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

Abstract

The present invention relates to the technical field of functional composite materials, and in particular to a light-weight metamaterial for absorbing and transmitting electromagnetic waves with both polarization stability and wide incident angle stability and a simplified preparation process thereof, which is a symmetrical structure including at least one square frequency selection unit structure arranged periodically; the square frequency selection unit structure 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. Through the coupling of multiple periodic unit arrays, the use of a carbon-based conductive film loss layer to replace the widely used metal pattern and an epoxy-reinforced glass fiber cloth composite material plate is used to obtain a light-weight metamaterial for absorbing and transmitting electromagnetic waves with the advantages of being cheap and easy to manufacture, having good polarization stability, excellent wide incident angle stability, low insertion loss in the wave transmission frequency band, high absorption rate in the wave absorption frequency band, easy frequency band adjustment, and light weight.

Description

Technical Field

[0001] 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 simplified preparation process thereof. Background Art

[0002] The electromagnetic wave (EMW) radiation that is ubiquitous in the environment not only interferes with the normal use of sensitive equipment such as civil aircraft radio, radar, and aerospace data transceivers, but also arouses public concern about its potential harm to human health. With the advent of the era of artificial intelligence and 5G communications, these situations will certainly become more and more serious. Therefore, when designing and manufacturing products, most of the EMW should be converted into heat energy under the premise of minimizing secondary pollution, and then the EMW that invades the medium should be dissipated. Materials with such functions, called absorbers, are currently a hot topic of research and development at home and abroad. As a typical dielectric material, carbon-based films have become a promising class of EMW absorbing materials due to their low density, good environmental stability, adjustable electron mobility, and designable structural configuration.

[0003] Metamaterials are a new type of material with extraordinary physical properties. They are composed of artificial units. Compared with traditional materials, they can more accurately control the action frequency band and performance strength, and have the advantages of light weight and small thickness. 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.

[0004] As a new type of electromagnetic wave absorbing material, frequency selective surface belongs to the category of metamaterials. It is a kind of periodic unit structure composed of patches or apertures. Through the structural regulation of patches and apertures, the frequency selective electromagnetic protection surface can achieve transparent transmission or strong reflection of the target frequency band. The frequency selective absorption surface derived on this basis can absorb electromagnetic waves in non-passband frequency bands. Traditional metal frequency selective surfaces do not meet the requirements of lightweight, and the absorption bandwidth is narrow. 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, the absorption bandwidth can be effectively expanded, so it has become a current research hotspot.

[0005] However, the existing bandpass frequency selective surface has large passband insertion loss for wide-angle incident electromagnetic waves, and the suppression is deteriorated due to the appearance of grating lobes outside the band. In addition, the absorption band of the existing metamaterial absorber is not stable, and there may still be a certain degree of radar wave reflection problem in the band, and the polarization stability and wide-angle oblique incidence performance stability are not ideal. Only materials with stable absorbing performance under wide incident angles and filtering characteristics in specific working frequency bands can be used in practice. Summary of the invention

[0006] 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 absorbing performance, the present invention provides a lightweight metamaterial that absorbs and transmits electromagnetic waves in one with both polarization stability and wide incident angle stability, and a simplified preparation process thereof.

[0007] The present invention is achieved through the following technical solutions: a light-weight metamaterial that absorbs and transmits electromagnetic waves in one, which has both polarization stability and wide incident angle stability, comprising a symmetrical structure of at least one square frequency selection unit structure arranged periodically;

[0008] The side length P of the square frequency selection unit structure is 50 mm, and 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, which are stacked in sequence from bottom to top; the bottom metal structure array layer is used as a frequency selection 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 are used as frequency selection 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; the top carbon-based conductive film structure array layer is composed of a primitive structure composed of four periodically arranged square ring patches.

[0009] 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.

[0010] 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 conductivity of the copper is 5.8×107 S / m; the sheet resistance of the carbon-based conductive film of the middle carbon-based conductive film structure array layer is 50~110 Ω / sq; the sheet resistance of the carbon-based conductive film of the top carbon-based conductive film structure array layer is 90~130 Ω / sq.

[0011] As a further improvement of the technical solution of the present invention, the bottom dielectric substrate, the middle dielectric substrate and the 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.

[0012] As a further improvement of the technical solution of the present invention, the thickness H1 of the bottom dielectric substrate of the square frequency selection 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.

