Wave-absorbing metamaterial with infrared / radar compatible function

Abstract

The invention provides a wave-absorbing metamaterial with an infrared / radar compatible function, and relates to the technical field of wave-absorbing materials, and the wave-absorbing metamaterial comprises an infrared reflection layer, a first bearing layer, a broadband impedance matching layer, a wave-absorbing layer and a second bearing layer which are sequentially arranged from top to bottom; the infrared reflecting layer is used for reflecting infrared radiation to realize low infrared emissivity; the first bearing layer is used for bearing the infrared reflecting layer; the broadband impedance matching layer is used for improving the broadband impedance matching performance of a radar band; the wave absorbing layer is used for absorbing electromagnetic energy of a radar wave band; the second bearing layer is used for bearing the wave absorbing layer. The wave-absorbing metamaterial with the infrared / radar compatible function provided by the invention has both infrared low emission performance and radar broadband absorption performance.

Description

Technical Field

[0001] The invention belongs to the technical field of wave-absorbing materials, and in particular relates to a wave-absorbing metamaterial with infrared / radar compatible functions. Background Art

[0002] With the widespread application of multi-spectrum reconnaissance technology, detection suppression materials that are sensitive to a single frequency band are difficult to improve the survival rate of high-value targets in the complex electromagnetic environment of infrared / radar cross-detection. Electromagnetic metamaterials are artificial structures with sub-wavelength scales that can flexibly control the electromagnetic properties of targets in different frequency bands by changing the geometric dimensions of the unit structure.

[0003] Most of the existing infrared / radar compatible functional materials are sprayed with a thick coating on the target surface, which cannot meet the engineering requirements of "thin, light, wide and strong" for radar absorbing materials. At the same time, the average emissivity of the coating structure in the infrared band is relatively high, making it difficult to take into account both the infrared low emissivity performance and the radar broadband absorption performance, and cannot adapt to the needs of modern industrialization.

[0004] Therefore, there is an urgent need to provide a metamaterial that has both low infrared emission performance and broadband radar absorption performance. Summary of the invention

[0005] In view of one or more problems existing in the prior art, the present invention provides an infrared / radar compatible absorbing metamaterial. The infrared / radar compatible absorbing metamaterial provided by the present invention has both infrared low emissivity and radar broadband absorption performance, can achieve a return loss of less than -10dB in a wider radar operating frequency band (4.06 to 20.68GHz), and has a lower infrared emissivity in the infrared band of 8 to 14μm.

[0006] The present invention provides an infrared / radar compatible functional absorbing metamaterial, the absorbing metamaterial comprising an infrared reflecting layer, a first bearing layer, a broadband impedance matching layer, an absorbing layer and a second bearing layer arranged in sequence from top to bottom;

[0007] The infrared reflection layer is used to reflect infrared radiation to achieve low infrared emissivity;

[0008] The first bearing layer is used to bear the infrared reflection layer;

[0009] The broadband impedance matching layer is used to improve the broadband impedance matching performance of the radar band;

[0010] The wave absorbing layer is used to absorb electromagnetic energy in the radar band;

[0011] The second bearing layer is used for bearing the absorbing layer.

[0012] Preferably, the infrared reflective layer is a low infrared emissivity coating;

[0013] The first bearing layer is a polyimide film;

[0014] The material of the broadband impedance matching layer is a polyurethane foam containing a wave absorber;

[0015] The material of the wave absorption layer is a polyethylene terephthalate film sputtered with indium tin oxide on the surface; and / or

[0016] The second bearing layer is a polymethacrylimide foam.

[0017] Preferably, the infrared reflection layer includes a plurality of square infrared reflection units arranged periodically; the side length of the square infrared reflection unit is 0.43 - 0.53 mm.

[0018] Preferably, the period of the arrangement of the square reflection units is 0.45 - 0.57 mm.

[0019] Preferably, the real part of the relative dielectric constant of the broadband impedance matching layer is 5.6 - 7.3; and / or

[0020] The thickness of the broadband impedance matching layer is 2.6 - 3.3 mm.

