Conformal coding metasurface for RCS reduction
By setting hollow holes and metal patches on the coding metasurface, combining space-time random coding, and optimizing the resonant unit structure, the problem of balancing conformality and RCS reduction in existing technologies is solved, and high conformality and efficient RCS reduction are achieved in the 4-6GHz frequency range.
Patent Information
- Application Number
- CN202511004610.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-09-16
AI Technical Summary
Existing coded metasurface designs, while achieving good RCS reduction performance, are unable to possess good conformal capabilities, resulting in limited usage scenarios.
A conformal coded metasurface was designed. By setting hollow holes and metal patches on the underlying substrate and adopting a space-time random coded electromagnetic wave control method, the structure of the resonant unit and the position of the active control element were optimized, thereby improving the conformal capability and reducing the RCS.
It achieves high conformal capability within a certain curvature range, further reduces RCS in the 4-6GHz frequency range, broadens the application scenarios, and achieves higher RCS reduction effect through space-time random coding.
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Figure CN120657453A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of artificial electromagnetic materials and communication technology, and particularly relates to a conformal coding metasurface for RCS reduction. Background Art
[0002] Currently, electromagnetic stealth technology primarily encompasses structural stealth, material stealth, and coded stealth. Electromagnetic stealth has long been a research hotspot in the fields of electromagnetics and materials science, and is widely studied by researchers. It has also been widely applied in civilian applications, such as aerospace, communications equipment, and drones. In coded metasurface stealth technology, optimization algorithms are typically used to determine the design parameters of the metasurface, enabling it to control incident electromagnetic waves within a specific frequency range, thereby achieving stealth.
[0003] Existing coded metasurface designs for radar cross section (RCS) reduction include the following technical solutions: one is to improve the amplitude and phase characteristics of electromagnetic waves in the coded metasurface units by adjusting the structural parameters of the units, so that the coded metasurface units achieve a stable phase difference within a broadband, thereby achieving a good RCS reduction effect. Another is to calculate the relationship between RCS reduction and the arrangement of the coded metasurface units, and then optimize the spatial arrangement of the coded metasurface units through algorithms, such as checkerboard distribution, spiral distribution, 0-1 phase cancellation distribution, etc., to achieve a better RCS effect.
[0004] Existing coded metasurface designs primarily achieve high RCS reduction by improving the amplitude and phase parameters of the coded metasurface units and optimizing their spatial arrangement. However, while coded metasurfaces designed from the perspective of space-time coding have good RCS reduction performance, these coded metasurfaces struggle to achieve good conformality, limiting their application scenarios.
[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention
[0006] To address the above-mentioned problems in the prior art, the present invention provides a conformal coding metasurface for RCS reduction. The technical problem to be solved by the present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a conformal coding metasurface for RCS reduction, comprising an underlying substrate, wherein the underlying substrate includes an electromagnetic control working area and a non-electromagnetic control working area; The electromagnetic control working area of the bottom substrate includes a plurality of resonant units arranged in an array on one side of the bottom substrate; The resonant unit includes a composite dielectric layer and a metal pattern layer sequentially stacked on a bottom substrate; the metal pattern layer includes a first metal layer, a first active control element and a second active control element; The first metal layer has a first rectangular hollow hole and a second rectangular hollow hole; a first metal patch is disposed in the middle of the first rectangular hollow hole, and a second metal patch is disposed in the middle of the second rectangular hollow hole, so that a "U"-shaped hollow hole is formed around the first metal patch and the second metal patch; One end of the first active control element is electrically connected to the first metal layer, and the other end of the first active control element is electrically connected to the first metal patch, the first metal patch has a first conductive through hole, and the first conductive through hole is used to electrically connect to the control circuit through the bottom substrate; One end of the second active control element is electrically connected to the first metal layer, and the other end of the second active control element is electrically connected to the second metal patch, the second metal patch has a second conductive through hole, and the second conductive through hole is used to electrically connect to the control circuit through the bottom substrate; The first metal layer further has a third conductive through hole, and the third conductive through hole is used to electrically connect to the bottom substrate; The electromagnetic wave control method of the coded metasurface is space-time random coding.
