Low RCS conformal dual-band dual-circular polarization transmission metasurface system

Abstract

Proposed is a kind of metasurface unit, unit from top to bottom includes upper metal layer patch, upper layer F4BTMS220 dielectric plate, intermediate PVC dielectric substrate, lower layer F4BTMS220 dielectric plate, lower metal layer patch.A low RCS conformal dual-band dual-circular polarization transmission metasurface system is also proposed, which adopts flexible conformal design.The application can convert x polarization into left-handed circular polarization (LHCP) wave and y polarization into right-handed circular polarization (RHCP) wave in 6.7-9.85GHz frequency band, and convert y polarization into LHCP wave and x polarization into RHCP wave in 18.66-20.63GHz frequency band.Meanwhile, due to the influence of conformal structure on metasurface scattering beam, the metasurface has obvious RCS reduction effect when linearly polarized wave is incident, and the overall reduction effect is about 6dB.

Description

Technical Field

[0001] This invention relates to conformal polarization conversion metasurface design technology, specifically to a low RCS conformal dual-band dual circular polarization transmission metasurface. Background Technology

[0002] Electromagnetic wave polarization is one of its key characteristics. Circular polarization, in particular, is widely used in satellite communications, radar systems, mobile communications, and other fields requiring reliable wireless transmission due to its strong anti-interference capabilities, signal stability, and ease of polarization matching. Metasurfaces are novel two-dimensional materials composed of a periodic arrangement of multiple subwavelength-scale microstructures. This design endows metasurfaces with unconventional capabilities, enabling precise control over the phase, amplitude, and polarization properties of electromagnetic waves. Transmissive metasurfaces can be used to achieve the conversion from linear to circular polarization. The paper "Dual-Frequency Dual-Circular Polarization Transmission Metasurface" (B.Han, S.Li, X.Cao, J.Han, L.Jidi, and Y.Li, AIP Advances, vol.10, no.12, 2020, doi:10.1063 / 5.0034762.) describes a dual-frequency dual-circular polarization transmission metasurface that can convert incident x-polarized waves into RHCP waves and y-polarized waves into LHCP waves in the frequency band from 7.31 GHz to 10.58 GHz. Simultaneously, it can convert incident x-polarized waves into LHCP waves and y-polarized waves into RHCP waves in the frequency band from 14.26 GHz to 17.36 GHz. The paper "Multi-frequency dual-circularly polarized transmission metasurface" (ZYLi,SJLi,BWHan,GSHuang,ZXGuo,andXYCao,Advanced Theory and Simulations,Article vol.4,no.8,Aug 2021,Art no.2100117,doi:10.1002 / adts.202100117.) presents a dual-frequency dual-circularly polarized transmission metasurface with a double-arrow unit structure, which can also realize the conversion of linearly polarized waves into circularly polarized waves in two different frequency bands. The paper "Asymmetric Transmission Characteristics of Dual Circular Polarization Based on Chiral Metasurface" (B.Han,S.Li,Z.Li,G.Huang,J.Tian,andX.Cao,OpticsExpress,vol.29,no.13,2021,doi:10.1364 / oe.425787.) presents a non-reciprocal transmission metasurface with a chiral structure that can convert x-polarized waves incident in one direction into RHCP waves and reflect LHCP waves incident in the opposite direction into LHCP waves within the frequency band of 4.69GHz-5.84GHz.

