Electromagnetic wave absorption-transmission integrated lightweight metamaterial with both polarization stability and wide-angle-of-incidence stability, and simplified preparation process therefor

Abstract

The present invention relates to the technical field of functional composite materials, and in particular to an electromagnetic wave absorption-transmission integrated lightweight metamaterial with both polarization stability and wide-angle-of-incidence stability, and a simplified preparation process therefor. The metamaterial is of a symmetrical structure comprising at least one periodically arranged square frequency-selection unit structure, wherein the square frequency-selection unit structure comprises a bottom-layer dielectric substrate, a bottom-layer metal structure array layer, a middle-layer dielectric substrate, a middle-layer carbon-based conductive thin-film structure array layer, a top-layer dielectric substrate and a top-layer carbon-based conductive thin-film structure array layer, which are stacked in sequence from bottom to top. By means of coupling cooperation of multiple layers of periodic unit arrays, and by means of replacing a widely used metal pattern with a carbon-based conductive film lossy layer and using an epoxy reinforced fiberglass cloth composite plate, an electromagnetic wave absorption-transmission integrated metamaterial with advantages, such as a low price, easiness of manufacturing, good polarization stability, good wide-angle-of-incidence stability, a low insertion loss in a wave-transmission frequency band, a high absorption rate in a wave-absorption frequency band, easiness of frequency-band adjustment and a light weight, is obtained.

Description

Lightweight metamaterial with both polarization stability and wide-incident-angle stability for absorbing and transmitting electromagnetic waves and its streamlined preparation process

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202410126663.1 filed with the Patent Office of China on January 30, 2024, entitled "Lightweight metamaterial with polarization stability and wide incident angle stability and streamlined preparation process for electromagnetic waves", the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of functional composite materials, and in particular to a lightweight metamaterial that absorbs and transmits electromagnetic waves and has both polarization stability and wide-incident-angle stability, and a streamlined preparation process thereof. Background Art

[0004] The ubiquitous presence of electromagnetic wave (EMW) radiation in the environment not only interferes with the normal operation of sensitive equipment such as civil aircraft radios, radars, and aerospace data transceivers, but also raises public concern about its potential harm to human health. With the advent of artificial intelligence and 5G communications, these issues are expected to become increasingly severe. Therefore, when designing and manufacturing products, it is crucial to convert most EMW into heat energy while minimizing secondary pollution, thereby dissipating any EMW that intrudes into the medium. Materials with this capability, known as absorbers, are currently a hot topic of research and development both domestically and internationally. As a typical dielectric material, carbon-based thin films have emerged as a promising class of EMW absorbers due to their low density, excellent environmental stability, adjustable electron mobility, and designable structural configurations.

[0005] Metamaterials are a new type of material with extraordinary physical properties. They are composed of artificially arranged units. Compared with traditional materials, they can more precisely control the operating frequency band and performance strength, and have advantages such as light weight and thinness. Metamaterials can exhibit properties such as negative dielectric constant, negative magnetic permeability, negative refractive index, and zero refractive index, and have important application value in many fields. As one of the application branches of metamaterials, metamaterial absorbers are materials that can absorb, scatter, or change the propagation direction of electromagnetic waves. They 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. It is a challenging research field with broad application prospects.

[0006] Frequency selective surfaces, a new type of electromagnetic wave absorbing material, fall into the category of metamaterials. They are a type of periodic unit structure composed of patches or apertures. By regulating the structure of the patches and apertures, frequency selective electromagnetic protection surfaces can achieve transparent transmission or strong reflection in the target frequency band. Frequency selective absorption surfaces derived from this structure can absorb electromagnetic waves in non-passband bands. Traditional metal frequency selective surfaces do not meet the requirements of lightweighting and have a narrow absorption bandwidth. New frequency selective surfaces made of carbon-based conductive composite materials have the advantages of light weight, corrosion resistance, and high temperature resistance. In particular, the absorption bandwidth can be effectively expanded, making it a current research hotspot.

[0007] However, existing bandpass frequency selective surfaces (FSSs) suffer from high insertion loss in the passband for wide-angle incident electromagnetic waves, and their suppression performance deteriorates due to the presence of grating lobes outside the band. Furthermore, existing metamaterial absorbers have uneven absorption bands, potentially exhibiting a certain degree of radar wave reflection within the band. Furthermore, their polarization stability and wide-angle oblique-incidence performance are less than ideal. Therefore, only materials with stable absorption performance at wide angles of incidence and filtering properties within specific operating frequency bands are likely to find practical application.

[0008] Summary of the Invention

[0009] In order to solve the problems of existing metamaterial absorbers such as large specific gravity, complex manufacturing process, large passband insertion loss and poor wide-angle absorption performance, the present invention provides a lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, and a streamlined preparation process.

