Carbon fiber felt-based light-weight frequency selective metamaterial with integrated absorption and permeability and its simplified preparation process

Abstract

The application relates to the technical field of functional composite materials, in particular to a carbon fiber felt-based light-weight frequency-selective metamaterial with electromagnetic wave absorption / transmission and a simplified preparation process thereof, which comprises a symmetric structure with at least one unit structure arranged periodically; the unit structure comprises, from bottom to top, a frequency-selective superstructure, a dielectric layer and a lossy frequency-selective superstructure which are sequentially stacked; the unit structure of the frequency-selective superstructure is a mouth-shaped structure; the unit structure of the dielectric layer is a square structure; and the unit structure of the lossy frequency-selective superstructure is a cross-shaped structure. The carbon fiber felt-based frequency-selective metamaterial replaces the currently widely used metal pattern superstructure through the coupling of a multilayer periodic unit array, so that the electromagnetic wave absorption / transmission metamaterial with the advantages of low cost, easy manufacturing, easy frequency band adjustment and light weight is obtained.

Description

Technical Field

[0001] This invention relates to the field of functional composite materials technology, and in particular to a lightweight frequency-selective metamaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission, and its simplified preparation process. Background Technology

[0002] The pervasive electromagnetic radiation (EMW) in the environment not only interferes with the normal operation of sensitive equipment such as civilian aircraft radios, radars, and aerospace data transceivers, but also raises public concern about its potential harm to human health. With the advent of the era of artificial intelligence and 5G communication, these issues are bound to worsen. Therefore, in product design and manufacturing, materials that convert most EMW into heat energy to dissipate EMW that intrudes into the medium, while minimizing secondary pollution, are currently a hot research topic both domestically and internationally.

[0003] Metamaterials, as artificial electromagnetic periodic structures, can be endowed with extraordinary physical properties and unique physical effects through the design of unit patterns, thereby achieving impedance adjustment and precise control of electromagnetic fields at the structural level. This excellent designability provides strong support for customized electromagnetic responses. As one of the application branches of metamaterials, metamaterial absorbers are materials that can absorb, scatter, or change the propagation direction of electromagnetic waves, and can be used to reduce electromagnetic interference, enhance stealth performance, and improve the efficiency of solar cells. The research on metamaterial absorbers involves multiple disciplines such as physics, materials science, and electronic engineering, and is a challenging research field with broad application prospects. To achieve precise structural design, it is necessary to select materials with good and stable conductivity as the basis of metamaterials. Metallic materials not only meet the requirements for conductivity but also have excellent processability, and are widely used in the design and fabrication of traditional metamaterials. However, due to the inherent problems of metals as the core materials that directly determine performance, such as easy rusting, heavy weight, and poor interfacial properties, the performance of these metamaterials in practical applications is far below expectations.

[0004] In recent years, the rapid development of carbon fiber materials has made it possible to overcome the limitations of traditional metal-based metamaterials. Compared with metallic materials, carbon fiber has many unique advantages, including excellent corrosion resistance, lightweight, and superior interfacial properties. These characteristics can effectively address the shortcomings of traditional metal-based metamaterials in practical applications. While carbon fiber has lower electrical conductivity than metals, this very property gives it a natural resistance. Therefore, compared to traditional metal-based metamaterials, novel carbon fiber-based metamaterials add a tunable material dimension, providing greater flexibility in performance control and structural design.

[0005] As a new type of electromagnetic wave absorbing material, frequency selective surface falls into the category of metamaterials. It is a type of periodic unit structure composed of patches or apertures. Through structural regulation of patches and apertures, the frequency selective electromagnetic protective surface can achieve transparent transmission or strong reflection in the target frequency band. The frequency selective absorbing surface derived on this basis can absorb electromagnetic waves in non-passband frequency bands. Traditional metallic frequency selective surfaces cannot meet the requirement of lightweight and have a narrow absorbing bandwidth. The new frequency selective surface made of carbon-based conductive composite materials has the advantages of light weight, corrosion resistance and high temperature resistance. In particular, its absorbing bandwidth can be effectively expanded, so it has become a current research hotspot. Summary of the Invention

[0006] To solve the problems of large specific weight and complex manufacturing process of existing metamaterial absorbers, the present invention provides a lightweight integrated absorbing / transmitting frequency selective metamaterial based on carbon fiber felt and a simplified preparation process thereof.