[0007] In one embodiment of the present invention, the conformal curvature of the conformal coding metasurface ranges from 0 to 10.5.
[0008] In one embodiment of the present invention, the operating frequency range of the coding metasurface is 4 GHz to 6 GHz. In one embodiment of the present invention, the bottom substrate includes a second metal layer, a single dielectric layer, and a third metal layer stacked in sequence; The third metal layer is located on a side of the second metal layer away from the metal pattern layer; The second metal layer is a ground layer, and the third conductive via is electrically connected to the second metal layer; The first conductive via and the second conductive via are both electrically connected to the third metal layer.
[0009] In one embodiment of the present invention, the bottom substrate further comprises a bias line, wherein the bias line is configured to be electrically connected to the control circuit; The third metal layer is a fan-shaped metal layer, and the fan-shaped metal layer forms a capacitor with the second metal layer; the bias line is electrically connected to the fan-shaped metal layer.
[0010] In one embodiment of the present invention, materials of the first metal layer, the second metal layer and the third metal layer are all copper.
[0011] In one embodiment of the present invention, both the first active control element and the second active control element are PIN diodes.
[0012] In one embodiment of the present invention, the composite dielectric layer includes a first composite material layer on a side close to the metal pattern layer and a prepreg material layer on a side away from the metal pattern layer; the single dielectric layer is a second composite material layer; the materials of the first composite material layer and the second composite material layer are both glass fiber reinforced polytetrafluoroethylene; The thickness of the first composite material layer is 2-4 mm, and the thickness of the second composite material layer is 0.1-0.2 mm.
[0013] In one embodiment of the present invention, in any one of the resonance units, the ratio of the surface area of the metal pattern layer to the surface area of the composite dielectric layer is 1:(1.2-1.6); The ratio of the total surface area of the composite dielectric layer of each resonant unit to the surface area of the electromagnetic control working area of the bottom substrate is 1:(2-2.5).
[0014] In one embodiment of the present invention, the relationship between the area of the first rectangular hollow hole and the area of the first metal patch is (3-5): 1; The ratio between the area of the second rectangular hollow hole and the area of the second metal patch is (3-5):1.
[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a hollow hole on the first metal layer and a metal patch in the hollow hole area, so that the active control element and the metal patch are both arranged in the middle area of the first metal layer, thereby improving the compactness of the structure of the two active control elements, thereby reducing the overall area occupied by the resonant unit and providing a structural basis for improving the conformal ability of the coding metasurface. According to the response simulation of the electromagnetic wave, the reserved area of the resonant unit is preset, and the area with little influence on the electromagnetic response is removed to obtain a coding metasurface with high conformal ability. The area of the composite dielectric layer is reduced, so that the flexible underlying substrate can be bent within a certain range to adapt to the application scenario of the coding metasurface without affecting the electromagnetic regulation. The conformal coding metasurface adopts an electromagnetic wave control method of space-time random coding, which has a higher RCS reduction compared with spatial random coding. In summary, the coding metasurface provided by the present invention has a high conformal ability while also reducing the RCS by designing the structure of the resonant unit and positioning the active control element on the metal pattern layer, overcoming the problem that excellent RCS reduction and high conformal ability cannot be achieved together in the prior art.
[0016] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a top view of a conformal coding metasurface for RCS reduction provided by an embodiment of the present invention; Figure 2 yes Figure 1 A partial enlarged schematic diagram of area A in the middle; Figure 3 yes Figure 2 A partial enlarged schematic diagram of area B in the middle; Figure 4 yes Figure 2 Schematic diagram of the expanded structure; Figure 5 1 is a schematic diagram of conformal bending of a conformal coding metasurface unit in a conformal coding metasurface provided by an embodiment of the present invention; Figure 6 1 is a schematic diagram of a conformal curved conformal coding metasurface provided by an embodiment of the present invention; Figure 7 is a simulation representation diagram of a coding metasurface unit provided by an embodiment of the present invention; Figure 8 1 is a schematic diagram comparing the composite dielectric layer of the coding metasurface unit before and after cutting in an embodiment of the present invention; Figure 9 1 is a graph representing a curve of changes in the electromagnetic wave amplitude of a coding metasurface unit versus frequency in an embodiment of the present invention; Figure 101 is a graph representing a change curve of the electromagnetic wave reflection phase of the coding metasurface unit in an embodiment of the present invention; Figure 11 Schematic diagram of a spatial random coding codebook for a coding metasurface in an embodiment of the present invention; Figure 12 2 is a schematic diagram of RCS reduction detection results of the coded metasurface under spatial random coding arrangement and space-time random coding arrangement in an embodiment of the present invention.
