Electromagnetic wave absorbing materials, devices and waveguide devices

Abstract

The present invention relates to an electromagnetic wave absorbing material, device and waveguide device. The electromagnetic wave absorbing material includes a substrate having an electromagnetic wave incident surface; a plurality of wave absorbing materials disposed in the substrate and arranged obliquely along at least one preset axis; and along the preset axis, the distance between two adjacent wave absorbing materials is less than the wavelength of the incident electromagnetic wave, and the thickness of each wave absorbing material is less than this distance; an antireflection material disposed on the electromagnetic wave incident surface; and moreover, each of the wave absorbing materials is obliquely disposed relative to the preset axis within a range of adding and subtracting a preset angle from the corresponding absorption inclination angle to absorb electromagnetic waves. The above electromagnetic wave absorbing material breaks through the limitation of achieving perfect absorption of electromagnetic waves under the original Brewster angle, and broadens the application range of electromagnetic wave absorbing materials in engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic wave absorption, and particularly to an electromagnetic wave absorbing material. Background Art

[0002] The research on electromagnetic wave absorption has always been a hot topic in the field of electromagnetic waves. Electromagnetic wave perfect absorbers are very important both in engineering applications and in national defense and military. Usually, the impedance of general electromagnetic wave absorbing materials cannot be directly matched with the impedance of air. Therefore, while absorbing electromagnetic waves, a relatively large amount of electromagnetic waves are also reflected, which cannot better meet the corresponding engineering application requirements.

[0003] In order to reduce reflection to achieve perfect absorption, researchers have proposed various methods:

[0004] (1) Methods such as designing an antireflection film with a thickness of a quarter wavelength and designing a surface microstructure (such as an absorbing sponge with a pyramidal surface) are used to achieve impedance matching to eliminate reflection, thereby achieving perfect absorption of electromagnetic waves. These methods can achieve absorption of electromagnetic waves with a relatively wide frequency range, but their thickness is often relatively large. For example, the thickness of the absorbing sponge is much larger than the wavelength of electromagnetic waves.

[0005] (2) Designing electromagnetic wave absorbing materials based on electromagnetic metamaterials and surface plasmon polaritons. These methods usually have the following several problems. One is that they are only applicable to the absorption of electromagnetic waves in a relatively narrow frequency band. The second is that it is difficult to achieve flexible regulation of electromagnetic wave absorption. The third is that it is difficult to absorb electromagnetic waves with a large incident angle (such as greater than or equal to 80°). Summary of the Invention

[0006] To solve at least one of the above problems, the present invention aims to provide a thin, flexible, and effective electromagnetic wave absorbing material, device, and waveguide device.

[0007] In a first aspect, the present application provides an electromagnetic wave absorbing material, including:

[0008] a substrate having an electromagnetic wave incident surface;

[0009] a plurality of wave absorbing materials disposed in the substrate and arranged obliquely along at least one preset axis; and, along the preset axis, there is a preset interval between two adjacent wave absorbing materials, the preset interval being less than the wavelength of the incident electromagnetic wave, and the thickness of each wave absorbing material being less than the preset interval;

[0010] an antireflection material disposed on the electromagnetic wave incident surface and configured to reduce the reflection of the incident electromagnetic wave;

[0011] Moreover, each of the absorbing materials has a first inclination angle with respect to the preset axis, and the electromagnetic wave incident on each of the absorbing materials has a second inclination angle with respect to the preset axis; when the first inclination angle of any absorbing material is symmetric to the second inclination angle of the electromagnetic wave incident on the absorbing material with respect to the preset axis, the first inclination angle of the absorbing material is the absorption inclination angle corresponding to the absorbing material;

[0012] Wherein, each of the absorbing materials is inclined with respect to the preset axis within a range of adding and subtracting a preset angle from the corresponding absorption inclination angle to absorb electromagnetic waves.

[0013] The above electromagnetic wave absorbing material, by providing an anti-reflection material on the electromagnetic wave incident surface of the substrate, is beneficial to improving the transmittance of the electromagnetic wave incident at different incident angles into the substrate, so that the electromagnetic wave incident at almost any angle can be perfectly absorbed within a relatively wide frequency band range, and at the same time, the electromagnetic wave incident at a large angle is also perfectly absorbed, breaking through the limitation of realizing perfect absorption of electromagnetic waves at a specific angle (Brewster angle) originally, and broadening the application range of the electromagnetic wave absorbing material in engineering.

[0014] Optionally, the absorption inclination angle is greater than 0° and less than 90°.

[0015] Optionally, the anti-reflection material includes a dielectric multilayer structure, and the dielectric multilayer structure includes:

[0016] Two first dielectric layers, respectively provided on both sides of the dielectric multilayer structure, the first dielectric layer having a first preset thickness; and, one second dielectric layer, provided between the two first dielectric layers, the second dielectric layer having a second preset thickness; the first preset thickness and the second preset thickness are configured to cause the incident electromagnetic wave to interfere and reduce the reflection of the incident electromagnetic wave.

[0017] Optionally, the anti-reflection material includes a conductive thin film, the conductive thin film having a third preset thickness, the third preset thickness being configured to cause the incident electromagnetic wave to interfere and reduce the reflection of the incident electromagnetic wave.

[0018] Optionally, the ratio of the third preset thickness to the wavelength of the incident electromagnetic wave is less than or equal to Or, the ratio of the third preset thickness to the wavelength of the incident electromagnetic wave is less than or equal to

[0019] Optionally, the plurality of absorbing materials include a plurality of absorbing material lines arranged in an array.

[0020] Optionally, the absorbing material line includes a plurality of dielectric material lines for absorbing transverse magnetic waves and / or a plurality of magnetic material lines for absorbing transverse electric waves.