[0010] The present invention is achieved through the following technical solutions: a lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, which is a symmetrical structure comprising at least one periodically arranged square frequency-selective unit structure;

[0011] The side length P of the square frequency selective unit structure is 50 mm, and it includes a bottom dielectric substrate, a bottom metal structure array layer, a middle dielectric substrate, a middle carbon-based conductive film structure array layer, a top dielectric substrate and a top carbon-based conductive film structure array layer stacked in sequence from bottom to top; the bottom metal structure array layer serves as a frequency selective wave-transmitting layer and is made of metal patches; the middle carbon-based conductive film structure array layer and the top carbon-based conductive film structure array layer serve as frequency selective wave-absorbing layers and are both made of carbon-based conductive film patches; the bottom metal structure array layer has a primitive structure composed of four periodically arranged square ring holes; the middle carbon-based conductive film structure array layer is composed of a primitive structure composed of a cross-shaped structure patch located in the center; and the top carbon-based conductive film structure array layer is composed of a primitive structure composed of four periodically arranged square ring patches.

[0012] As a further improvement of the technical solution of the present invention, the square frequency selection unit structure takes the center point of the elementary structure composed of the cross-shaped structure patch as the center of symmetry, and the elementary structure composed of four square ring holes of the bottom metal structure array layer is centrally symmetrically arranged and respectively located in the four areas divided by the elementary structure composed of the cross-shaped structure patch; the elementary structure composed of four square ring patches of the top carbon-based conductive film structure array layer corresponds to the elementary structure composed of four square ring holes of the bottom metal structure array layer.

[0013] As a further improvement of the technical solution of the present invention, the material of the metal patch of the bottom metal structure array layer of the square frequency selection unit structure is copper, and the electrical conductivity of the copper is 5.8×10 7 S / m; the sheet resistance of the carbon-based conductive film of the middle carbon-based conductive film structure array layer is 50~110Ω / sq; the sheet resistance of the carbon-based conductive film of the top carbon-based conductive film structure array layer is 90~130Ω / sq.

[0014] As a further improvement of the technical solution of the present invention, the bottom dielectric substrate, middle dielectric substrate and top dielectric substrate of the square frequency selection unit structure are all epoxy resin reinforced glass fiber cloth composite materials; the relative dielectric constant of the epoxy resin reinforced glass fiber cloth composite materials is 4.3.

[0015] As a further improvement of the technical solution of the present invention, the thickness H1 of the bottom dielectric substrate of the square frequency selective unit structure is 0.5-0.7 mm; the thickness H2 of the middle dielectric substrate is 1.5-1.8 mm; and the thickness H3 of the top dielectric substrate is 0.9-1.3 mm.

[0016] As a further improvement of the technical solution of the present invention, the outer ring side length L of the four square ring holes constituting the elementary structure of the bottom metal structure array layer of the square frequency selection unit structure is 19 to 21 mm, and the inner ring side length L1 is 16 to 18 mm; the four sides of the cross-shaped structure patch constituting the elementary structure of the middle carbon-based conductive thin film structure array layer have a side length L2 of 14 to 18 mm, and a width L3 of 2 to 4 mm; the inner ring side length L4 of the four square ring patches constituting the elementary structure of the top carbon-based conductive thin film structure array layer is 7 to 10 mm, and the outer ring side length L5 is 15 to 18 mm.

[0017] The present invention also provides a method for preparing the aforementioned electromagnetic wave absorbing and transmitting integrated lightweight metamaterial having both polarization stability and wide incident angle stability, comprising the following steps:

[0018] ① Design a symmetrical metamaterial with a square frequency selective unit structure arranged in an N*M array (N and M are both positive integers), and cut the bottom dielectric substrate, middle dielectric substrate, and top dielectric substrate according to the design;

[0019] ② Based on the elementary structure composed of the cross-shaped structure patch of the middle carbon-based conductive film structure array layer of the square frequency selective unit structure and the elementary structure composed of four square ring patches of the top carbon-based conductive film structure array layer as templates, N*M elementary structures are cut respectively;

[0020] ③ Based on the basic structure of the bottom metal structure array layer consisting of four square ring holes, use an engraving machine to carve out the designed N*M basic structures on the metal patch;

[0021] ④ Draw the corresponding elementary structure position on each dielectric substrate obtained in step ①, paste the elementary structure of the corresponding array layer on each dielectric substrate, and then paste the dielectric substrates with array layers together in sequence to complete the preparation of an integrated lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide incident angle stability.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1) The present invention combines an epoxy resin reinforced glass fiber cloth composite material plate with a carbon-based conductive film as an absorbing layer, and combines an epoxy resin reinforced glass fiber cloth composite material plate with a metal copper sheet as a frequency-selective wave-transmitting layer. Through the coupling of a multi-layer periodic unit array, an integrated electromagnetic wave absorbing and transmitting metamaterial is obtained, which has the advantages of being inexpensive and easy to manufacture, having good polarization stability, excellent stability over a wide range of incident angles, low insertion loss in the wave-transmitting frequency band, high absorptivity in the wave-absorbing frequency band, easy frequency band adjustment, and light weight.

