Radar-infrared compatible stealth composite material with infrared camouflage function

Abstract

The invention discloses a radar and infrared compatible stealth composite material with an infrared camouflage function, and belongs to the technical field of multi-spectrum compatible stealth. The radar infrared compatible stealth composite material sequentially comprises a top coding layer, a first dielectric layer, a second dielectric layer, a conductive reflecting layer and a third dielectric layer from top to bottom in the electromagnetic wave propagation direction. The top coding layer comprises a plurality of zero patch large units and one patch large unit; the zero patch large unit and the first patch large unit from top to bottom respectively form a zero coding unit and a first coding unit together with the dielectric layer and the reflecting layer below the zero patch large unit and the first patch large unit from top to bottom along the electromagnetic wave propagation direction; and array structures are formed according to coding patterns generated by a multi-objective optimization algorithm. The zero coding unit and the one coding unit are arranged, an infrared camouflage pattern matched with complex background thermal radiation characteristics is constructed in an infrared band, and the reflection phase difference between the two coding units is utilized in a microwave band, so that the radar cross section is reduced, and radar infrared compatible stealth is completed.

Description

Technical Field

[0001] This invention belongs to the field of multi-spectrum compatible stealth technology, specifically relating to a radar-infrared compatible stealth composite material with infrared camouflage function. Background Technology

[0002] With the rapid development of modern military detection technology, battlefield reconnaissance methods have expanded from single-band to comprehensive detection systems covering multiple bands such as infrared and microwave. Single-band stealth technology is no longer sufficient to meet the survivability requirements of weapons and equipment in complex battlefield environments. Therefore, achieving radar-infrared compatible stealth is crucial to improving the battlefield survivability of weapons and equipment. Radar detection, as an active detection method, works by emitting electromagnetic waves to illuminate the target and receiving the backscattered echoes reflected from the target surface, using the intensity of the echoes to detect and track the target. Infrared detection, a passive detection method, works by detecting the thermal radiation energy emitted by the target surface itself, identifying the target based on the contrast in radiation intensity between the target and the background. For both detection methods, microwave radar band stealth mainly relies on the energy loss mechanism of absorbing materials to attenuate reflected waves, or scattering electromagnetic waves into non-threat areas to reduce the radar cross section (RCS). For the infrared band, stealth mainly relies on reducing surface temperature or surface emissivity. However, according to Kirchhoff's thermal radiation law, low emissivity implies high reflectivity, which inherently contradicts the low reflectivity required for microwave stealth in terms of material properties. Therefore, it is difficult to meet the stealth requirements of both microwave and infrared compatibility by relying on a single material.

[0003] The emergence of electromagnetic metamaterials offers a new approach to solving this problem. As a composite material composed of subwavelength artificial microstructures arranged according to specific rules, it breaks through the constraints of the intrinsic properties of traditional materials, enabling precise control over the propagation mode of electromagnetic waves. Given its unique physical properties, various radar-infrared compatible stealth metamaterial structures have been proposed in recent studies. While these materials solve the problem of compatibility and stealth in both bands, they neglect the complexity and non-uniformity of the infrared background, making it impossible to match with environmental thermal texture characteristics (i.e., infrared camouflage), thus limiting their survivability in real battlefield environments.

[0004] Existing infrared stealth technologies generally rely on a single low-emissivity material to suppress the overall thermal radiation intensity of the target. This globally uniform low-emissivity strategy is only suitable for environments with uniform and simple background thermal radiation. However, in complex backgrounds such as jungles, wilderness, and grasslands where thermal radiation distribution is non-uniform, a single low-emissivity target will exhibit a single radiation profile feature due to its significantly lower radiation intensity compared to the surrounding environment. This results in a strong contrast between the target and the background in infrared thermal imagers, making it easier to identify and track.

[0005] Therefore, how to overcome the defect of uniform spatial distribution of infrared emissivity on the surface of radar-infrared compatible stealth metamaterials, which has already solved the contradiction of the intrinsic properties of traditional materials, and design a radar-infrared compatible stealth composite material that can achieve infrared camouflage against complex non-uniform background features, is a key technical problem that urgently needs to be solved in the field of multi-spectrum compatible stealth technology. Summary of the Invention

[0006] To address the problem that existing radar-infrared compatible stealth materials cannot match complex infrared backgrounds, this invention provides a radar-infrared compatible stealth composite material with infrared camouflage functionality.

[0007] A radar-infrared compatible stealth composite material with infrared camouflage function comprises a top coding layer 1, a first dielectric layer 2, a second dielectric layer 3, a conductive reflective layer 4, and a third dielectric layer 5 connected sequentially from top to bottom along the electromagnetic wave propagation direction;

[0008] The material of the top coding layer 1 is a conductive film, and the top coding layer 1 is composed of 50 zero-patch large units 11 and 50 one-patch large units 12.