[0021] Preferably, the wave absorption layer includes a plurality of wave absorption units arranged periodically; the wave absorption unit includes a plurality of concentric open cross-shaped structures from the outside to the inside; the openings of the open cross-shaped structures are arranged at the four corners of the outer frame of the cross-shaped structure, separating the outer frame of the cross-shaped structure into four non-connected congruent isosceles trapezoids.

[0022] Preferably, the wave absorption unit includes a first open cross-shaped structure, a second open cross-shaped structure, and a third open cross-shaped structure that are concentric from the outside to the inside;

[0023] The length of the lower base of the trapezoid in the first open cross-shaped structure is 13.6 - 14.1 mm, and the height is 1.3 - 2.7 mm;

[0024] The length of the lower base of the trapezoid in the second open cross-shaped structure is 9.1 - 11.6 mm, and the height is 1.3 - 2.7 mm; and / or

[0025] The length of the lower base of the trapezoid in the third open cross-shaped structure is 6.2 - 8.4 mm, and the height is 0.5 - 1.2 mm.

[0026] Preferably, the period of the arrangement of the wave absorption units is 14.2 - 16.7 mm.

[0027] Preferably, the inherent sheet resistance of the wave absorption layer is 54 - 78 Ω / sq.

[0028] Preferably, the thickness of the first bearing layer is 0.16-0.18 mm; and / or

[0029] The thickness of the second bearing layer is 2.8-3.6 mm.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] The present invention sets an infrared reflection layer on the side where the electromagnetic wave is incident to achieve the infrared low emissivity function; a broadband impedance matching layer is set in the middle to improve the broadband impedance matching performance of the radar band; and the wave absorbing layer is used to absorb the electromagnetic energy of the radar band. The infrared / radar compatible wave absorbing metamaterial provided by the present invention can achieve a return loss of less than -10dB in a wider radar operating frequency band (4.06 to 20.68GHz) and has a lower infrared emissivity in the infrared band of 8 to 14μm, which effectively solves the problem that the existing wave absorbing metamaterials are difficult to take into account both infrared low emissivity and radar broadband absorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 2 is a schematic diagram of the structure of an infrared / radar compatible absorbing metamaterial provided by an embodiment of the present invention;

[0034] Figure 2 It is a schematic structural diagram of an infrared reflection unit of an infrared / radar compatible absorbing metamaterial provided by an embodiment of the present invention;

[0035] Figure 3 It is a schematic structural diagram of an absorbing unit of an absorbing metamaterial with infrared / radar compatible functions provided by an embodiment of the present invention;

[0036] Figure 4 It is a comparison diagram of a measured return loss curve of an infrared / radar compatible absorbing metamaterial provided by an embodiment of the present invention and a simulated return loss curve of a metamaterial structure simulated by CST;

[0037] Figure 5 This is a measured infrared emissivity curve of the infrared / radar compatible absorbing metamaterial provided by an embodiment of the present invention in the 8-14 μm infrared band.

[0038] Reference numerals:

[0039] 1-infrared reflection layer; 11-square reflection unit; 2-first bearing layer; 3-broadband impedance matching layer; 4-wave absorbing layer; 41-wave absorbing unit; 5-second bearing layer; L1-the bottom length of the trapezoid in the first open field-shaped structure; w 1- The height of the trapezoid in the first open field-shaped structure; L2-the length of the lower base of the trapezoid in the second open field-shaped structure; w2-the height of the trapezoid in the second open field-shaped structure; L3-the length of the lower base of the trapezoid in the third open field-shaped structure; w3-the height of the trapezoid in the third open field-shaped structure; p-the arrangement period of the square reflection unit; t-the arrangement period of the absorbing unit; the bottom angle β of the trapezoid in the open field-shaped structure. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] like Figure 1 As shown, an infrared / radar compatible functional absorbing metamaterial comprises an infrared reflecting layer 1, a first bearing layer 2, a broadband impedance matching layer 3, an absorbing layer 4 and a second bearing layer 5 arranged in sequence from top to bottom;