[0024] 2) The metamaterial of the present invention exhibits both excellent incident wave polarization and stable electromagnetic control performance at wide incident angles. Due to the miniaturized design of the periodic unit structure and the elementary structure, the metamaterial of the present invention can achieve oblique incident responses of up to 45° for transverse electric (TE) and transverse magnetic (TM) polarizations. At incident angles of up to 45° for TE and TM waves, 80% of the EMW energy can still be absorbed, with the insertion loss of the wave-transmitting window as low as 0.6dB and a wave transmittance exceeding 85%.

[0025] 3) The present invention uses a lossy layer based on a carbon-based conductive film to replace the metal pattern superstructure currently widely used at home and abroad, and uses an epoxy resin reinforced glass fiber cloth composite material board to give the entire metamaterial advantages such as light weight, corrosion resistance, high temperature resistance, and low insertion loss.

[0026] 4) The present invention can adjust the parameters of the 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. In addition, the metamaterial has excellent wave transmission performance in the required working frequency band, with the minimum insertion loss reaching 0.6 dB. At the same time, it has excellent wave absorption performance in the required working frequency band, with an absorption rate of more than 90% (RL≤-10 dB). BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] FIG1 is a schematic diagram of a square frequency selective unit structure of a lightweight metamaterial that absorbs and transmits electromagnetic waves and has both polarization stability and wide-incident-angle stability according to the present invention.

[0030] FIG2 is a schematic diagram of the elementary structure of the bottom metal structure array layer of the square frequency selective unit structure of the present invention and its arrangement on the bottom dielectric substrate.

[0031] FIG3 is a schematic diagram showing the elementary structure of the middle carbon-based conductive film structure array layer of the square frequency selective unit structure of the present invention and its arrangement on the middle dielectric substrate.

[0032] FIG4 is a schematic diagram showing the elementary structure of the top carbon-based conductive film structure array layer in the square frequency selective unit structure of the present invention and its arrangement on the top dielectric substrate.

[0033] Figure 5 is a radar wave reflection loss (RL) curve of the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide incident angle stability manufactured in Examples 1, 2, 3 and 4 of the present invention in the electromagnetic wave frequency range of 2-18 GHz.

[0034] Figure 6 shows the radar wave insertion loss (IL) curve of the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide incident angle stability manufactured in Examples 1, 2, 3 and 4 of the present invention in the electromagnetic wave frequency range of 2-18 GHz.

[0035] FIG7 shows the RL simulation results of the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide-incident-angle stability manufactured in Example 1 of the present invention at different incident angles of TE waves.

[0036] FIG8 shows the RL simulation results of the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide-incident-angle stability manufactured in Example 1 of the present invention at different incident angles of TM waves.

[0037] FIG9 shows the IL simulation results of the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide-incident-angle stability manufactured in Example 1 of the present invention at different incident angles of TE waves.

[0038] FIG10 is an IL simulation result of the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide-incident-angle stability manufactured in Example 1 of the present invention at different incident angles of TM waves. DETAILED DESCRIPTION

[0039] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] The present invention provides a lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, and is a symmetrical structure comprising at least one periodically arranged square frequency-selective unit structure.

[0042] The side length P of the square frequency selective unit structure is 50 mm, and includes a bottom dielectric substrate 1, a bottom metal structure array layer 2, a middle dielectric substrate 3, a middle carbon-based conductive thin film structure array layer 4, a top dielectric substrate 5 and a top carbon-based conductive thin film structure array layer 6, which are stacked in sequence from bottom to top (the electromagnetic wave incident direction is from top to bottom); the bottom metal structure array layer 2 serves as a frequency selective wave-transmitting layer and is made of metal patches; the middle carbon-based conductive thin film structure array layer 4 and the top carbon-based conductive thin film structure array layer 6 serve as frequency selective wave-absorbing layers and are both made of carbon-based conductive thin film patches; the bottom metal structure array layer 2 has a basic structure composed of four periodically arranged square ring holes 201; the middle carbon-based conductive thin film structure array layer 4 is composed of a basic structure composed of a cross-shaped structure patch 401 located in the center; and the top carbon-based conductive thin film structure array layer 6 is composed of a basic structure composed of four periodically arranged square ring patches 601.