[0013] 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 19~21 mm, and the inner ring side length L1 is 16~18 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 14~18 mm, and a width L3 of 2~4 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 7~10 mm, and the outer ring side length L5 is 15~18 mm.

[0014] The present invention also provides a method for preparing the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial having both polarization stability and wide incident angle stability, comprising the following steps:

[0015] ① Design a symmetrical metamaterial with a square frequency selective unit structure arranged in an N*M (N and M are both positive integers) array, and cut the bottom dielectric substrate, the middle dielectric substrate and the top dielectric substrate according to the design;

[0016] 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;

[0017] ③ According to the primitive structure composed of four square ring holes in the bottom metal structure array layer, use an engraving machine to carve out the designed N*M primitive structures on the metal patch;

[0018] ④ Draw the corresponding unit structure position on each dielectric substrate obtained in step ①, paste the corresponding unit structure of the array layer on each dielectric substrate, and then paste the dielectric substrates with the array layer together in turn to complete the preparation of the integrated lightweight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide incident angle stability.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 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 electromagnetic wave absorbing-transmitting integrated metamaterial is obtained, which has the advantages of being cheap and easy to manufacture, having good polarization stability, excellent stability at a wide incident angle, low insertion loss in the wave-transmitting frequency band, high absorption rate in the wave-absorbing frequency band, easy frequency band adjustment, and light weight.

[0021] 2) The metamaterial of the present invention has excellent incident wave polarization and stability of electromagnetic control performance under wide incident angles. Due to the miniaturized design of the periodic unit structure and the elementary structure, the oblique incident responses of the transverse electric (TE) polarization mode and the transverse magnetic (TM) polarization mode of the metamaterial of the present invention can reach 45° and 45° respectively. When the incident angle of TE wave and TM wave is as high as 45°, 80% of the EMW energy can still be absorbed, the insertion loss of the wave-transmitting window is as low as 0.6 dB, and the wave transmittance is above 85%.

[0022] 3) The present invention utilizes 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 the advantages of light weight, corrosion resistance, high temperature resistance, and low insertion loss.

[0023] 4) The present invention can adjust the parameters of the specific structure according to actual needs, and obtain the required electromagnetic wave transmission and absorption frequency bands by changing the electrical performance parameters of the metamaterial. It has excellent wave transmission performance in the required working frequency band, and the minimum insertion loss can reach 0.6 dB. At the same time, it has excellent wave absorption performance in the required working frequency band, and the absorption rate can reach more than 90% (RL≤-10 dB). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 It is a schematic diagram of a square frequency selection unit structure of the electromagnetic wave absorbing and transmitting integrated lightweight metamaterial with both polarization stability and wide incident angle stability of the present invention.

[0027] Figure 2 The schematic diagram is a basic unit 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.

[0028] Figure 3 The schematic diagram is a schematic diagram of the elementary structure of the middle-layer carbon-based conductive film structure array layer of the square frequency selective unit structure of the present invention and its arrangement on the middle-layer dielectric substrate.

[0029] Figure 4 It is a schematic diagram of 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.

[0030] Figure 5 Radar wave reflection loss (RL) curves 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.

[0031] Figure 6 Radar wave insertion loss (IL) curves of the electromagnetic wave absorbing-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.

[0032] Figure 7 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.

[0033] Figure 8 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.

[0034] Fig. 9IL 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.

[0035] Fig.10 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 TM waves. DETAILED DESCRIPTION

[0036] 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 the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0037] 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 of the embodiments.

[0038] The present invention provides a light-weight metamaterial that absorbs and transmits electromagnetic waves in one, which has both polarization stability and wide incident angle stability, and includes a symmetrical structure of at least one square frequency selection unit structure arranged periodically;

[0039] The side length P of the square frequency selection 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 film structure array layer 4, a top dielectric substrate 5 and a top carbon-based conductive 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 is used as a frequency selective 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 are used as frequency selective wave-absorbing layers and are both made of carbon-based conductive 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 film structure array layer 4 is composed of a basic structure composed of a cross-shaped structure patch 401 located in the center; the top carbon-based conductive film structure array layer 6 is composed of a basic structure composed of four periodically arranged square ring patches 601.

[0040] like Figure 1As shown, the square frequency selection unit structure takes the center point of the elementary structure composed of the cross-shaped structure patch 401 as the symmetry center, 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.