[0003] Traditional metasurfaces often struggle to adapt to diverse application scenarios, leading to the growing interest in conformal metasurfaces. The paper "Wide-bandwidth, low-scattering conformal metasurface designed based on genetic algorithm" (S.Li et al., in International Applied-Computational-Electromagnetics-Society Symposium-China (ACES), Nanjing, PEOPLES R CHINA, 2019 Aug 08-11 2019, doi:10.23919 / aces48530.2019.9060674.) proposes a reflective conformal metasurface with a checkerboard structure. This design achieves monostatic RCS reduction within the 8GHz to 12GHz frequency band. The papers "Conformal OAM Transmissive Metasurface Design" (B.Fu,S.-X.Yu,N.Kou,Z.Ding,andZ.-P.Zhang,Chinese Physics B,Article vol.31,no.4,Mar 1 2022,Art no.040703,doi:10.1088 / 1674-1056 / ac3a65.) and "Conformal OAM Metasurface Antenna Based on Holographic Principle" (X.Ren,L.Deng,C.Zhang,andB.Feng,presented at the 2020IEEE Asia-Pacific Microwave Conference (APMC),2020.) designed two different transmissive conformal metasurfaces that convert incident waves of different frequency bands into OAM vortex beams. The paper "Design of a Conformal Metasurface Radome Based on Printed Components" (M. Elman and R. Shavit, presented at the 2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS), 2021.) demonstrates a conical radome that improves radome gain by reducing transmission loss through the addition of patch capacitors. The paper "Wide-Angle Beam Control Based on Active Conformal Metasurface Lenses" (H. Li et al., IEEE Access, vol. 7, pp. 185264-185272, 2019, doi:10.1109 / access.2019.2960639.) proposes a 1-bit conformal metasurface with a PIN diode, which enables scanning and focusing of the transmitted beam by controlling the phase of the incident wave.

[0004] There are few existing reports on conformal dual-frequency dual-circular polarization transmission metasurfaces. Circular polarization is highly demanding in practical applications, and circularly polarized antennas or planar polarization-conversion metasurfaces alone are insufficient to meet these requirements. Therefore, this invention has significant application value. Summary of the Invention

[0005] To adapt to complex application scenarios, this invention proposes a metasurface unit, hereinafter referred to as "unit". The unit, from top to bottom, includes an upper metal layer patch, an upper F4BTMS220 dielectric substrate, a middle PVC dielectric substrate, a lower F4BTMS220 dielectric substrate, and a lower metal layer patch. The middle PVC dielectric substrate is hereinafter referred to as "substrate".

[0006] The substrate is a thin cuboid with square top and bottom surfaces;

[0007] The upper metal layer patch is attached to the upper surface of the substrate and is symmetrical about the upper left-lower right diagonal of the substrate; from the upper left corner to the lower right corner, it includes the upper left right angle, the upper left semicircle, the serrated line, the lower right semicircle and the lower right right angle respectively.

[0008] The upper left right angle consists of two metal strips extending from two adjacent sides of the upper left corner of the substrate at right angles to each other. The two metal strips meet at the upper left corner of the substrate to form a whole. The length and width of the two metal strips are equal, and their outer edges maintain a certain distance from the corresponding side of the substrate.

[0009] The upper left semicircle is a semicircular ring that faces away from the upper left right angle and opens toward the center of the substrate. It is symmetrical about the upper left-lower right diagonal of the substrate.

[0010] The lower right semicircle is symmetrical to the upper left semicircle about the upper right-lower left diagonal of the substrate.

[0011] The lower right angle is symmetrical to the upper left right angle about the upper right-lower left diagonal of the substrate.

[0012] The line starts from the upper left right angle, passes through the upper left semicircle and the lower right semicircle, and reaches the lower right right angle. The line connects the upper left right angle, the upper left semicircle, the lower right semicircle, and the lower right right angle. The line consists of three segments: upper, middle, and lower. The upper segment is a metal strip that starts from the vertex of the upper left right angle and extends along the upper left-lower right diagonal of the substrate. Its length is about one-third of the upper left-lower right diagonal of the substrate. The lower segment is symmetrical to the upper segment about the upper right-lower left diagonal of the substrate. The middle segment is serrated, and its two ends are connected to the upper segment and the lower segment near the middle segment, respectively.

[0013] The upper and lower F4BTMS220 media boards completely cover the upper and lower surfaces of the PVC board, and the projections of the three on the horizontal plane overlap.

[0014] The lower metal layer patch is attached to the lower surface of the substrate, and its projection on the horizontal plane coincides with that of the upper metal layer patch.

[0015] In one embodiment of the present invention, the upper metal layer patch is integrally formed; the widths of the two right angles, the two semicircles, and the connecting line are not necessarily equal.