[0043] As shown in Figure 1, the square frequency selection unit structure takes the center point of the elementary structure composed of the cross-shaped structure patch 401 as the center of symmetry, and the elementary structure composed of four square ring holes 201 of the bottom metal structure array layer 2 is centrally symmetrically arranged and respectively located in the four areas divided by the elementary structure composed of the cross-shaped structure patch 401; the elementary structure composed of four square ring patches 601 of the top carbon-based conductive film structure array layer 6 corresponds to the elementary structure composed of four square ring holes 201 of the bottom metal structure array layer 2.

[0044] As shown in Figure 2, the basic structure of the bottom metal structure array layer 2 of the square frequency selection unit structure is composed of four square ring holes 201, and the inner ring edge and the outer ring edge of each square ring hole 201 are respectively parallel to the corresponding edges of the bottom dielectric substrate 1; as shown in Figure 3, the four sides of the basic structure composed of the cross-shaped structure patch 401 of the middle carbon-based conductive thin film structure array layer 4 are respectively parallel to the corresponding edges of the middle dielectric substrate 3; as shown in Figure 4, the inner ring edge and the outer ring edge of the basic structure composed of four square ring patches 601 of the top carbon-based conductive thin film structure array layer 6 are respectively parallel to the corresponding edges of the top dielectric substrate 5.

[0045] In one embodiment of the present invention, the metal patch of the bottom metal structure array layer 2 of the square frequency selection unit structure is made of copper, and the electrical conductivity of the copper is 5.8×10 7 S / m; the sheet resistance of the carbon-based conductive film of the middle carbon-based conductive film structure array layer 4 is 50 to 110Ω / sq; the sheet resistance of the carbon-based conductive film of the top carbon-based conductive film structure array layer 6 is 90 to 130Ω / sq.

[0046] In another embodiment provided by the present invention, the bottom dielectric substrate 1, the middle dielectric substrate 3 and the top dielectric substrate 5 of the square frequency selective unit structure are all epoxy resin reinforced glass fiber cloth composite materials; the relative dielectric constant of the epoxy resin reinforced glass fiber cloth composite materials is 4.3.

[0047] In one embodiment of the present invention, the thickness H1 of the bottom dielectric substrate 1 of the square frequency selective unit structure is 0.5-0.7 mm; the thickness H2 of the middle dielectric substrate 3 is 1.5-1.8 mm; and the thickness H3 of the top dielectric substrate 5 is 0.9-1.3 mm.

[0048] In another embodiment provided by the present invention, the outer ring side length L of the four square ring holes 201 constituting the elementary structure of the bottom metal structure array layer 2 of the square frequency selection unit structure is 19 to 21 mm, and the inner ring side length L1 is 16 to 18 mm; the four sides of the cross-shaped structure patch 401 constituting the elementary structure of the middle carbon-based conductive thin film structure array layer 4 have a side length L2 of 14 to 18 mm, and a width L3 of 2 to 4 mm; the four square ring patches 601 constituting the elementary structure of the top carbon-based conductive thin film structure array layer 6 have an inner ring side length L4 of 7 to 10 mm, and an outer ring side length L5 of 15 to 18 mm.

[0049] The present invention further provides a method for preparing the aforementioned electromagnetic wave absorbing and transmitting integrated lightweight metamaterial having both polarization stability and wide-incident-angle stability, comprising the following steps:

[0050] ① Design a symmetrical metamaterial with a square frequency selective unit structure arranged in an N*M array (N and M are both positive integers), and cut the bottom dielectric substrate 1, the middle dielectric substrate 3, and the top dielectric substrate 5 according to the design;

[0051] ② Using the elementary structure composed of the cross-shaped patch 401 of the middle carbon-based conductive thin film structure array layer 4 of the square frequency selective unit structure and the elementary structure composed of four square ring patches 601 of the top carbon-based conductive thin film structure array layer 6 as templates, N*M elementary structures are cut respectively;

[0052] ③ Based on the basic structure composed of four square ring holes 201 of the bottom metal structure array layer 2, use an engraving machine to carve out the designed N*M basic structures on the metal patch;

[0053] ④ Draw the corresponding elementary structure position on each dielectric substrate obtained in step ①, paste the elementary structure of the corresponding array layer on each dielectric substrate, and then paste the dielectric substrates with array layers together in sequence to complete the preparation of an integrated lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide incident angle stability.