[0018] Description of reference numerals: 1-bottom substrate; 101-electromagnetic control working area; 102-non-electromagnetic control working area; 11-second metal layer; 12-single dielectric layer; 13-third metal layer; 14-bias line; 2-composite dielectric layer; 21-first composite material layer; 22-prepreg material layer; 3-metal pattern layer; 30-first metal layer; 31-first rectangular hollow hole; 32-first metal patch; 33-first conductive via; 34-first active control element; 35-second rectangular hollow hole; 36-second metal patch; 37-second conductive via; 38-second active control element; 39-third conductive via; CMS-conformal coded metasurface; DV-column direction. DETAILED DESCRIPTION
[0019] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description of a conformal coding metasurface for RCS reduction proposed in accordance with the present invention in combination with the accompanying drawings and specific implementation methods.
[0020] The aforementioned and other technical contents, features, and effects of the present invention are clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are provided for reference and illustration purposes only and are not intended to limit the technical solutions of the present invention.
[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.
[0022] The orientation or positional relationship indicated by terms such as "thickness", "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.
[0023] The terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not explicitly listed. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the article or device comprising the element.
[0024] The embodiment of the present invention provides a conformal coding metasurface for RCS reduction, such as Figure 1 As shown, the conformal coding metasurface CMS includes a bottom substrate 1, which includes an electromagnetic control working area 101 and a non-electromagnetic control working area 102. The electromagnetic control working area 101 of the bottom substrate 1 includes a plurality of resonant units arrayed on one side of the bottom substrate 1. Figure 2 、 Figure 3 and Figure 4 As shown, the resonant unit includes a composite dielectric layer 2 and a metal pattern layer 3 stacked sequentially on a base substrate 1. The metal pattern layer 3 includes a first metal layer 30, a first active control element 34, and a second active control element 38. The first metal layer 30 has a first rectangular hollow hole 31 and a second rectangular hollow hole 35. A first metal patch 32 is positioned in the center of the first rectangular hollow hole 31, and a second metal patch 36 is positioned in the center of the second rectangular hollow hole 35, forming a U-shaped hollow hole around each of the first and second metal patches 32 and 36. One end of the first active control element 34 is electrically connected to the first metal layer 30, and the other end of the first active control element 34 is electrically connected to the first metal patch 32. The first metal patch 32 has a first conductive via 33, which is used to electrically connect to the control circuit through the base substrate 1. One end of the second active control element 38 is electrically connected to the first metal layer 30, and the other end of the second active control element 38 is electrically connected to the second metal patch 36. The second metal patch 36 has a second conductive via 37, which is used to electrically connect to the control circuit through the underlying substrate 1. The first metal layer 30 also has a third conductive via 39, which is used to electrically connect to the underlying substrate 1. The electromagnetic wave control method of the coded metasurface is spatial-temporal random coding.
[0025] In this embodiment, by providing a hollow hole on the first metal layer 30 and providing a metal patch in the hollow hole area, the active control element and the metal patch are both provided in the middle area of the first metal layer 30, thereby improving the compactness of the structure of the two active control elements, thereby reducing the overall area occupied by the resonant unit, and providing a structural basis for improving the conformal ability of the coded metasurface. According to the response simulation of the electromagnetic wave, the reserved area of the resonant unit is preset, and the area with little influence on the electromagnetic response is removed to obtain a coded metasurface with high conformal ability. Figure 5 As shown, the area of the composite dielectric layer 2 is reduced, allowing the flexible underlying substrate 1 to bend within a certain range to adapt to the application scenario of the coding metasurface without affecting electromagnetic regulation. At the same time, the conformal coding metasurface CMS adopts a space-time random coding electromagnetic wave control method, which has a higher RCS reduction compared to spatial random coding. In this way, the coding metasurface provided by the present invention has a high conformal ability while also reducing the RCS through the structural design of the resonant unit and the position setting of the active control element on the metal pattern layer 3, overcoming the problem in the prior art that excellent RCS reduction and high conformal ability cannot be achieved simultaneously.