[0016] In one specific embodiment of the present invention, other parameters of the unit are shown in Table 1:

[0017] Table 1

[0018]

[0019] In the table, W is the line width, L is the length of the long side of the serrated structure, D1 is the length of the line connecting the serrated structure and the right-angle patch, D2 is the length of the short side of the serrated structure, D3 is the length of the right-angle patch, Rc is the radius of the semi-circular patch, Wb is the width of the right-angle patch, and Wc is the width of the semi-circular patch.

[0020] In another embodiment of the present invention, the dielectric constant of the substrate is in the range of 2 to 3, the loss tangent is in the range of 0.01 to 0.06, the unit size is in the range of 8 to 12 mm, the thickness is less than 5 mm, the proportion of metal patches is 10% to 20%, and the thickness of the metal patches is in the range of 0.01 to 0.02 mm.

[0021] In another specific embodiment of the present invention, the unit size is 8*8mm, the substrate is a PVC board with a thickness of 3mm; the lower F4BTMS220 dielectric board has a thickness of 0.127mm, and the metal patch has a thickness of 0.035mm.

[0022] In another embodiment of the present invention, the number of sawtooth segments in the middle section of the connecting line is 1 to 5, and each sawtooth segment is in the shape of a periodic rectangular wave.

[0023] A low RCS conformal dual-band dual-circular polarization transmission metasurface system is also provided. The overall shape of the system is a fan-shaped cylinder. If the overall curvature of the system is not considered, the system is composed of multiple arrays of the above-mentioned metasurface units.

[0024] In one embodiment of the present invention, the number of units is greater than 40, and the conformal bend angle of the entire system is greater than 60°.

[0025] In one specific embodiment of the present invention, the conformal bend angle of the entire system is 120°; two F4BTMS220 dielectric boards with a thickness of 0.127mm are used.

[0026] This invention achieves a high polarization conversion rate while enabling a low RCS design for metasurfaces, making metasurfaces better suited for practical applications and broadening their applicability. Attached Figure Description

[0027] Figure 1 shows the conceptual diagram, structural diagram, functional conceptual diagram, and fabricated sample of the low RCS conformal dual-band dual-circular polarization transmission metasurface unit (hereinafter referred to as "unit") proposed in this invention. Figure 1(a) shows the overall conceptual diagram of the unit, Figure 1(b) shows the top view of the unit and parameter diagram, and the specific parameters are shown in Table 1. Figure 1(c) shows the conceptual diagram of the conformal array composed of the unit to realize the polarization conversion function.

[0028] Figure 2 shows the transmittance curves, transmission phase and phase difference curves, total transmittance and axial ratio curves, polarization conversion rate curves, and spatial electric field distribution diagrams of the element under x- and y-polarized incident incidence. Figure 2(a) shows the common polarization and cross-polarization transmittance when linearly polarized waves are incident. Figure 2(b) shows the phase and phase difference of the transmitted waves when x-polarized and y-polarized waves are incident. Figure 2(c) shows the total transmittance and axial ratio of the linearly polarized incident wave. Figure 2(d) shows the transmission conversion rate of x- and y-polarized waves after being incident and converted into LHCP or RHCP waves. Figure 2(e) shows the electric field distribution diagrams of y-polarized waves transmitted and converted into circularly polarized waves at frequencies of 9.6 GHz and 18.95 GHz.

[0029] Figure 3 A two-dimensional heatmap of the wide-angle domain characteristics of the unit is given, where Figure 3 (a) and (b) present heatmaps showing the conversion rate of the incident wave to an LHCP polarized wave as a function of phi and theta. Figure 3 (c) and (d) present heatmaps showing the conversion rate of the incident wave to an RHCP polarized wave as a function of phi and theta. Figure 3 (e) and (f) present heatmaps of AR as a function of phi and theta.

[0030] Figure 4 shows a two-dimensional heat map of the unit robustness. Figures 4(a), (b), (c), and (d) show two-dimensional heat maps of AR as a function of D3, D1, L, and Rc, respectively.

