Large-angle multi-spectral stealth device

Abstract

A multispectral stealth device is disclosed. The multispectral stealth device comprises: a selective wavelength absorption pattern layer formed of an electrically conductive material and having conductive thin film patterns capable of causing electromagnetic resonance at a first wavelength and a second wavelength different from the first wavelength; a first dielectric layer formed of a dielectric material and disposed below the selective wavelength absorption pattern layer and formed of a dielectric material; a reflective layer disposed below the first dielectric layer and formed of an electrically conductive material; a semiconductor layer disposed above the selective wavelength absorption pattern layer and formed of a semiconductor material; and a second dielectric layer disposed above the semiconductor layer and formed of a dielectric material.

Description

Technology Field

[0001] The present invention relates to a broadband multispectral stealth device capable of responding to electromagnetic waves of a wide incident angle. Background Technology

[0002] Detection technologies used in modern battlefields can be primarily divided into radar and infrared detection technologies. Radar detection is a method of detecting electromagnetic waves transmitted by an antenna and reflected from a target, while infrared detection is a method of detecting radiation signals emitted from objects based on temperature, mainly according to Planck's law.

[0003] Stealth technology can generally be defined as a technology that evades detection by minimizing radar reflection signals or infrared radiation signals. Depending on the principles of each detection technology, radar stealth technology minimizes radar reflection signals by increasing absorption or scattering of radar signals, while infrared stealth technology, conversely to radar stealth technology, minimizes infrared radiation signals by increasing reflection of infrared rays and decreasing absorption to lower emissivity.

[0004] Because modern military detection technology uses both radar and infrared detection simultaneously, developing multispectral stealth materials or devices equipped with both radar stealth and infrared stealth capabilities has been a challenging task in the field of military stealth technology. In particular, with the recent miniaturization and unmanned operation of military equipment, there is an increasing need for multispectral stealth materials or device technologies that include millimeter-wave band (26.5–110 GHz) radar stealth capabilities used for detecting ground equipment and drones.

[0005] Recently, there have been many attempts to apply frequency selective surfaces (FSS), which can reflect or transmit incident electromagnetic waves of a specific frequency depending on their structure, to the aforementioned stealth technology. FSS devices function as inductor-capacitor circuits (LC circuits) connected in series or parallel, and can absorb, reflect, or transmit electromagnetic waves corresponding to the resonant frequency. In previous research on stealth devices using FSS, multilayer FSS absorbers were proposed in which an infrared shielding layer (IRSL) and a radar absorbing layer (RAL) were stacked vertically.

[0006] In addition, conventional stealth technology research has proposed large-area devices for absorbing lasers, infrared, and millimeter waves using single-layer-based multi-scale patterns. However, while these devices exhibited excellent stealth performance across the three bands, they lacked camouflage capabilities due to the shimmering color of the metal nanoarray structure located at the outermost layer. Furthermore, because the absorption mechanism of the 1.54 µm laser wavelength relies on Surface Plasmon Polarity (SPP) resonance, the absorption peak is significantly affected by the angle of incidence. Recently, tracking detectors with a wide Field of View (FOV) are being developed to increase the probability of intercepting missiles. Currently, techniques are being proposed to guide lasers from various angles rather than guiding designation from a single direction, as well as wide-angle guiding designation techniques to intercept fast-moving weapon systems.

[0007] In order to counter laser-guided missile interception that is investigated from various angles, a stealth element is required that simultaneously possesses the ability to respond to electromagnetic waves with a wide angle of incidence and emit color. The problem to be solved

[0008] One objective of the present invention is to provide a multispectral stealth element capable of responding to electromagnetic waves of a wide incident angle while simultaneously enabling color expression.

