A stealth metasurface with radar RCS reduction and adjustable infrared emissivity

Abstract

The present invention discloses a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity, relating to the technical field of multi-spectrum stealth. The present invention comprises a structure formed by multiple annular ITO patches with different duty cycles, which is etched in a checkerboard pattern on a four-part PET plate to form a functional layer, and a stealth metasurface formed together with a heat insulation layer, a reflective backplane, and a dielectric layer. When electromagnetic waves in the microwave frequency band are incident on the stealth metasurface, the specific arrangement of the annular ITO patches causes the electromagnetic waves to respond in phase and reflect in different directions, thereby achieving radar diffuse reflection stealth. The adjustability of the infrared emissivity is characterized by changing the duty cycle of the annular ITO patch unit while ensuring that microwave stealth performance is met. The larger the ITO duty cycle, the lower the infrared emissivity. The overall radar RCS reduction and adjustable infrared emissivity are organically combined, and bidirectional adjustment can be performed according to demand.

Description

Technical Field

[0001] The present invention relates to the field of multi-spectrum stealth technology, and in particular to a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity. Background Art

[0002] With the development of multi-spectrum composite detection technology, single-band stealth is far from meeting the response needs of military equipment. At present, the rapid development of infrared-compatible multi-spectral stealth materials and technologies has attracted great attention, especially the research on radar-infrared stealth compatibility. Radar stealth requires low reflectivity and high absorptivity, while infrared stealth requires low emissivity and high reflectivity, and there is a contradiction between the two.

[0003] Current research focuses on two methods. One involves a multilayer structure with high metal surface coverage or a specific frequency selective surface (FSS) combined with radar absorbing materials; the other is to coat a specific low-emissivity layer on the surface of the radar stealth material.

[0004] However, since radar stealth requires low reflectivity and high absorptivity, and infrared stealth requires low emissivity and high reflectivity, at the current stage, when used in combination, the two usually have a large impact on each other, making it difficult to achieve both radar RCS reduction and adjustable infrared emissivity at the same time. Summary of the Invention

[0005] An embodiment of the present invention provides a stealth metasurface that is compatible with radar RCS reduction and adjustable infrared emissivity, which can solve the problem in the prior art that it is difficult to simultaneously achieve radar RCS reduction and adjustable infrared emissivity.

[0006] An embodiment of the present invention provides a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity, comprising a functional layer, wherein the functional layer comprises a PET plate and a square ITO patch etched on the top surface of the PET plate; annular ITO patches with different duty cycles are formed by hollowing out the square ITO patch;

[0007] A first structure is formed by hollowing out a square ITO patch on a functional layer to form an annular ITO patch with a first duty cycle; a second structure is formed by hollowing out a square ITO patch on another functional layer to form nine annular ITO patches arranged in an array and with the first duty cycle; and a plurality of the first and second structures are alternately arranged to form a first coding element surface;

[0008] A third structure is formed by hollowing out a square ITO patch on a functional layer to form an annular ITO patch with a second duty cycle; a fourth structure is formed by hollowing out a square ITO patch on another functional layer to form nine annular ITO patches arranged in an array and with a second duty cycle; and a plurality of third and fourth structures are alternately arranged to form a second coding element surface.

[0009] A square ITO patch on one functional layer is hollowed out to form an annular ITO patch with a third duty cycle, forming a fifth structure; a square ITO patch on another functional layer is hollowed out to form nine annular ITO patches arranged in an array and with a third duty cycle, forming a sixth structure; multiple fifth and sixth structures are alternately arranged to form a third coding element plane;

[0010] Hollowing out a square ITO patch on a functional layer to form a ring-shaped ITO patch with a fourth duty cycle, forming a seventh structure; hollowing out a square ITO patch on another functional layer to form nine ring-shaped ITO patches arranged in an array and with a fourth duty cycle, forming an eighth structure; and alternately arranging multiple seventh and eighth structures to form a fourth coding element plane;

[0011] Alternately arranging the first coding element surface, the second coding element surface, the third coding element surface, and the fourth coding element surface to form a stealth metasurface;

[0012] The annular ITO patches on the surfaces of the first structure, the second structure, the third structure, the fourth structure, the fifth structure, the sixth structure, the seventh structure, and the eighth structure are used to cause a phase response of the electromagnetic wave to form radar diffuse reflection;

[0013] The emissivity of multiple annular ITO patches with different duty ratios arranged in sequence on the stealth metasurface is different, which is used to adjust the infrared emissivity.