[0042] The infrared reflective layer 1 is used to reflect infrared radiation to achieve low infrared emissivity;

[0043] The first bearing layer 2 is used to bear the infrared reflection layer;

[0044] The broadband impedance matching layer 3 is used to improve the broadband impedance matching performance of the radar band;

[0045] The wave absorbing layer 4 is used to absorb electromagnetic energy in the radar band;

[0046] The second bearing layer 5 is used to bear the absorbing layer.

[0047] The present invention sets an infrared reflection layer on the side where the electromagnetic wave is incident, which can reflect most of the infrared radiation back to the free space, and realize the infrared low emissivity function of the absorbing metamaterial; a broadband impedance matching layer is set in the middle, which can improve the impedance adaptation effect caused by the pattern structure size problem of the infrared reflection layer and the absorbing layer, and improve the broadband impedance matching performance of the radar band; the absorbing layer is used to absorb electromagnetic energy in the radar band. The absorbing metamaterial with infrared / radar compatible function provided by the present invention can achieve a return loss of less than -10dB in a wider radar operating frequency band (4.06~20.68GHz), and has a lower infrared emissivity in the infrared band of 8~14μm, which effectively solves the problem that the existing absorbing metamaterials are difficult to take into account both infrared low emissivity and radar broadband absorption performance.

[0048] It should be noted that, in the infrared / radar compatible absorbing metamaterial provided by the present invention, each layer is laminated by adhesive film by vacuum bag pressing.

[0049] In some embodiments, the infrared reflective layer 1 is a low infrared emissivity coating.

[0050] In some preferred embodiments, the low infrared emissivity coating is a low infrared emissivity coating comprising flaky aluminum powder and waterborne polyurethane resin; its preparation method comprises: mixing flaky aluminum powder with waterborne polyurethane resin, film former and auxiliary agent to obtain low emissivity coating slurry; wherein, flaky aluminum powder accounts for 8-14wt%, waterborne polyurethane resin accounts for 85-90wt%, and film former and auxiliary agent account for 1-2wt%. Use a spray gun to evenly spray on the first bearing layer, dry, and form a low infrared emissivity coating on the surface of the first bearing layer. Specifically: evenly mix flaky aluminum powder and waterborne polyurethane resin, use a special film former and other auxiliary agents to adjust the viscosity of the slurry to obtain a low emissivity coating slurry, use a spray gun to evenly spray the low emissivity coating slurry on the first bearing layer, place it in an oven, adjust the oven temperature to 85°C, dry the uncured coating for 12 hours, and form a low emissivity coating on the first bearing layer; then use a laser etching process to etch the low emissivity coating into a specific pattern according to demand, and an infrared reflective layer can be obtained.

[0051] In some embodiments, the first carrier layer 2 is a polyimide film.

[0052] In some embodiments, the material of the broadband impedance matching layer 3 is polyurethane foam containing an absorbent;

[0053] In some preferred embodiments, the material of the broadband impedance matching layer is a modified polyurethane foam containing carbon black, preferably a modified polyurethane foam containing carbon black and epoxy resin; its preparation method includes: mixing isocyanate, epoxy resin, carbon black, foaming agent and auxiliary agent to obtain modified polyurethane slurry; curing and molding the modified polyurethane slurry to obtain modified polyurethane foam; wherein isocyanate accounts for 12-18wt%, epoxy resin accounts for 80-85wt%m, and foaming agent and auxiliary agent account for 2-8wt%; the curing temperature is 80°C and the time is 2h. Specifically: adding isocyanate to epoxy resin three times, adjusting the viscosity of the slurry by using foaming agent and auxiliary agent, adding a certain proportion of carbon black powder to improve the relative dielectric constant of the slurry, and obtaining modified polyurethane slurry. Pour the modified polyurethane slurry into a custom metal trough with dimensions of 320mm×320mm×10mm and let it stand for 1 hour. Then adjust the oven temperature to 80°C and dry it for 2 hours. After the foam is cured and formed, cut it into cubes with a height of 2.6mm to 3.3mm for use. The real part of the relative dielectric constant measured by the coaxial method is 5.6 to 7.3.