[0009] Another objective of the present invention is to provide a tank, drone, or airplane in which the stealth element is placed on the surface. means of solving the problem

[0010] A multispectral stealth device according to an embodiment of the present invention may include: a selective wavelength absorption pattern layer formed of an electrically conductive material and having conductive thin film patterns capable of causing electromagnetic resonance at a first wavelength and a second wavelength different from the first wavelength; a first dielectric layer formed of a dielectric material and disposed below the selective wavelength absorption pattern layer and formed of a dielectric material; a reflective layer disposed below the first dielectric layer and formed of an electrically conductive material; a semiconductor layer disposed above the selective wavelength absorption pattern layer and formed of a semiconductor material; and a second dielectric layer disposed above the semiconductor layer and formed of a dielectric material.

[0011] In one embodiment, the stacked structure of the selective wavelength absorption pattern layer, the dielectric layer, and the reflection layer can cause electromagnetic wave resonance to absorb electromagnetic waves of the first wavelength and the second wavelength.

[0012] In one embodiment, the second dielectric layer, the semiconductor layer, and the selective wavelength absorption can cause a preset visible light color expression and widen the incident angle at which the electromagnetic wave can be absorbed.

[0013] In one embodiment, each of the conductive thin film patterns is formed from one or more materials selected from the group consisting of nickel (Ni), titanium (Ti), platinum (Pt), copper (Cu), chromium (Cr), tungsten (W), and alloys comprising one or more of these, and the semiconductor layer may be formed from one or more materials selected from the group consisting of germanium (Ge), gallium arsenide (GaAs), silicon (Si), and zinc sulfide (ZnS).

[0014] In one embodiment, each of the conductive thin film patterns may have the same thickness of 100 nm to 10 μm.

[0015] In one embodiment, the selective wavelength absorption pattern layer is composed of a plurality of unit regions having a square shape formed by two sides parallel to a first direction and two sides parallel to a second direction perpendicular to the first direction, and the conductive thin film patterns are disposed in each of the plurality of unit regions, wherein the conductive thin film patterns comprise: a first thin film pattern having a planar shape of a first square having a side length of a first length and two sides parallel to the first direction and two sides parallel to the second direction; and a second thin film pattern having a planar shape of a second square having a side length of a second length smaller than the first length and two sides parallel to the first direction and two sides parallel to the second direction, disposed to have a diagonal identical to one of the diagonals of the first thin film pattern. It may include two third thin film patterns, each having a rectangular planar shape in which the length of the long side parallel to the second direction is the first length and the length of the short side parallel to the first direction is the second length, one of which is positioned adjacent to the first side of the first thin film pattern, and the other of which is positioned adjacent to the second side of the first thin film pattern perpendicular to the first side.

[0016] In one embodiment, the selective wavelength absorption pattern layer is composed of a plurality of unit regions having a square shape formed by two sides parallel to a first direction and two sides parallel to a second direction perpendicular to the first direction, and the conductive thin film patterns are disposed in each of the plurality of unit regions. In this case, the conductive thin film patterns include: one first thin film pattern disposed in an area adjacent to the first corner of the unit region, having a planar shape of a first square with a side length of a first length and two sides parallel to the first direction and two sides parallel to the second direction; and N, each having a planar shape of a second square with a side length of a second length smaller than the first length and two sides parallel to the first direction and two sides parallel to the second direction, disposed in an N×matrix form in an area adjacent to the third corner of the unit region facing diagonally opposite the first corner. 2 It includes 2N second thin film patterns; and 2N third thin film patterns arranged in a row, each having a rectangular planar shape in which the length of the long side parallel to the second direction is the first length and the length of the short side parallel to the first direction is the second length, and in a region adjacent to the second corner of the unit region adjacent to the first corner and in a region adjacent to the fourth corner of the unit region diagonally opposite the second corner, wherein N may be an integer from 2 to 5. For example, N may be 2 or 3.

[0017] In one embodiment, the selective wavelength absorption pattern layer may have absorption peaks at a first wavelength corresponding to a frequency range of 20 to 50 GHz and a second wavelength corresponding to a frequency range of 80 to 110 GHz.