[0014] Preferably, a dielectric layer is provided on the bottom surface of the functional layer, a reflective back plate is provided on the bottom surface of the dielectric layer, and a heat insulation layer is provided on the bottom surface of the reflective back plate.

[0015] Preferably, the side length of the annular ITO patch on the first structure is three times the side length of the annular ITO patch on the second structure;

[0016] The side length of the annular ITO patch on the third structure is three times the side length of the annular ITO patch on the fourth structure;

[0017] The side length of the annular ITO patch on the fifth structure is three times the side length of the annular ITO patch on the sixth structure;

[0018] The side length of the annular ITO patch on the seventh structure is three times the side length of the annular ITO patch on the eighth structure.

[0019] Preferably, the duty ratios of the square ITO patch on the first coding element surface, the second coding element surface, the third coding element surface and the fourth coding element surface are 0.9, 0.58, 0.41 and 0.25 respectively.

[0020] Preferably, the width between the annular ITO patches formed on the second structure, the fourth structure, the sixth structure and the eighth structure is 0.56 mm, and the period thereof is p=50 mm.

[0021] Preferably, the functional layer is formed by etching an ITO ring patch with a square resistance of 5.0Ω / sq on a polyethylene terephthalate (PET) board.

[0022] Preferably, the reflective back plate and the functional layer both use polyethylene terephthalate (PET) plates as substrates, and the dielectric constant thereof is 3.0 (1-j0.06).

[0023] Preferably, the thermal insulation layer is made of SiO2 aerogel felt, and its temperature range is -200°C to 650°C.

[0024] The embodiments of the present invention provide a stealth metasurface that is compatible with radar RCS reduction and adjustable infrared emissivity. Compared with the prior art, the advantages thereof are as follows:

[0025] The present invention etches a structure formed by multiple annular ITO patches with different duty cycles on four PET plates in a checkerboard pattern to form a functional layer, and forms a stealth metasurface with the thermal insulation layer, the reflective backplane and the dielectric layer. When electromagnetic waves in the microwave frequency band are incident on the stealth metasurface, the specific arrangement of the annular ITO patches causes the electromagnetic waves to respond in phase and reflect in different directions, thereby achieving radar diffuse reflection stealth. The adjustability of the infrared emissivity is characterized by changing the duty cycle of the annular ITO patch unit while ensuring that the microwave stealth performance is met. The larger the ITO duty cycle, the lower the infrared emissivity. When electromagnetic waves in the infrared band are incident on the stealth metasurface, the infrared emissivity of the infrared band electromagnetic waves is adjustable by regulating the duty cycle of multiple sequentially arranged annular ITO patches on the stealth metasurface, thereby achieving infrared stealth. The overall radar RCS reduction and infrared emissivity adjustability are organically combined to simultaneously achieve radar RCS reduction and infrared emissivity adjustability, and can be bidirectionally adjusted according to demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the overall structure of a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided by an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the coding structure of a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided by an embodiment of the present invention;

[0028] Figure 3A schematic diagram of a processing sample of a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided in an embodiment of the present invention;

[0029] Figure 4 Schematic diagram of reflectivity simulation and test results of a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided by an embodiment of the present invention;

[0030] Figure 5 A schematic diagram of the results of measuring the emissivity of a sample using an infrared emissivity tester under a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided by an embodiment of the present invention;

[0031] Figure 6 A schematic diagram of the results of measuring the emissivity of a sample at 3-14 μm using a FRIR spectrometer under a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided by an embodiment of the present invention;

[0032] Figure 7 Schematic diagram of a far-field experimental environment for a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided by an embodiment of the present invention;

[0033] Figure 8 Schematic diagram of far-field simulation and test results of a stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity provided in an embodiment of the present invention.

[0034] Among them: 1. thermal insulation layer, 2. reflective backboard, 3. dielectric layer, 4. functional layer. DETAILED DESCRIPTION

[0035] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0038] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0040] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0041] See also Figures 1 and 2 An embodiment of the present invention provides a stealth metasurface that is compatible with radar RCS reduction and adjustable infrared emissivity, which includes, from bottom to top, a thermal insulation layer 1, a reflective backplane 2, a dielectric layer 3, and a functional layer 4.