[0054] In some embodiments, the material of the wave absorbing layer 4 is a polyethylene terephthalate film with indium tin oxide sputtered on the surface. The preparation method of the wave absorbing layer includes: first pre-treating the surface of the polyethylene terephthalate, uniformly sputtering indium tin oxide particles onto the surface of the treated polyethylene terephthalate film by a magnetron sputtering instrument, and after curing at room temperature, the polyethylene terephthalate film with indium tin oxide sputtered on the surface is processed into a desired pattern by a laser etching process according to the use requirements to obtain the wave absorbing layer. By controlling the sputtering thickness of the indium tin oxide particles during the sputtering process, a film with different square resistances can be obtained, preferably a film with an intrinsic square resistance of 54 to 78Ω / sq as the material of the absorption layer.

[0055] In some embodiments, the second bearing layer 5 is polymethacrylimide foam.

[0056] like Figure 2 As shown, in some embodiments, the infrared reflection layer 1 includes a plurality of periodically arranged square infrared reflection units 11; the side length a of the square infrared reflection units is 0.43-0.53 mm.

[0057] In some embodiments, the period p of the arrangement of the square reflection units 11 is 0.45-0.57 mm.

[0058] The present invention adopts a low infrared emissivity coating as an infrared reflective layer, which can reflect most of the infrared radiation back to the free space. At the same time, the gaps between the square reflective units (square patterns) can transmit radar waves, allowing them to enter the metamaterial structure to dissipate energy.

[0059] In some embodiments, the real part of the relative permittivity of the broadband impedance matching layer 3 is 5.6 to 7.3. The present invention corrects the impedance matching effect caused by the pattern structure size problems of the infrared reflection layer and the wave absorbing layer by customizing the broadband impedance matching layer with a relative permittivity, and improves the impedance matching performance of the wave absorbing metamaterial.

[0060] In some embodiments, the thickness of the broadband impedance matching layer 3 is 2.6 to 3.3 mm.

[0061] In some embodiments, the wave absorbing layer 4 includes a plurality of periodically arranged wave absorbing units 41; the wave absorbing unit 41 includes a plurality of concentric open cross-shaped structures from outside to inside; the openings of the open cross-shaped structures are arranged at the four corners of the outer frame of the cross-shaped structure, and the outer frame of the cross-shaped structure is divided into four non-connected congruent isosceles trapezoids.

[0062] The present invention flexibly controls the operating frequency and the maximum amplitude of the radar wave energy absorption by adjusting and optimizing the pattern and geometric parameters of the wave absorbing units in the wave absorbing layer, so as to ensure that a wave absorbing metamaterial with excellent wave absorbing performance is obtained.

[0063] As Figure 3 shown, in some embodiments, the wave absorbing unit 41 includes a first open cross-shaped structure, a second open cross-shaped structure and a third open cross-shaped structure that are concentric from outside to inside.

[0064] In some embodiments, the length of the lower base L1 of the trapezoid in the first open cross-shaped structure is 13.6 to 14.1 mm, and the height w1 is 1.3 to 2.7 mm.

[0065] In some embodiments, the length of the lower base L2 of the trapezoid in the second open cross-shaped structure is 9.1 to 11.6 mm, and the height w2 is 1.3 to 2.7 mm.

[0066] In some embodiments, the length of the lower base L3 of the trapezoid in the third open cross-shaped structure is 6.2 to 8.4 mm, and the height w3 is 0.5 to 1.2 mm.

[0067] In some preferred embodiments, the base angle β of the trapezoid in the open cross-shaped structure is 45°.

[0068] In some embodiments, the period t of the arrangement of the wave absorbing units is 14.2 to 16.7 mm.