[0007] The present invention is implemented through the following technical solutions: a lightweight integrated absorbing / transmitting electromagnetic wave frequency selective metamaterial based on carbon fiber felt, comprising a symmetric structure of n×n unit structures arranged periodically; wherein n is a positive integer; The unit structure comprises a frequency selection superstructure, a dielectric layer and a lossy frequency selection superstructure which are sequentially stacked from bottom to top; The unit structure of said frequency selection superstructure is a square-frame shape, with a unit size a1=15.23 - 23.71 mm, an inner side length a2=9.10-14.33 mm, and a2 < a1; it is formed by laminating and pressing carbon fiber felt with a sheet resistance of 3-5 Ω / sq and an areal density of 40-80 g / m 2 and quartz fiber cloth / epoxy composite material; a square-frame-shaped groove with the carbon fiber felt removed is provided in the middle of the unit structure of the frequency selection superstructure, said square-frame-shaped groove exposes the inner quartz fiber cloth / epoxy composite material, forming a unit structure with carbon fiber felt at the peripheral edges; The unit structure of said dielectric layer is square, with a unit size a1 and a thickness h=3.20-9.16 mm; when h varies within the range of 3.20-9.16 mm, the positions of the absorbing band and the transmitting band of the carbon fiber felt-based lightweight integrated absorbing / transmitting electromagnetic wave frequency selective metamaterial are always respectively near the series resonance point of said lossy frequency selection superstructure and the parallel resonance point of said frequency selection superstructure; said dielectric layer is made of polystyrene foam board; The lossy frequency-selective superstructure has a cross-shaped unit structure with unit size a1, arm length b1 = 15.00 - 20.75 mm, arm width b2 = 1.51 - 3.25 mm, and b2 < b1 < a1; with a sheet resistance of 4-25 Ω / sq and an areal density of 5-50 g / m³. 2 It is made of carbon fiber felt and quartz fiber cloth / epoxy composite material laminated together; the unit structure of the lossy frequency selective superstructure has a cross-shaped protrusion with the carbon fiber felt removed from the periphery, and the quartz fiber cloth / epoxy composite material is exposed on the periphery of the cross-shaped protrusion, forming a unit structure with carbon fiber felt in the cross-shaped protrusion.

[0008] As a further improvement to the technical solution of the present invention, the thicknesses of the carbon fiber felt and the quartz fiber cloth / epoxy composite material of the unit structure of the frequency selective superstructure are 0.05-1 mm and 0.5-5 mm, respectively.

[0009] As a further improvement to the technical solution of the present invention, the thicknesses of the carbon fiber felt and the quartz fiber cloth / epoxy composite material of the unit structure of the lossy frequency selective superstructure are 0.05-1 mm and 0.5-5 mm, respectively.

[0010] As a further improvement to the technical solution of the present invention, the unit structures of the frequency selective superstructure, the dielectric layer and the lossy frequency selective superstructure correspond one-to-one from bottom to top.

[0011] As a further improvement to the technical solution of the present invention, the frequency-selective superstructure has a reflection effect similar to that of an ideal conductor in the absorbing band, and generates a wave-transmitting effect through LC parallel resonance in the wave-transmitting band.

[0012] As a further improvement to the technical solution of the present invention, the lossy frequency selective superstructure achieves impedance matching conditions through LC series resonance in the absorbing band and generates a wave transmission effect through LC parallel resonance in the transparent band.

[0013] As a further improvement to the technical solution of the present invention, the lossy frequency-selective superstructure as the top structure and the frequency-selective superstructure as the bottom structure achieve effective transmission of electromagnetic waves by jointly resonating in the wave-transmitting band.