[0021] Optionally, the same type of electromagnetic wave absorbing material lines are arranged at intervals along the first axis, and different types of electromagnetic wave absorbing material lines are alternately arranged at intervals along a second axis perpendicular to the first axis.

[0022] Optionally, along the first axis, there is a first spacing distance D1 between two adjacent same-type electromagnetic wave absorbing material lines; along the second axis, there is a second spacing distance D2 between two adjacent different-type electromagnetic wave absorbing material lines; the first spacing distance D1 and the second spacing distance D2 satisfy: D2 ≤ D1 ≤ 2D2.

[0023] Optionally, the range of the preset angle is 0 to 10°.

[0024] Optionally, the thickness of the anti-reflection material is less than the wavelength of the incident electromagnetic wave; or, the thickness of the anti-reflection material is less than or equal to one-half of the wavelength of the incident electromagnetic wave.

[0025] Optionally, the material of the substrate includes at least one of glass, foam plastic, and plexiglass.

[0026] In a second aspect, the present application further provides an electromagnetic wave absorption device for shielding electromagnetic waves, including the electromagnetic wave absorption material as described above.

[0027] The above-mentioned electromagnetic wave absorption device can make electromagnetic waves incident at almost any angle be absorbed more perfectly, and at the same time, it also realizes the more perfect absorption of electromagnetic waves incident at a large angle, breaking through the limitation of achieving perfect absorption of electromagnetic waves at a specific angle (Brewster angle) originally, and broadening the application range of the electromagnetic wave absorption device in engineering.

[0028] In a third aspect, the present application further provides a waveguide device, including the above-mentioned electromagnetic wave absorption device provided at a preset position of the waveguide device.

[0029] The above-mentioned waveguide device can effectively absorb electromagnetic waves by arranging the above-mentioned electromagnetic wave absorption device at a preset position, so as to meet the application requirements of the waveguide device for electromagnetic waves in different working scenarios. Description of the Drawings

[0030] In order to more clearly illustrate the embodiments of the present specification or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present specification. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 A schematic structural diagram of the electromagnetic wave absorption material shown in the patent with the publication number CN111478057B;

[0032] Figure 2 Schematic diagram of the structure of the electromagnetic wave absorbing material according to an embodiment of the present application;

[0033] Figure 3 Schematic diagram of the structure of the electromagnetic wave absorbing material according to another embodiment of the present application;

[0034] Figure 4 In figure (a) is Figure 3 Schematic diagram of the operation of the electromagnetic wave absorbing material of the illustrated embodiment when incident at positive and negative angles of TE wave;

[0035] Figure 4 In figure (b) is Figure 3 Schematic diagram of the operation of the electromagnetic wave absorbing material of the illustrated embodiment when incident at positive and negative angles of TM wave;

[0036] Figure 5 Schematic diagram of the structure of the electromagnetic wave absorbing material according to still another embodiment of the present application;

[0037] Figure 6 Is Figure 5 Schematic diagram of the operation of the electromagnetic wave absorbing material of the illustrated embodiment when incident at 70° of TM wave;

[0038] Figure 7 Is Figure 5 Graph of the electromagnetic wave absorption rate of the illustrated embodiment varying with frequency;

[0039] Figure 8 Schematic diagram of the operation of the electromagnetic wave absorbing material according to still another embodiment of the present application when incident at 80° of TM wave;

[0040] Figure 9 Is Figure 8 Graph of the electromagnetic wave absorption rate of the illustrated embodiment varying with frequency. Detailed implementation manners

[0041] To make the technical solutions and beneficial effects of the present invention more obvious and understandable, the following provides a detailed description by way of listing specific embodiments. Among them, the drawings are not necessarily drawn to scale, and local features can be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical and scientific fields to which the present application belongs.

[0042] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0043] As Figure 1 shown, the electromagnetic wave absorbing material 100 shown in the patent with publication number CN111478057B has a substrate 20 and an absorbing film array 10 disposed in the substrate 20. However, there are still several defects in this patent:

[0044] (1) To achieve a relatively perfect electromagnetic wave absorption effect, the electromagnetic wave absorbing material 100 needs to rely on the Brewster effect when the electromagnetic wave is incident on the substrate 20, and in combination with the electromagnetic reciprocity principle, the absorbing film array 10 is set at a specific tilt angle. Therefore, for the electromagnetic wave absorbing material 100 shown in this patent, when the material of the substrate 20 is fixed, it is limited by the Brewster angle when the electromagnetic wave is incident, and it is difficult to achieve a relatively perfect absorption of electromagnetic waves incident at any incident angle.

[0045] (2) Further, for the electromagnetic wave absorbing material 100 shown in this patent, the incident angle of the electromagnetic wave needs to satisfy θ i = -arctan(n), where n is the refractive index of the substrate 20. When θ i is close to 90°, the corresponding n needs to approach infinity, which is obviously impossible to achieve. Therefore, the electromagnetic wave absorbing material 100 shown in this patent cannot achieve a relatively perfect absorption of electromagnetic waves incident at any large incident angle.

[0046] (3) On the other hand, the electromagnetic wave absorbing material 100 shown in this patent relies on the Brewster effect, so it can only be applied to the relatively perfect absorption of transverse magnetic waves and cannot be applied to electromagnetic waves of other polarizations.

[0047] Based on the above defects, the present application provides a novel electromagnetic wave absorbing material 200 to at least achieve a relatively perfect absorption of electromagnetic waves incident at any incident angle.

[0048] As Figure 2As shown, the electromagnetic wave absorbing material 200 includes: a substrate 40 having an electromagnetic wave incident surface P; a plurality of wave absorbing materials disposed in the substrate 40 and arranged obliquely along at least one preset axis (such as axis AY); and, along axis AY, there is a preset interval a between two adjacent wave absorbing materials, and the preset interval a is less than the wavelength of the incident electromagnetic wave, and the thickness d of each wave absorbing material is less than the preset interval a. Wherein, the preset interval a represents the distance between the centers of two adjacent wave absorbing materials on axis AY, and the thickness d of the wave absorbing material represents the material thickness of the wave absorbing material along the normal direction of its electromagnetic wave incident surface.