[0042] Among them, the functional layer 4 is mainly composed of an ITO coating with a periodic pattern, and the ITO substrate is made of a PET sheet with a thickness of 0.22 mm and a square resistance of 5.0 Ω / sq. The functional layer 4 and the reflective backplane 2 are both highly transparent polyethylene terephthalate (PET), with a dielectric constant of 3.0 (1-j0.06) and an ITO film with a square resistance of 5.0 Ω / sq. The functional layer 4 is etched on a 0.22 mm PET sheet with a square resistance of 5.0 Ω / sq. The dielectric layer 3 is air; and the thermal insulation layer 1 is SiO2 aerogel felt with a dielectric constant of 3.0.

[0043] The annular ITO patches in the functional layer 4 are arranged in a checkerboard pattern on the PET. The size of the "0" unit patch is 4.67 mm, the size of the "1" unit patch is three times that of the "0" unit, the gap size is 0.56 mm, and the structural unit period p is 50 mm. The functional layer 4 is composed of four parts of optically transparent conductive film with different duty cycles on the PET. Each part is arranged in a checkerboard pattern according to the square "0" and "1" unit patches. The duty cycle is adjusted by hollowing out to form a square ring. The inner ring side lengths of the square rings of the four parts are 0 mm, 1 mm, 1.8 mm, and 2.5 mm in the upper left, upper right, lower left, and lower right respectively, that is, the ITO duty cycles are 0.85, 0.77, 0.68, and 0.59 respectively.

[0044] When electromagnetic waves in the microwave frequency band are incident on the stealth metasurface, the movement of electron excitation along the annular ITO patches on the surfaces of the first structure, second structure, third structure, fourth structure, fifth structure, sixth structure, seventh structure and eighth structure respectively causes the electromagnetic waves to respond in phase and reflect in different directions in turn, realizing radar diffuse reflection stealth.

[0045] When electromagnetic waves in the infrared band are incident on the stealth metasurface, the emissivity of multiple annular ITO patches with different duty ratios arranged in sequence on the stealth metasurface is different, realizing the adjustable change of the infrared emissivity of electromagnetic waves in the infrared band to achieve infrared stealth function.

[0046] The infrared emissivity and reflectivity of the structure of the present invention are calculated. The infrared emissivity is calculated according to the formula: , the calculation of the four parts can be obtained as 0.22, 0.29, 0.36, 0.43, and the reflection characteristics are as follows Figure 4 As shown in the figure, when the electromagnetic wave is incident vertically, the stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity can achieve diffuse reflection in the 4.5GHz-10.3GHz band with a reflectivity of less than 10%.

[0047] To further verify the simulation results, the conductive ITO film deposited on the optically transparent PET substrate was etched into the designed structure by laser etching technology; the processed layers were glued together with the help of a highly transparent adhesive, such as Figure 3 The processed sample of the stealth metasurface that is compatible with radar RCS reduction and adjustable infrared emissivity has a size of 300mm×300mm. We can clearly see the image information through the processed sample.

[0048] When measuring, first select a metal base plate of the same size for normalization. The measured reflectivity is as follows: Figure 4 As shown in the figure, the black line is the simulation result and the red line is the measurement result. The reflection curve differs greatly in the 2-4 GHz range because the "0" and "1" coding units can no longer form a stable 180° phase difference. In the 4-18 GHz range, the measurement results are generally larger than the simulation results due to factors such as environment and loss, but the trend changes are consistent. Considering the possible errors in testing and experimental processing, it is believed that the experimental and simulation results are basically consistent.

[0049] The infrared emissivity of the structure is obtained by measuring its reflection spectrum. The infrared reflection curve is measured by an infrared emissivity tester and a FRIR spectrometer. The measured infrared emissivity is as follows: Figure 5 and Figure 6 As shown, Figure 5 This is the result of measuring the sample emissivity using an infrared emissivity tester. Figure 6 This is the result of measuring the emissivity of the sample at 3-14μm using a FRIR spectrometer; furthermore, the ITO duty cycle can be adjusted by changing the patch size or the square ring size, making the infrared emissivity more adjustable in the range of radar diffuse reflection compatible camouflage structure.

[0050] The far-field effect of the sample is obtained through CST simulation. The far-field experimental environment is as follows: Figure 7 As shown; through far-field testing, the test results and simulation results are compared. Figure 8 As shown; considering the possible errors in testing and experimental processing, it is believed that the experimental and simulation results are basically consistent.