[0026] In one embodiment of the present invention, Figure 6 As shown in FIG, the conformal curvature range of the conformal coding metasurface is 0 to 10.5. Within this curvature range, the coding metasurface provided by the present invention has good conformal capability, which broadens the application scenarios of the coding metasurface.
[0027] In one embodiment of the present invention, the operating frequency range of the coding metasurface is 4 GHz to 6 GHz. Within the operating frequency range of this embodiment, the conformal coding metasurface (CMS) has the effect of further reducing RCS while maintaining conformal capability.
[0028] Exemplarily, the first active control element 34 and the second active control element 38 are both PIN diodes.
[0029] In one embodiment of the present invention, Figure 4 As shown, the bottom substrate 1 includes a second metal layer 11, a single dielectric layer 12, and a third metal layer 13 stacked in sequence; the third metal layer 13 is located on the side of the second metal layer 11 away from the metal pattern layer 3. The second metal layer 11 is a ground layer, and the third conductive via 39 is electrically connected to the second metal layer 11. The first conductive via 33 and the second conductive via 37 are both electrically connected to the third metal layer 13.
[0030] Exemplarily, the materials of the first metal layer 30 , the second metal layer 11 and the third metal layer 13 are all copper.
[0031] In one example, the bottom substrate 1 also includes a bias line 14, which is electrically connected to the control circuit. The third metal layer 13 is a fan-shaped metal layer that forms a capacitor with the second metal layer 11; the bias line 14 is electrically connected to the fan-shaped metal layer. Specifically, one end of the first active control element 34 (diode) is electrically connected to the ground layer via a third conductive via 39; the other end of the first active control element 34 (diode) is electrically connected to the third metal layer 13 via a first conductive via 33, and further connected to the control circuit via the bias line 14 to enable real-time control of the first active control element 34. One end of the second active control element (diode) is electrically connected to the ground layer via a third conductive via 39; the other end of the second active control element 38 (diode) is electrically connected to the third metal layer 13 via a second conductive via 37, and further connected to the control circuit via the bias line 14 to enable real-time control of the second active control element 38. In this way, the coded metasurface in this embodiment has high conformality while also enabling real-time control of each coded metasurface unit.
[0032] In one embodiment of the present invention, the composite dielectric layer 2 includes a first composite material layer 21 on the side adjacent to the metal pattern layer 3 and a prepreg material layer 22 on the side distal to the metal pattern layer 3. The single dielectric layer 12 serves as the second composite material layer; both the first composite material layer 21 and the second composite material layer are made of glass fiber reinforced polytetrafluoroethylene. The thickness of the first composite material layer 21 is 2 to 4 mm, and the thickness of the second composite material layer is 0.1 to 0.2 mm. In other words, the thickness of the first composite material layer 21 in the composite dielectric layer 2 is relatively large. If the area of the composite dielectric layer 2 is large, the coding metasurface will not easily conform to the curved surface, or the accuracy of electromagnetic control will be reduced after conforming to the curved surface. The coding metasurface in this embodiment of the present invention reduces the surface area of the metal pattern layer 3 through the structural design. According to electric field simulations, areas with greater electromagnetic influence are concentrated at the edge of the metal pattern. Therefore, when designing the coding metasurface unit, areas with less electromagnetic influence can be cut away, reducing the overall footprint of the resonant unit and improving the conformality of the coding metasurface.
[0033] For example, in any resonant unit, the ratio of the surface area of the metal pattern layer 3 to the surface area of the composite dielectric layer 2 is 1:(1.2-1.6). Figure 2 Shown Figure 1 A partial enlarged view of area A. Figure 2 For example, the surface area of the metal pattern layer 3 is mx * my ; The surface area of the composite dielectric layer 2 is ls * lsIn this example, the upper surface of the composite dielectric layer 2 is a square. It is understood that the composite dielectric layer 2 can be in other shapes such as a rectangle.