[0049] Optionally, the material of the substrate 40 can be glass, foam plastic or plexiglass. In some other embodiments, it can also be a fluid such as air or water, and can be specifically selected according to the actual application scenarios and requirements. When selected as a solid material, it can be used as a sheet or block for electromagnetic shielding. For example, the sheet or block can be used to prepare or attach to different electronic devices, driving devices (such as vehicles, airplanes, tanks), base stations, and can also be used to prepare boxes and walls with electromagnetic shielding functions. It should be noted that when the relative permittivity of the substrate 40 is the same as or close to the relative permittivity of the electromagnetic wave incident medium, for example, when the electromagnetic wave incident medium is air (relative permittivity is 1), and the substrate 40 is air or foam plastic (relative permittivity is about 1.05 - 1.1), it can be considered that when the electromagnetic wave is incident on the substrate 40, refraction hardly occurs.

[0050] Optionally, as Figure 2 shown, the plurality of wave absorbing materials can also include a plurality of different types of wave absorbing materials 103' and a plurality of wave absorbing materials 104'; optionally, the wave absorbing material 103' can be used to absorb transverse magnetic waves (TM waves), and the wave absorbing material 104' can be used to absorb transverse electric waves (TE waves). Of course, the plurality of wave absorbing materials can also include a plurality of wave absorbing materials of the same type. Optionally, the material of the wave absorbing material can be wave absorbing sponge, indium tin oxide, metal, graphene, etc. Optionally, the thickness d of the wave absorbing material is less than or equal to one-fifth of the preset interval a, so as to be conducive to ensuring that when the electromagnetic wave is incident along the direction parallel to the surface of the wave absorbing material, the wave absorbing material hardly exerts any influence on the electromagnetic wave.

[0051] It should be noted that in addition to being arranged obliquely along axis AY, the plurality of wave absorbing materials can also be arranged along axis AX extending parallel to the x direction (perpendicular to the paper surface). Of course, they can also be arranged along any axis in the x - y plane, and can be specifically selected according to the actual situation. This application does not make any restrictions on this.

[0052] In addition, each wave absorbing material has a first inclination angle with respect to axis AY (such as Figure 2 shown α1, α2), and the electromagnetic wave incident on each wave absorbing material has a second inclination angle with respect to axis AY (such asFigure 2 (β1, β2 as shown); when the first inclination angle of any wave-absorbing material is symmetric with respect to the axis AY to the second inclination angle of the electromagnetic wave incident on the wave-absorbing material, the first inclination angle of the wave-absorbing material is the absorption inclination angle corresponding to the wave-absorbing material. Wherein, each wave-absorbing material is inclined with respect to the axis AY within a range of plus or minus a preset angle of the corresponding absorption inclination angle, so as to absorb electromagnetic waves through the electromagnetic reciprocity effect.

[0053] Although the above structure can achieve the absorption of electromagnetic waves, it is limited by the Brewster angle, and the adjustment freedom of the incident angle is too small, which is not conducive to engineering applications. Therefore, we have made at least the following improvements. Please continue to refer to Figure 2 The electromagnetic wave absorbing material 200 further includes an antireflection material 30. The antireflection material 30 is disposed on the electromagnetic wave incident surface P and is configured to reduce the reflection of the incident electromagnetic wave. Optionally, the antireflection material 30 is configured to achieve the antireflection effect by causing multiple reflections of the electromagnetic wave in the antireflection material 30 and then causing interference cancellation. Optionally, the antireflection material 30 can utilize a multi-layer dielectric structure, a single-layer conductive structure, a refractive index gradient structure, etc. to achieve the above antireflection effect. Wherein, the thickness of the antireflection material 30 (i.e., the thickness along the normal direction of the electromagnetic wave incident surface of the antireflection material 30) can be less than or much less than the wavelength of the incident electromagnetic wave. For example, the thickness of the antireflection material 30 can be less than one-half, one-quarter, one-eighth, etc. of the wavelength of the incident electromagnetic wave. In this way, the thickness of the electromagnetic wave absorbing material 200 can be prevented from being too thick, which is beneficial to ensuring its engineering application range.

[0054] It should be noted that after the antireflection material 30 is provided, the absorption inclination angle α corresponding to the wave-absorbing material can theoretically be expressed as:

[0055]

[0056] Where ε in represents the relative dielectric constant of the medium where the electromagnetic wave is incident, ε tr represents the relative dielectric constant of the substrate 40, and θ represents the incident angle of the incident electromagnetic wave. In actual application, fine adjustment of each wave-absorbing material can be performed on the basis of this angle, so that the electromagnetic wave absorbing material 200 has a better absorption effect.

[0057] By providing an anti-reflection material 30 on the electromagnetic wave incident surface P of the substrate 40, when electromagnetic waves are incident at any incident angle, the reflection of the electromagnetic waves on the electromagnetic wave incident surface P can be effectively reduced, the transmittance of the electromagnetic waves incident at different incident angles into the substrate 40 can be increased, and more electromagnetic waves can penetrate into the substrate 40. Furthermore, through multiple absorbing materials and combined with the electromagnetic reciprocity effect, relatively perfect absorption of electromagnetic waves can be achieved within a relatively wide frequency band range, and relatively perfect absorption of electromagnetic waves incident at large angles can also be achieved, breaking through the limitation that perfect absorption of electromagnetic waves can only be achieved at the original Brewster angle, and broadening the application range of electromagnetic wave absorbing materials in engineering.