[0041] like Figure 2 As shown, the square frequency selection unit structure bottom metal structure array layer 2 is a basic unit structure 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 edge of the bottom dielectric substrate 1; Figure 3 As shown, the four sides of the elementary structure formed by the cross-shaped structure patch 401 of the middle-layer carbon-based conductive film structure array layer 4 are respectively parallel to the corresponding sides of the middle-layer dielectric substrate 3; Figure 4 As shown, the inner ring edge and the outer ring edge of the elementary structure composed of four square ring patches 601 of the top carbon-based conductive thin film structure array layer 6 are parallel to the corresponding edges of the top dielectric substrate 5 .

[0042] In one embodiment of the present invention, the material of the metal patch of the bottom metal structure array layer 2 of the square frequency selection unit structure is copper, and the 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 50~110 Ω / sq; the sheet resistance of the carbon-based conductive film of the top carbon-based conductive film structure array layer 6 is 90~130 Ω / sq.

[0043] 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 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.

[0044] In an embodiment provided by 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.

[0045] 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 19~21 mm, and the inner ring side length L1 is 16~18 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 14~18 mm, and a width L3 of 2~4 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 is 7~10 mm, and the outer ring side length L5 is 15~18 mm.

[0046] The present invention further provides a method for preparing the above-mentioned electromagnetic wave absorbing and transmitting integrated lightweight metamaterial having both polarization stability and wide incident angle stability, comprising the following steps:

[0047] ① Design a symmetrical metamaterial with a square frequency selection unit structure arranged in an N*M (N and M are both positive integers) array, and cut a bottom dielectric substrate 1, a middle dielectric substrate 3, and a top dielectric substrate 5 according to the design;

[0048] ② Using the elementary structure composed of the cross-shaped patch 401 of the middle carbon-based conductive 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 film structure array layer 6 as templates, N*M elementary structures are cut respectively;

[0049] ③ According to the elementary structure composed of four square ring holes 201 of the bottom metal structure array layer 2, the designed N*M elementary structures are engraved on the metal patch by using an engraving machine;

[0050] ④ Draw the corresponding unit structure position on each dielectric substrate obtained in step ①, paste the unit structure of the corresponding array layer on each dielectric substrate, and then paste the dielectric substrates with array layers together in turn to complete the preparation of the electromagnetic wave absorbing and penetrating integrated lightweight metamaterial with both polarization stability and wide incident angle stability.

[0051] 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 a FR-4 board purchased from Shenzhen Xiongyihua Insulation Materials Co., Ltd., and the carbon-based conductive film is purchased from Dongguan Hengsheng Co., Ltd. Example 1

[0052] A light-weight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, including a symmetrical structure of periodically arranged 4*4 (N=4, M=4) square frequency-selective unit structures, that is, a periodically arranged 16 Figure 1 The symmetrical structure of the square frequency selective unit structure shown;

[0053] The side length P of the square frequency selection 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 film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive film structure array layer 6, which are stacked in sequence from bottom to top (from top to bottom in the incident direction of electromagnetic waves);

[0054] The bottom dielectric substrate 1 is a FR-4 board with a size of 200 mm×200 mm×0.7 mm, that is, the thickness H1 is 0.7 mm and the relative dielectric constant is 4.3.

[0055] The middle-layer dielectric substrate 3 is an FR-4 board with a size of 200 mm×200 mm×1.6 mm, that is, the thickness H2 is 1.6 mm and the relative dielectric constant is 4.3.

[0056] The top dielectric substrate 5 is an FR-4 board with a size of 200 mm×200 mm×1.2 mm, that is, the thickness H3 is 1.2 mm and the relative dielectric constant is 4.3.

[0057] The bottom metal structure array layer 2 has 16 (N=4, M=4) Figure 2 The basic structure shown is composed of four periodically arranged square ring holes 201, L = 19 mm, L1 = 17.5 mm. The material of the bottom metal structure array layer 2 is copper, and the electrical conductivity of the copper is 5.8×10 7 S / m.

[0058] The middle carbon conductive film structure array layer 4 consists of 16 Figure 3 The basic structure of the cross-shaped patch 401 located in the center is shown, L2 = 15 mm, L3 = 3 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, and has a square resistance of 80 Ω / sq.

[0059] The top carbon conductive film structure array layer 6 consists of 16 Figure 4 The basic structure shown is composed 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, and has a square resistance of 100 Ω / sq.