[0018] In one embodiment, the ratio of the first length to the second length may be about 2 to 400.

[0019] A tank according to an embodiment of the present invention may include the multispectral stealth element disposed on its surface.

[0020] An aircraft according to an embodiment of the present invention may include the multispectral stealth element disposed on its surface. Effects of the invention

[0021] According to the transmission multispectral stealth device of the present invention, by utilizing a magnetic resonance mechanism caused by a combination of a conductive frequency-selective surface layer, an insulator layer, and a conductor layer configured relatively lower down, it is possible to selectively absorb millimeter dual bands (Ka, W) while simultaneously emitting low wavelengths in the infrared band. Additionally, by utilizing a combination of a dielectric layer, a semiconductor layer, and a conductive frequency-selective surface layer configured relatively upper up, it is possible to absorb laser wavelengths with a wide angle of incidence.

[0022] That is, according to the present invention, a stealth device capable of color realization and simultaneous absorption of wide-angle laser, infrared, and millimeter wave multi-bands can be realized through a structure composed of a frequency-selective surface layer combination that combines magnetic resonance phenomena by a lower MIM structure and destructive interference by an upper structure, without nano-scale patterns. Brief explanation of the drawing

[0023] FIG. 1 is a cross-sectional view illustrating a multispectral stealth element according to one embodiment of the present invention. FIG. 2 is a plan view illustrating one embodiment of the selective wavelength absorption pattern layer shown in FIG. 1. FIGS. 3a and FIGS. 3b are plan views illustrating other embodiments of the selective wavelength absorption pattern layer shown in FIG. 1. FIG. 4a is a graph showing the theoretical absorption rate and the absorption rate measured in an actual experiment according to the wavelength of a stealth element according to an embodiment of the present invention, and FIG. 4b is a graph showing the results of measuring the absorption rate for laser light of various incident angles. Specific details for implementing the invention

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. Similar reference numerals have been used for similar components in the description of each drawing. In the attached drawings, the dimensions of the structures are shown enlarged compared to the actual dimensions for the clarity of the present invention.

[0025] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, or combinations thereof.

[0026] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0027] In the description of this specification, a material capable of transmitting visible light refers to a material having a transmittance of 70% or more, for example, 85% or more, for light in the visible light band.

[0029] FIG. 1 is a cross-sectional view illustrating a multispectral stealth element according to one embodiment of the present invention, and FIG. 2 is a plan view illustrating one embodiment of a selective wavelength absorption pattern layer shown in FIG. 1.

[0030] Referring to FIG. 1 and FIG. 2, a multispectral stealth element (100) according to one embodiment of the present invention may include a selective wavelength absorption pattern layer (110), a first dielectric layer (120), a reflective layer (130), a semiconductor layer (140), and a second dielectric layer (150).

[0031] The multispectral stealth element (100) of the present invention is placed on the surface of an object (not shown) such as a fighter jet, drone, tank, vehicle, etc., and can exhibit stealth capabilities for multiple frequency bands (35 GHz, 94 GHz) mainly used for millimeter wave lasers and stealth capabilities for thermal infrared detectors, etc. while exhibiting color.

[0032] The selective wavelength absorption pattern layer (110) may include a plurality of conductive thin film patterns (111, 112, 113) having a certain thickness and capable of transmitting millimeter-wave radar wavelengths, and may absorb electromagnetic waves within a preset wavelength range together with the first dielectric layer (120) and the reflection layer (130) using electromagnetic resonance, etc. Additionally, since the selective wavelength absorption pattern layer (110) may reflect at least a portion of infrared rays having a wavelength of about 3 μm or more, such as mid-wave infrared rays, long-wave infrared rays, and far-infrared rays to the outside, the emissivity of the object to which the stealth element (100) of the present embodiment is applied can be lowered.