[0058] In some embodiments, the absorption inclination angle is greater than 0° and less than 90°. Optionally, the absorption inclination angle can be 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 85°, etc. By providing the anti-reflection material 30, electromagnetic waves incident at any angle can penetrate into the substrate 40 with a relatively high transmittance, so the absorption inclination angle of the absorbing material should also satisfy the setting range of 0 to 90° correspondingly to better absorb electromagnetic waves through the electromagnetic reciprocity principle.

[0059] In some embodiments, the thickness of the anti-reflection material 30 is less than or equal to a predetermined thickness. Since the thicker the anti-reflection material 30, the greater the absorption and / or energy dissipation of the electromagnetic waves, and the higher the preparation cost, the thickness of the anti-reflection material 30 should be less than or equal to a predetermined thickness to control the absorption and / or energy dissipation of the electromagnetic waves and also control the preparation cost. Optionally, the range of the preset thickness can be less than or equal to 15 mm, for example, it can be 15 mm, 12 mm, 10 mm, 8 mm, 5 mm, 1 mm, etc.

[0060] In some embodiments, as Figure 3 shown, the anti-reflection material 30 includes a dielectric multilayer structure, and the dielectric multilayer structure includes: two first dielectric layers 301 respectively provided on both sides of the dielectric multilayer structure, and the first dielectric layer 301 has a first preset thickness; and one second dielectric layer 302 provided between the two first dielectric layers 301, and the second dielectric layer 302 has a second preset thickness; the first preset thickness and the second preset thickness are configured to cause the incident electromagnetic waves to interfere and reduce the reflection of the incident electromagnetic waves.

[0061] By adopting the dielectric multilayer structure, when the reflectivity of the incident electromagnetic waves approaches 0, the layer thicknesses of the first dielectric layer 301 and the second dielectric layer 302 can be obtained by the classical transfer matrix method according to the electromagnetic parameters of the surrounding environment and the electromagnetic parameters of each layer in the multilayer structure.

[0062] Specifically, taking the incident of a transverse magnetic wave (i.e., an electromagnetic wave with the magnetic field direction perpendicular to the y-z plane) as an example, the electromagnetic wave is incident from a medium with permittivity and permeability of εin , μ in incident on a medium with permittivity and permeability ε tr , μ tr , the free-space (i.e., vacuum) wave vector can be expressed as The wave vector of the incident material (such as air) can be expressed as The wave vector of the substrate 40 can be expressed as Free-space admittance y0, incident material admittance y1, substrate 40 admittance y2.

[0063] According to the transfer matrix principle, the total transfer matrix of this multi-layer dielectric structure can be obtained as:

[0064] And,

[0065] where x A,B = a A,B ·b A,B ·k0·d A,B , ε A represents the relative permittivity of the first dielectric layer 301, ε B represents the relative permittivity of the second dielectric layer 302, d A represents the layer thickness of the first dielectric layer 301 (i.e., the first preset thickness), d B represents the layer thickness of the second dielectric layer 302 (i.e., the second preset thickness), k x represents the wave vector of the electromagnetic wave in the incident material in the x direction;

[0066] According to the reflectivity formula: It can be obtained that when the reflectivity approaches 0, the anti-reflection material 30 satisfies the following relationship: Thus, the layer thickness d A of the first dielectric layer 301 and the layer thickness d B of the second dielectric layer 302 can be further obtained.

[0067] For the transverse electric wave (i.e., the electromagnetic wave with the electric field direction perpendicular to the y-z plane), the finally obtained relationship is the same as that of the transverse magnetic wave, which will not be elaborated here. Through the above method, a multi-layer structure can be constructed using common dielectric materials to prepare the anti-reflection material 30, which is beneficial to reducing the preparation cost of the anti-reflection material 30 and at the same time will not make the thickness of the anti-reflection material 30 too thick. For example, the thickness of the anti-reflection material 30 can be controlled within a range less than half of the wavelength of the incident electromagnetic wave.

[0068] In some embodiments, such as Figure 5As shown, the anti-reflection material 30 may include a conductive thin film. In this case, the electromagnetic wave absorbing material 200 is only applicable to transverse magnetic waves. Optionally, the conductive thin film may include indium tin oxide thin film, metal thin film, graphene thin film, etc. Further, the conductive thin film has a third preset thickness, and the third preset thickness is configured to cause the incident electromagnetic wave to interfere and reduce the reflection of the incident electromagnetic wave. Since the conductive thin film needs to transmit the electromagnetic wave while serving as an anti-reflection film, the thickness of the conductive thin film is often less than the skin depth at its corresponding operating frequency, so that the conductive thin film can be made very thin. In this way, the thickness of the electromagnetic wave absorbing material 200 will not be significantly increased, thus better ensuring the adaptability of the electromagnetic wave absorbing material 200 in engineering. Optionally, the ratio of the third preset thickness to the wavelength of the incident electromagnetic wave is less than or equal to For example, the ratio may be 0.002, 0.004, 0.006, 0.008; optionally, the ratio of the third preset thickness to the wavelength of the incident electromagnetic wave is less than or equal to For example, the ratio may be 0.0002, 0.0004, 0.0006, 0.0008.

[0069] Specifically, the sheet resistance Rs of the conductive thin film satisfies the following relational expression:

[0070]

[0071] where Z0 represents the vacuum impedance, θ represents the incident angle of the incident electromagnetic wave, and the reflection coefficient

[0072] Optionally, when the incident angle of the incident electromagnetic wave is greater than the Brewster angle of the substrate 40, the conductive thin film is an absorption-type conductive thin film; when the incident angle of the incident electromagnetic wave is less than the Brewster angle of the substrate 40, the conductive thin film is a gain-type conductive thin film. Among them, the absorption-type conductive thin film shows an absorption effect on the electromagnetic wave, that is, the electromagnetic wave energy will decrease after passing through the conductive thin film; while the gain-type conductive thin film shows an enhancement effect on the electromagnetic wave, that is, the electromagnetic wave energy will increase after passing through the conductive thin film.