[0060] Its manufacturing process is:

[0061] ① Design a square frequency selective unit structure in a 4*4 (i.e., N=M=4) array arrangement; use a cutting machine to cut the purchased FR-4 board into a bottom dielectric substrate 1 with a size of 200 mm×200 mm×0.7 mm, a middle dielectric substrate 3 with a size of 200 mm×200 mm×1.6 mm, and a top dielectric substrate 5 with a size of 200 mm×200 mm×1.2 mm.

[0062] ② Draw the designed elementary structure of the middle carbon-based conductive film structure array layer 4 and the elementary structure of the top carbon-based conductive film structure array layer 6 on the computer, then print and use the printed hard film as a template to cut the purchased carbon-based conductive film product to obtain 16 elementary structures of the middle carbon-based conductive film structure array layer 4 and 16 elementary structures of the top carbon-based conductive film structure array layer 6;

[0063] ③ Using an engraving machine to engrave 16 designed square frequency selection unit structures of the underlying metal structure array layer 2 on the metal copper sheet;

[0064] 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, and then use commercially available high-transmittance double-sided adhesive tape to stick each dielectric substrate with the array layer together in turn, to obtain the designed electromagnetic wave absorbing and penetrating integrated lightweight metamaterial with both polarization stability and wide incident angle stability.

[0065] Depend on Figure 5 (a) It can be seen that the minimum RL of the integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide incident angle stability appears at 14.96 GHz, producing a strong absorption of -39.98 dB; the effective absorption bandwidth (RL≤-10 dB) is 10.5-16 GHz, reaching 5.5 GHz.

[0066] Depend on Figure 6 (a) It can be seen that the minimum IL of the integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide incident angle stability appears at 2.37 GHz, the insertion loss is as low as 0.66 dB, and the transmittance can reach more than 85%; the IL in the 2.09-2.69 GHz frequency band is ≤-3 dB.

[0067] Depend on Figure 7 and Figure 8It can be seen that in the TE polarization mode, when the incident angle increases from 0° to 45°, the strong absorbing performance of the absorption band of the metamaterial remains stable (absorption rate is greater than 90%); in the TM polarization mode, when the incident angle increases from 0° to 45°, the overall absorbing performance of the absorption band of the metamaterial remains stable, and the wide incident angle stability is good. This shows that the metamaterial absorber of the present invention has both excellent polarization stability and wide incident angle stability, which is due to the strong symmetry and miniaturization of the designed unit structure and elementary structure. The oblique incidence responses of the TE mode and TM mode under different polarization conditions can reach 45° and 45° respectively.

[0068] Depend on Fig. 9 and Fig.10 It can be seen that in the TE polarization mode, when the incident angle of the electromagnetic wave increases from 0° to 45°, the transmittance of the metamaterial's wave-transmitting window remains above 85%; in the TM polarization mode, when the incident angle increases from 0° to 45°, the transmittance of the metamaterial's wave-transmitting window remains almost unchanged, and the wide incident angle stability is good. This shows that the metamaterial absorber of the present invention has both excellent polarization stability and wide incident angle stability, which is due to the strong symmetry and miniaturization of the designed unit structure and elementary structure. The oblique incidence responses of the TE mode and TM mode under different polarization conditions can reach 45° and 45° respectively. Example 2

[0069] A light-weight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, including a symmetrical structure of periodically arranged 2*2 (N=2, M=2) square frequency-selective unit structures, that is, a structure including periodically arranged 4 Figure 1 The symmetrical structure of the square frequency selective unit structure shown;

[0070] The side length P of the square frequency selection 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 film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive film structure array layer 6, which are stacked in sequence from bottom to top (from top to bottom in the incident direction of electromagnetic waves);

[0071] The bottom dielectric substrate 1 is an FR-4 board with a size of 100 mm×100 mm×0.5 mm, that is, the thickness H1 is 0.5 mm and the relative dielectric constant is 4.3.

[0072] The middle-layer dielectric substrate 3 is an FR-4 board with a size of 100 mm×100 mm×1.8 mm, that is, the thickness H2 is 1.8 mm and the relative dielectric constant is 4.3.

[0073] 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.

[0074] The bottom metal structure array layer 2 has 4 (N=2, M=2) Figure 2 The basic structure shown is composed of four periodically arranged square ring holes 201, L = 19 mm, L1 = 18 mm. The material of the bottom metal structure array layer 2 is copper, and the electrical conductivity of the copper is 5.8×10 7 S / m.

