A Design Method for Temperature-Insensitive Metamaterials

Abstract

The present invention relates to the technical field of electromagnetic functional materials, and particularly relates to a design method for a temperature-insensitive metamaterial. The present invention adopts a design method of dielectric compensation, analyzes the influence of the dielectric properties of the substrate and the electrical properties of the electromagnetic regulation layer on the wave absorption performance of the metamaterial wave absorption structure respectively, extracts the quantitative relationship and proposes a compensation formula, that is, the change of the electrical properties of the electromagnetic regulation layer material compensates for the change of the dielectric properties of the substrate material, so as to realize the stability of the position of the absorption peak of the metamaterial with temperature change. The present invention does not need to regulate the dielectric properties of the substrate through complex processes such as doping, and can endow the wave absorption performance of the metamaterial with temperature-insensitive characteristics without damaging the substrate material, providing a new design idea for the metamaterial wave absorption structure; moreover, the present invention has a wide environmental adaptability, great practical application feasibility, and a more flexible implementation method, and has wide applications in fields such as microwave high-temperature resistant stealth skins and high-temperature resistant wave absorption devices.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic functional materials, and particularly relates to a design method for a temperature-insensitive metamaterial. Background Art

[0002] As a composite functional structural material, the metamaterial absorbing structure can effectively reduce the transmission, reflection or scattering of electromagnetic waves, and has gradually become an important technical way to improve the radar stealth performance of contemporary weaponry. With the increase in the flight speed of aircraft, the heat resistance and temperature stability of the metamaterial should also be improved. However, the electromagnetic parameters of high-temperature absorbents are greatly affected by temperature, increasing the instability of the absorbing performance in high-temperature environments. For example, although the SiC absorbent can withstand temperatures exceeding 800 °C, its dielectric constant will increase with the increase in temperature, resulting in impedance mismatch and poor absorbing performance.

[0003] Regarding the change of electromagnetic parameters with temperature, it is often compensated by doping materials. For example, a negative temperature coefficient material is doped into a positive temperature coefficient material. This method has limited compensation for electromagnetic parameters and requires starting from the preparation of materials, increasing the preparation process of the metamaterial. After doping other impurities, the original mechanical properties of the material will also be affected.

[0004] The metamaterial technology is a new technology that is expected to break through this bottleneck. On the one hand, the metamaterial realizes the regulation of electromagnetic waves through the design of structural units. On the other hand, the metamaterial can realize the equivalence of electromagnetic parameters through the design of structural units. However, the current ideal design ideas have all encountered technical bottlenecks. Summary of the Invention

[0005] In view of the above existing problems or deficiencies, in order to solve the technical problems that the absorbing performance of current high-temperature absorbing metamaterials is sensitive to temperature and the design flexibility is insufficient, the present invention provides a design method for a temperature-insensitive metamaterial.

[0006] A design method for a temperature-insensitive absorbing metamaterial is as follows:

[0007] S1. For a metamaterial absorbing structure composed of a metal total reflection layer, a base layer, and an electromagnetic regulation layer in sequence:

[0008] Determine the pattern parameters of the electromagnetic regulation layer that can meet the index requirements at room temperature according to actual needs;

[0009] The material of the metal total reflection layer is a metal that totally reflects electromagnetic waves (such as copper, aluminum) to prevent electromagnetic waves from passing through.

[0010] The material of the base layer is a dielectric material, such as SiC, SiC composite material, magnetic material or semiconductor material, which provides support for the surface electromagnetic regulation layer and forms a space for electromagnetic wave loss between the electromagnetic regulation layer and the metal total reflection layer.

[0011] The material of the electromagnetic regulation layer is a resistive film material, such as a metal resistive film, a carbon-based resistive film or an indium tin oxide film, which adjusts the wave absorption performance of the metamaterial (such as the strength and position of the absorption peak); and compensates for the influence of the change of the substrate dielectric with temperature on the wave absorption performance.