[0033] In one embodiment, each of the conductive thin film patterns (111, 112, 113) may be formed of nickel (Ni), titanium (Ti), platinum (Pt), copper (Cu), chromium (Cr), tungsten (W), or an alloy containing one or more of these, wherein the material includes all compounds, composites, alloys, etc., including metals, with a real value of the refractive index in the range of 4.5 (±2.5) and an imaginary value of 5.0 (±2.8)i, considering high 90% absorption of a specific laser wavelength by bonding with the upper semiconductor layer (140). When considering a laser wavelength absorption rate of less than 90%, the real and imaginary range values ​​of the refractive index may be wider.

[0034] In one embodiment, the thickness of each of the conductive thin film patterns (111, 112, 113) is not particularly limited. For example, each of the conductive thin film patterns (111, 112, 113) may be formed with a thickness of about 50 nm to 10 μm, for example, about 50 to 500 nm. Meanwhile, each of the conductive thin film patterns (111, 112, 113) may have a flat upper surface and a lower surface, and an opening such as a through hole that can expose the first dielectric layer (120) disposed on the bottom may not be formed within the boundary line.

[0035] In one embodiment, the conductive thin film patterns (111, 112, 113) can simultaneously correspond to the frequency bands (35 GHz, 94 GHz) mainly used for millimeter wave radar by simultaneously causing electrical resonance at a first wavelength and a second wavelength belonging to the millimeter wave region, thereby simultaneously exhibiting absorption peaks for electromagnetic waves at each of these frequencies.

[0036] In one embodiment, the selective wavelength absorption pattern layer (110) may be composed of a plurality of unit regions having a square shape formed by two sides parallel to a first direction (x) and two sides parallel to a second direction (y) perpendicular to the first direction (x) and regularly arranged, and the plurality of conductive thin film patterns (111, 112, 113) may be arranged in each of the unit regions.

[0037] For convenience of explanation below, the two corners of the unit area located on the first diagonal among the two diagonals of the unit area are referred to as the first corner and the third corner, and the two corners of the unit area located on the second diagonal are referred to as the second corner and the fourth corner.

[0038] In one embodiment, the plurality of conductive thin film patterns (111, 112, 113) disposed in one unit area may include one first thin film pattern (111), one second thin film pattern (112), and two third thin film patterns (113).

[0039] The first thin film pattern (111) may have a first square planar shape having a side length of a first length (a) and two sides parallel to the first direction (x) and two sides parallel to the second direction (y), and the second thin film pattern (112) may have a second square planar shape having a side length of a second length (b) which is smaller than the first length (a) and two sides parallel to the first direction (x) and two sides parallel to the second direction (y). The first thin film pattern (111) may exhibit an absorption peak for wavelengths in the low-frequency band among the frequency bands mainly used for millimeter-wave radar, and the second thin film pattern (112) may exhibit an absorption peak for wavelengths in the high-frequency band among the frequency bands mainly used for millimeter-wave radar. Each of the above third thin film patterns (113) may have a rectangular planar shape in which the length of the long side parallel to the second direction (y) is equal to the length of the first length (a) and the length of the short side parallel to the first direction (x) is equal to the length of the second length (b).

[0040] In one embodiment, the first thin film pattern (111) and the second thin film pattern (112) may be arranged within the unit area such that one vertex is adjacent to the other, having a diagonal that overlaps with one of the diagonals of the unit area. For example, the first thin film pattern (111) may be placed in a first area adjacent to the first corner of the unit area, and the second thin film pattern (112) may be placed in a second area adjacent to the third corner. In another embodiment, the first thin film pattern (111) may be placed in a third area adjacent to the second corner of the unit area, and the second thin film pattern (112) may be placed in a fourth area adjacent to the fourth corner.