[0069] In some embodiments, the intrinsic sheet resistance of the wave absorbing layer 4 is 54 to 78 Ω / sq.

[0070] In some embodiments, the thickness of the first carrier layer 2 is 0.16 to 0.18 mm; and / or

[0071] The thickness of the second bearing layer 5 is 2.8-3.6 mm.

[0072] In some specific embodiments of the present invention, Figure 1-3 As shown, the infrared / radar compatible functional absorbing metamaterial includes: an infrared reflection layer 1, a first bearing layer 2, a broadband impedance matching layer 3, an absorbing layer 4 and a second bearing layer 5 arranged in sequence from top to bottom; the material of the infrared reflection layer 1 is a low infrared emissivity coating containing flaky aluminum powder and water-based polyurethane resin. The infrared reflection layer 1 includes a plurality of periodically arranged square infrared reflection units 11, the side length a of the square infrared reflection unit is 0.43 to 0.53 mm, and the period p of the arrangement of the square reflection units 11 is 0.45 to 0.57 mm. The material of the first bearing layer 2 is a polyimide film with a thickness of 0.16 to 0.18 mm. ； The material of the broadband impedance matching layer 3 is a modified polyurethane foam containing carbon black and epoxy resin, the real part of the relative dielectric constant is 5.6-7.3, and the thickness is 2.6-3.3 mm. The absorbing layer 4 is a polyethylene terephthalate film with indium tin oxide sputtered on the surface, and the inherent square resistance is 54-78Ω / sq. The absorbing layer 4 includes a plurality of periodically arranged absorbing units 41; the period t of the arrangement of the absorbing units is 14.2-16.7 mm, and the absorbing unit 41 includes a first open field-shaped structure, a second open field-shaped structure, and a third open field-shaped structure that are concentric from the outside to the inside; the opening of the open field-shaped structure is set at the four corners of the outer frame of the field-shaped structure, dividing the outer frame of the field-shaped structure into four non-connected congruent isosceles trapezoids, and the base angle β of the isosceles trapezoid in the open field-shaped structure is 45°. The length L1 of the bottom base of the trapezoid in the first open field-shaped structure is 13.6-14.1 mm, and the height w1 is 1.3-2.7 mm. The length L2 of the bottom base of the trapezoid in the second open field-shaped structure is 9.1-11.6 mm, and the height w2 is 1.3-2.7 mm. The length L3 of the bottom base of the trapezoid in the third open field-shaped structure is 6.2-8.4 mm, and the height w3 is 0.5-1.2 mm. The material of the second bearing layer 5 is polymethyl methacrylimide foam with a thickness of 2.8-3.6 mm. The parameters of each layer of the above-mentioned infrared / radar compatible functional absorbing metamaterial provided by the present invention are set within the above-mentioned range to ensure that the absorbing material has both infrared low emission performance and radar broadband absorption performance.

[0073] In order to verify that the infrared / radar compatible functional absorbing metamaterial provided by the present invention has excellent radar wave absorption performance, the inventor used a 300mm×300mm absorbing metamaterial structure as a test sample, and verified the electromagnetic wave absorption characteristics of the test sample through the "arch frame + broadband double horn antenna" test system; Figure 4As shown in the figure (the horizontal axis is frequency, and the vertical axis is return loss), the test sample has a return loss below -10dB in the operating frequency band of 4.06 to 20.68 GHz, and the experimental test curve (circle) and the simulation curve (pentagram) have a good fit and the change trends are relatively consistent.

[0074] In order to verify that the infrared / radar compatible functional absorbing metamaterial provided by the present invention has excellent infrared low emissivity performance, the inventor used a 20mm×20mm absorbing metamaterial structure as a test sample, and verified the emissivity of the test sample in the infrared wavelength range of 8 to 14 μm using a Bruker v70 infrared band comprehensive tester; Figure 5 As shown in the figure (the horizontal axis is wavelength, and the vertical axis is infrared emissivity), the average infrared emissivity of the test sample in the infrared wavelength range of 8 to 14 μm is 0.205, which has low infrared reflection characteristics.