[0034] For example, the ratio of the total surface area of the composite dielectric layer 2 of each resonant unit to the surface area of the electromagnetic control working area 101 of the bottom substrate 1 is 1:(2-2.5). For example, the coding metasurface has N Figure 2 The total surface area of the composite dielectric layer 2 of each resonant unit in the coding metasurface unit shown is N* ls * ls The surface area of the electromagnetic control working area 101 of the bottom substrate 1 is N* a * a .
[0035] For example, the area of the first rectangular hollow hole 31 and the area of the first metal patch 32 are in the ratio of (3-5):1. The area of the second rectangular hollow hole 35 and the area of the second metal patch 36 are in the ratio of (3-5):1. Figure 3 As shown, Figure 2 A partially enlarged schematic diagram of the second rectangular hollow hole 35 in the middle B area. The area of the second rectangular hollow hole 35 is cw * cl The area of the second metal patch 36 is tl * tw .
[0036] The following is a further explanation of the specific conformal coding metasurface CMS structure for RCS reduction.
[0037] 1. Design and testing of coding metasurface units like Figure 2 and Figure 3 As shown, the size of the coding metasurface unit structure is: a = 30mm, d = 3mm, mx = 15.92mm, my = 17mm, ls = 20mm, dp = 0.2mm, p 1 = 2.9 mm, p 2 = 2.1 mm, cw = 2mm, cl = 2.95mm, tl = 1.45mm, tw = 1mm, rk = 0.5mm. d is the thickness of the first composite material layer 21, dp is the thickness of the prepreg material layer 22,p 1 is the distance from the first active control element 34 to the third conductive through hole 39, p 2 is the distance from the second active control element 38 to the third conductive through hole 39, rk is the radius of the second conductive via 37. The first composite material layer 21 (glass fiber reinforced polytetrafluoroethylene layer, F4B layer) has a thickness of 3 mm and a dielectric constant of 3.5; the prepreg material layer 22 has a thickness of 0.2 mm and a dielectric constant of 2.55. The second composite material layer (glass fiber reinforced polytetrafluoroethylene layer, F4B layer) has a thickness of 0.127 mm; the third metal layer 13 is a sector-shaped metal sheet with a radius rc = 9.7 mm.
[0038] The PIN diode used in the coding metasurface unit is model SMP1345-079LF, which has a small off-capacitance and can ensure excellent on- and off-characteristics. When the PIN diode is in the on state, the circuit characteristics it presents can be equivalent to the form of a resistor and an inductor in series, where the resistance value is Ron = 3Ω and the inductance value is Lon = 0.7nH. When the PIN diode is in the off state, the circuit characteristics it presents can be roughly equivalent to the form of a resistor and a capacitor in series, with the off resistance being Roff = 10Ω and the off capacitance being Coff = 0.165pF. In order to minimize the difficulty of design, the capacitor used in this embodiment has a package specification of 0201inch (the first two digits "02" represent the length (0.02 inches), and the last two digits "01" represent the width (0.01 inches)).
[0039] 1. Electric field simulation detection of coding metasurface units The commercial software CST is used to simulate the coding metasurface unit, and the results are as follows: Figure 7 As shown. The electric field is mainly distributed in the edge area of the metal pattern of the metal pattern layer 3, while the electric field distribution is smaller outside the metal pattern. It can be seen that the area outside the metal pattern has little effect on the electromagnetic characteristics of the coding metasurface unit. Therefore, in the subsequent simulation of the coding metasurface unit, the composite dielectric layer 2 outside the metal pattern is cut out. Figure 8 As shown ( Figure 8 (The schematic diagram on the left in the middle does not show the diodes, metal patches, and other structures on the metal pattern layer 3.) When processing the coding metasurface unit, the unnecessary composite dielectric layer 2 is removed through a laser cutting process, retaining only the flexible bottom layer and the area of the composite dielectric layer 2 required for microwave resonance. After reducing part of the area of the composite dielectric layer 2, the microwave performance of the coding metasurface unit is almost unaffected. The area of the composite dielectric layer 2 that is ultimately retained is only 4 / 9 of the area of the original composite dielectric layer. Such a compact structural design provides excellent conditions for the conformal design of the coding metasurface unit.