[0051] The present invention changes the duty cycle by changing the size of the inner diameter hollowing of the annular ITO patch, thereby achieving adjustable emissivity ranges.

[0052] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity, characterized by: include: A functional layer (4), the functional layer (4) comprising a PET plate and a square ITO patch etched on the top surface of the PET plate; the annular ITO patches with different duty ratios are formed by hollowing out the square ITO patch; A square ITO patch on a functional layer (4) is hollowed out to form an annular ITO patch with a first duty cycle, thereby forming a first structure; a square ITO patch on another functional layer (4) is hollowed out to form nine annular ITO patches arranged in an array and having a first duty cycle, thereby forming a second structure; and a plurality of first structures and second structures are alternately arranged to form a first coding element surface; A square ITO patch on a functional layer (4) is hollowed out to form an annular ITO patch with a second duty cycle, thereby forming a third structure; a square ITO patch on another functional layer (4) is hollowed out to form nine annular ITO patches arranged in an array and having a second duty cycle, thereby forming a fourth structure; and a plurality of third structures and fourth structures are alternately arranged to form a second coding element surface; A square ITO patch on a functional layer (4) is hollowed out to form a ring-shaped ITO patch with a third duty ratio, thereby forming a fifth structure; a square ITO patch on another functional layer (4) is hollowed out to form nine ring-shaped ITO patches arranged in an array and having a third duty ratio, thereby forming a sixth structure; and a plurality of the fifth structure and the sixth structure are alternately arranged to form a third coding element surface; A square ITO patch on a functional layer (4) is hollowed out to form an annular ITO patch with a fourth duty cycle, thereby forming a seventh structure; a square ITO patch on another functional layer (4) is hollowed out to form nine annular ITO patches arranged in an array and having a fourth duty cycle, thereby forming an eighth structure; and a plurality of the seventh structure and the eighth structure are alternately arranged to form a fourth coding element surface; Alternately arranging the first coding element surface, the second coding element surface, the third coding element surface, and the fourth coding element surface to form a stealth metasurface; The annular ITO patches on the surfaces of the first structure, the second structure, the third structure, the fourth structure, the fifth structure, the sixth structure, the seventh structure, and the eighth structure are used to cause a phase response of the electromagnetic wave to form radar diffuse reflection; The emissivity of multiple annular ITO patches with different duty ratios arranged in sequence on the stealth metasurface is different, which is used to adjust the infrared emissivity.

2. The stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity according to claim 1, characterized in that: The bottom surface of the functional layer (4) is provided with a dielectric layer (3), the bottom surface of the dielectric layer (3) is provided with a reflective back plate (2), and the bottom surface of the reflective back plate (2) is provided with a heat insulation layer (1).

3. The stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity according to claim 1, characterized in that: The side length of the annular ITO patch on the first structure is three times the side length of the annular ITO patch on the second structure; The side length of the annular ITO patch on the third structure is three times the side length of the annular ITO patch on the fourth structure; The side length of the annular ITO patch on the fifth structure is three times the side length of the annular ITO patch on the sixth structure; The side length of the annular ITO patch on the seventh structure is three times the side length of the annular ITO patch on the eighth structure.

4. The stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity according to claim 1, characterized in that: The duty ratios of the square ITO patch on the first coding element surface, the second coding element surface, the third coding element surface and the fourth coding element surface are 0.9, 0.58, 0.41 and 0.25 respectively.

5. The stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity according to claim 1, characterized in that: The width between the annular ITO patches formed on the second structure, the fourth structure, the sixth structure and the eighth structure is 0.56 mm, and the period thereof is p=50 mm.

6. The stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity according to claim 1, characterized in that: The functional layer (4) is formed by etching an ITO annular patch with a square resistance of 5.0Ω / sq on a polyethylene terephthalate (PET) board.

7. The stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity according to claim 2, characterized in that: The reflective back plate (2) and the functional layer (4) both use a polyethylene terephthalate (PET) plate as a substrate, and the dielectric constant thereof is 3.0 (1-j0.06).

8. The stealth metasurface compatible with radar RCS reduction and adjustable infrared emissivity according to claim 2, characterized in that: The thermal insulation layer (1) adopts SiO2 aerogel felt board, and its temperature range is -200°C to 650°C.

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