[0073] In some embodiments, the plurality of wave-absorbing materials include a plurality of wave-absorbing material lines arranged in an array. By using the wave-absorbing material lines, it is beneficial to broaden the incident dimension of the electromagnetic wave, so that the electromagnetic wave absorbing material 200 has a better absorption effect on the electromagnetic waves incident within any conical angle range, thus ensuring the wave absorption effect of the electromagnetic wave absorbing material 200 in actual application.

[0074] Optionally, such as Figure 2 、 Figure 3 、 Figure 5As shown, the wave-absorbing material lines may include a plurality of dielectric material lines 103 with a large imaginary part for absorbing transverse magnetic waves and / or a plurality of magnetic material lines 104 with a large imaginary part for absorbing transverse electric waves. The presence of the imaginary part in the electromagnetic parameters indicates that the material absorbs electromagnetic waves. The larger the imaginary part, the greater the absorption. According to the electromagnetic reciprocity principle, when the incident angle is θ i , the refracted electromagnetic waves in the substrate 40 will not be affected by the dielectric material lines 103 and / or the magnetic material lines 104; while when the incident angle is -θ i , the electromagnetic waves with transverse magnetic polarization will induce surface currents in the dielectric material lines 103, thereby causing a large absorption of the transverse magnetic waves. Similarly, the electromagnetic waves with transverse electric polarization will be greatly absorbed by the magnetic material lines 104.

[0075] The above settings are conducive to achieving full-polarization absorption of electromagnetic waves and ensuring the actual application effect of the electromagnetic wave absorption material 200. Optionally, the material of the dielectric material line 103 can be titanium oxide, silicon nitride, silicon carbide, silicon oxide, etc.; the material of the magnetic material line 104 can be iron, cobalt, nickel, etc.

[0076] Optionally, the same type of wave-absorbing material lines are arranged at intervals along the first axis, and different types of wave-absorbing material lines are arranged alternately at intervals along the second axis perpendicular to the first axis. Continuing to refer to Figure 2 , a plurality of dielectric material lines 103 can be arranged at intervals along the first axis (such as the x direction), and a plurality of magnetic material lines can also be arranged at intervals along the first axis, while a plurality of dielectric material lines 103 and a plurality of magnetic material lines 104 can be arranged alternately at intervals along the second axis (such as the y direction) perpendicular to the first axis. It should be noted that each wave-absorbing material line is inclined at a corresponding absorption angle with respect to the first axis and the second axis. In this way, it is conducive to ensuring a more balanced and better absorption effect for transverse electric waves and transverse magnetic waves, and at the same time, it is also conducive to simplifying the arrangement of a plurality of wave-absorbing material lines.

[0077] Optionally, along the first axis, there is a first spacing distance D1 between two adjacent wave-absorbing material lines of the same type; along the second axis perpendicular to the first axis, there is a second spacing distance D2 between two adjacent wave-absorbing material lines of different types; the first spacing distance D1 and the second spacing distance D2 satisfy: D2 ≤ D1 ≤ 2D2. The influence of the values of D2 and D1 can be manifested as the smaller the value, the greater the absorption rate of the electromagnetic wave absorption material 200; while the larger the value, the smaller the absorption rate of the electromagnetic wave absorption material 200. Of course, to avoid the occurrence of diffraction, the values of D2 and D1 should be much smaller than the wavelength and much larger than the diameter of the wave-absorbing material line. Optionally, D2 can be taken to be less than or equal to one-tenth of the wavelength of the incident electromagnetic wave.

[0078] Specifically, continuing to refer to Figure 2, take the first axis parallel to the x - direction and the second axis parallel to the y - direction. When the electromagnetic wave absorbing material 200 is applicable to both transverse electric waves and transverse magnetic waves, the first interval distance D1 between adjacent dielectric material lines 103 or adjacent magnetic material lines 104 on the first axis can be greater than or equal to the second interval distance a between adjacent two different types of wave - absorbing material lines on the second axis; while when the electromagnetic wave absorbing material 200 is only applicable to transverse magnetic waves, the first interval distance D1 between adjacent dielectric material lines 103 or adjacent magnetic material lines 104 on the first axis can be less than or equal to twice the second interval distance a between adjacent two different types of wave - absorbing material lines on the second axis.

[0079] Through the above - mentioned settings, it is beneficial to adapt the corresponding interval parameters according to different electromagnetic wave absorption situations, so as to obtain a better electromagnetic wave absorption effect.

[0080] In some embodiments, each wave - absorbing material is inclined with respect to the preset axis within an angular range of the corresponding absorption inclination angle ±10° to have a better electromagnetic wave absorption effect. Further, it can be inclined with respect to the preset axis within an angular range of the corresponding absorption inclination angle ±5°. Still further, it can be inclined with respect to the preset axis within an angular range of the corresponding absorption inclination angle ±3°. The closer the inclination angle of each wave - absorbing material is to its corresponding absorption inclination angle, the better the wave - absorbing effect of the electromagnetic wave absorbing material 200. Particularly, when the electromagnetic wave is incident perpendicularly to the electromagnetic wave absorbing material 200 (i.e., incident along the direction perpendicular to the axis AY), the wave - absorbing materials can be made to have an inclination angle of 85° - 90° (excluding 90°) with respect to the axis AY for electromagnetic wave absorption, and a better wave - absorbing effect can also be achieved.

[0081] The following refers to Figures 3 to 9 Further describe specific embodiments of the electromagnetic wave absorbing material 200 applicable to the above - mentioned embodiments. Specific Embodiment 1

[0083] The following refers to Figures 3 to 4 Describe the electromagnetic wave absorbing material 200 of Specific Embodiment 1. Figure 3 Shows a schematic structural diagram of the electromagnetic wave absorbing material 200 of Specific Embodiment 1.

