A conformal ultra-thin broadband low-observable electromagnetic metasurface

Abstract

The present invention discloses a conformal ultra-thin broadband low-detectable electromagnetic metasurface, which is a combined metasurface composed of a metal substrate layer, a first dielectric layer, a frequency selection layer, a second dielectric layer, and a polarization conversion layer arranged in sequence from bottom to top, and its electromagnetic scattering characteristics are determined by the polarization conversion module, the broadband frequency selection module, and the structure and arrangement of the basic units in the polarization conversion module and the broadband frequency selection module. The conformal ultra-thin broadband low-detectable electromagnetic metasurface of the present invention has the characteristics of broadband low-detectability, has low requirements on the uniqueness of raw materials, has less limitations on available materials, and is suitable for various extreme and complex scenes; the submodule structure pattern is simple, only includes one combined metasurface structure, and the arrangement mode is not strictly set, which effectively reduces the processing cost and is helpful for practical engineering applications.

Description

Technical Field

[0001] The invention belongs to the field of artificial electromagnetic stealth materials and relates to an electromagnetic supersurface, in particular to a conformal ultra-thin broadband low-detectable electromagnetic supersurface. Background Art

[0002] The performance of traditional low-detectable materials can no longer meet the needs of weapons' continued survival, and the development of new artificial low-detectable electromagnetic metasurfaces has become the dominant trend in the future. Currently, there are many methods to achieve low detectability of electromagnetic metasurfaces, most of which are limited to electromagnetic metasurfaces with planar structures and low-detectability performance indicators in specific bands, while research on electromagnetic metasurfaces that can conform to three-dimensional targets and meet broadband low-detectability is relatively scarce.

[0003] Radar detection is the mainstream detection method. It detects and identifies targets by acquiring the target's echo. It is the most effective long-range electronic detection method so far. Therefore, all countries regard reducing the electromagnetic detectability of weapon equipment targets as one of the most important performance indicators. By changing the electromagnetic characteristics, three-dimensional shape and material of the target, the detectability of the target can be greatly reduced, which is also the focus of research by researchers in various countries. The traditional electromagnetic low-detectable material realization technology is mainly physical means such as absorbing material technology and low-scattering shape technology. By selecting a combination of specific special materials and structures, the preparation can achieve the expected electromagnetic low-scattering characteristics and low longitudinal extension height, thereby achieving the purpose of low radar target detectability. However, the materials under this design rule also have serious defects. Most of the designed low-detectable materials are heavy, thick, and have electromagnetic parameter dispersion variations. They cannot achieve the low-detectability expectations of the entire radar broadband frequency band, and the actual production process and maintenance are also under great pressure. Therefore, traditional low-detectable technology cannot meet the expected requirements of high-performance low-detectable materials in various fields. How to achieve broadband, ultra-thin, conformable, low-detectability, and moderate processing and maintenance cost material design has become the focus of attention in various fields.

[0004] In order to meet the application requirements of higher performance, in recent years, researchers have explored emerging artificial electromagnetic structures - subwavelength structures, which can be used to achieve low detectability of targets. Artificial materials based on subwavelength structures are called metamaterials, which can achieve novel functions that are difficult or even impossible to achieve with natural materials and traditional composite materials. Metasurfaces are extremely thin metamaterials, which can be regarded as new two-dimensional metamaterials. They are microscopic combinations of periodic or non-periodic structures. They have the advantages of thin thickness and small volume. They can achieve the purpose of flexible regulation of electromagnetic waves by changing external patterns, sizes and other parameters. The low-detectable metasurfaces can be attributed to polarization conversion metasurfaces (PCMs), frequency selective surfaces (FSSs), coding metasurfaces, etc. PCM is a typical structure that dissipates electromagnetic waves by rotating the direction of the light beam. FSS interacts with the light beam through electromagnetic resonance, reducing the detectability at a specific frequency. However, most of the current research on low-detectable metasurfaces focuses on planar structures, and less consideration is given to conformal metasurfaces for three-dimensional targets, which contradicts the need to reduce the detectability of three-dimensional targets.