[0075] The middle carbon conductive film structure array layer 4 consists of 4 Figure 3 The basic structure of the cross-shaped patch 401 located in the center is shown, L2 = 14 mm, L3 = 3 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, and has a square resistance of 110 Ω / sq.

[0076] The top carbon conductive film structure array layer 6 consists of 4 Figure 4 The basic structure shown is composed of four periodically arranged square ring patches 601, L4 = 10 mm, L5 = 15 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, and has a square resistance of 100 Ω / sq.

[0077] The manufacturing process is the same as that of Example 1, except that the materials and structural parameters are different.

[0078] Depend on Figure 5 (b) It can be seen that the minimum RL of the integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide incident angle stability appears at 15.12 GHz, producing a strong absorption of -47.7 dB; the effective absorption bandwidth (RL≤-10 dB) is 10.7-16.2 GHz, reaching 5.5 GHz.

[0079] Depend on Figure 6 (b) It can be seen that the minimum IL of this lightweight metamaterial that absorbs and transmits electromagnetic waves and has both polarization stability and wide incident angle stability appears at 2.42 GHz, the insertion loss is as low as 0.67 dB, and the transmittance can reach more than 85%; the IL in the 2.12-2.75 GHz frequency band is ≤-3 dB. Example 3

[0080] A light-weight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, including a symmetrical structure of periodically arranged 5*5 (N=5, M=5) square frequency-selective unit structures, that is, a periodically arranged 25 Figure 1 The symmetrical structure of the square frequency selective unit structure shown;

[0081] The side length P of the square frequency selection 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 film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive film structure array layer 6, which are stacked in sequence from bottom to top (from top to bottom in the incident direction of electromagnetic waves);

[0082] The bottom dielectric substrate 1 is an FR-4 board with a size of 250 mm×250 mm×0.6 mm, that is, the thickness H1 is 0.6 mm and the relative dielectric constant is 4.3.

[0083] The middle-layer dielectric substrate 3 is an FR-4 board with a size of 250 mm×250 mm×1.5 mm, that is, the thickness H2 is 1.5 mm and the relative dielectric constant is 4.3.

[0084] The middle-layer dielectric substrate 5 is an FR-4 board with a size of 250 mm×250 mm×1.3 mm, that is, the thickness H3 is 1.3 mm and the relative dielectric constant is 4.3.

[0085] There are 25 (N=5, M=5) on the bottom metal structure array layer 2 Figure 2 The basic structure shown is composed of four periodically arranged square ring holes 201, L = 21 mm, L1 = 17.5 mm. The material of the bottom metal structure array layer 2 is copper, and the electrical conductivity of the copper is 5.8×10 7 S / m.

[0086] The middle carbon conductive film structure array layer 4 consists of 25 Figure 3 The basic structure of the cross-shaped patch 401 located in the center is shown, L2 = 16 mm, L3 = 2 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, and has a square resistance of 50 Ω / sq.

[0087] The top carbon conductive film structure array layer 6 consists of 25 Figure 4 The basic structure shown is composed 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, and has a square resistance of 130 Ω / sq.

[0088] The manufacturing process is the same as that of Example 1, except that the materials and structural parameters are different.

[0089] Depend on Figure 5(c) It can be seen that the minimum RL of the integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide incident angle stability appears at 15.04 GHz, producing a strong absorption of -45.76 dB; the effective absorption bandwidth (RL≤-10 dB) is 10.6-15.9 GHz, reaching 5.3 GHz.

[0090] Depend on Figure 6 (c) It can be seen that the minimum IL of this lightweight metamaterial that absorbs and transmits electromagnetic waves and has both polarization stability and wide incident angle stability appears at 2.37 GHz, the insertion loss is as low as 0.65 dB, and the transmittance can reach more than 85%; the IL in the 2.10-2.68 GHz frequency band is ≤-3 dB. Example 4

[0091] A light-weight metamaterial that absorbs and transmits electromagnetic waves with both polarization stability and wide-incident-angle stability, including a symmetrical structure of periodically arranged 6*5 (N=6, M=5) square frequency-selective unit structures, that is, a structure including 30 periodically arranged Figure 1 The symmetrical structure of the square frequency selective unit structure shown;

[0092] The side length P of the square frequency selection 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 film structure array layer 4, a top dielectric substrate 5, and a top carbon-based conductive film structure array layer 6, which are stacked in sequence from bottom to top (from top to bottom in the incident direction of electromagnetic waves);

[0093] The bottom dielectric substrate is an FR-4 board with a size of 300 mm×250 mm×0.7 mm, that is, the thickness H1 is 0.7 mm and the relative dielectric constant is 4.3.