[0040] 2. Electromagnetic wave response detection of coded metasurface units like Figure 2 and Figure 3 As shown in the figure, by adjusting the length and width of the metal patch and the position of the PIN diode, the size of the coding metasurface unit structure is determined, and finally a precise 90° phase difference is achieved in the four working states of the two diodes ("00", "01", "10", and "11", where "0" means off and "1" means on). The final coding metasurface unit is simulated using CST. Figure 9 and Figure 10 The curves of amplitude variation with frequency and reflection phase variation under four working conditions are shown. Figure 9 It can be seen that the reflection amplitude under the four working conditions remains stable in a wide frequency range and is close to 0dB, indicating that the amplitude of the reflected wave is basically consistent with that of the incident wave. In other words, when using this group of frequency coding metasurface units to design a coding metasurface, the error caused by the amplitude of the coding metasurface units can be ignored. Figure 10 It can be seen that in the four working states, the coded metasurface unit based on 2-bit phase control presents a precise phase interval of 90° at a frequency of 5 GHz.
[0041] (2) Forming a Coding Metasurface and Testing Its Performance The above-mentioned coding metasurface units are arranged in a 10*10 array to form a coding metasurface. On the back side of the coding metasurface (away from the metal pattern layer 3), the bias line 14 along the column direction DV is led out to the level input end connected to the corresponding column. The level input end is electrically connected to the level output end of the control circuit board and is controlled by direct input-output (IO). A field programmable gate array (FPGA) and a power supply interface are also provided on the control circuit board. The control circuit board can provide a control voltage for the PIN diode. The reference voltage connected to the control circuit board is 1.2V, and a 200Ω resistor is connected in series to limit the forward current. In this way, a total of 200 independent IO direct connection pins are required. The control circuit board is driven by the FPGA and can directly connect all 200 pins. This control method enables the metasurface to achieve a refresh frequency of 200MHz.
[0042] Experimental group: The coded metasurface with a 10*10 array was placed on a curved support with a curvature of 4.5, and the support was made of photosensitive resin.
[0043] Control group: a copper plate of the same size as the coding metasurface in the experimental group.
[0044] Measurement method: In a darkroom test environment, the feed source adopts a positive feed structure, and the distance from the feed source aperture to the center of the coding metasurface is 300 mm.
[0045] In order to achieve the effect of RCS reduction, the reflection characteristics of the coded metasurface are utilized, and spatial random coding arrangement and space-time random coding arrangement are adopted respectively. Figure 11 As shown in Figure 2, the spatial random coding arrangement can cause the electromagnetic waves incident on the coding metasurface to form diffuse reflection, thereby achieving the purpose of reducing RCS. The spatial-temporal random coding arrangement can randomly change the code of each unit over time based on the spatial random coding.
[0046] The test results of spatial random coding arrangement and spatial-temporal random coding arrangement are as follows Figure 12 Results show that within the 4-6 GHz frequency band, the spatial random coding metasurface has an RCS reduction bandwidth of 0.56 GHz, with a maximum RCS reduction of approximately 12 dB at around 5 GHz. The spatial-temporal random coding metasurface has an RCS reduction bandwidth of 0.74 GHz, with a maximum RCS reduction of approximately 14 dB at around 5 GHz. These results demonstrate that, despite possessing a certain degree of conformality, reconfigurable coding metasurfaces still exhibit strong RCS reduction properties. Compared to spatial random coding, space-temporal random coding can further reduce RCS.
[0047] According to the above test results, the present invention proposes a conformal coded metasurface CMS for RCS reduction. The coded metasurface operates at 4-6GHz, and the coded metasurface unit used has a certain conformal capability, realizing a flexible coded metasurface design. In order to achieve real-time control of the metasurface, FPGA is used and controlled by IO direct connection, and the refresh frequency of the metasurface can reach 200MHz. The test results show that on the basis of having a certain conformal capability, the coded metasurface still has good RCS reduction performance. After spatial random coding, the maximum reduction of the radar scattering cross section is 12dB in the frequency range of 4GHz to 6GHz; after space-time random coding, the maximum reduction of the radar scattering cross section is 14dB. The coded metasurface has broad application prospects in the field of electromagnetic stealth.