[0005] Based on the above description, it can be seen that how to design an ultra-thin, conformal, broadband, polarization-insensitive, low-detectable electromagnetic metasurface suitable for actual three-dimensional targets has become an urgent problem to be solved in the current metasurface field. Summary of the invention

[0006] In view of the problem that existing low-detectable metasurface designs are limited to planar electromagnetic metasurfaces and specific bands, and there is a lack of electromagnetic metasurfaces for achieving broadband low-detectability for three-dimensional targets, the present invention provides a conformal ultra-thin broadband low-detectable electromagnetic metasurface.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A conformal ultra-thin broadband low-detectable electromagnetic metasurface is a finite-size combined metasurface consisting of a metal substrate layer, a first dielectric layer, a frequency selection layer, a second dielectric layer, and a polarization conversion layer arranged in sequence from bottom to top, wherein:

[0009] The frequency selection layer is composed of broadband frequency selection modules, which are arranged above the first dielectric layer in a periodic sequence;

[0010] The surface of the broadband frequency selection module is designed with a metal pattern layer and a lumped circuit;

[0011] The metal pattern layer includes a deformed square ring, which is a square ring that is recessed and extended inward, including two forms, S1 and S2. The two deformed square ring structures are nested, and the S2 form is nested and surrounded by the S1 form.

[0012] In the S1 form, each side has two sawtooth grooves recessed inward along each side with the midpoint as the symmetry point;

[0013] In the S2 form, the four vertices of the square ring are concave inwards;

[0014] The lumped circuit is a resistor element nested in a deformed square ring. R , R It can be selected according to actual needs, and the commonly used empirical value is 50~150Ω;

[0015] The polarization conversion layer is composed of polarization conversion modules;

[0016] The polarization conversion module is composed of two complementary sub-array modules, "0 state" and "1 state", arranged in a periodic sequence;

[0017] The “0 state” and “1 state” are the initial state of the polarization conversion module and its rotation state after being rotated 90°, and the two are complementary subarray modules;

[0018] The complementary subarray module is a polarization conversion module with a reflection phase difference of 180° in two states, each state is composed of n 2 It is composed of polarization conversion sub-modules. n 2 The submodules are n × n The arrangement is arrayed, and the two state arrays are arranged alternately;

[0019] Said n The selection of must satisfy the requirement that the submodule can clearly reflect the scattering phase characteristics, and the commonly used empirical value is 2~8;

[0020] The surface of the polarization conversion submodule is designed with a metal pattern layer, and the metal pattern layer includes a V-shaped metal patch, a square ring metal patch and a symmetrical microstrip metal patch;

[0021] The V-shaped metal patch includes four types, V1 to V4, which are centrally symmetrically distributed along the diagonal of the polarization conversion submodule and all have hole structures;

[0022] In the V1 form, the angle between the single-sided hole structure and the diagonal of the polarization conversion submodule is θ 1;

[0023] In the V2 form, the angle between the single-sided hole structure and the diagonal of the polarization conversion submodule is θ 2;

[0024] Said θ 1 and θThe selection of 2 must satisfy the requirement of no overlap with the symmetrical microstrip metal patch and must clearly reflect the phase rotation characteristics of polarization conversion. The commonly used empirical value is 15°~30°;

[0025] The V3 form is a centrosymmetric structure of the V2 form about the center point of the polarization conversion module, and the angle between its single-sided hole structure and the diagonal of the polarization conversion submodule is θ 3. θ 3= θ 2;

[0026] The V4 form is a centrosymmetric structure of the V1 form about the center point of the polarization conversion module, and the angle between its single-sided hole structure and the diagonal of the polarization conversion submodule is θ 4. θ 4= θ 1;