[0084] As Figure 3As shown, the electromagnetic wave absorbing material 200 includes a substrate 40, and a plurality of dielectric material lines 103 and a plurality of magnetic material lines 104 that are alternately arranged at intervals along the axis AY inside the substrate 40. The plurality of dielectric material lines 103 of the same type are arranged at intervals along the axis AX (not shown in the figure) parallel to the x direction, and the plurality of magnetic material lines 104 of the same type are arranged at intervals along the axis AX (not shown in the figure) parallel to the x direction; the antireflection material 30 is provided on the electromagnetic wave incident surface P and is a dielectric multilayer structure of the "ABA" sandwich type.

[0085] Specifically, the electromagnetic wave incident medium is air (ε in = 1, μ in = 1); the material of the substrate 40 is an acrylic plate (ε tr = 2.55, μ tr = 1), with a thickness of 45 mm. The dotted line represents the normal line of the electromagnetic wave incident surface P of the substrate 40; the relative dielectric constant of the first dielectric layer 301 is ε A = 1.9, and the thickness is 3.2 mm; the relative dielectric constant of the second dielectric layer 302 is ε B = 5.52, and the thickness is 6.5 mm; each dielectric material line 103 and each magnetic material line 104 are inclined with respect to the axis AY (parallel to the y direction) at an angle near the corresponding absorption inclination angle (an angle within ±5° of the absorption inclination angle), and are alternately arranged at intervals of 2 mm along the axis AY. In the x direction, the plurality of dielectric material lines 103 are arranged at intervals of 2 mm along the axis AX (not shown in the figure) parallel to the x direction, the plurality of magnetic material lines 104 are arranged at intervals of 2 mm along the axis AX (not shown in the figure) parallel to the x direction, and the plurality of dielectric material lines 103 and the plurality of magnetic material lines 104 are also inclined with respect to the axis AX at the corresponding absorption inclination angle. The resistance of the dielectric material line 103 is 130 ohms, and the magnetic resistance of the magnetic material line is 300 ohms.

[0086] Taking the microwave model (the incident electromagnetic wave frequency is 10 GHz, and the wavelength is about 30 mm) as an example, Figure 4 shows a simulation schematic diagram of the electromagnetic wave incident from the air to the electromagnetic wave absorbing material 200.

[0087] Among them, Figure 4 (a) of shows a schematic diagram of the magnetic field distribution when the transverse electric wave (TE wave) is incident on the electromagnetic wave absorbing material 200. It can be seen that when the TE wave is incident at an incident angle θ i = 40°, the absorption inclination angle corresponding to each wave absorbing material line can be equal to the complementary angle of the refraction angle of the incident electromagnetic wave in the substrate 40. In this embodiment, the first inclination angle α of each wave absorbing material line is 66.3°. At this time, basically no reflection occurs (the reflectivity is about 0.1%), and the TE wave has a transmittance of about 86%; when the TE wave is incident at an incident angle θi When the incident angle is θ = -40° to the electromagnetic wave absorbing material 200, there is also almost no reflection. However, due to the presence of the wave-absorbing material lines, there is also almost no electromagnetic wave transmitted through the substrate 40. Specifically, the electromagnetic wave absorption rate can reach about 93%.

[0088] Figure 4 Figure (b) shows the magnetic field distribution diagram when the transverse magnetic wave (TM wave) is incident on the electromagnetic wave absorbing material 200. It can be seen that when the TM wave is incident at an incident angle θ i = 40°, the absorption inclination angles corresponding to the wave-absorbing material lines can be equal to the complementary angles of the refraction angles of the incident electromagnetic waves in the substrate 40. In this embodiment, the first inclination angle α of each wave-absorbing material line is 66.3°. At this time, there is also almost no reflection (the reflectivity is about 0.1%), and the TM wave has a transmittance of about 93%. When the TM wave is incident on the electromagnetic wave absorbing material 200 at an incident angle θ i = -40°, there is also almost no reflection. However, due to the presence of the wave-absorbing material lines, there is also almost no electromagnetic wave transmitted through the substrate 40. Specifically, the electromagnetic wave absorption rate can reach about 94%. Specific Embodiment Two

[0090] The following refers to Figures 5 to 7 to describe the electromagnetic wave absorbing material 200 of Specific Embodiment Two. Figure 5 shows the structural schematic diagram of the electromagnetic wave absorbing material 200 of Specific Embodiment Two.

[0091] As Figure 5 shown, the electromagnetic wave absorbing material 200 includes a substrate 40, and a plurality of dielectric material lines 103 arranged at intervals along the axis AY inside the substrate 40, and the plurality of dielectric material lines 103 are also arranged at intervals along an axis AX (not shown in the figure) parallel to the x direction; the anti-reflection material 30 is provided on the electromagnetic wave incident surface P and is a layer of conductive thin film. It should be noted that when using a conductive thin film as the anti-reflection material 30, a plurality of magnetic material lines 104 can also be arranged in the substrate 40 as in Specific Embodiment One, but at this time the magnetic material lines 104 will not affect the transverse magnetic wave.

[0092] Specifically, the electromagnetic wave incident medium is air (ε in = 1, μ in = 1); the material of the substrate 40 is an acrylic plate (ε tr = 2.55, μ tr= 1), with a thickness of 30 mm. The dashed line represents the normal of the incident surface P of the substrate 40 for the electromagnetic wave. The thickness of the conductive thin film is approximately one-thousandth of the wavelength of the incident electromagnetic wave. Each dielectric material line 103 is inclined with respect to the axis AY (parallel to the y-direction) at an angle near the corresponding absorption inclination angle (an angle within the range of absorption inclination angle ±5°), and is arranged at intervals of 4 mm along the axis AY. In the x-direction, multiple dielectric material lines 103 are arranged at intervals of 2 mm along the axis AX (not shown in the figure) parallel to the x-direction, and are also inclined with respect to the axis AX at the corresponding absorption inclination angle. The resistance of the dielectric material line 103 is 130 ohms.