[0014] This invention further provides a method for preparing a lightweight frequency-selective metamaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission, comprising the following steps: (1) Cut square carbon fiber felt and quartz fiber cloth according to the side length n×a1. A total of 2-10 layers of quartz fiber cloth are required. Prepare epoxy resin solution, lay a layer of quartz fiber cloth, brush the resin solution once and make the resin solution penetrate the quartz fiber cloth. After laying, compact it. Impregnate the carbon fiber felt with epoxy resin solution and place it on the surface of the laid and compacted quartz fiber cloth to obtain the frequency-selective superstructure and the lossy frequency-selective superstructure carbon fiber felt-quartz fiber cloth / epoxy resin prepreg respectively. (2) After uniformly applying the release agent to the mold surface, place the carbon fiber felt-quartz fiber cloth / epoxy resin prepreg of frequency selective superstructure and lossy frequency selective superstructure into the mold, close the mold and cure at 120 ℃ and 15 MPa. After curing, naturally cool to room temperature and demold to obtain carbon fiber felt-quartz fiber cloth / epoxy resin composite board of frequency selective superstructure and lossy frequency selective superstructure respectively. (3) Place the carbon fiber felt-quartz fiber cloth / epoxy resin composite board of the frequency selective superstructure and the lossy frequency selective superstructure on the table of the engraving machine and fix them. Use a milling cutter to remove the carbon fiber felt of a part of the carbon fiber felt-quartz fiber cloth / epoxy resin composite board of the frequency selective superstructure to form n×n square grooves, exposing the quartz fiber cloth / epoxy composite material on the inside, forming a unit structure of the frequency selective superstructure with periodic distribution, and obtain the frequency selective superstructure; use a milling cutter to remove the carbon fiber felt of a part of the carbon fiber felt-quartz fiber cloth / epoxy resin composite board of the lossy frequency selective superstructure to form n×n cross-shaped protrusions, exposing the quartz fiber cloth / epoxy composite material on the inside around the cross-shaped protrusions, forming a unit structure of the lossy frequency selective superstructure with periodic distribution, and obtain the lossy frequency selective superstructure. (4) The frequency-selective superstructure and the lossy frequency-selective superstructure are glued to the two surfaces of the polystyrene foam board through the quartz fiber cloth / epoxy composite material side, and after compaction, the lightweight frequency-selective supermaterial based on carbon fiber felt that absorbs / transmits electromagnetic waves is obtained.

[0015] Compared with the prior art, the present invention has the following advantages: 1) By coupling and coordinating a multi-layer periodic unit array, a frequency-selective metamaterial based on carbon fiber felt is used to replace the currently widely used metal patterned metastructure, resulting in an electromagnetic wave absorbing / transmitting metamaterial with advantages such as low cost, ease of manufacture, easily tunable frequency band, and light weight. This invention utilizes a frequency-selective metamaterial based on carbon fiber felt to replace the currently widely used metal patterned metastructure, and combines it with an epoxy resin-reinforced quartz fiber cloth composite material plate to endow the entire metamaterial with advantages such as light weight, corrosion resistance, and high temperature resistance.

[0016] 2) The present invention can adjust the parameters of a specific structure according to actual needs. By changing the electrical performance parameters of the metamaterial, the required electromagnetic wave transmission and absorption frequency bands can be obtained. It has excellent wave transmission performance in the required operating frequency band, with the lowest insertion loss reaching -1.14 dB. At the same time, it has excellent wave absorption performance in the required operating frequency band, with an absorption rate of over 0.9. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the unit structure of the lightweight frequency-selective metamaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission according to the present invention.

[0020] Figure 2 This is a schematic diagram of the frequency-selective superstructure unit of the present invention.

[0021] Figure 3 This is a schematic diagram of the lossy frequency-selective superstructure unit of the present invention.

[0022] Figure 4 A frontal photograph of the lightweight frequency-selective metamaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission, prepared in Example 1 of the present invention.

[0023] Figure 5 A photograph of the back of the lightweight frequency-selective metamaterial based on carbon fiber felt that absorbs / transmits electromagnetic waves, prepared in Example 1 of this invention.

[0024] Figure 6 The figures show the radar wave absorptivity curves of the lightweight, frequency-selective metamaterials based on carbon fiber felt, manufactured in Embodiments 1, 2, 3, and 4 of this invention, in the range of 2-18 GHz. As can be seen from the figures, the metastructures of all embodiments achieve an absorptivity greater than 0.9 at different frequencies. Specifically, Embodiments 1 and 2 primarily absorb at low frequencies below 12 GHz, while Embodiments 3 and 4, in addition to exhibiting high absorptivity at low frequencies, also show high absorptivity at high frequencies above 16 GHz.

[0025] Figure 7The S-parameter curves of the lightweight, frequency-selective metamaterials based on carbon fiber felt, which integrate electromagnetic wave absorption and transmission, manufactured in Embodiments 1, 2, 3, and 4 of this invention, are shown in the range of 2-18 GHz. As can be seen from the figure, the metastructures of all embodiments can achieve an insertion loss (IL) of less than -3 dB at different frequencies. The main transmission frequency bands of Embodiments 1 and 2 are concentrated in the high-frequency range above 13 GHz, while the main transmission frequency bands of Embodiments 3 and 4 are concentrated in the mid-frequency range of 8-10 GHz. Detailed Implementation

[0026] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0028] The specific embodiments of the present invention will be described in detail below.