[0054] The specific embodiments of the present invention are described in detail below. The epoxy resin reinforced glass fiber cloth composite material board used in the following embodiments is FR-4 board purchased from Shenzhen Xiongyihua Insulation Material Co., Ltd., and the carbon conductive film is purchased from Dongguan Hengsheng Co., Ltd.

[0055] Example 1

[0056] A lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability is provided, the metamaterial comprising a symmetrical structure of periodically arranged 4*4 (N=4, M=4) square frequency selective unit structures, i.e., a symmetrical structure comprising 16 periodically arranged square frequency selective unit structures as shown in FIG. 1 ;

[0057] The square frequency selective unit structure has a side length P of 50 mm and includes a bottom dielectric substrate 1, a bottom metal structure array layer 2, a middle dielectric substrate 3, a middle carbon-based conductive thin film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive thin film structure array layer 6, which are stacked in sequence from bottom to top (the electromagnetic wave incident direction is from top to bottom);

[0058] The bottom dielectric substrate 1 is an FR-4 board with a size of 200 mm×200 mm×0.7 mm, that is, a thickness H1 of 0.7 mm and a relative dielectric constant of 4.3.

[0059] The middle dielectric substrate 3 is an FR-4 board with a size of 200 mm×200 mm×1.6 mm, that is, a thickness H2 of 1.6 mm and a relative dielectric constant of 4.3.

[0060] The top dielectric substrate 5 is an FR-4 board with a size of 200 mm×200 mm×1.2 mm, that is, a thickness H3 of 1.2 mm and a relative dielectric constant of 4.3.

[0061] The bottom metal structure array layer 2 has 16 (N=4, M=4) elementary structures consisting of four periodically arranged square ring holes 201 as shown in FIG2 , with L=19 mm and L1=17.5 mm. The bottom metal structure array layer 2 is made of copper, which has an electrical conductivity of 5.8×10 7 S / m.

[0062] The middle carbon-based conductive film array layer 4 consists of a basic structure consisting of 16 centrally located cross-shaped patches 401, as shown in Figure 3. L2 = 15 mm, L3 = 3 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 80 Ω / sq.

[0063] The top carbon-based conductive film array layer 6 consists of 16 elementary structures, as shown in Figure 4, consisting of four periodically arranged square ring patches 601. L4 = 9 mm, L5 = 16 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 100 Ω / sq.

[0064] Its manufacturing process is:

[0065] ① Design a square frequency selective unit structure arranged in a 4*4 (i.e., N=M=4) array; use a cutting machine to cut the purchased FR-4 board into a bottom dielectric substrate 1 with a size of 200mm×200mm×0.7mm, a middle dielectric substrate 3 with a size of 200mm×200mm×1.6mm, and a top dielectric substrate 5 with a size of 200mm×200mm×1.2mm.

[0066] ② Draw the designed elementary structure of the middle carbon-based conductive thin film structure array layer 4 and the elementary structure of the top carbon-based conductive thin film structure array layer 6 on a computer, then print and use the printed hard film as a template to cut the purchased carbon-based conductive thin film product to obtain 16 elementary structures of the middle carbon-based conductive thin film structure array layer 4 and 16 elementary structures of the top carbon-based conductive thin film structure array layer 6;

[0067] ③ Using an engraving machine to carve out 16 designed square frequency selective unit structures of the underlying metal structure array layer 2 on the metal copper sheet;

[0068] ④ Draw the position of the corresponding elementary structure on each dielectric substrate obtained in step ①, and use commercially available high-transmittance double-sided adhesive tape to stick the unit structure of the corresponding number of array layers on each dielectric substrate. Then, each dielectric substrate with the array layer is sequentially stuck together with commercially available high-transmittance double-sided adhesive tape to obtain the designed electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide-incident-angle stability.

[0069] As shown in Figure 5(a), the minimum RL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide-incident-angle stability appears at 14.96 GHz, resulting in a strong absorption of -39.98 dB; the effective absorption bandwidth (RL≤-10 dB) is 10.5-16 GHz, reaching 5.5 GHz.

[0070] As shown in Figure 6(a), the minimum IL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide-incident-angle stability appears at 2.37 GHz, with an insertion loss as low as 0.66 dB and a transmittance of more than 85%; the IL in the 2.09-2.69 GHz frequency band is ≤-3 dB.

[0071] As shown in Figures 7 and 8, in the TE polarization mode, when the incident angle increases from 0° to 45°, the metamaterial's strong absorption performance remains stable across the absorption band (absorption rate greater than 90%). In the TM polarization mode, when the incident angle increases from 0° to 45°, the metamaterial's overall absorption performance remains stable across the absorption band, with good stability across a wide range of incident angles. This demonstrates that the metamaterial absorber of the present invention exhibits both excellent polarization stability and wide-angle stability. This is due to the strong symmetry and miniaturization of the designed unit and elementary structures, allowing the oblique incidence responses of TE and TM modes to reach 45° and 45°, respectively, under different polarization conditions.