[0012] S2. Analyze the influence of the electromagnetic parameters of the base layer material on the wave absorption performance of the formed metamaterial structure according to the known variation range of the electromagnetic parameters of the base layer material with temperature and the Debye equation. According to the Debye equations (1), (2) and (3), the dielectric of the dielectric material increases with the increase of temperature.

[0013]

[0014]

[0015]

[0016] Among them, ε′, ε", ω, ε ,

[0014] ,

[0019] , , s ,

[0018] ,

[0017] ,

[0016] ,

[0020] , , ,

[0015] , a , , , ∞ , , , ,

[0013] , 、ε s 、ε0、σ(T)、E a 、τ0、τ(T) respectively represent the real part of the dielectric constant, the imaginary part of the dielectric constant, the angular frequency, the optical frequency dielectric constant, the static dielectric constant, the vacuum dielectric constant, the material conductivity, the activation energy, the diffusion factor and the relaxation time, and k is a constant.

[0017] S3. Analyze the influence of the electrical properties of the electromagnetic regulation layer material on the wave absorption performance of the formed metamaterial wave absorption structure according to the known variation range and variation law of the electrical properties of the electromagnetic regulation layer material with temperature;

[0018] S4. Fix the absorption peak position of the metamaterial wave absorption structure composed of the base material and the electromagnetic regulation layer material, change the electromagnetic parameters of the base material, calculate the electrical property parameters of the electromagnetic regulation layer required to keep the absorption peak position unchanged, and summarize the relationship equation between the electromagnetic parameters of the base material and the electrical properties of the electromagnetic regulation layer when the absorption peak position remains unchanged;

[0019] S5. Select the electromagnetic regulation layer material and the required range of electrical properties of the electromagnetic regulation layer material that have a complementary effect on the influence of the base material on the absorption peak of the metamaterial wave absorption structure according to the calculation results of S2, S3 and S4;

[0020] S6. The electromagnetic regulation layer material and the substrate material screened according to S5 form a metamaterial absorbing structure, and calculate the variation relationship of the absorbing performance of the formed metamaterial absorbing structure with temperature to determine whether the absorbing performance is temperature-insensitive. If it is satisfied, the design is completed.

[0021] S7. If the absorbing performance of the newly formed metamaterial absorbing structure in S6 is not temperature-insensitive, re-adjust the pattern parameters (unit pattern and period size) of the electromagnetic regulation layer, and repeatedly execute S1 - S6 until the absorption peak of the metamaterial absorbing structure reaches the index of temperature-insensitivity.

[0022] Furthermore, for the complementary substrate material and electromagnetic regulation layer material selected in S5, when the temperature rises, the dielectric change of the substrate material causes the absorption peak of the metamaterial to shift to the low frequency, and the change in the electrical properties of the resistive film causes the absorption peak to shift to the high frequency.

[0023] Furthermore, the shape of the unit pattern of the electromagnetic regulation layer is cross-shaped, square, circular or Jerusalem-shaped.

[0024] Furthermore, the index of temperature-insensitivity of the absorption peak of the metamaterial absorbing structure in steps S6 and S7 is that the left and right offset changes of the absorption peak at different temperatures do not exceed 1%.

[0025] Furthermore, the index of temperature-insensitivity of the absorption peak of the metamaterial absorbing structure in steps S6 and S7 is that the peak values of the absorption peak at different temperatures are all less than -10 dB.

[0026] The present invention studies and utilizes a simple metamaterial structure to compensate for the influence of the electromagnetic parameters of the substrate material or absorber at high temperature on the absorbing performance, and realizes the regulation of the overall equivalent electromagnetic parameters and the design of temperature-insensitive absorbing performance without changing the original material components.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] (1) The present invention does not adopt the method of using traditional high-temperature resistant materials to dope and maintain the stability of dielectric properties, does not damage the components and structure of the original materials, and can maintain the original mechanical properties of the substrate material.