[0029] The polystyrene foam boards used in the following examples were purchased from Shanxi Sihai Youcheng Building Materials Technology Co., Ltd. Example 1

[0030] A lightweight frequency-selective metamaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission, comprising 10×10 periodically arranged... Figure 1 The unit structure shown is a symmetrical structure; The frequency-selective superstructure has a U-shaped unit structure with unit size a1 = 18 mm and inner side length a2 = 11.48 mm; it has a sheet resistance of 4 Ω / sq and a surface density of 50 g / m³. 2 It is made of carbon fiber felt and quartz fiber cloth / epoxy resin composite material, with a carbon fiber felt thickness of 1 mm and a quartz fiber cloth / epoxy resin composite material thickness of 2 mm.

[0031] The thickness of the dielectric layer is h = 7.9 mm.

[0032] The lossy frequency-selective superstructure has a cross-shaped unit structure with unit dimensions a1 = 18 mm, arm length b1 = 17.16 mm, and arm width b2 = 2.16 mm; and a sheet resistance of 25 Ω / sq and a surface density of 5 g / m³. 2 It is made of carbon fiber felt and quartz fiber cloth / epoxy resin composite material, with a carbon fiber felt thickness of 0.05 mm and a quartz fiber cloth / epoxy resin composite material thickness of 3 mm.

[0033] Its manufacturing process is as follows: (1) Preparation of E-51 epoxy resin solution First, the curing agent, cis-hexahydrophthalic anhydride (HHPA), was preheated to a liquid state in a 70 ℃ oven. Next, E-51 epoxy resin and HHPA were weighed at a mass ratio of 1:0.8 and mechanically stirred at 500 rpm and ultrasonically dispersed at 100 W in a 60 ℃ water bath to ensure thorough mixing. During this process, 0.1 wt% of the accelerator 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) and 0.3 wt% of the silicone oil defoamer were added sequentially to the resin system. Finally, the mixture was defoamed in a 70 ℃ vacuum oven for 30 min to obtain the prepared epoxy resin solution.

[0034] (2) Preparation of carbon fiber felt-quartz fiber cloth / epoxy resin prepreg First, cut four layers of 180×180 mm quartz fiber cloth and carbon fiber mat (SCFV) of the same size. Then, weigh the quartz fiber cloth and weigh E-51 resin solution at 40% of its volume fraction. Lay a layer of quartz fiber cloth, brush it with the resin solution, and allow the solution to fully saturate the quartz fiber cloth. After laying, compact it. Next, impregnate the SCFV with epoxy resin solution and place it on the surface of the laid and compacted quartz fiber cloth, obtaining the SCFV-quartz fiber cloth / epoxy resin prepreg of the frequency-selective superstructure.

[0035] Six layers of 180×180 mm quartz fiber cloth and a lossy frequency selective superstructure SCFV of the same size were cut. Then, the quartz fiber cloth was weighed, and E-51 resin was weighed at 40% of its volume fraction. One layer of quartz fiber cloth was laid, and the resin was brushed on once to saturate the cloth. After laying, the cloth was compacted. Next, the SCFV of the lossy frequency selective superstructure was impregnated with epoxy resin and placed on the surface of the laid and compacted quartz fiber cloth, resulting in a lossy frequency selective superstructure SCFV-quartz fiber cloth / epoxy resin prepreg.

[0036] (3) Hot pressing-machining preparation of frequency-selective superstructures and lossy frequency-selective superstructures After uniformly applying a release agent to the surface of a 250×250 mm steel mold, it is placed in a 100 ℃ oven for thorough preheating. Frequency-selective superstructure or lossy frequency-selective superstructure SCFV-quartz fiber cloth / epoxy resin prepreg is laid on the lower base plate of the mold and prepolymerized for 30 min on a 100 ℃ hot press. After prepolymerization, the mold is closed and a pressure of 15 MPa is applied. The hot press temperature is then increased to 120 ℃ for curing for 2 h. Finally, after holding the pressure and allowing it to cool naturally to room temperature, the mold is demolded to obtain a frequency-selective superstructure or lossy frequency-selective superstructure SCFV-quartz fiber cloth / epoxy resin composite board.