[0009] The zero-patch large unit 11 is a periodic array planar structure composed of 10×10 zero-patch small units 111;

[0010] The large patch unit 12 is a periodic array planar structure composed of 5×5 small patch units 121;

[0011] Each zero-surface unit 111 and each one-surface unit 121 is a square surface patch;

[0012] Along the direction of electromagnetic wave propagation, from top to bottom, the zero-patch large unit 11, the first dielectric layer 2, the second dielectric layer 3, the conductive reflective layer 4, and the third dielectric layer 5 constitute a zero-coding unit;

[0013] Along the direction of electromagnetic wave propagation, from top to bottom, a patch unit 12, a first dielectric layer 2, a second dielectric layer 3, a conductive reflective layer 4, and a third dielectric layer 5 constitute an encoding unit;

[0014] The reflection phase difference between the zero-coding unit and the one-coding unit is 180±37°, thus achieving radar stealth capability.

[0015] The difference in infrared emissivity between the zero-coding unit and the one-coding unit is greater than 0.3, thereby achieving infrared stealth functionality;

[0016] The zero-coding units and one-coding units are arranged according to the coding pattern optimized by the genetic algorithm to form a 10×10 array structure, thereby achieving the best match between radar stealth performance and infrared stealth performance.

[0017] The generation of the coded pattern includes the following steps:

[0018] (1) Obtain the original infrared background thermal image of the application scenario, perform edge detection and binarization on the original infrared background thermal image, and then count its edge feature quantity;

[0019] (2) Extract the two main colors of the original infrared background thermal image and assign them to the zero coding unit and the one coding unit respectively. Randomly generate a coding pattern composed of the zero coding unit and the one coding unit to realize the equivalent simulation of the infrared temperature distribution by the coding pattern;

[0020] (3) Based on the actual size ratio between the coded pattern and the original background, the coded pattern is placed in the middle of the original infrared background thermal image to generate a fused image;

[0021] (4) Calculate the matrix factor of the coding pattern The edge shape similarity S between the fused image and the original infrared background thermal image is used to select the optimal coding pattern using a genetic algorithm.

[0022] The optimization objective of the genetic algorithm is as follows: 1. The maximum value of the matrix factor of the encoding pattern. 1. The similarity S between the edge shape of the fused image and the original infrared background thermal image is less than 30 to achieve the microwave diffuse scattering effect; 2. The similarity S between the edge shape of the fused image and the original infrared background thermal image is greater than 0.3 to achieve the infrared camouflage function;

[0023] The materials of the first dielectric layer 2, the second dielectric layer 3, and the third dielectric layer 4 are all dielectric materials suitable for high frequencies and with low tangent loss.

[0024] The material of the conductive reflective layer 4 is a conductive thin film;

[0025] The radar-infrared compatible stealth composite material is a plate-shaped material with a thickness of less than 3 mm;

[0026] The radar-infrared compatible stealth composite material achieves a radar cross-section reduction of more than 10dB in the 8.2-13.4 GHz frequency band. In the infrared band, it utilizes the difference in infrared emissivity between zero-coding units and one-coding units that is greater than 0.3 to arrange a thermal radiation pattern similar to the background, so as to adapt to complex infrared backgrounds and achieve dual-band simultaneous stealth.

[0027] Further technical solutions are as follows:

[0028] The side length of both the zero-patch large unit 11 and the one-patch large unit 12 is 30mm.

[0029] The zero-patch unit 111 has a size of 1.40-1.60 mm; the one-patch unit 121 has a side length of 5.30-5.50 mm.

[0030] The spacing between adjacent zero-patch small units 111 in the zero-patch large unit 11 is 1.40-1.60mm, so that the equivalent infrared emissivity of the zero-patch large unit 11 is 0.66-0.71.

[0031] The spacing between adjacent small patch units 121 in the large patch unit 12 is 0.50-0.70 mm, so that the equivalent infrared emissivity of the large patch unit 12 is 0.18-0.24.

[0032] The conductive film is an indium tin oxide (ITO) film with a thickness of 60-100 nm.

[0033] The thickness of the first dielectric layer 2 and the third dielectric layer 5 is 0.125 mm, and the material is polyethylene terephthalate (PET).

[0034] The second dielectric layer 3 has a thickness of 2.40-2.60 mm and is made of polymethyl methacrylate (PMMA).

[0035] The genetic algorithm parameters are set as follows: population size 50, maximum number of iterations 500, crossover probability 0.8, and mutation probability 0.05.