[0041] One of the two third thin film patterns (113) may be positioned adjacent to the first side of the first thin film pattern (111), and the other may be positioned adjacent to the second side of the first thin film pattern (111) perpendicular to the first side. For example, one of the third thin film patterns (113) may be positioned such that one of its long sides faces the first side of the first thin film pattern (111) and one of its short sides faces one side of the second thin film pattern (112), and the other may be positioned such that one of its long sides faces the second side of the first thin film pattern (111) and one of its short sides faces the other side of the second thin film pattern (112). In this case, the long side of the third thin film pattern (113) and the side of the first thin film pattern (111) facing it may be spaced apart by a first interval (g1), and the short side of the third thin film pattern (113) and the side of the second thin film pattern (112) facing it may be spaced apart by a second interval (g2).

[0042] In one embodiment, in order to correspond to thermal infrared rays in a detector, low emissivity must be achieved. To achieve this, the reflectivity of mid-wavelength infrared rays, long-wavelength infrared rays, far-infrared rays, etc., by the selective wavelength absorption pattern layer (110) must be increased. To this end, the first to third thin film patterns (111, 112, 113) of the selective wavelength absorption pattern layer (110) may be formed to have a filling ratio of about 90% or more, preferably about 95% or more, for the unit area. For example, the spacing (g1) between one long side of the third thin film pattern (113) and one side of the first thin film pattern (111) facing it, and the spacing (g2) between one short side of the third thin film pattern (113) and one side of the second thin film pattern (112) facing it may be about 10 to 100 μm.

[0043] In one embodiment, to correspond to millimeter wave (94 GHz and 35 GHz) radars primarily applied to detect ground equipment such as tanks and armored vehicles, and small unmanned equipment such as drones, the selective wavelength absorption pattern layer (110) may have first to third thin film patterns (111, 112, 113) formed such that the first wavelength corresponding to a frequency range of about 20 to 50 GHz and the second wavelength corresponding to a frequency range of about 80 to 110 GHz have absorption peaks.

[0044] In one embodiment, so as to have absorption peaks at the first wavelength and the second wavelength, the ratio of the length of one side of the first thin film pattern (111) to the length of one side of the second thin film pattern (112) may be in the range of about 2 to 400, preferably about 5 to 45. For example, the length of one side of the first thin film pattern (111) may be about 1.0 to 4.0 mm, and the length of one side of the second thin film pattern (112) may be about 0.01 to 0.5 mm. For example, the length of one side of the first thin film pattern (111) may be about 1.3 to 3.0 mm, and the length of one side of the second thin film pattern (112) may be about 0.07 to 0.25 mm.

[0045] The first dielectric layer (120) is disposed below the selective wavelength absorption pattern layer (110) and can be formed of a dielectric material.

[0046] In one embodiment, the first dielectric layer (120) may be formed from an organic dielectric material such as polyethylene terephthalate (PET), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate (PC), polyaramid, polyimide, polyethylene naphthalate (PEN), or an inorganic dielectric material such as silicon oxide (SiO2) or glass.

[0047] In one embodiment, the thickness of the first dielectric layer (120) is not particularly limited. For example, the first dielectric layer (120) may be formed with a thickness of about 100 μm to 500 μm. Meanwhile, the conductive thin film patterns (111, 112, 113) and the first dielectric layer (120) may form a direct interface.

[0048] The reflective layer (130) may be positioned below the first dielectric layer (120), for example, between the first dielectric layer (120) and the object, and may be formed of a conductive material capable of reflecting at least a portion of infrared rays. For example, the reflective layer (130) may be formed of a metal material having low absorption and high reflectivity for infrared rays with wavelengths greater than 3 μm, such as medium-wavelength infrared rays and long-wavelength infrared rays. For example, the reflective layer (130) may be formed of silver (Ag), aluminum (Al), copper (Cu), gold (Au), platinum (Pt), or an alloy containing one or more of these.

[0049] Since at least some of the infrared rays having a wavelength of about 3 μm or more, such as medium-wavelength infrared rays, long-wavelength infrared rays, and far-infrared rays, can be reflected outward without reaching the object, the emissivity of the object to which the stealth element (100) of the present embodiment is applied can be lowered.