[0029] (2) The design steps of the high-temperature resistant metamaterial are optimized. There is no need to start from the preparation of materials. Only need to extract the temperature-dielectric relationship of the existing known materials, bring it into the design steps of the present invention, and find the electromagnetic regulation layer material matching the substrate material, then the design of the temperature-insensitive metamaterial absorbing structure can be completed, and the design is more flexible and efficient.

[0030] (3) Compared with the existing high-temperature resistant metamaterials whose microwave absorption performance is greatly affected by temperature, the metamaterials designed in the present invention can take into account both high-temperature resistance and stable high-temperature microwave absorption performance, and can significantly broaden the application scenarios of microwave absorption materials.

[0031] (4) The design method proposed in the present invention is not limited by the unit shape and size. The key parameter is the directional matching selection of the dielectric properties of the substrate and the electrical properties of the electromagnetic regulation layer. Therefore, it is also applicable to metamaterial microwave absorption structures in the terahertz and even higher frequency ranges, as well as flexible and non-flexible material systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the flow chart of the design method of the present invention;

[0033] Figure 2 is the metamaterial microwave absorption structure diagram with a cross-shaped periodic pattern on the top layer of the embodiment;

[0034] Figure 3 is the influence diagram of the dielectric properties of the substrate on the microwave absorption performance of the metamaterial in the embodiment;

[0035] Figure 4 is the variation diagram of the electrical properties of the metal (conductive silver paste) resistance film with temperature;

[0036] Figure 5 is the variation diagram of the electrical properties of the carbon-based (graphene conductive paste) resistance film with temperature;

[0037] Figure 6 is the influence diagram of the electrical properties of the resistance film on the microwave absorption performance of the metamaterial;

[0038] Figure 7 is the relationship diagram of the dielectric of the substrate and the sheet resistance of the resistance film when the absorption peak position is stable in the embodiment;

[0039] Figure 8 is the schematic diagram of compensating the S parameters of the microwave absorption structure through the sheet resistance of the resistance film when the dielectric changes in the embodiment; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The present invention aims to provide a design method for temperature-insensitive metamaterials, and designs the substrate dielectric and surface electromagnetic regulation layer of the metamaterials based on the dielectric compensation principle to achieve stable microwave absorption performance of the metamaterials within a large temperature change range, so as to provide design guidance for high-temperature resistant and temperature-stable microwave absorption metamaterials.

[0041] To better understand the present invention, the present invention will be described in detail below with reference to the drawings and embodiments.

[0042] This embodiment takes a common cross-shaped periodic structure with one absorption peak as an example for temperature-insensitive design. Refer toFigure 1 Design process and Figure 2 Periodic structure model. The thickness of the bottom copper plate is 0.025 mm. The intermediate dielectric layer uses SiC composite material. The electromagnetic parameters of the SiC composite material vary greatly with temperature. The range of electromagnetic parameters intercepted in this embodiment is 3.5 - 5. The top layer is a metal resistive film material. According to the design steps of the present invention:

[0043] S1, determine the electromagnetic regulation layer pattern that can meet the index requirements at room temperature according to actual needs as a cross-shaped structure, such as Figure 2 ;

[0044] S2, according to the variation range of electromagnetic parameters of common SiC dielectric materials with temperature and the Debye equation, the dielectric constant increases with the increase of temperature. Therefore, take the variation range of the dielectric constant with temperature as 3.5 - 5, analyze the influence of the substrate electromagnetic parameters on the metamaterial absorption performance, and the calculation results are as Figure 3 , the absorption peak of the metamaterial absorption structure moves to the low frequency with the increase of the dielectric. Therefore, in order to make the absorption performance of the metamaterial absorption structure insensitive to temperature changes, the absorption peak of the metamaterial absorption structure should move to the high frequency with the increase of the sheet resistance of the electromagnetic regulation layer;