[0075] In summary, the infrared / radar compatible absorbing metamaterial provided by the present invention has both infrared low-emission performance and radar broadband absorption performance, can achieve a return loss below -10dB in a wider radar operating frequency band (4.06-20.68GHz), and has a lower infrared emissivity in the infrared band of 8-14μm.

[0076] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first", "second", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple groups" refers to two or more groups; the terms "connected", "fixed", etc. should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An infrared / radar compatible functional absorbing metamaterial, characterized in that: The wave-absorbing metamaterial includes an infrared reflection layer, a first carrier layer, a broadband impedance matching layer, a wave-absorbing layer, and a second carrier layer, which are arranged in sequence from top to bottom; The infrared reflection layer is used to reflect infrared radiation and achieve a low infrared emissivity; The first carrier layer is used to carry the infrared reflection layer; The broadband impedance matching layer is used to improve the broadband impedance matching performance in the radar band; The wave-absorbing layer is used to absorb electromagnetic energy in the radar band; The second carrier layer is used to carry the wave-absorbing layer.

2. The wave absorbing metamaterial according to claim 1, characterized in that: The infrared reflection layer is a low infrared emissivity coating; The first carrier layer is a polyimide film; The material of the broadband impedance matching layer is a polyurethane foam containing a wave-absorbing agent; The material of the wave-absorbing layer is a polyethylene terephthalate film sputtered with indium tin oxide on the surface; and / or The second carrier layer is a polymethacrylimide foam.

3. The electromagnetic absorbing metamaterial according to claim 1, characterized in that: The infrared reflection layer includes a plurality of square infrared reflection units arranged periodically; the side length of the square infrared reflection unit is 0.43 - 0.53 mm.

4. The electromagnetic absorbing metamaterial according to claim 3, characterized in that: The period of the arrangement of the square reflection units is 0.45 - 0.57 mm.

5. The electromagnetic absorbing metamaterial according to claim 2, characterized in that: The real part of the relative permittivity of the broadband impedance matching layer is 5.6 - 7.3; and / or The thickness of the broadband impedance matching layer is 2.6 - 3.3 mm.

6. The wave absorbing metamaterial according to claim 1, characterized in that: The wave-absorbing layer includes a plurality of wave-absorbing units arranged periodically; each wave-absorbing unit includes a plurality of concentric open cross-shaped structures from outside to inside; the openings of the open cross-shaped structures are arranged at the four corners of the outer frame of the cross-shaped structure, dividing the outer frame of the cross-shaped structure into four non-connected congruent isosceles trapezoids.

7. The wave absorbing metamaterial according to claim 6, characterized in that: The wave-absorbing unit includes a first open cross-shaped structure, a second open cross-shaped structure, and a third open cross-shaped structure that are concentric from outside to inside; In the first open cross-shaped structure, the length of the lower base of the trapezoid is 13.6 - 14.1 mm, and the height is 1.3 - 2.7 mm; In the second open cross-shaped structure, the length of the lower base of the trapezoid is 9.1 - 11.6 mm, and the height is 1.3 - 2.7 mm; and / or In the third open cross-shaped structure, the length of the lower base of the trapezoid is 6.2 - 8.4 mm, and the height is 0.5 - 1.2 mm.

8. The wave absorbing metamaterial according to claim 6, characterized in that: The period of the arrangement of the wave-absorbing units is 14.2 - 16.7 mm.

9. The electromagnetic absorbing metamaterial according to claim 2, characterized in that: The intrinsic sheet resistance of the wave-absorbing layer is 54 - 78 Ω / sq.

10. The electromagnetic absorbing metamaterial according to claim 2, characterized in that: The thickness of the first carrier layer is 0.16 - 0.18 mm; and / or The thickness of the second carrier layer is 2.8 - 3.6 mm.

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