[0050] The semiconductor layer (140) may be placed on top of the selective wavelength absorption pattern layer (110) and may be formed of a semiconductor material. In one embodiment, the semiconductor layer (140) may be formed of a crystalline or amorphous material such as germanium (Ge), gallium arsenide (GaAs), silicon (Si), zinc sulfide (ZnS), etc. In this case, the material includes all compounds, composites, alloys, etc., including semiconductors, for which the real value of the refractive index of the material is in the range of 3.5 (±0.4) and the imaginary value is in the range of 0.25 (±0.25)i, considering high 90% absorption of a specific laser wavelength through combination with the lower conductor layer (110). When considering a laser wavelength absorption rate of less than 90%, the real and imaginary range values ​​of the corresponding refractive index may be wider.

[0051] In one embodiment, the semiconductor layer (140) may be formed with a thickness of about 5 nm to 10 μm. At this time, the thickness of the semiconductor layer (140) can control the absorption rate of a specific laser wavelength through combination with the underlying conductive selective wavelength absorption pattern (110). For example, if the goal is to absorb more than 90% of the laser of the specific wavelength and the semiconductor layer (140) is formed of amorphous silicon (a-Si), the thickness of the semiconductor layer (140) may be about 66 to 96 nm. Alternatively, if the absorption rate of the laser of the specific wavelength is less than 90%, the thickness range of the semiconductor layer (140) may be wider. Meanwhile, the thickness of the semiconductor layer (140) that achieves a high absorption rate may be expressed at a periodic thickness where destructive interference occurs.

[0052] The second dielectric layer (150) may be disposed on top of the semiconductor layer (140) and may be formed of a dielectric material. In one embodiment, the dielectric layer (150) may be formed of a material such as aluminum oxide (e.g., Al2O3, etc.), titanium oxide (e.g., TiO2, etc.), silicon oxide (e.g., SiO2, etc.), iron oxide (e.g., Fe2O3, etc.), copper oxide (e.g., CuO, etc.), germanium oxide (e.g., GeO2, etc.), zinc oxide (e.g., ZnO, etc.). In this case, since the material absorbs and reflects visible light through combination with the lower semiconductor layer (140), any material having a refractive index in the visible light region is applicable. If there is no imaginary part of the material's refractive index, bright light can be produced through the absorption mechanism of only the lower conductor, and if there is an imaginary part of the refractive index, dark color expression is possible.

[0053] In one embodiment, the dielectric layer (150) may be formed with a thickness of about 1 nm or more. At this time, since the material absorbs and reflects visible light through combination with the lower semiconductor layer (140), the absorption rate in the visible light region can be controlled to realize the color.

[0054] FIGS. 3a and FIGS. 3b are plan views illustrating other embodiments of the selective wavelength absorption pattern layer shown in FIG. 1.

[0055] Referring to FIG. 1 and FIG. 3a and FIG. 3b, a selective wavelength absorption pattern layer (110) according to another embodiment of the present invention may include a plurality of conductive thin film patterns (111', 112', 113')(111'', 112'', 113''). The selective wavelength absorption pattern layer (110) may be composed of a plurality of unit regions having a square shape formed by two sides parallel to a first direction (x) and two sides parallel to a second direction (y) perpendicular to the first direction (x), and the plurality of conductive thin film patterns (111', 112', 113')(111'', 112'', 113'') may be arranged in each of the unit regions.

[0056] The selective wavelength absorption pattern layer according to the present embodiment has a larger number of second thin film patterns (112', 112'') associated with absorption peaks in the high-frequency region than the selective wavelength absorption pattern layer shown in FIG. 2, so the size of the absorption peaks in the high-frequency region can be increased compared to the selective wavelength absorption pattern layer shown in FIG. 2.