[0093] Taking the microwave model (the frequency of the incident electromagnetic wave is 10 GHz and the wavelength is approximately 30 mm) as an example, Figure 6 The simulation diagram of the electromagnetic wave (transverse magnetic wave) incident from air to the electromagnetic wave absorbing material 200 is shown. The thickness of the corresponding conductive thin film is approximately 0.03 mm. It can be seen that when the TM wave is incident on the electromagnetic wave absorbing material 200 at an incident angle θ i = -70°, the absorption inclination angle corresponding to each wave-absorbing material line can be equal to the complementary angle of the refraction angle of the incident electromagnetic wave in the substrate 40. In this embodiment, the first inclination angle α of each wave-absorbing material line is 53.95°. At this time, there is also basically no reflection, but at the same time, due to the existence of the wave-absorbing material line, there is also basically no electromagnetic wave transmitted through the substrate 40. Specifically, the electromagnetic wave absorption rate can reach approximately 99%.

[0094] Furthermore, Figure 7 The curve graph showing the variation of the electromagnetic wave absorption rate with frequency is shown. It can be seen that in the frequency range of 5 GHz to 25 GHz, the electromagnetic wave absorbing material 200 has an absorption rate of more than 98% for the TM wave. Specific Embodiment Three

[0096] The following refers to Figures 8 to 9 Describe the electromagnetic wave absorbing material 200 of Specific Embodiment Three. The structure of the electromagnetic wave absorbing material 200 in Specific Embodiment Three is almost the same as that in Specific Embodiment Two, with the only difference being that in Specific Embodiment Three, the incident angle θ of the electromagnetic wave i = ±80°. Therefore, the absorption inclination angles of each wave-absorbing material line with respect to the axis AY and AX are different.

[0097] Taking the microwave model (the frequency of the incident electromagnetic wave is 10 GHz and the wavelength is approximately 30 mm) as an example, Figure 8 The simulation diagram of the electromagnetic wave (transverse magnetic wave) incident from air to the electromagnetic wave absorbing material 200 is shown. The thickness of the corresponding conductive thin film is approximately 0.03 mm. It can be seen that when the TM wave is incident on the electromagnetic wave absorbing material 200 at an incident angle θ iWhen the incident angle is -80° to the electromagnetic wave absorbing material 200, the absorption inclination angles corresponding to the absorbing material lines can be equal to the complementary angles of the refraction angles of the incident electromagnetic waves in the substrate 40. In this embodiment, the first inclination angle α of each absorbing material line is 51.92°. At this time, there is basically no reflection, but at the same time, due to the existence of the absorbing material lines, there is basically no electromagnetic wave transmitted through the substrate 40. Specifically, the electromagnetic wave absorption rate can reach about 99%.

[0098] Furthermore, Figure 9 A graph showing the variation of the electromagnetic wave absorption rate with frequency is shown. It can be seen that in the frequency range of 5 GHz to 25 GHz, the electromagnetic wave absorbing material 200 has an absorption rate of more than 99% for TM waves.

[0099] The present application also provides an electromagnetic wave absorption device, which can be used to shield electromagnetic waves and includes the electromagnetic wave absorbing material 200 as described above.

[0100] Since the material of the substrate 40 can be glass, foam plastic or plexiglass, in some other embodiments, it can also be a fluid such as air or water. Therefore, when the material of the substrate 40 is selected as a solid material, the electromagnetic wave absorption device can be a plate or block for realizing the electromagnetic shielding function, or a box, shell, wall, etc. prepared by using the plate or block. The preparation is simple and the adaptability is strong. In addition, it should be noted that generally, the higher the working frequency, the smaller the distance between adjacent absorbing materials in the electromagnetic wave absorbing material 200. Therefore, the size of the electromagnetic wave absorption device can be adjusted correspondingly according to the actual working frequency band. Optionally, for the microwave band, the distance between adjacent absorbing materials can be dozens of microns or hundreds of microns; optionally, for the infrared band, the distance between adjacent absorbing materials can be several microns to dozens of microns; optionally, for the visible light band, the distance between adjacent absorbing materials can be less than or equal to 1 micron.

[0101] The above-mentioned electromagnetic wave absorption device can make the electromagnetic waves incident at almost any angle be absorbed more perfectly, and at the same time, it also realizes the more perfect absorption of the electromagnetic waves incident at a large angle, breaking through the limitation of realizing the perfect absorption of electromagnetic waves at a specific angle (Brewster angle) originally, and broadening the application range of the electromagnetic wave absorption device in engineering.

[0102] The present application also provides a waveguide device, which includes the electromagnetic wave absorption device as described above provided at a preset position of the waveguide device.

[0103] Since the electromagnetic wave will have a reflection with a large incident angle on the inner wall of the waveguide in the waveguide device, when the waveguide device needs to absorb the electromagnetic wave, the absorption of ordinary materials for large angles is very limited. Although there are some materials with high absorption, such materials often have a very complex structure, which is not conducive to preparation and cost reduction.

[0104] Specifically, the electromagnetic wave absorption device of the present application can have the following application scenarios in waveguide devices:

[0105] A. Microwave filters. Currently, the vast majority are reflective filters, and the reflected electromagnetic waves interfere with the front end. However, we can place our material on the inner wall of the waveguide where needed to achieve perfect absorption of electromagnetic waves, thereby preparing a microwave filter. Additionally, at the same frequency, the electromagnetic wave absorption device of the present application can also select between TE waves and TM waves.