[0037] (4) The frequency selective superstructure SCFV-quartz fiber cloth / epoxy resin composite material board is placed on the table of the engraving machine and fixed. It is then processed into 10×10 frequency selective superstructures in a U-shape unit structure. The U-shape unit structure has a U-shape groove in the middle to remove the carbon fiber felt. The U-shape groove exposes the inner side of the quartz fiber cloth / epoxy composite material, forming a unit structure with carbon fiber felt on all four sides. Thus, the frequency selective superstructure is obtained. A lossy frequency selective superstructure SCFV-quartz fiber cloth / epoxy resin composite material board is placed on the table of an engraving machine and fixed. It is then machined into 10×10 cross-shaped unit structures of lossy frequency selective superstructure. Each cross-shaped unit structure has a cross-shaped protrusion in the center with the carbon fiber felt removed from the periphery. The quartz fiber cloth / epoxy composite material on the inner side is exposed around the periphery of the cross-shaped protrusion, forming a unit structure with carbon fiber felt on the cross-shaped protrusion, thus obtaining a lossy frequency selective superstructure.

[0038] (5) Assemble and prepare a lightweight frequency-selective metamaterial based on carbon fiber felt that absorbs / transmits electromagnetic waves The frequency-selective superstructure and the frequency-selective superstructure were glued to the two surfaces of a 7.9 mm thick polystyrene foam board by means of a quartz fiber cloth / epoxy resin composite material. After compaction, a lightweight frequency-selective supermaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission was obtained.

[0039] Depend on Figure 6 (a) It can be seen that the strongest absorption of this lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, occurs at 5.38 GHz, producing an absorption rate of 0.93; the effective absorption bandwidth (S) 11 ≤-10 dB and S 21 The range is 4.60-10.08 GHz (≤-10 dB), reaching 5.48 GHz.

[0040] Depend on Figure 7(a) It can be seen that the minimum IL of this lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, appears at 15.12 GHz, as low as -1.14 dB, and the transmittance can reach more than 70%; effective transmission (S) is achieved in the range of 12.54-16.88 GHz. 11 ≤-10 dB and S 21 ≥-3 dB). Example 2

[0041] Its manufacturing process is the same as in Example 1, except that the areal density of the carbon fiber felt with frequency-selective superstructure is 40 g / m². 2 The sheet resistance is 5Ω / sq; the areal density of the carbon fiber felt in the lossy frequency-selective superstructure is 10 g / m³. 2 The sheet resistance is 20Ω / sq. The thickness of the carbon fiber felt in the frequency-selective superstructure is 0.05 mm, and the thickness of the quartz fiber cloth / epoxy resin composite material is 0.5 mm. The thickness of the lossy frequency-selective superstructure carbon fiber felt is 1 mm, and the thickness of the quartz fiber cloth / epoxy resin composite material is 5 mm. In addition, the structural parameters are: a1=15.23 mm, a2=9.10 mm, b1=15.00 mm, b2=1.51 mm, h=3.20 mm.

[0042] Depend on Figure 6 (b) It can be seen that the strongest absorption of this lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, occurs at 4.98 GHz, producing an absorption rate of 0.94; the effective absorption bandwidth (S) 11 ≤-10 dB and S 21 The range is 4.09-10.04 GHz (≤-10 dB), reaching 5.95 GHz.

[0043] Depend on Figure 7 (b) It can be seen that the minimum IL of this lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, appears at 14.43 GHz, as low as -1.95 dB, and the transmittance can reach more than 60%; effective transmission (S) is achieved in the 12.80-15 GHz range. 11 ≤-10 dB and S 21 ≥-3 dB). Example 3

[0044] Its manufacturing process is the same as in Example 1, except that the areal density of the carbon fiber felt with frequency-selective superstructure is 70 g / m². 2 The sheet resistance is 3.5 Ω / sq; the areal density of the carbon fiber felt in the lossy frequency-selective superstructure is 20 g / m². 2The sheet resistance is 15 Ω / sq. The thickness of the carbon fiber felt in the frequency-selective superstructure is 1 mm, and the thickness of the quartz fiber cloth / epoxy resin composite material is 0.5 mm. The thickness of the lossy frequency-selective superstructure carbon fiber felt is 1 mm, and the thickness of the quartz fiber cloth / epoxy resin composite material is 0.5 mm. In addition, the structural parameters are: a1=20.45 mm, a2=11.74 mm, b1=19 mm, b2=3.00 mm, and h=8.30 mm.