[0036] The preparation steps of a radar-infrared compatible stealth composite material with infrared camouflage function are as follows:

[0037] (1) Preparation of the top coding layer

[0038] Polyethylene terephthalate (PET) material is selected as the first dielectric layer 2, and the surface of the first dielectric layer 2 is cleaned and dried. An indium tin oxide (ITO) thin film is deposited on the upper surface of the first dielectric layer 2 using a magnetron sputtering process. Based on the matrix coding pattern optimized by a genetic algorithm, the indium tin oxide thin film is patterned using a laser etching process to form the top coding layer 1.

[0039] (2) Preparation of bottom reflective layer

[0040] Polyethylene terephthalate (PET) material is selected as the third dielectric layer 5, and a metal layer or a high conductivity film is deposited on the upper surface of the third dielectric layer 5 to form a total reflection conductive reflective layer 4.

[0041] (3) Structural integration

[0042] Polymethyl methacrylate (PMMA) is selected as the second dielectric layer 3. The first dielectric layer 2, on which the top coding layer 1 is deposited, is bonded to the upper surface of the second dielectric layer 3 with optically transparent adhesive. The third dielectric layer 5, on which the conductive reflective layer 4 is deposited, is bonded to the lower surface of the second dielectric layer 3 with optically transparent adhesive, thereby forming an integral radar-infrared compatible stealth composite material with infrared camouflage function.

[0043] Compared with the prior art, the beneficial technical effects of the present invention are reflected in the following aspects:

[0044] 1. This invention employs metamaterials technology to effectively resolve the contradiction between broadband radar stealth and infrared stealth in terms of physical mechanisms, while overcoming the technical shortcomings of traditional infrared camouflage in adapting to complex and non-uniform infrared backgrounds. This invention utilizes a genetic algorithm to optimize the spatial arrangement of zero-coded and one-coded units: in the microwave band, the phase difference in reflection between the two types of units allows the reflected electromagnetic waves to interfere with each other, scattering the reflected energy in other directions, thereby reducing microwave scattering in the incident direction. This achieves a radar cross-section reduction of greater than 10 dB in the 8.2-13.4 GHz frequency band; in the infrared band, the significant emissivity difference between the two types of units is utilized to arrange a thermal radiation pattern similar to the background, better adapting to complex infrared backgrounds and achieving simultaneous stealth in both bands.

[0045] 2. This invention integrates microwave and infrared stealth functions into the same physical layer, eliminating the need to fabricate separate infrared and microwave stealth layers. While ensuring microwave-infrared compatible stealth, it effectively avoids the bulky problem caused by multiple layers, achieving a thickness of less than 3mm and making the stealth material lighter and thinner.

[0046] 3. The conductive thin film materials and their structural designs selected in this invention can all be realized using existing mature micro-nano processing technologies. The preparation process is simple and controllable, and the processing cost is low. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the radar-infrared compatible stealth composite material structure with infrared camouflage function of the present invention.

[0048] Figure 2 This is a schematic diagram of the zero-patch large unit of the top coding layer of the radar-infrared compatible stealth composite material with infrared camouflage function of the present invention.

[0049] Figure 3 This is a schematic diagram of a large patch unit on the top coding layer of the radar-infrared compatible stealth composite material with infrared camouflage function according to the present invention.

[0050] Figure 4 It refers to the reflection phase of the zero coding unit and the one coding unit in Example 1, and the phase difference between them.

[0051] Figure 5 This is the coded pattern of the radar-infrared compatible stealth composite material in Example 1.

[0052] Figure 6 This is an image showing the effect of placing the optimized coding pattern from Example 1 into a background of fallen leaves.

[0053] Figure 7 This is a three-dimensional far-field image of the radar-infrared compatible stealth composite material of Example 1.

[0054] Figure 8 The results are simulations of the radar cross section of the radar-infrared compatible stealth composite material and the same size metal plate in the 2-18GHz range, as shown in Example 1.

[0055] Figure 9 The results are simulation and test results of the radar cross section reduction of the radar-infrared compatible stealth composite material in the 2-18GHz range of Example 1.

[0056] Figure 10 This is a photograph of the radar-infrared compatible stealth composite material sample from Example 1.

[0057] Figure 11 This is a comparison image of the radar-infrared compatible stealth composite material sample from Example 1 with the thermal camouflage effects of metal and PMMA.

[0058] Figure 12 It refers to the reflection phase of the zero coding unit and the one coding unit in Example 2, and the phase difference between them.

[0059] Figure 13 This is the coded pattern of the radar-infrared compatible stealth composite material in Example 2.

[0060] Figure 14 This is an image showing the effect of placing the optimized coding pattern from Example 2 into a grassy background.