[0106] B. Electromagnetic wave switch. It can make the electromagnetic wave absorption device work at the corresponding position when electromagnetic waves need to be absorbed, and leave that position when electromagnetic waves do not need to be absorbed, achieving the function of an electromagnetic wave switch.

[0107] C. Waveguide non-reflection device. At the end of the waveguide or at positions where propagation is not required, the electromagnetic wave absorption device of the present application can be used to absorb electromagnetic waves. And because the electromagnetic wave absorption device also has the absorption effect for large-angle incidence, it can prevent interference and other effects between the incident electromagnetic waves.

[0108] For the above-mentioned waveguide devices, by setting the above-mentioned electromagnetic wave absorption device at the preset position, electromagnetic waves can be effectively absorbed, thereby meeting the application requirements of waveguide devices for electromagnetic waves in different working scenarios.

[0109] The present application also provides a through-type acoustic wave absorber, including the electromagnetic wave absorption device as described above.

[0110] For the above-mentioned through-type acoustic wave absorber, it can be designed according to the required working frequency in the acoustic wave band. As long as a very small inclination is set, a device that is light-transmitting and air-permeable but absorbs sound and reduces noise can be made, thereby overcoming the defect that traditional noise reduction devices absorb sound but are not air-permeable.

[0111] It should be understood that the above embodiments are all exemplary and do not cover all possible implementation manners included in the claims. Without departing from the scope of the present disclosure, various deformations and changes can be made based on the above embodiments. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form additional embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only represent several implementation manners of the present invention and do not limit the protection scope of the present invention patent.

Claims

1. An electromagnetic wave absorbing material, characterized in that, Comprising: a substrate having an electromagnetic wave incident surface; a plurality of wave-absorbing materials disposed within the substrate and arranged obliquely along at least one preset axis; and, along the preset axis, there is a preset interval between two adjacent wave-absorbing materials, the preset interval being less than the wavelength of the incident electromagnetic wave, and the thickness of each wave-absorbing material being less than the preset interval; an antireflection material disposed on the electromagnetic wave incident surface and configured to reduce the reflection of the incident electromagnetic wave; the antireflection material includes at least one of a multi-layer dielectric structure, a single-layer conductive structure, and a refractive index gradient structure; And, each wave-absorbing material has a first inclination angle with respect to the preset axis, and the electromagnetic wave incident on each wave-absorbing material has a second inclination angle with respect to the preset axis; when the first inclination angle of any wave-absorbing material is symmetric with respect to the preset axis to the second inclination angle of the electromagnetic wave incident on the wave-absorbing material, the first inclination angle of the wave-absorbing material is the absorption inclination angle corresponding to the wave-absorbing material; Wherein, each wave-absorbing material is inclined with respect to the preset axis within a range of adding and subtracting a preset angle to the corresponding absorption inclination angle to absorb electromagnetic waves.

2. The electromagnetic wave absorbing material according to claim 1, wherein The absorption inclination angle is greater than 0° and less than 90°.

3. The electromagnetic wave absorbing material according to claim 1 or 2, characterized in that, The antireflection material includes a dielectric multi-layer structure, and the dielectric multi-layer structure includes: two first dielectric layers respectively disposed on both sides of the dielectric multi-layer structure, the first dielectric layer having a first preset thickness; and, one second dielectric layer disposed between the two first dielectric layers, the second dielectric layer having a second preset thickness; The first preset thickness and the second preset thickness are configured to cause the incident electromagnetic wave to interfere and reduce the reflection of the incident electromagnetic wave.

4. The electromagnetic wave absorbing material according to claim 1 or 2, characterized in that, The antireflection material includes a conductive thin film, and the conductive thin film has a third preset thickness, and the third preset thickness is configured to cause the incident electromagnetic wave to interfere and reduce the reflection of the incident electromagnetic wave.

5. The electromagnetic wave absorbing material according to claim 4, wherein The ratio of the third preset thickness to the wavelength of the incident electromagnetic wave is less than or equal to Or The ratio of the third preset thickness to the wavelength of the incident electromagnetic wave is less than or equal to 6. The electromagnetic wave absorbing material according to claim 1 or 2, characterized in that, the plurality of wave-absorbing materials include a plurality of wave-absorbing material lines arranged in an array.

7. The electromagnetic wave absorbing material according to claim 6, wherein The wave-absorbing material line includes a plurality of dielectric material lines for absorbing transverse magnetic waves and / or a plurality of magnetic material lines for absorbing transverse electric waves.

8. The electromagnetic wave absorbing material according to claim 7, characterized in that, The same type of wave-absorbing material lines are arranged at intervals along a first axis, and different types of wave-absorbing material lines are arranged alternately at intervals along a second axis perpendicular to the first axis.

9. The electromagnetic wave absorbing material according to claim 8, wherein along the first axis, there is a first interval distance D1 between two adjacent wave-absorbing material lines of the same type; along the second axis, there is a second interval distance D2 between two adjacent wave-absorbing material lines of different types; The first interval distance D1 and the second interval distance D2 satisfy: D2 ≤ D1 ≤ 2D2.

10. The electromagnetic wave absorbing material according to claim 1 or 2, characterized in that, The range of the preset angle is 0 to 10°.

11. The electromagnetic wave absorbing material according to claim 1 or 2, wherein the thickness of the antireflection material is less than the wavelength of the incident electromagnetic wave; or, the thickness of the antireflection material is less than or equal to one-half of the wavelength of the incident electromagnetic wave.

12. The electromagnetic wave absorbing material according to claim 1 or 2, characterized in that, The material of the substrate includes at least one of glass, foam plastic, and plexiglass.

13. An electromagnetic wave absorption device for shielding electromagnetic waves, characterized in that, Comprising the electromagnetic wave absorbing material according to any one of claims 1-12.

14. A waveguide device, characterized in that, Comprising the electromagnetic wave absorbing device according to claim 13 provided at a preset position of the waveguide device.

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