[0048] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.
Claims
1. A conformal coding metasurface for RCS reduction, characterized in that: It includes a bottom substrate, wherein the bottom substrate includes an electromagnetic control working area and a non-electromagnetic control working area; The electromagnetic control working area of the bottom substrate includes a plurality of resonant units arranged in an array on one side of the bottom substrate; The resonant unit includes a composite dielectric layer and a metal pattern layer sequentially stacked on a bottom substrate; the metal pattern layer includes a first metal layer, a first active control element and a second active control element; The first metal layer has a first rectangular hollow hole and a second rectangular hollow hole; a first metal patch is disposed in the middle of the first rectangular hollow hole, and a second metal patch is disposed in the middle of the second rectangular hollow hole, so that a "U"-shaped hollow hole is formed around the first metal patch and the second metal patch; One end of the first active control element is electrically connected to the first metal layer, and the other end of the first active control element is electrically connected to the first metal patch, the first metal patch has a first conductive through hole, and the first conductive through hole is used to electrically connect to the control circuit through the bottom substrate; One end of the second active control element is electrically connected to the first metal layer, and the other end of the second active control element is electrically connected to the second metal patch, the second metal patch has a second conductive through hole, and the second conductive through hole is used to electrically connect to the control circuit through the bottom substrate; The first metal layer further has a third conductive through hole, and the third conductive through hole is used to electrically connect to the bottom substrate; The electromagnetic wave control method of the conformal coded metasurface is space-time random coding.
2. The conformal coding metasurface for RCS reduction according to claim 1, wherein: The conformal curvature of the conformal coding metasurface ranges from 0 to 10.
5.
3. The conformal coding metasurface for RCS reduction according to claim 1, wherein: The operating frequency range of the conformal coding metasurface is 4 GHz to 6 GHz.
4. The conformal coding metasurface for RCS reduction according to any one of claims 1 to 3, wherein: The bottom substrate comprises a second metal layer, a single dielectric layer and a third metal layer stacked in sequence; The third metal layer is located on a side of the second metal layer away from the metal pattern layer; The second metal layer is a ground layer, and the third conductive via is electrically connected to the second metal layer; The first conductive via and the second conductive via are both electrically connected to the third metal layer.
5. The conformal coding metasurface for RCS reduction according to claim 4, wherein: The bottom substrate further includes a bias line, wherein the bias line is configured to be electrically connected to the control circuit; The third metal layer is a fan-shaped metal layer, and the fan-shaped metal layer forms a capacitor with the second metal layer; the bias line is electrically connected to the fan-shaped metal layer.
6. The conformal coding metasurface for RCS reduction according to claim 5, characterized in that The first metal layer, the second metal layer and the third metal layer are all made of copper.
7. The conformal coding metasurface for RCS reduction according to claim 6, wherein: The first active control element and the second active control element are both PIN diodes.
8. The conformal coding metasurface for RCS reduction according to claim 7, wherein: The composite dielectric layer comprises a first composite material layer on a side close to the metal pattern layer and a prepreg material layer on a side away from the metal pattern layer; the single dielectric layer is a second composite material layer; the materials of the first composite material layer and the second composite material layer are both glass fiber reinforced polytetrafluoroethylene; The thickness of the first composite material layer is 2-4 mm, and the thickness of the second composite material layer is 0.1-0.2 mm.
9. The conformal coding metasurface for RCS reduction according to claim 4, wherein: In any resonant unit, the ratio of the surface area of the metal pattern layer to the surface area of the composite dielectric layer is 1:(1.2-1.6); The ratio of the total surface area of the composite dielectric layer of each resonant unit to the surface area of the electromagnetic control working area of the bottom substrate is 1:(2-2.5).
10. The conformal coding metasurface for RCS reduction according to claim 9, wherein: The relationship between the area of the first rectangular hollow hole and the area of the first metal patch is (3-5): 1; The ratio between the area of the second rectangular hollow hole and the area of the second metal patch is (3-5):1.