[0061] Figure 15 This is a three-dimensional far-field image of the radar-infrared compatible stealth composite material of Example 2. Detailed Implementation

[0062] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be provided below with reference to specific embodiments.

[0063] Example 1 This embodiment 1 provides a radar-infrared compatible stealth composite material with infrared camouflage function suitable for use against a background of fallen leaves.

[0064] See Figure 1The radar-infrared compatible stealth composite material adopts a multi-layered structure, consisting of the following layers from top to bottom along the electromagnetic wave propagation direction: a top coding layer 1, a first dielectric layer 2, a second dielectric layer 3, a conductive reflective layer 4, and a third dielectric layer 5. The entire structure is a plate-like material with a thickness of 2.75 mm. The first dielectric layer 2 and the third dielectric layer 5 are both 0.125 mm thick polyethylene terephthalate (PET) films. The second dielectric layer 3 is made of 2.5 mm thick polymethyl methacrylate (PMMA) sheet. To reduce infrared radiation energy, the top coding layer 1 is made of indium tin oxide (ITO) conductive film with a thickness of 80 nm, and the conductive reflective layer 4 also has an 80 nm thick ITO film.

[0065] The top coding layer 1 consists of 50 zero-patch large units 11 and 50 one-patch large units 12. Both the zero-patch large units 11 and the one-patch large units 12 are square with a side length of 30mm.

[0066] See Figure 2 The zero-patch large unit 11 is a periodic array planar structure composed of 10×10 zero-patch small units 111; the side length of the zero-patch small unit 111 is 1.50mm, and the gap between adjacent zero-patch small units 111 is 1.50mm.

[0067] See Figure 3 The large patch cell 12 is a periodic array planar structure composed of 5×5 small patch cells 121; the side length of the small patch cell 121 is 5.40mm, and the gap between adjacent small patch cells 121 is 0.60mm.

[0068] Each zero-surface patch 111 and each one-surface patch 121 is a square patch.

[0069] Along the direction of electromagnetic wave propagation, from top to bottom, a zero-coded unit consists of a large zero-patch unit 11, a first dielectric layer 2, a second dielectric layer 3, a conductive reflective layer 4, and a third dielectric layer 5; along the direction of electromagnetic wave propagation, from top to bottom, a large one-coded unit consists of a large one-patch unit 12, a first dielectric layer 2, a second dielectric layer 3, a conductive reflective layer 4, and a third dielectric layer 5.

[0070] To achieve radar and infrared stealth capabilities, the reflection phase difference between the zero-code unit and the one-code unit must satisfy 180±37°; the difference in infrared emissivity between the zero-code unit and the one-code unit must be greater than 0.3 to achieve infrared stealth capabilities.

[0071] To achieve the best match between radar stealth performance and infrared stealth performance, see [reference needed]. Figure 5 The zero-coding units and one-coding units are arranged according to the coding pattern optimized by the genetic algorithm to form a 10×10 array structure.

[0072] From the formula ………(1) The infrared emissivity of the coding unit is calculated, in equation (1) The infrared emissivity of the coding unit; and Infrared emissivity of indium tin oxide (ITO) film and polyethylene terephthalate (PET) film, respectively; The percentage of area occupied by the indium tin oxide (ITO) film in either zero-patch large cell 11 or one-patch large cell 12. Infrared emissivity of the indium tin oxide (ITO) film. The infrared emissivity of polyethylene terephthalate (PET) is approximately 0.05. Approximately 0.9. Percentage of area occupied by indium tin oxide (ITO) film in zero-patch large cell 11. Substituting 0.25 into formula (1), we obtain the infrared emissivity of the zero-coding unit as 0.69; the area percentage occupied by the indium tin oxide (ITO) film in the large patch unit 12. The value is 0.81. Substituting it into formula (1), we can obtain that the infrared emissivity of the one-code unit is 0.21.

[0073] The reflection phase of coding units with different indium tin oxide (ITO) thin film fill rates can be simulated using CST commercial simulation software. During the simulation, the boundary conditions in the x and y directions are set to "unit cell," and the z direction is set to "open addspace." Figure 4 Simulation results show that in the 8.2-18GHz frequency band, the reflection phase difference between the two coding units satisfies 180±37°, which satisfies the phase cancellation condition of microwave diffuse scattering. By arranging and combining them in a certain pattern, a radar cross section reduction of more than 10dB can be achieved.