[0045] Depend on Figure 6 (c) It can be seen that the strongest absorption of this lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, occurs at 17.75 GHz, producing a strong absorption rate of 0.98; the effective absorption bandwidth (S) 11 ≤-10 dB and S 21 The ranges (≤-10dB) are 2.98-4.55, 6.15-8, and 16.72-18 GHz, totaling 4.7 GHz.

[0046] Depend on Figure 7 (c) It can be seen that the minimum IL of the lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, appears at 10.79 GHz, as low as -2.39 dB, with a transmittance of over 50%; effective transmission (S) is achieved in the range of 10.06-11.41 GHz. 11 ≤-10 dB and S 21 ≥-3 dB). Example 4

[0047] Its manufacturing process is the same as in Example 1, except that the areal density of the carbon fiber felt with frequency-selective superstructure is 80 g / m². 2 The sheet resistance is 3 Ω / sq; the areal density of the carbon fiber felt in the lossy frequency-selective superstructure is 5 g / m³. 2 The sheet resistance is 25 Ω / sq. The thickness of the carbon fiber felt in the frequency-selective superstructure is 1 mm, and the thickness of the quartz fiber cloth / epoxy resin composite material is 5 mm. The thickness of the lossy frequency-selective superstructure carbon fiber felt is 0.05 mm, and the thickness of the quartz fiber cloth / epoxy resin composite material is 0.5 mm. In addition, the structural parameters are: a1=23.71 mm, a2=14.33 mm, b1=20.75 mm, b2=3.25 mm, and h=9.16 mm.

[0048] Depend on Figure 6 (d) shows that the strongest absorption of this lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, occurs at 17.02 GHz, producing a strong absorption rate of 0.99; the effective absorption bandwidth (S) 11≤-10 dB and S 21 The range of ≤-10dB is 3.17-6.88 GHz and 15.84-18 GHz, reaching 5.87 GHz.

[0049] Depend on Figure 7 (d) shows that the minimum IL of this lightweight frequency-selective metamaterial based on carbon fiber felt, which integrates electromagnetic wave absorption and transmission, appears at 9.48 GHz, as low as -2.20 dB, with a transmittance of over 50%; effective transmission (S) is achieved in the range of 8.64-10.15 GHz. 11 ≤-10 dB and S 21 ≥-3 dB).

[0050] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and all should be covered by the protection scope of the claims.

Claims

1. A lightweight frequency-selective metamaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission, characterized in that, A symmetrical structure comprising n×n periodically arranged unit structures; where n is a positive integer; the unit structure comprises a frequency-selective superstructure, a dielectric layer, and a lossy frequency-selective superstructure stacked sequentially from bottom to top; The unit structure of the frequency-selective metasurface is a square-frame shape, with the unit size a1=15.23 - 23.71 mm, the inner side length a2=9.10 - 14.33 mm, and a2<a1; it is laminated and manufactured from carbon fiber felt with a sheet resistance of 3-5 Ω / sq and an areal density of 40-80 g / m 2 and quartz fiber cloth-epoxy composite material; a square-frame-shaped groove with the carbon fiber felt removed is provided in the middle of the unit structure of the frequency-selective metasurface, the square-frame-shaped groove exposes the inner quartz fiber cloth-epoxy composite material, forming a unit structure with carbon fiber felt on the peripheral edges; The dielectric layer has a square unit structure with a unit size of a1 and a thickness of h = 3.20-9.16 mm. When h varies within the range of 3.20-9.16 mm, the absorbing and transmitting band positions of the lightweight frequency-selective metamaterial based on carbon fiber felt are always near the series resonant point of the lossy frequency-selective metastructure and the parallel resonant point of the frequency-selective metastructure, respectively. The dielectric layer is made of polystyrene foam board. The lossy frequency-selective superstructure has a cross-shaped unit structure with unit size a1, arm length b1 = 15.00 - 20.75 mm, arm width b2 = 1.51 - 3.25 mm, and b2 < b1 < a1; with a sheet resistance of 4-25 Ω / sq and an areal density of 5-50 g / m³. 2 It is made of carbon fiber felt and quartz fiber cloth-epoxy composite material laminated together; the unit structure of the lossy frequency selective superstructure has a cross-shaped protrusion with the carbon fiber felt removed from the periphery, and the quartz fiber cloth-epoxy composite material is exposed on the periphery of the cross-shaped protrusion, forming a unit structure with carbon fiber felt in the cross-shaped protrusion. The thicknesses of the carbon fiber felt and quartz fiber cloth-epoxy composite material of the unit structure of the frequency selective superstructure are 0.05-1 mm and 0.5-5 mm, respectively. The thicknesses of the carbon fiber felt and quartz fiber cloth-epoxy composite material of the unit structure of the lossy frequency selective superstructure are 0.05-1 mm and 0.5-5 mm, respectively.