[0027] The square ring metal patch is mounted at the center of the polarization conversion submodule, and its diagonal is in a straight line with the diagonal of the polarization conversion submodule;

[0028] The square ring metal patch is a nest of three square ring structures, and the ring width of the square ring is w 1, the interval between rings is w 2;

[0029] Said w 1 and w The selection of 2 must clearly reflect the resonance characteristics of the square ring and meet the structural size requirements. The commonly used empirical value is 0.1~0.5 mm;

[0030] The symmetrical microstrip metal patch is two microstrip lines along the diagonal of the polarization conversion submodule, and the middle of the two microstrip lines is cut off by a square ring metal patch;

[0031] The metal pattern layer is made of ITO transparent flexible metal material with a thickness of h m ;

[0032] Said h m The selection of must be combined with the three-dimensional form of the three-dimensional target and the design index to ensure that the value is as small as possible to ensure the bending stress of the metal material. The commonly used empirical value is 0.01~0.03 mm;

[0033] The first dielectric layer and the second dielectric layer are made of a flexible dielectric material PET with a thickness of h s ;

[0034] Said h sThe selection of must meet the design index of conformal ultra-thinness and ensure that the value is as small as possible to ensure that the material properties do not change during bending conformity. The commonly used empirical value is 1~5 mm;

[0035] The two-dimensional size of the combined metasurface is p × p , p The value of should meet the requirements of micro-indicators, and the commonly used empirical value is 4~8 mm;

[0036] The electromagnetic scattering characteristics of the combined metasurface are determined by the structure and arrangement of the polarization conversion module, the broadband frequency selection module, and the basic units within the polarization conversion module and the broadband frequency selection module.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. The combined metasurface designed in the present invention is thin as a whole, and the stress borne by the structural bending is small, which is suitable for structures with conformal requirements;

[0039] 2. The conformal ultra-thin broadband low-detectable electromagnetic metasurface of the present invention has the characteristics of broadband low-detectability. Both the metal and the material are selected as transparent and flexible structures. On the basis of low-detectability, an optical stealth surface coating can be further introduced to achieve multi-band low-detectability;

[0040] 3. The conformal ultra-thin broadband low-detectable electromagnetic metasurface of the present invention adopts an artificial electromagnetic structure, which effectively suppresses the serious thermal effect formed after the energy absorption of the absorbing material compared with the traditional absorbing stealth;

[0041] 4. The conformal ultra-thin broadband low-detectable electromagnetic metasurface of the present invention has low requirements on the uniqueness of raw materials, has little limitation on available materials, and is suitable for various extremely complex scenarios; the sub-module structure pattern is simple, including only one combined metasurface structure, and the arrangement method is not strictly set, which effectively reduces the processing cost and is conducive to practical engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a design flow chart of the conformal ultra-thin broadband low-detectable electromagnetic metasurface of the present invention.

[0043] Figure 2 The overall structural schematic diagram of the conformal ultra-thin broadband low-detectable electromagnetic metasurface using the present invention is shown in FIG. 1 , in which the complementary modules are periodically arranged in a 3×3 subarray sequence.

[0044] Figure 3 This is a schematic cross-sectional diagram of a conformal ultra-thin broadband low-detectable electromagnetic metasurface using the present invention.

[0045] Figure 4The figure is an equivalent circuit diagram of the conformal ultra-thin broadband low-detectable electromagnetic metasurface of the present invention.

[0046] Figure 5 This is a schematic diagram of a polarization conversion module using the present invention.

[0047] Figure 6 This is a schematic diagram of a frequency selective surface module using the present invention.

[0048] Figure 7 Schematic diagram of 3×3 complementary submodules. (a) is the schematic diagram of the 3×3 module in "0 state", and (b) is the schematic diagram of the 3×3 module in "1 state". The two state modules are Figure 2 Arranged in an alternating periodic manner.