[0072] As shown in Figures 9 and 10, in the TE polarization mode, the transmittance of the metamaterial's wave-transmitting window remains above 85% when the incident angle of the electromagnetic wave increases from 0° to 45°. In the TM polarization mode, the transmittance of the metamaterial's wave-transmitting window remains almost unchanged when the incident angle increases from 0° to 45°, demonstrating excellent stability across a wide range of incident angles. This demonstrates that the metamaterial absorber of the present invention exhibits both excellent polarization stability and wide-angle stability. This is due to the strong symmetry and miniaturization of the designed unit and elementary structures, enabling oblique-incidence responses of up to 45° for the TE and 45° for the TM modes, respectively, under different polarization conditions.

[0073] Example 2

[0074] A lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability is provided, the metamaterial comprising a symmetrical structure of periodically arranged 2*2 (N=2, M=2) square frequency selective unit structures, i.e., a symmetrical structure comprising four periodically arranged square frequency selective unit structures as shown in FIG. 1 ;

[0075] The square frequency selective unit structure has a side length P of 50 mm and includes a bottom dielectric substrate 1, a bottom metal structure array layer 2, a middle dielectric substrate 3, a middle carbon-based conductive thin film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive thin film structure array layer 6, which are stacked in sequence from bottom to top (the electromagnetic wave incident direction is from top to bottom);

[0076] The bottom dielectric substrate 1 is an FR-4 board with a size of 100 mm×100 mm×0.5 mm, that is, a thickness H1 of 0.5 mm and a relative dielectric constant of 4.3.

[0077] The middle dielectric substrate 3 is an FR-4 board with a size of 100 mm×100 mm×1.8 mm, that is, a thickness H2 of 1.8 mm and a relative dielectric constant of 4.3.

[0078] The top dielectric substrate 5 is an FR-4 board with a size of 100 mm×100 mm×0.9 mm, that is, a thickness H3 of 0.9 mm and a relative dielectric constant of 4.3.

[0079] The bottom metal structure array layer 2 has four (N=2, M=2) elementary structures consisting of four periodically arranged square ring holes 201 as shown in FIG2 , L=19 mm, L1=18 mm. The bottom metal structure array layer 2 is made of copper, which has an electrical conductivity of 5.8×10 7 S / m.

[0080] The middle carbon-based conductive film array layer 4 consists of a basic structure consisting of four centrally located cross-shaped patches 401, as shown in Figure 3. L2 = 14 mm, L3 = 3 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 110 Ω / sq.

[0081] The top carbon-based conductive film array layer 6 consists of four periodically arranged square ring patches 601, as shown in Figure 4. L4 = 10 mm, L5 = 15 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 100 Ω / sq.

[0082] The manufacturing process is the same as that of Example 1, except for the different materials and structural parameters.

[0083] As shown in Figure 5(b), the minimum RL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide incident angle stability appears at 15.12 GHz, resulting in a strong absorption of -47.7 dB; the effective absorption bandwidth (RL≤-10 dB) is 10.7-16.2 GHz, reaching 5.5 GHz.

[0084] As shown in Figure 6(b), the minimum IL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide-incident-angle stability appears at 2.42 GHz, with an insertion loss as low as 0.67 dB and a transmittance of more than 85%; the IL in the 2.12-2.75 GHz frequency band is ≤-3 dB.

[0085] Example 3

[0086] A lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, comprising a symmetrical structure comprising periodically arranged 5*5 (N=5, M=5) square frequency selective unit structures, i.e., a symmetrical structure comprising 25 periodically arranged square frequency selective unit structures as shown in FIG. 1 ;

[0087] The square frequency selective unit structure has a side length P of 50 mm and includes a bottom dielectric substrate 1, a bottom metal structure array layer 2, a middle dielectric substrate 3, a middle carbon-based conductive thin film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive thin film structure array layer 6, which are stacked in sequence from bottom to top (the electromagnetic wave incident direction is from top to bottom);

[0088] The bottom dielectric substrate 1 is an FR-4 board with a size of 250 mm×250 mm×0.6 mm, that is, a thickness H1 of 0.6 mm and a relative dielectric constant of 4.3.

[0089] The middle dielectric substrate 3 is an FR-4 board with a size of 250 mm×250 mm×1.5 mm, that is, a thickness H2 of 1.5 mm and a relative dielectric constant of 4.3.