[0057] In one embodiment, the plurality of conductive thin film patterns (111', 112', 113') (111'', 112'', 113'') disposed in one of the unit regions are one first thin film pattern (111', 111''), N 2 It may include 2 second thin film patterns (112', 112'') and 2N third thin film patterns (113', 113''). Here, N may represent an integer from 2 to 5. For example, when N is 2, it may be identical to the selective wavelength absorption pattern layer shown in FIG. 3a, and when N is 3, it may be identical to the selective wavelength absorption pattern layer shown in FIG. 3b.

[0058] Since the planar shape, thickness, and material of each of the first to third thin film patterns (111', 112', 113') (111'', 112'', 113'') are identical or similar to the first to third thin film patterns (111, 112, 113) described with reference to FIG. 2, a redundant detailed description thereof is omitted.

[0059] The first thin film pattern (111', 111'') is placed in an area adjacent to one corner of the unit area, and the N 2 The second thin film patterns (112', 112'') may be arranged in an N×N matrix form in an area adjacent to another corner in the direction of the diagonal (hereinafter referred to as the 'first diagonal') of the unit area. For example, the N 2 The two second thin film patterns (112', 112'') can be arranged in a matrix form in the first direction (x) and the second direction (y). At this time, the N 2 The diagonals of N second thin film patterns (112', 112'') among the second thin film patterns (112', 112'') can be arranged to coincide with the first diagonal of the unit area.

[0060] Among the 2N third thin film patterns (113', 113''), N third thin film patterns (113', 113'') may be placed in an area adjacent to one corner of the unit area along the second diagonal intersecting the first diagonal, and the remaining N third thin film patterns (113', 113'') may be placed in an area adjacent to another corner of the unit area along the second diagonal. At this time, the N third thin film patterns (113', 113'') of each of the two areas may be arranged in a line such that their long sides face one side of the first thin film pattern (111', 111'') and their short sides face one side of the second thin film pattern (112', 112'').

[0061] In one embodiment, so that the first to third thin film patterns (111', 112', 113') (111'', 112'', 113'') can have a filling ratio of about 90% or more, preferably about 95% or more, for the unit area, the spacing between the first thin film pattern (111', 111'') and the third thin film pattern (113', 113''), the spacing between the second thin film pattern (112', 112'') and the third thin film pattern (113', 113''), the spacing between the second thin film patterns (112', 112'') and the spacing between the third thin film patterns (113', 113'') may each be about 10 to 100 μm independently of each other.

[0062] In one embodiment, the ratio of the length of one side of the first thin film pattern (111) to the length of one side of the second thin film pattern (112) may be in the range of about 2 to 400, preferably about 5 to 45, so that the selective wavelength absorption pattern layer (110) has absorption peaks at a first wavelength corresponding to a frequency range of about 20 to 50 GHz and a second wavelength corresponding to a frequency range of about 80 to 110 GHz. For example, the length of one side of the first thin film pattern (111) may be about 1.0 to 4.0 mm, and the length of one side of the second thin film pattern (112) may be about 0.01 to 0.5 mm. For example, the length of one side of the first thin film pattern (111) may be about 1.3 to 3.0 mm, and the length of one side of the second thin film pattern (112) may be about 0.07 to 0.25 mm.

[0063] According to the multispectral stealth element of the present invention, the combination of the selective wavelength absorption pattern layer, the first dielectric layer, and the reflection layer can selectively absorb dual-band electromagnetic waves in the frequency band (35 GHz, 94 GHz) mainly used for millimeter-wave radar through electromagnetic resonance, so as to not only be able to implement dual-band stealth capabilities against millimeter-wave radar, but also to respond to thermal infrared detection technology by lowering the emissivity for infrared.

[0064] In addition, in the present invention, the combination of the second dielectric layer, the semiconductor layer, and the selective wavelength absorption layer causes destructive interference, thereby enabling selective color expression and absorption of laser wavelengths with a wide angle of incidence.

[0065] FIG. 4a is a graph showing the theoretical absorption rate and the absorption rate measured in an actual experiment according to the wavelength of a stealth element according to an embodiment of the present invention, and FIG. 4b is a graph showing the results of measuring the absorption rate for laser light of various incident angles.

