amounts. In this embodiment, in order to further broaden the frequency band based on multiple absorption resonance peaks, a square groove with a side length k of 2 mm is added in the center of the 14 pairs of metal-dielectric layers.

[0057] (4) Modeling and simulation in CST. Calculate the corresponding metal-dielectric composite layer side length w according to different single center frequency points i (i=1,2,…,14), and add square grooves with a side length of k in each metal-dielectric layer to further achieve ultra-wideband absorption. Under the far-field condition in an infinite plane, the frequency domain solver is selected to simulate and calculate the metamaterial absorbing unit structure. Figure 3 As shown, the multi-layer metal dielectric metamaterial absorber unit structure in this embodiment can achieve more than 90% of the absorbing effect in the 1.5-40 GHz frequency band.

[0058] (5) 3D printing. Figure 5 As shown in the figure, samples were prepared by 3D printing additive manufacturing technology, and the test was completed in a microwave darkroom to observe the effect achieved by the device; under far-field conditions, the metamaterial absorbing unit structure can achieve more than 90% absorbing effect in the 1.5-40GHz frequency band, and the resonant frequency is basically the same. The experimental results are consistent with the simulation, verifying the feasibility of the structure.

[0059] The present invention provides a multi-layer metal dielectric metamaterial absorber and a design and production method thereof. The multi-layer metal dielectric metamaterial absorber can achieve a high-efficiency wave absorbing effect in an ultra-wide frequency band. The design and production method of the multi-layer metal dielectric metamaterial absorber can flexibly select dielectric materials and sizes to achieve absorption of electromagnetic waves of a specific frequency. The method uses 3D printing additive manufacturing technology for production, thereby reducing processing difficulty and production cost.

[0060] The above is only an explanation of the preferred embodiments of the present invention, which should not be construed as a limitation on the claims. Any equivalent process changes made using the present invention specification are included in the patent protection scope of the present invention.

Claims

1. A multi-layer metal dielectric metamaterial absorber, characterized in that: The multi-layer metal dielectric metamaterial absorber includes a plurality of structural units, and the plurality of structural units are arranged in rows; wherein each of the structural units includes a metal base and a plurality of metal-dielectric composite layers in the shape of hollow square rings stacked up and down, the metal-dielectric composite layers are stacked vertically on the metal base in order of side lengths, and the side length of each metal-dielectric composite layer is smaller than the metal-dielectric composite layer stacked below it; the metal bases of the structural units are arranged in a rectangular array to form the multi-layer metal dielectric metamaterial absorber.

2. The multilayer metal dielectric metamaterial absorber according to claim 1, characterized in that: The metal-dielectric composite layer includes a metal layer and a dielectric layer, and the metal layer is vertically stacked on the upper surface of the dielectric layer; the cross-sectional shapes of the metal layer and the dielectric layer are both hollow square rings, the material of the metal layer is a low-conductivity metal with a conductivity of 5S / m, and the thickness of the metal layer and the thickness of the dielectric layer are both 0.6mm; The cross-sectional shape of the metal base is a square; the side length of the metal base is greater than any metal-dielectric composite layer; the thickness of the metal base is greater than the skin depth of the material and the material of the metal base has an electrical conductivity of 6.3×10 7 S / m metallic silver.

3. A 3D printing method for manufacturing a multilayer metal dielectric metamaterial absorber according to claim 1 or 2, characterized in that: The following steps are involved: Step 1, determining the overall thickness of the multi-layer metal dielectric metamaterial absorber structure unit and the side length range of the metal-dielectric composite layer in the structure unit according to the highest operating frequency and the lowest operating frequency of the actual absorbing requirements; further determining the material, the number of layers of the metal-dielectric composite layer in the multi-layer metal dielectric metamaterial absorber structure unit and the side length of each metal-dielectric layer; Step 2, building a model, using computer-aided modeling software to build a three-dimensional model of the multi-layer metal dielectric metamaterial absorber, using slicing software to process the model, and selecting a corresponding molding method according to the settings of the 3D printer; Step 3, 3D printing, printing two-dimensional sheets layer by layer on the raw material according to the working path, and after printing, vertically stacking the two-dimensional sheets layer by layer to form the multi-layer metal dielectric metamaterial absorber.

4. The 3D printing manufacturing method according to claim 3, characterized in that: In step 1, the overall thickness of the structural unit of the multi-layer metal dielectric metamaterial absorber is less than one tenth of the longest operating wavelength.

5. The 3D printing manufacturing method according to claim 3, characterized in that: In step 1, according to formulas (1) and (2), the side length of the metal-dielectric composite layer in the structural unit of the multi-layer metal-dielectric metamaterial absorber within a given operating frequency range is calculated, and the optimization is continuously iterated according to the design results; For a single metal-dielectric composite layer with a side length of w, the effective electromagnetic wave frequency absorbed is: Where c is the speed of light, ε′ r and μ′ r They represent the real part of the dielectric constant and the real part of the magnetic permeability of the medium, respectively, and w is the side length of the metal-dielectric composite layer; For a total of N l Multiple layers of metal-dielectric composite layers are stacked, and the absorbing frequency of the i-th layer is:

6. The 3D printing manufacturing method according to claim 3, characterized in that: The relative bandwidth FB is used as the quality evaluation index; the relative bandwidth is the ratio of the signal bandwidth to the center frequency, expressed as: In the formula, f min is the minimum frequency and f of the band with coefficients greater than 90% max is the maximum frequency of the band with coefficients greater than 90%, f c is the center frequency.

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