[0074] After the zero-coding unit and the one-coding unit satisfy the phase cancellation condition (the reflection phase difference satisfies 180°±37°), the zero-coding unit 11 and the one-coding unit 12 are arranged according to the designed coding pattern to achieve diffuse scattering of electromagnetic waves. The array factor reflects the microwave diffuse scattering effect of the material. Assuming that the entire structure contains a total of M×N coding units, when an electromagnetic wave is incident along the normal direction on the surface of the radar-infrared compatible stealth composite material of this embodiment 1, according to antenna array theory, its array factor is expressed by the following formula:

[0075] ...(2)

[0076] In equation (2), The elevation angle for electromagnetic wave scattering ( ), The azimuth angle of electromagnetic wave scattering ( ), d is the side length of the zero coding unit or the one coding unit, k is the wave number, m and n are the horizontal and vertical counts of the zero coding unit or the one coding unit in the M×N coding array, M is the number of coding units in the vertical direction (10 in this embodiment 1), and N is the number of coding units in the horizontal direction (10 in this embodiment 1). It is the reflection phase of the zero or one coding unit located at the mth horizontal position and the nth vertical position.

[0077] Furthermore, altering the arrangement of zero-coding units and one-coding units changes the spatial distribution of infrared emissivity in radar-infrared compatible stealth composite materials, thus affecting the infrared camouflage effect. In the infrared band, edge shape similarity is used as a key indicator for evaluating infrared camouflage effectiveness. Edge detection and binarization are performed on the image using the Canny operator, and then the edge feature quantities are statistically analyzed. The edge feature quantities of the original infrared background are calculated. , , , And edge feature quantities of a fused image with radar-infrared compatible stealth composite material incorporating infrared camouflage functionality into the original infrared background. , , , The edge shape similarity between the two is represented by the following formula (3):

[0078] ... (3)

[0079] In equation (3), The first-order ordinary moment of the original infrared background, The second-order ordinary moment of the original infrared background, The first central moment of the original infrared background, The second central moment of the original infrared background, To fuse the first-order ordinary moments of the images, To fuse the second-order ordinary moments of the image, To fuse the first-order central moments of the images, To fuse the second-order central moments of the images, Array factor The maximum value ( The smaller the value of S, the better the microwave scattering effect of the material; the larger the edge shape similarity S, the higher the degree of integration between the infrared camouflage pattern and the background, and the better the camouflage effect. The arrangement of the coding units will simultaneously change the array factor of the structure. The similarity S between the shape and the edge is such that the encoding pattern needs to be optimized.

[0080] The specific optimization process for the coding pattern is as follows:

[0081] (1) Obtain the original infrared background thermal image of the application scenario, perform edge detection and binarization on the original infrared background thermal image, and then count its edge feature quantity;

[0082] (2) Extract the two main colors from the original infrared leaf background thermal image and assign them to the zero coding unit and the one coding unit respectively. Randomly generate a coding pattern composed of the zero coding unit and the one coding unit to realize the equivalent simulation of the infrared temperature distribution by the coding pattern.

[0083] (3) Based on the actual size ratio of the coded pattern to the original background, place the coded pattern into the middle of the original infrared background thermal image to generate a fused image; see [link to relevant documentation]. Figure 6 The optimized coded pattern is placed against a background of fallen leaves.

[0084] (4) Minimize the maximum value of the matrix factor ( With the objectives of minimizing the edge shape similarity (S) between the fused image and the original infrared background thermal image, a genetic algorithm is used to select the optimal digital coding pattern.

[0085] The optimization objective of the genetic algorithm is as follows: 1. Maximize the matrix factor of the encoding pattern. 1. The similarity S between the edges of the fused image and the original infrared background thermal image is less than 30 to achieve excellent microwave diffuse scattering effect; 2. The similarity S between the edges of the fused image and the original infrared background thermal image is greater than 0.3 to achieve excellent infrared camouflage function. The parameters of the genetic algorithm are set as follows: population size is 50, maximum number of iterations is 500, crossover probability is 0.8, and mutation probability is 0.05.

[0086] To achieve radar-infrared compatible stealth against a background of fallen leaves in the wild, this embodiment 1 extracts the fallen leaf background and optimizes the coding pattern using a genetic algorithm. The optimized coding pattern is shown below. Figure 5 As shown. See also Figure 7 The study demonstrates that radar-infrared compatible stealth composite materials exhibit efficient diffuse scattering characteristics against incident microwaves against a background of fallen leaves in the field. At an operating frequency of 10 GHz (corresponding to a wavenumber k of 209.4 rad / m), the reflection phase of the zero-coded unit is -75°, and the reflection phase of the one-coded unit is 72°. Figure 5 Substituting the determined coding matrix (containing the positions of each coding unit) into formula (2) yields the result that when , At that time, the radar-infrared compatible stealth composite material of this embodiment 1 The value is less than 30, which satisfies the optimization objective. In Example 1, the first-order ordinary moments of the fallen leaf background were calculated. Second-order ordinary moments First-order central moment Second-order central moments The first-order ordinary moments of the fused image after placing the coded pattern into the background... Second-order ordinary moments First-order central moment Second-order central moments Substituting these two sets of specific features into formula (3), we get S=0.32, which is greater than 0.3, thus satisfying the optimization objective.