[0049] Figure 8 The S of the conformal ultra-thin broadband low-detectable electromagnetic metasurface with a single polarization conversion module, a single frequency selection module, and a combination of the two modules 11 Comparison of reflection coefficient experimental results.

[0050] Fig. 9 The S of the conformal ultra-thin broadband low-detectable electromagnetic metasurface with a single polarization conversion module, a single frequency selection module, and a combination of the two modules 11 Reflection coefficient relative to the perfect electrical conductor PEC S 11 Comparison of experimental results on the reflection coefficient reduction effect.

[0051] Fig.10 The experimental results of the reflection coefficients of the polarization conversion module layer of the combined metasurface under TE and TM polarizations, as well as the polarization conversion efficiency of the polarization conversion surface, are presented.

[0052] Fig.11 The figures are the experimental results of the backscattering cross-section comparison between the present invention and a perfect conductor, and the RCS reduction results relative to a perfect conductor.

[0053] Fig.12 Schematic diagram of the overall structure of the conformal ultra-thin broadband low-detectable electromagnetic metasurface that combines the polarization conversion module and the frequency selection module to conform to the three-dimensional target. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0055] The present invention provides a design method for a conformal ultra-thin broadband low-detectable electromagnetic metasurface, such as Figure 1 As shown, the method includes the following design steps:

[0056] Step 1: Design the polarization conversion module L1 in the planar broadband low-detectable electromagnetic metasurface based on electromagnetic performance indicators.

[0057] Combination Figure 1 The focus of this step is to design the polarization conversion module and the corresponding complementary sub-modules within the module, and arrange them periodically to meet performance requirements.

[0058] In this step, the polarization conversion module is composed of two complementary sub-array modules, "0 state" and "1 state", arranged in a periodic sequence, wherein:

[0059] The complementary subarray module may be implemented by units with different structural parameters, in which case different structural parameters correspond to different polarization conversion phases;

[0060] The “0 state” and “1 state” are the initial state of the polarization conversion module and its rotation state after being rotated 90°, and the two are complementary subarray modules;

[0061] The complementary sub-array module is a polarization conversion module with a reflection phase difference of 180° in two states, each state is composed of 9 polarization conversion sub-modules. 3 × 3 The arrangement is arrayed, and the two state arrays are arranged alternately.

[0062] In this step, the surface of the polarization conversion submodule is designed with a metal pattern layer, such as Figure 5 As shown, the metal pattern layer includes a V-shaped metal patch, a square ring metal patch and a symmetrical microstrip metal patch, wherein:

[0063] The V-shaped metal patch includes four types, V1 to V4, which are centrally symmetrically distributed along the diagonal of the polarization conversion submodule and all have hole structures;

[0064] In the V1 form, the angle between the single-sided hole structure and the diagonal of the polarization conversion submodule is θ 1=30°;

[0065] In the V2 form, the angle between the single-sided hole structure and the diagonal of the polarization conversion submodule is θ 2 = 30°;

[0066] The V3 form is a centrosymmetric structure of the V2 form about the center point of the polarization conversion module, and the angle between its single-sided hole structure and the diagonal of the polarization conversion submodule is θ 3 = 30°;

[0067] The V4 form is a centrosymmetric structure of the V1 form about the center point of the polarization conversion module, and the angle between its single-sided hole structure and the diagonal of the polarization conversion submodule is θ 4 = 30°;

[0068] The square ring metal patch is mounted at the center of the polarization conversion submodule, and its diagonal is in a straight line with the diagonal of the polarization conversion submodule, so as to realize electromagnetic wave consumption in addition to polarization conversion;

[0069] The square ring metal patch is composed of three nested square ring structures, with a ring width of w 1=0.2mm, the interval is w 2=0.2mm;

[0070] The symmetrical microstrip metal patch is two microstrip lines along the diagonal of the polarization conversion submodule, and the middle of the two microstrip lines is cut off by a square ring metal patch. s 1=0.1mm;

[0071] The metal pattern layer is made of ITO transparent flexible metal material.