[0045] S3, according to the variation law of the electrical properties of common electromagnetic regulation layer materials with temperature, such as Figure 4 the sheet resistance of the conductive silver paste increases with the increase of temperature, Figure 5 the sheet resistance of the conductive graphene paste decreases with the increase of temperature, analyze the influence of the electrical properties of the electromagnetic regulation layer on the metamaterial absorption performance, such as Figure 6 , the absorption peak of the absorption structure moves to the high frequency with the increase of the sheet resistance of the electromagnetic regulation layer; Therefore, in the temperature-insensitive design of this structure, it is more appropriate to select a metal conductive paste to prepare the electromagnetic regulation layer. It should be noted that the resistance value of the metal electromagnetic regulation layer can be adjusted by adjusting the addition amount of the metal conductive agent;

[0046] S4, fix the absorption peak position of the metamaterial absorption structure composed of the substrate material and the electromagnetic regulation layer material, change the electromagnetic parameters of the substrate material, calculate the electrical property parameters of the electromagnetic regulation layer required to keep the absorption peak position unchanged, and summarize the relationship equation between the electromagnetic parameters of the substrate material and the electrical property parameters of the electromagnetic regulation layer that keep the absorption peak position unchanged, such as Figure 7 , according to the relationship equation, the relationship between the electromagnetic parameters of the substrate material and the electrical property parameters of the electromagnetic regulation layer that keep the absorption peak position unchanged at any temperature can be calculated;

[0047] R □ (ε′) = -30.357ε′ 2 +256.68ε′ - 506.18 (4)

[0048] S5. Based on the calculation results of S2, S3, and S4, it is more appropriate to select a metal conductive paste to prepare the electromagnetic regulation layer;

[0049] S6. The electromagnetic regulation layer material selected according to S5 and the substrate material form a metamaterial absorbing structure, and calculate the variation relationship of the absorbing performance of the newly formed metamaterial absorbing structure with temperature. The calculation results are as Figure 8 , from Figure 8 (a), it can be seen that the dielectric constant increases from 3.5 to 3.7, and the left and right offset of the absorption peak is 2.2%. Adjust the resistance value of the electromagnetic regulation layer from 20 Ω / □ to 28 Ω / □ to compensate for the left and right offset of the absorption peak. After compensation, the left and right offset of the absorption peak is 0. From Figure 8 (b), it can be seen that the dielectric constant increases from 3.5 to 4, and the left and right offset of the absorption peak is 4.8%. Adjust the resistance value of the electromagnetic regulation layer from 20 Ω / □ to 35 Ω / □ to compensate for the left and right offset of the absorption peak. After compensation, the left and right offset of the absorption peak is 0, which means that the left and right offset of the absorption peak after compensation is insensitive to temperature changes, achieving the expected design goal, and the temperature-insensitive design of the metamaterial is completed.

[0050] As can be seen from the above embodiments, the present invention adopts a dielectric compensation design method, analyzes the influence of the dielectric properties of the substrate and the electrical properties of the periodic structure layer on the absorbing performance of the metamaterial absorbing structure respectively, extracts the quantitative relationship and proposes a compensation formula, that is, compensates for the change of the dielectric properties of the substrate material through the change of the electrical properties of the electromagnetic regulation layer material, so as to realize the stability of the position of the absorption peak of the metamaterial with temperature change. The present invention does not need to regulate the dielectric properties of the substrate through complex processes such as doping, and can endow the absorbing performance of the metamaterial with temperature-insensitive characteristics without damaging the substrate material. It has a wide environmental adaptability and great practical application feasibility. The implementation method is more flexible and has wide applications in the fields of microwave high-temperature resistant stealth skins, high-temperature resistant absorbing devices, etc.