[0087] The preparation steps of a radar-infrared compatible stealth composite material with infrared camouflage function are as follows:

[0088] (1) Preparation of the top coding layer

[0089] Polyethylene terephthalate (PET) material is selected as the first dielectric layer 2, and the surface of the first dielectric layer 2 is cleaned and dried. An indium tin oxide (ITO) thin film is deposited on the upper surface of the first dielectric layer 2 using a magnetron sputtering process. Based on the matrix coding pattern optimized by a genetic algorithm, the indium tin oxide thin film is patterned using a laser etching process to form the top coding layer 1.

[0090] In this embodiment 1, the encoding pattern is based on a background of fallen leaves, which is optimized by a genetic algorithm.

[0091] (2) Preparation of bottom reflective layer

[0092] Polyethylene terephthalate (PET) material is selected as the third dielectric layer 5, and a metal layer or a high conductivity film is deposited on the upper surface of the third dielectric layer 5 to form a total reflection conductive reflective layer 4.

[0093] (3) Structural integration

[0094] Polymethyl methacrylate (PMMA) is selected as the second dielectric layer 3. The first dielectric layer 2, on which the top coding layer 1 is deposited, is bonded to the upper surface of the second dielectric layer 3 with optically transparent adhesive. The third dielectric layer 5, on which the conductive reflective layer 4 is deposited, is bonded to the lower surface of the second dielectric layer 3 with optically transparent adhesive, thereby forming an integral radar-infrared compatible stealth composite material with infrared camouflage function.

[0095] The RCS reduction characteristics and infrared stealth characteristics of the radar-infrared compatible stealth composite material with infrared camouflage function in Example 1 were tested. The specific details are as follows:

[0096] Depend on Figure 8 It can be seen that compared with metal plates of the same size, thanks to the scattering effect of the top coding layer on electromagnetic waves, the radar cross section of the metamaterial is significantly reduced in the 2-18GHz range.

[0097] The radar cross section reduction was measured using a microwave anechoic chamber bow-shaped frame test method. In an anechoic chamber environment shielded from external electromagnetic interference, the sample under test was placed on a support at the center of a bow-shaped frame. Measurements were performed using a bow-shaped frame system connected to a vector network analyzer. Electromagnetic wave signals from the sample were acquired via transmitting and receiving horn antennas on the frame, and calibration was performed using the reflected signal from a metal plate of the same size as a total reflection reference. By comparing the reflected echoes from the sample and the metal plate, the radar cross section reduction of the sample within a specific frequency band was calculated. See also... Figure 9 Simulation and test results of radar cross-section reduction of composite materials in the 2-18 GHz range. Figure 9 As can be seen from the test results, the accuracy of the simulation model is confirmed, and the reduction in radar cross section is greater than 10 dB in the range of 8.2-13.4 GHz.

[0098] See Figure 10 The image shown is a photograph of the radar-infrared compatible stealth composite material with infrared camouflage function in this embodiment 1.

[0099] See Figure 11 The radar-infrared compatible stealth composite material of Example 1 was placed on a heating element set to 40°C and placed against an outdoor background of fallen leaves. Infrared thermal imager results are shown (see attached image). Figure 11 In (a), the infrared temperature of the metal plate is significantly lower than that of the surrounding environment, and the intensity of its emitted infrared radiation is significantly lower than that of the surrounding background radiation. Its geometry is therefore easily and accurately identified and located by the detection system. (See also...) Figure 11 In (b) of the diagram, the infrared temperature of the pure PMMA substrate is significantly higher than that of the surrounding environment, and the infrared radiation energy it emits is much higher than the background radiation, making it easily detectable under infrared camera conditions; see also Figure 11 In (c), the surface of the top coding layer 1 shows broken infrared thermal radiation patches, whose infrared texture features are highly integrated with the surrounding fallen leaves and are difficult to identify.