[0072] In this step, the arrangement of the complementary submodule array is as follows Figure 7 As shown, the two sub-arrays of "0 state" and "1 state" are combined in a 3×3 arrangement.

[0073] Step 2: Based on the resonance principle, design the resonant broadband frequency selection module L2.

[0074] In this step, if Figure 6 As shown, the surface of the broadband frequency selection module is designed with a metal pattern layer and a lumped circuit, wherein:

[0075] The metal pattern layer includes a deformed square ring;

[0076] The deformed square ring is a square ring that is recessed and extended inward, including two forms, S1 and S2. The two deformed square ring structures are nested, and the S2 form is nested and surrounded by the S1 form.

[0077] In the S1 form, each side has two sawtooth grooves recessed inward along each side with the midpoint as the symmetric point, and the size of the sawtooth groove is d 1=0.2mm, d 2=1mm, d 3=1mm;

[0078] In the S2 form, the four vertices of the square ring are concave inwards, and the size of the inward concave vertices is d 4 = 0.6 mm, d 5=0.6mm;

[0079] Said d 1. d 2. d 3. d4. d 5 are all size parameters, corresponding to the scattering characteristics, and can be adjusted according to the design indicators;

[0080] The lumped circuit is a resistor element nested in a deformed square ring. R , resistor element R Nested in the midpoint of each straight line segment of the deformed square ring to fully consume electromagnetic waves.

[0081] In this step, the metal pattern layer is made of ITO transparent flexible metal material.

[0082] Step 3: Generate a metal bottom layer of the super surface by fitting the target surface, and flatten the metal bottom layer into plane L3.

[0083] In this step, the metal bottom layer is made of ITO transparent metal material.

[0084] Step 4: Generate a first dielectric layer L4 on the plane L3, and arrange the resonant frequency selective surfaces L2 on the first dielectric layer L4 in a periodic sequence.

[0085] In this step, the medium of the first dielectric layer is selected from PET flexible medium to meet the conformal requirements of the three-dimensional structure.

[0086] Step 5: Generate a second dielectric layer L5 on the resonant frequency selective surface L2, and arrange the polarization conversion modules L1 on the second dielectric layer L5 in a periodic sequence.

[0087] In this step, the medium of the second dielectric layer is selected from PET flexible medium to meet the conformal requirements of the three-dimensional structure.

[0088] Step 6: Restore the overall planar joint metasurface arranged with the polarization conversion module and the frequency selection module to the target geometric shape, and complete the conformal ultra-thin broadband low-detectable electromagnetic metasurface composed of the polarization conversion module and the frequency selection module.

[0089] In this step, the equivalent circuit of the conformal ultra-thin broadband low-detectable electromagnetic metasurface is designed based on the transmission line theory, such as Figure 4 As shown in the figure, the dielectric layer is regarded as an equivalent transmission line, and the polarization conversion layer and the frequency selection layer are regarded as capacitors. C ,inductance L and resistor R Combination structure of lumped elements. The lumped element parameters corresponding to the PCM layer are expressed as C PCM , L PCM , R PCM , the lumped component parameters corresponding to the FSS layer are expressed as CFSS , L FSS , R FSS .

[0090] In this step, the arrangement of the conformal ultra-thin broadband low-detectable electromagnetic metasurface of the combined polarization conversion module and the frequency selection module is as follows: Figure 2 As shown in the figure, the joint hypersurface and the three-dimensional target are conformal. Fig.12 As shown, the states of the complementary submodules are alternately arranged in subarrays, and the number of periods of the arrangement is designed according to the actual size. The key structural parameters of the joint metasurface are: the metal bottom layer and the metal pattern layer are made of transparent metal material ITO, with a thickness of h m =0.0175mm; the dielectric layer is made of flexible dielectric material PET, with a thickness of h s =2mm; the unit 2D size is p × p , p =6mm.