[0090] The middle dielectric substrate 5 is an FR-4 board with a size of 250 mm×250 mm×1.3 mm, that is, a thickness H3 of 1.3 mm and a relative dielectric constant of 4.3.

[0091] The bottom metal structure array layer 2 has 25 (N=5, M=5) elementary structures consisting of four periodically arranged square ring holes 201 as shown in FIG2 , with L=21 mm and L1=17.5 mm. The bottom metal structure array layer 2 is made of copper, which has an electrical conductivity of 5.8×10 7 S / m.

[0092] The middle carbon-based conductive film array layer 4 consists of a basic structure consisting of 25 centrally located cross-shaped patches 401, as shown in Figure 3. L2 = 16 mm, L3 = 2 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 50 Ω / sq.

[0093] The top carbon-based conductive film array layer 6 consists of 25 elementary structures, as shown in Figure 4, consisting of four periodically arranged square ring patches 601. L4 = 7 mm, L5 = 15 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 130 Ω / sq.

[0094] The manufacturing process is the same as that of Example 1, except for the different materials and structural parameters.

[0095] As shown in Figure 5(c), the minimum RL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide-incident-angle stability appears at 15.04 GHz, resulting in a strong absorption of -45.76 dB; the effective absorption bandwidth (RL≤-10 dB) is 10.6-15.9 GHz, reaching 5.3 GHz.

[0096] As shown in Figure 6(c), the minimum IL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide-incident-angle stability appears at 2.37 GHz, with an insertion loss as low as 0.65 dB and a transmittance of more than 85%; the IL in the 2.10-2.68 GHz frequency band is ≤-3 dB.

[0097] Example 4

[0098] A lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability is provided, the metamaterial comprising a symmetrical structure of 6*5 (N=6, M=5) periodically arranged square frequency selective unit structures, i.e., a symmetrical structure comprising 30 periodically arranged square frequency selective unit structures as shown in FIG. 1 ;

[0099] The square frequency selective unit structure has a side length P of 50 mm and includes a bottom dielectric substrate 1, a bottom metal structure array layer 2, a middle dielectric substrate 3, a middle carbon-based conductive thin film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive thin film structure array layer 6, which are stacked in sequence from bottom to top (the electromagnetic wave incident direction is from top to bottom);

[0100] The bottom dielectric substrate is an FR-4 board with a size of 300 mm×250 mm×0.7 mm, that is, a thickness H1 of 0.7 mm and a relative dielectric constant of 4.3.

[0101] The middle-layer dielectric substrate is an FR-4 board with a size of 300 mm×250 mm×1.6 mm, that is, a thickness H2 of 1.6 mm and a relative dielectric constant of 4.3.

[0102] The top dielectric substrate is an FR-4 board with a size of 300 mm × 250 mm × 1.2 mm, that is, a thickness H3 of 1.2 mm and a relative dielectric constant of 4.3.

[0103] The bottom metal structure array layer 2 has 30 (N=6, M=5) elementary structures consisting of four periodically arranged square ring holes 201 as shown in FIG2 , with L=20 mm and L1=16 mm. The bottom metal structure array layer is made of copper, which has an electrical conductivity of 5.8×10 7 S / m.

[0104] The middle carbon-based conductive film array layer 4 consists of 30 centrally located cross-shaped patches 401, as shown in Figure 3. L2 = 18 mm, L3 = 4 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 80 Ω / sq.

[0105] The top carbon-based conductive film array layer 6 consists of 30 elementary structures, as shown in Figure 4, consisting of four periodically arranged square ring patches 601. L4 = 9 mm, L5 = 18 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, with a sheet resistance of 90 Ω / sq.

[0106] The manufacturing process is the same as that of Example 1, except for the different materials and structural parameters.

[0107] As shown in Figure 5(d), the minimum RL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide incident angle stability appears at 15.53 GHz, resulting in a strong absorption of -23.17 dB; the effective absorption bandwidth (RL≤-10 dB) is 11-16.10 GHz, reaching 5.1 GHz.

[0108] As shown in Figure 6(d), the minimum IL of this integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide-incident-angle stability appears at 2.37 GHz, with an insertion loss as low as 0.66 dB and a transmittance of more than 85%; the IL in the 2.09-2.69 GHz frequency band is ≤-3 dB.

[0109] The above description is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions have been made with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments, and they should all be included in the scope of protection of the claims.