[0100] Example 2

[0101] This embodiment 2 provides a radar-infrared compatible stealth composite material suitable for grassland backgrounds. The laminated structure of the radar-infrared compatible stealth composite material in this embodiment 2 is exactly the same as that in embodiment 1. In embodiment 2, the overall thickness of the composite material sample is 2.65 mm. The first dielectric layer 2 and the third dielectric layer 5 still use 0.125 mm thick polyethylene terephthalate (PET) film. The second dielectric layer 3 uses 2.40 mm thick polymethyl methacrylate (PMMA) sheet. The indium tin oxide (ITO) film thickness in the top coding layer 1 is 90 nm, and the indium tin oxide (ITO) film thickness in the conductive reflective layer 4 is 60 nm. The side length of the zero patch small unit 111 is 1.55 mm, and the adjacent gap is 1.45 mm; the side length of the one patch small unit 121 is 5.35 mm, and the adjacent gap is 0.65 mm. The percentage of area occupied by the indium tin oxide (ITO) film in the zero patch large unit 11 is shown in the figure. The value is 0.27. Substituting this into formula (1), we can obtain the infrared emissivity of the zero-coding unit as 0.67; the percentage of the area occupied by the indium tin oxide (ITO) film in the large patch unit 12. The value is 0.80. Substituting this into formula (1), we obtain the infrared emissivity of the first coding unit as 0.22. From... Figure 12 Simulation results show that, within the 8-18 GHz frequency band, the reflection phase difference between the zero coding unit and the one coding unit satisfies 180±37°.

[0102] To achieve radar-infrared compatible stealth against a grassland background, this embodiment extracts the grassland background and optimizes the encoding pattern using a genetic algorithm. The optimized encoding pattern is shown below. Figure 13 As shown. See also Figure 14 The effect of placing the optimized coded pattern into a grassy background. Figure 15 The display material exhibits highly efficient diffuse scattering characteristics for incident microwaves. At an operating frequency of 10 GHz (corresponding to a wavenumber k of 209.4 rad / m), the reflection phase of the zero-coding unit is -75°, and the reflection phase of the one-coding unit is 72°. Figure 13 Substituting the determined coding matrix (containing the positions of each coding unit) into formula (2) yields the result that when , At that time, the radar-infrared compatible stealth composite material of this embodiment 2 The value is less than 30, which satisfies the optimization objective. In Example 2, the first-order ordinary moments of the grassland background... Second-order ordinary moments First-order central moment Second-order central moments The first-order ordinary moments of the fused image after placing the coded pattern into the background... Second-order ordinary moments First-order central moment Second-order central moments Substituting these two sets of specific features into formula (3), we get S=0.31, which is greater than 0.3, thus satisfying the optimization objective.

[0103] In this embodiment 2, the preparation steps of the radar-infrared compatible stealth composite material suitable for grassland background are the same as in embodiment 1. The difference is that when the top coding layer 1 is made, the coding pattern optimized by the genetic algorithm is the coding pattern of the grassland background.

[0104] The radar-infrared compatible stealth composite material designed in this invention successfully integrates radar stealth and infrared camouflage functions. The digitally encoded pattern of the top encoding layer 1, selected through a multi-target optimization algorithm, not only reduces the radar cross-section, effectively countering radar detection, but also utilizes the difference in infrared emissivity between the two encoding units to successfully construct an infrared camouflage that blends seamlessly with complex, non-uniform backgrounds, solving the problem of easy exposure under infrared detection with traditional single low-emissivity camouflage. Furthermore, thanks to its excellent structural thinness (less than 3mm), this invention has broad application prospects in the field of radar-infrared compatible stealth.

[0105] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A radar-infrared compatible stealth composite material with infrared camouflage function, characterized in that, It consists of a top coding layer (1), a first dielectric layer (2), a second dielectric layer (3), a conductive reflective layer (4), and a third dielectric layer (5) connected sequentially from top to bottom along the direction of electromagnetic wave propagation; The material of the top coding layer (1) is a conductive film, and the top coding layer (1) is composed of 50 zero-patch large units (11) and 50 one-patch large units (12); The zero-patch large unit (11) is a periodic array planar structure composed of 10×10 zero-patch small units (111); The large patch unit (12) is a periodic array planar structure composed of 5×5 small patch units (121); Each zero-surface patch unit (111) and each one-surface patch unit (121) is a square patch; The zero-coding unit is composed of a top-to-bottom zero patch unit (11), a first dielectric layer (2), a second dielectric layer (3), a conductive reflective layer (4), and a third dielectric layer (5) along the direction of electromagnetic wave propagation. Along the direction of electromagnetic wave propagation, from top to bottom, a patch unit (12), a first dielectric layer (2), a second dielectric layer (3), a conductive reflective layer (4), and a third dielectric layer (5) constitute a coding unit; The reflection phase difference between the zero-coding unit and the one-coding unit is 180±37°, thus achieving radar stealth capability. The difference in infrared emissivity between the zero-coding unit and the one-coding unit is greater than 0.3, thereby achieving infrared stealth functionality; The zero-coding units and one-coding units are arranged according to the coding pattern optimized by the genetic algorithm to form a 10×10 array structure, thereby achieving the best match between radar stealth performance and infrared stealth performance. The generation of the coded pattern includes the following steps: (1) Obtain the original infrared background thermal image of the application scenario, perform edge detection and binarization on the original infrared background thermal image, and then count its edge feature quantity; (2) Extract the two main colors of the original infrared background thermal image and assign them to the zero coding unit and the one coding unit respectively. Randomly generate a coding pattern composed of the zero coding unit and the one coding unit to realize the equivalent simulation of the infrared temperature distribution by the coding pattern; (3) Based on the actual size ratio between the coded pattern and the original background, the coded pattern is placed in the middle of the original infrared background thermal image to generate a fused image; (4) Calculate the matrix factor of the coding pattern The edge shape similarity S between the fused image and the original infrared background thermal image is used to select the optimal coding pattern using a genetic algorithm. The optimization objective of the genetic algorithm is as follows:

1. The maximum value of the matrix factor of the encoding pattern.

1. The similarity S between the edge shape of the fused image and the original infrared background thermal image is less than 30 to achieve the microwave diffuse scattering effect; 2. The similarity S between the edge shape of the fused image and the original infrared background thermal image is greater than 0.3 to achieve the infrared camouflage function; The materials of the first dielectric layer (2), the second dielectric layer (3) and the third dielectric layer (5) are all dielectric materials that are suitable for high frequency and have low tangent loss. The material of the conductive reflective layer (4) is a conductive thin film; The radar-infrared compatible stealth composite material is a plate-shaped material with a thickness of less than 3 mm; The radar-infrared compatible stealth composite material achieves a radar cross-section reduction of more than 10dB in the 8.2-13.4 GHz frequency band. In the infrared band, it utilizes the difference in infrared emissivity between zero-coding units and one-coding units that is greater than 0.3 to arrange a thermal radiation pattern similar to the background, so as to adapt to complex infrared backgrounds and achieve dual-band simultaneous stealth.

2. The radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that; The side length of both the zero-patch large unit (11) and the one-patch large unit (12) is 30mm.

3. The radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that, The size of the zero-patch unit (111) is 1.40-1.60mm; the side length of the one-patch unit (121) is 5.30-5.50mm.

4. The radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that: The spacing between adjacent zero-patch small units (111) in the zero-patch large unit (11) is 1.40-1.60mm, so that the equivalent infrared emissivity of the zero-patch large unit (11) is 0.66-0.

71.

5. A radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that: The spacing between adjacent small patch units (121) in the large patch unit (12) is 0.50-0.70 mm, so that the equivalent infrared emissivity of the large patch unit (12) is 0.18-0.

24.

6. The radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that, The conductive film is an indium tin oxide (ITO) film with a thickness of 60-100 nm.

7. The radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that, The thickness of the first dielectric layer (2) and the third dielectric layer (5) is 0.125 mm, and the material is polyethylene terephthalate (PET).

8. A radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that, The second dielectric layer (3) has a thickness of 2.40-2.60 mm and is made of polymethyl methacrylate (PMMA).

9. A radar-infrared compatible stealth composite material with infrared camouflage function according to claim 1, characterized in that: The genetic algorithm parameters are set as follows: population size 50, maximum number of iterations 500, crossover probability 0.8, and mutation probability 0.

05.

10. A method for preparing a radar-infrared compatible stealth composite material with infrared camouflage function according to claims 1-8, characterized in that: (1) Preparation of the top coding layer Polyethylene terephthalate (PET) material was selected as the first dielectric layer (2), and the surface of the first dielectric layer (2) was cleaned and dried. Indium tin oxide (ITO) thin film is deposited on the upper surface of the first dielectric layer (2) using magnetron sputtering; based on the matrix coding pattern optimized by genetic algorithm, the indium tin oxide thin film is patterned using laser etching process to form the top coding layer (1). (2) Preparation of bottom reflective layer Polyethylene terephthalate (PET) material is selected as the third dielectric layer (5), and a metal layer or a high conductivity film is deposited on the upper surface of the third dielectric layer (5) to form a total reflection conductive reflective layer (4). (3) Structural integration Polymethyl methacrylate (PMMA) is selected as the second dielectric layer (3). The first dielectric layer (2) with the top coding layer (1) deposited is attached to the upper surface of the second dielectric layer (3) with optically transparent adhesive. The third dielectric layer (5) with the conductive reflective layer (4) deposited is attached to the lower surface of the second dielectric layer (3) with optically transparent adhesive, thereby forming an integral radar-infrared compatible stealth composite material with infrared camouflage function.

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