[0066] Referring to FIGS. 4a and 4b, it can be seen that the stealth element according to an embodiment of the present invention can absorb laser wavelengths with a wide angle of incidence.

[0067] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims. Explanation of the symbols

[0068] 100: Multispectral stealth device 110: Selective wavelength absorption pattern layer 120: First dielectric layer 130: Reflection layer 140: Semiconductor layer 150: Second dielectric layer

Claims

Claim 1 A selective wavelength absorption pattern layer formed of an electrically conductive material and having conductive thin film patterns capable of causing electromagnetic resonance at a first wavelength and a second wavelength different from the first wavelength; a first dielectric layer formed of a dielectric material and disposed below the selective wavelength absorption pattern layer and formed of a dielectric material; a reflective layer disposed below the first dielectric layer and formed of an electrically conductive material; and a semiconductor layer disposed above the selective wavelength absorption pattern layer and formed of a semiconductor material. and a second dielectric layer formed of a dielectric material disposed on top of the semiconductor layer; wherein the stacked structure of the selective wavelength absorption pattern layer, the first dielectric layer, and the reflection layer causes electromagnetic resonance to absorb electromagnetic waves of the first wavelength and the second wavelength, and the second dielectric layer, the semiconductor layer, and the selective wavelength absorption pattern layer cause destructive interference to produce a preset visible light color and widen the incident angle capable of absorbing the electromagnetic waves, and the selective wavelength absorption pattern layer is composed of a plurality of unit regions having a square shape consisting of two sides parallel to a first direction and two sides parallel to a second direction perpendicular to the first direction, and the conductive thin film patterns are disposed in each of the plurality of unit regions, and the conductive thin film patterns include one first thin film pattern disposed in an area adjacent to the first corner of the unit region, having a planar shape of a first square having a side length of a first length and having two sides parallel to the first direction and two sides parallel to the second direction; and one side length of N, each having a second square planar shape having a second length smaller than the first length and having two sides parallel to the first direction and two sides parallel to the second direction, and arranged in an N×matrix form in an area adjacent to the third corner of the unit area facing the first corner diagonally. 2 A multispectral stealth device characterized by comprising: 2N second thin film patterns; and 2N third thin film patterns arranged in a row, each having a rectangular planar shape in which the length of the long side parallel to the second direction is the first length and the length of the short side parallel to the first direction is the second length, and N in each area adjacent to the second corner of the unit area adjacent to the first corner and the area adjacent to the fourth corner of the unit area facing diagonally opposite the second corner, wherein N is an integer between 2 and 5. Claim 2 delete Claim 3 delete Claim 4 A multispectral stealth device according to claim 1, wherein each of the conductive thin film patterns is formed of one or more materials selected from the group consisting of nickel (Ni), titanium (Ti), platinum (Pt), copper (Cu), chromium (Cr), tungsten (W), and alloys comprising one or more of these, and the semiconductor layer is formed of one or more materials selected from the group consisting of germanium (Ge), gallium arsenide (GaAs), silicon (Si), and zinc sulfide (ZnS). Claim 5 A multispectral stealth device according to claim 1, characterized in that each of the conductive thin film patterns has a mutually identical thickness of 100 nm to 10 μm. Claim 6 delete Claim 7 delete Claim 8 A multispectral stealth device according to claim 1, characterized in that N is 2 or 3. Claim 9 A multispectral stealth device according to claim 1, characterized in that the selective wavelength absorption pattern layer has absorption peaks at a first wavelength corresponding to a frequency range of 20 to 50 GHz and a second wavelength corresponding to a frequency range of 80 to 110 GHz. Claim 10 A multispectral stealth element according to claim 9, characterized in that the ratio of the first length to the second length is 2 to 400. Claim 11 A tank having a multispectral stealth element according to paragraph 1 disposed on its surface. Claim 12 An airplane having a multispectral stealth element according to paragraph 1 disposed on its surface.

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