[0094] The middle-layer dielectric substrate is an FR-4 board with a size of 300 mm×250 mm×1.6 mm, that is, the thickness H2 is 1.6 mm and the relative dielectric constant is 4.3.

[0095] The top dielectric substrate is an FR-4 board with dimensions of 300 mm × 250 mm × 1.2 mm, that is, the thickness H3 is 1.2 mm and the relative dielectric constant is 4.3.

[0096] The bottom metal structure array layer 2 has 30 (N=6, M=5) Figure 2 The basic structure shown is composed of four periodically arranged square ring holes 201, L = 20 mm, L1 = 16 mm. The material of the bottom metal structure array layer is copper, and the electrical conductivity of the copper is 5.8×10 7 S / m.

[0097] The middle carbon conductive film structure array layer 4 consists of 30 Figure 3 The cross-shaped structure patch 401 in the center is shown, L2 = 18 mm, L3 = 4 mm. The carbon-based conductive film is made of carbon black and carbon nanotubes, and has a square resistance of 80 Ω / sq.

[0098] The top carbon conductive film structure array layer 6 consists of 30 Figure 4 The basic structure shown is composed 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, and has a square resistance of 90 Ω / sq.

[0099] The manufacturing process is the same as that of Example 1, except that the materials and structural parameters are different.

[0100] Depend on Figure 5 (d) It can be seen that the minimum RL of the integrated electromagnetic wave absorption and transmission lightweight metamaterial with both polarization stability and wide incident angle stability appears at 15.53 GHz, producing a strong absorption of -23.17 dB; the effective absorption bandwidth (RL≤-10 dB) is 11-16.10 GHz, reaching 5.1 GHz.

[0101] Depend on Figure 6 (d) It can be seen that the minimum IL of this lightweight metamaterial that absorbs and transmits electromagnetic waves and has both polarization stability and wide incident angle stability appears at 2.37 GHz, the insertion loss is as low as 0.66 dB, and the transmittance can reach more than 85%; the IL in the 2.09-2.69 GHz frequency band is ≤-3 dB.

[0102] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope 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 square frequency selection unit structure arranged periodically; The square frequency selection unit structure has a side length P of 50 mm and 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 stacked in sequence from bottom to top; the bottom metal structure array layer (2) is used 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) are used 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 central 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 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 50-110 Ω / sq; the sheet resistance of the carbon-based conductive film of the top carbon-based conductive film structure array layer (6) is 90-130 Ω / sq.

4. 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 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 plate is 4.

3.

5. 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 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 four square ring holes (201) constituting the elementary structure of the bottom metal structure array layer (2) of the square frequency selection unit structure have an outer ring side length L of 19-21 mm and an inner ring side length L1 of 16-18 mm; the cross-shaped structure patch (401) constituting the elementary structure of the middle carbon-based conductive film structure array layer (4) have four sides with a side length L2 of 14-18 mm and a width L3 of 2-4 mm; the four square ring patches (601) constituting the elementary structure of the top carbon-based conductive film structure array layer (6) have an inner ring side length L4 of 7-10 mm and an outer ring side length L5 of 15-18 mm.

7. A method for preparing a lightweight metamaterial having both polarization stability and wide incident angle stability for absorbing and transmitting electromagnetic waves according to any one of claims 1 to 6, characterized in that: The steps include: ① Design a square frequency selective unit structure with N*M, where N and M are both positive integers, and arrange the symmetrical metamaterial in an array, and cut the bottom dielectric substrate (1), the middle dielectric substrate (3) and the top dielectric substrate (5) according to the design; ② Using the elementary structure composed of the cross-shaped structure 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; ③ Based on the elementary structure composed of four square ring holes (201) of the bottom metal structure array layer (2), a carving machine is used to carve out the designed N*M elementary structures on the metal patch; ④ Draw the corresponding unit structure position on each dielectric substrate obtained in step ①, paste the unit structure of the corresponding array layer on each dielectric substrate, and then paste the dielectric substrates with array layers together in turn to complete the preparation of the electromagnetic wave absorbing and penetrating integrated lightweight metamaterial with both polarization stability and wide incident angle stability.

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