Claims

1. A design method for a temperature-insensitive wave-absorbing metamaterial, characterized in that, The specific steps are as follows: S1. For a metamaterial absorbing structure composed of a metal total reflection layer, a base layer, and an electromagnetic modulation layer in sequence: Determine the pattern parameters of the electromagnetic modulation layer that can meet the index requirements at room temperature according to actual needs; The material of the metal total reflection layer is a metal that totally reflects electromagnetic waves; The material of the base layer is a dielectric material, which provides support for the surface electromagnetic modulation layer and forms a space for electromagnetic wave loss between the electromagnetic modulation layer and the metal total reflection layer; The material of the electromagnetic modulation layer is a resistive film material, which adjusts the absorbing performance of the metamaterial absorbing structure and compensates for the influence of the change of the substrate dielectric with temperature on the absorbing performance; S2. Analyze the influence of the substrate electromagnetic parameters on the absorbing performance of the composed metamaterial structure according to the known temperature change range of the electromagnetic parameters of the base layer material and the Debye equation; according to the Debye equations (1), (2), and (3), the dielectric of the dielectric material increases with the increase of temperature; Among them, ε′, ε", ω, ε ∞ , ε s , ε0, σ(T), E a , τ0, τ(T) respectively represent the real part of the dielectric constant, the imaginary part of the dielectric constant, the angular frequency, the optical frequency dielectric constant, the static dielectric constant, the vacuum dielectric constant, the material conductivity, the activation energy, the diffusion factor and the relaxation time, and k is a constant; S3. Analyze the influence of the electrical performance of the electromagnetic modulation layer on the absorbing performance of the composed metamaterial absorbing structure according to the known temperature change range and change law of the electrical performance of the electromagnetic modulation layer material; S4. Fix the position of the absorption peak of the metamaterial absorbing structure composed of the substrate material and the electromagnetic modulation layer material, change the electromagnetic parameters of the substrate material, calculate the electrical performance parameters of the electromagnetic modulation layer required to keep the absorption peak position unchanged, and summarize the relationship equation between the electromagnetic parameters of the substrate material and the electrical performance of the electromagnetic modulation layer that keeps the absorption peak position unchanged; S5. According to the calculation results of S2, S3, and S4, select the electromagnetic modulation layer material and the required electrical performance range of the electromagnetic modulation layer material that have a complementary effect on the influence of the substrate material on the absorption peak of the metamaterial absorbing structure; S6. Compose a metamaterial absorbing structure with the electromagnetic modulation layer material and the substrate material selected in S5, and calculate the change relationship of the absorbing performance of the composed metamaterial absorbing structure with temperature, and judge whether the absorbing performance is temperature-insensitive. If it is satisfied, the design is completed; the index of the absorption peak of the metamaterial absorbing structure being temperature-insensitive is that the left and right offset changes of the absorption peak at different temperatures do not exceed 1%; S7. If the absorbing performance of the newly composed metamaterial absorbing structure in S6 is not temperature-insensitive, readjust the pattern parameters of the electromagnetic modulation layer, and repeatedly execute S1 - S6 until the absorption peak of the metamaterial absorbing structure reaches the temperature-insensitive index.

2. The design method of the temperature-insensitive microwave absorbing metamaterial according to claim 1, characterized in that: For the complementary substrate material and electromagnetic modulation layer material selected in S5, when the temperature rises, the dielectric change of the substrate material makes the absorption peak of the metamaterial shift to the low frequency, and the change of the electrical performance of the resistive film makes the absorption peak shift to the high frequency.

3. The design method of the temperature-insensitive microwave absorbing metamaterial according to claim 1, wherein: The unit graphic shape of the pattern parameters of the electromagnetic modulation layer is cross-shaped, square, circular, or Jerusalem-shaped.

4. The design method of the temperature-insensitive absorbing metamaterial according to claim 1, characterized in that: The index of the absorption peak of the metamaterial absorbing structure in steps S6 and S7 being temperature-insensitive is that the peak value of the absorption peak at different temperatures is less than -10 dB.

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