Claims

1. A lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, characterized in that: A symmetrical structure comprising at least one periodically arranged square frequency selective unit structure; The side length P of the square frequency selection unit structure is 50 mm, and the structure comprises a bottom dielectric substrate (1), a bottom metal structure array layer (2), a middle dielectric substrate (3), a middle carbon-based conductive film structure array layer (4), a top dielectric substrate (5), and a top carbon-based conductive film structure array layer (6) which are sequentially stacked from bottom to top; the bottom metal structure array layer (2) serves as a frequency selection wave-transmitting layer and is made of metal patches; the middle carbon-based conductive film structure array layer (4) and the top carbon-based conductive film structure array layer (6) serve as frequency selection wave-absorbing layers and are both made of carbon-based conductive film patches; the bottom metal structure array layer (2) has a basic structure consisting of four periodically arranged square ring holes (201); the middle carbon-based conductive film structure array layer (4) is composed of a basic structure consisting of a cross-shaped structure patch (401) located in the center; and the top carbon-based conductive film structure array layer (6) is composed of a basic structure consisting of four periodically arranged square ring patches (601).

2. The electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide incident angle stability according to claim 1, characterized in that: The square frequency selection unit structure takes the center point of the elementary structure formed by the cross-shaped structure patch (401) as the symmetry center; the elementary structure formed by the four square ring holes (201) of the bottom metal structure array layer (2) is centrally symmetrically arranged and respectively located in the four areas divided by the elementary structure formed by the cross-shaped structure patch (401); the elementary structure formed by the four square ring patches (601) of the top carbon-based conductive film structure array layer (6) corresponds to the elementary structure formed by the four square ring holes (201) of the bottom metal structure array layer (2).

3. The electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide incident angle stability according to claim 1, characterized in that: The material of the metal patch of the bottom metal structure array layer (2) of the square frequency selection unit structure is metal copper, and the electrical conductivity of the metal copper is 5.8×10 7 S / m; the sheet resistance of the carbon-based conductive film of the middle carbon-based conductive film structure array layer (4) is 50 to 110 Ω / sq; the sheet resistance of the carbon-based conductive film of the top carbon-based conductive film structure array layer (6) is 90 to 130 Ω / sq.

4. The lightweight metamaterial having both polarization stability and wide-incident-angle stability for absorbing and transmitting electromagnetic waves according to claim 1, characterized in that: The bottom dielectric substrate (1), the middle dielectric substrate (3) and the top dielectric substrate (5) of the square frequency selection unit structure are all epoxy resin reinforced glass fiber cloth composite material plates; the relative dielectric constant of the epoxy resin reinforced glass fiber cloth composite material plates is 4.

3.

5. The lightweight metamaterial having both polarization stability and wide-incident-angle stability and capable of absorbing and transmitting electromagnetic waves according to claim 1, characterized in that: The thickness H1 of the bottom dielectric substrate (1) of the square frequency selection unit structure is 0.5-0.7 mm; the thickness H2 of the middle dielectric substrate (3) is 1.5-1.8 mm; and the thickness H3 of the top dielectric substrate (5) is 0.9-1.3 mm.

6. The electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide incident angle stability according to claim 1, characterized in that: The outer ring side length L of the four square ring holes (201) constituting the elementary structure of the bottom metal structure array layer (2) of the square frequency selection unit structure is 19 to 21 mm, and the inner ring side length L1 is 16 to 18 mm; the four sides of the cross-shaped structure patch (401) constituting the elementary structure of the middle carbon-based conductive thin film structure array layer (4) have a side length L2 of 14 to 18 mm and a width L3 of 2 to 4 mm; the inner ring side length L4 of the four square ring patches (601) constituting the elementary structure of the top carbon-based conductive thin film structure array layer (6) have a side length L5 of 15 to 18 mm.

7. A method for preparing a lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability according to any one of claims 1 to 6, characterized in that: The steps include: ① Designing a square frequency selective unit structure with N*M, where N and M are both positive integers, and symmetrical metamaterials arranged in an array, and cutting a bottom dielectric substrate (1), a middle dielectric substrate (3) and a top dielectric substrate (5) according to the design; ② Based on the elementary structure composed of the cross-shaped patch structure (401) of the middle carbon-based conductive thin film structure array layer (4) of the square frequency selective unit structure and the elementary structure composed of four square ring patches (601) of the top carbon-based conductive thin film structure array layer (6) as templates, N*M elementary structures are cut respectively; ③ Based on the elementary structure composed of four square ring holes (201) of the bottom metal structure array layer (2), an engraving machine is used to carve out the designed N*M elementary structures on the metal patch; ④ Draw the corresponding elementary structure position on each dielectric substrate obtained in step ①, paste the elementary structure of the corresponding array layer on each dielectric substrate, and then paste the dielectric substrates with array layers together in sequence to complete the preparation of an integrated lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide incident angle stability.

Images