[0091] According to the design principle of polarization conversion surface, the present invention achieves the purpose of low detectability by converting the phase of reflected electromagnetic waves; at the same time, two polarization conversion complementary submodules that are symmetrical about the axis are periodically alternately arranged, and the "0 state" and the "1 state" meet the rotation angle difference of 90° to ensure polarization insensitivity. The reflection phase difference of the two complementary submodules is 180°. According to the principle of interference destructiveness, the effect of reducing detectability is further achieved. The center of the complementary submodule is loaded with a ring structure, and the resonance consumption of redundant waves is further achieved on the basis of the phase destructiveness of the electromagnetic waves.

[0092] The present invention designs a frequency selective surface based on the equivalent circuit theory, recesses the square ring structure to further introduce a resonant circuit, and nests the resistors internally to increase the internal heat loss of the frequency selective surface module and broaden the absorption bandwidth of the electromagnetic metasurface as much as possible to achieve the purpose of low detectability in a wide electromagnetic band.

[0093] The present invention realizes broadband low detectability of conformal ultra-thin combined metasurface through the integrated design of polarization conversion and frequency selective surface. The polarization conversion surface is the first layer structure of the combined metasurface. When the electromagnetic wave irradiates the polarization conversion module, the electromagnetic wave undergoes a 90° phase deflection relative to the original incident direction, forming a 180° phase difference with the phase deflection of the complementary submodule, so as to achieve the purpose of mutual interference and cancellation of scattered waves. A ring structure is nested in the middle position of the complementary submodule to further consume or transmit the beam part that cannot complete the polarization conversion; the frequency selective surface consumes and resonates the electromagnetic waves passing through the surface of the polarization conversion layer, and multiple square rings and complex deformation structures increase the resonant frequency points and increase the low detectability bandwidth; the overall metal and material are selected as transparent and flexible structures, and an optical stealth surface coating can be further introduced on the basis of low detectability to achieve multi-band low detectability.

[0094] In order to better illustrate the effect of the technology of the present invention, the electromagnetic characteristics of the sub-modules of the joint metasurface are compared, and the low detectable performance is explained in combination with a perfect conductor; at the same time, the polarization conversion rate of "0 state" and "1 state" is calculated; a Gaussian signal is used as the electromagnetic wave transmission signal, and the simulation software uses CST full-wave simulation software, the frequency is 0~15GHz, and the boundary condition is in unit cell format.

[0095] Figure 8 The experimental results of reflection coefficient comparison of the polarization conversion module, the frequency selection module and the combined metasurface of the present invention are given. Among them, in the range of 0~5GHz, the low detectability effect of the polarization conversion surface is better than that of the combined metasurface, but the advantage is not obvious; in the range of 5~15GHz, the low detectability effect of the combined metasurface is obviously better than that of the polarization conversion module, and the maximum difference is close to 0.5 reflection coefficients; although for the polarization conversion module, the effect is slightly advantageous in the local frequency band, on the whole, the detectability of the polarization conversion module is inferior to that of the combined metasurface; for the frequency selection module, the advantage of the combined metasurface is more obvious. In the entire 0~15GHz band, the absorption advantage of the combined metasurface is far better than that of the frequency selection module, which is sufficient to prove the superiority of the metasurface designed by the present invention. Fig. 9 The difference in reflection coefficients of the polarization conversion module, the frequency selection module and the combined metasurface designed in the present invention relative to the perfect conductor is given. Figure 8 The experimental results are similar to those of , among which the worst effect is the frequency selection module. Overall, the combined metasurface designed according to the present invention has an obvious advantage of low detectability. Fig.10 , and the overall level is maintained at a high level, which fully demonstrates the effectiveness of the low detectable performance of the polarization conversion surface designed in the present invention. Fig.11The backscattering coefficient RCS curves corresponding to the combined metasurface and the perfect conductor, as well as the detectability reduction of the combined metasurface relative to the perfect conductor, are given. It can be clearly seen from the figure that the RCS of the combined metasurface is significantly lower than that of the perfect conductor. For ultra-thin metasurfaces, an RCS less than -5 dB is considered to have an excellent detectability reduction effect. The bandwidth where the RCS reduction is less than -5dB also maintains broadband characteristics, which are 8~15.5 GHz and 22~30 GHz, respectively. This is a relatively excellent reduction effect for ultra-thin metasurfaces.