2. The lightweight frequency-selective metamaterial based on carbon fiber felt for absorbing and transmitting electromagnetic waves as described in claim 1, characterized in that, The unit structures of the frequency-selective superstructure, dielectric layer, and lossy frequency-selective superstructure correspond one-to-one from bottom to top.

3. The lightweight frequency-selective metamaterial based on carbon fiber felt for absorbing and transmitting electromagnetic waves as described in claim 1, characterized in that, The frequency-selective superstructure exhibits a reflection effect similar to that of an ideal conductor within the absorbing band, and generates a wave-transmitting effect through LC parallel resonance within the wave-transmitting band.

4. The lightweight frequency-selective metamaterial based on carbon fiber felt for absorbing and transmitting electromagnetic waves as described in claim 1, characterized in that, The lossy frequency-selective superstructure achieves impedance matching through LC series resonance in the absorbing band and generates a wave-transmitting effect through LC parallel resonance in the transparent band.

5. The lightweight frequency-selective metamaterial based on carbon fiber felt for absorbing and transmitting electromagnetic waves according to claim 1, characterized in that, The lossy frequency-selective superstructure as the top structure and the frequency-selective superstructure as the bottom structure achieve effective transmission of electromagnetic waves by resonating in parallel within the wave-transmitting band.

6. The method for preparing a lightweight frequency-selective metamaterial based on carbon fiber felt that integrates electromagnetic wave absorption and transmission, as described in any one of claims 1 to 5, is characterized in that... Includes the following steps: (1) Cut square carbon fiber felt and quartz fiber cloth according to the side length n×a1 respectively. A total of 2-10 layers of quartz fiber cloth are required. Prepare epoxy resin solution, lay a layer of quartz fiber cloth, brush the resin solution once and make the resin solution penetrate the quartz fiber cloth. After laying, compact it. Impregnate the carbon fiber felt with epoxy resin solution and place it on the surface of the laid and compacted quartz fiber cloth to obtain quartz fiber cloth-epoxy resin prepreg with carbon fiber felt on the surface of frequency selective superstructure and lossy frequency selective superstructure respectively. (2) After uniformly applying the release agent to the mold surface, the quartz fiber cloth-epoxy resin prepreg with carbon fiber felt on the surface of the frequency selective superstructure and the lossy frequency selective superstructure are placed in the mold, the mold is closed and cured at 120 ℃ and 15MPa. After curing, the mold is demolded after naturally cooling to room temperature, and the quartz fiber cloth-epoxy resin composite board with carbon fiber felt on the surface of the frequency selective superstructure and the lossy frequency selective superstructure are obtained respectively. (3) Place the quartz fiber cloth-epoxy resin composite board with carbon fiber felt on the surface of the frequency selective superstructure and the lossy frequency selective superstructure on the table of the engraving machine and fix them. Use a milling cutter to remove the carbon fiber felt in the middle area of ​​the quartz fiber cloth-epoxy resin composite board with carbon fiber felt on the surface of the frequency selective superstructure to form n×n square grooves, exposing the inner quartz fiber cloth-epoxy composite material, forming a unit structure of the frequency selective superstructure with periodic distribution, and obtain the frequency selective superstructure; use a milling cutter to remove the carbon fiber felt in the peripheral area of ​​the quartz fiber cloth-epoxy resin composite board with carbon fiber felt on the surface of the lossy frequency selective superstructure to form n×n cross-shaped protrusions, exposing the inner quartz fiber cloth-epoxy composite material around the cross-shaped protrusions, forming a unit structure of the lossy frequency selective superstructure with periodic distribution, and obtain the lossy frequency selective superstructure. (4) The frequency-selective superstructure and the lossy frequency-selective superstructure are glued to the two surfaces of the polystyrene foam board through the quartz fiber cloth-epoxy composite material. After compaction, the lightweight frequency-selective supermaterial based on carbon fiber felt is obtained.

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