Claims

1. A conformal ultra-thin broadband low-detectable electromagnetic metasurface, characterized in that The metasurface is a combined metasurface consisting of a metal substrate layer, a first dielectric layer, a frequency selection layer, a second dielectric layer, and a polarization conversion layer arranged in sequence from bottom to top, wherein: The frequency selection layer is composed of broadband frequency selection modules, which are arranged above the first dielectric layer in a periodic sequence; The surface of the broadband frequency selection module is designed with a metal pattern layer and a lumped circuit; The metal pattern layer includes a deformed square ring, which is a square ring that is recessed and extended inward, including two forms, S1 and S2. The two deformed square ring structures are nested, and the S2 form is nested and surrounded by the S1 form. In the S1 form, each side has two sawtooth grooves recessed inward along each side with the midpoint as the symmetry point; In the S2 form, the four vertices of the square ring are concave inwards; The lumped circuit is a resistor element nested in a deformed square ring. R ; The resistance element R Nested in the midpoint of each straight line segment of the deformed square ring; The polarization conversion layer is composed of polarization conversion modules; The polarization conversion module is composed of two complementary sub-array modules, "0 state" and "1 state", arranged in a periodic sequence; The "0 state" and "1 state" are the initial state of the polarization conversion module and its rotation state after being rotated 90°, and the two are complementary subarray modules; The complementary subarray module is a polarization conversion module with a reflection phase difference of 180° in two states, each state is composed of n 2 It is composed of polarization conversion sub-modules. n 2 The submodules are n × n The arrangement is arrayed, and the two state arrays are arranged alternately; The surface of the polarization conversion submodule is designed with a metal pattern layer, and the metal pattern layer includes a V-shaped metal patch, a square ring metal patch and a symmetrical microstrip metal patch; The V-shaped metal patch includes four types, V1 to V4, which are centrally symmetrically distributed along the diagonal of the polarization conversion submodule and all have hole structures; In the V1 form, the angle between the single-sided hole structure and the diagonal of the polarization conversion submodule is θ 1; In the V2 form, the angle between the single-sided hole structure and the diagonal of the polarization conversion submodule is θ 2; The V3 form is a centrosymmetric structure of the V2 form about the center point of the polarization conversion module, and the angle between its single-sided hole structure and the diagonal of the polarization conversion submodule is θ 3. θ 3= θ 2; The V4 form is a centrosymmetric structure of the V1 form about the center point of the polarization conversion module, and the angle between its single-sided hole structure and the diagonal of the polarization conversion submodule is θ 4. θ 4= θ 1; The square ring metal patch is mounted at the center of the polarization conversion submodule, and its diagonal is in a straight line with the diagonal of the polarization conversion submodule; The symmetrical microstrip metal patches are two microstrip lines along the diagonal line of the polarization conversion submodule, and the middle of the two microstrip lines is cut off by a square ring metal patch.

2. The conformal ultra-thin broadband low-detectable electromagnetic metasurface according to claim 1, characterized in that The square ring metal patch is a nested structure of three square rings.

3. The conformal ultra-thin broadband low-detectable electromagnetic metasurface according to claim 1, characterized in that The metal pattern layer is made of ITO transparent flexible metal material.

4. The conformal ultra-thin broadband low-detectable electromagnetic metasurface according to claim 1, characterized in that The first dielectric layer and the second dielectric layer are made of a flexible dielectric material PET.

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