[0031] Figure 5 shows the RCS comparison diagram. Figure 5(a) is a schematic diagram of the RCS test of the conformal metasurface, and Figure 5(b) is the RCS comparison curve of the conformal metasurface and the metal when TE and TM waves are incident.

[0032] Figure 6 The simulation and test results of the radiation pattern at a frequency of 9.6 GHz for Y-polarized incident radiation are presented. Detailed Implementation

[0033] As shown in Figure 1(c), the overall shape of the low RCS conformal dual-band dual-circular polarization transmission metasurface system is a fan-shaped cylinder, composed of different dielectric substrates and metal patches. The intermediate dielectric substrate should be made of a conformally conformal material with a low dielectric constant to ensure high transmittance and polarization conversion efficiency. The dielectric constant should be in the range of 2–3, and its loss tangent should not be too low, within the range of 0.01–0.06, to ensure both a certain absorption effect and appropriate transmittance, thereby achieving RCS reduction. The unit size should preferably be in the range of 8–12 mm, and the thickness should be less than 5 mm. The specific dimensions depend on the material selection and operating frequency band. If the material is difficult to attach the metal patch, a 0.127 mm thick dielectric substrate such as Rogers 5880 or Wanling F4BTMS220, which has good flexibility and is easily conformal, can be used. This type of ultra-thin substrate can serve as a transitional dielectric material for attaching the metal patch.

[0034] The metal patch should adopt a 45° symmetrical structure to ensure that the cell is insensitive to x and y polarization. The proportion of the metal patch should not be too high, generally between 10% and 20%, to ensure that the array has good polarization conversion efficiency while also ensuring transmittance. The thickness of the metal patch should be in the range of 0.01 to 0.02 mm to ensure that problems such as patch breakage do not occur during conformal processing.

[0035] In a specific embodiment of the present invention, the overall curvature of the system is disregarded, and the unit is considered as a planar structure. The functional schematic diagrams of the unit and metasurface structure are shown in Figures 1(a), (b), and (c). The unit size is 8*8mm, and from top to bottom includes an upper metal layer patch, an upper F4BTMS220 dielectric substrate, a middle PVC dielectric substrate (hereinafter referred to as "substrate"), a lower F4BTMS220 dielectric substrate, and a lower metal layer patch. The lower F4BTMS220 dielectric substrate has a thickness of 0.127mm and is adhered to the PVC substrate with epoxy adhesive for attaching the metal patch, which has a thickness of 0.035mm. Other parameters of the unit are shown in Table 1, which provides the specific values ​​for each parameter in the unit structure proposed in this invention.

[0036] Table 1

[0037]

[0038] In the table, W is the line width, L is the length of the long side of the serrated structure, D1 is the length of the line connecting the serrated structure and the right-angle patch, D2 is the length of the short side of the serrated structure, D3 is the length of the right-angle patch, Rc is the radius of the semi-circular patch, Wb is the width of the right-angle patch, and Wc is the width of the semi-circular patch.

[0039] The substrate is a thin cuboid structure with square top and bottom surfaces. The substrate is made of 3mm thick PVC board (at a center frequency of 14GHz, ε...). PVC=2.3, tanδ PVC =0.06), the measured RCS reduction effect is good, and the transmittance is above 0.6.

[0040] The upper metal layer patch is attached to the upper surface of the substrate and is symmetrical about the upper left-lower right diagonal of the substrate. From the upper left corner to the lower right corner, it includes an upper left right angle, an upper left semicircle, a zigzag line, a lower right semicircle, and a lower right right angle.

[0041] The upper left right angle consists of two metal strips extending from two adjacent sides of the upper left corner of the substrate at right angles to each other. The two metal strips meet at the upper left corner of the substrate to form a whole. The two metal strips are equal in length and width, and their outer edges maintain a certain distance from the corresponding side of the substrate.

[0042] The upper left semicircle is a semicircular ring, which faces away from the upper left right angle and opens towards the center of the substrate. It is symmetrical about the upper left-lower right diagonal of the substrate.

[0043] The lower right semicircle is symmetrical to the upper left semicircle about the upper right-lower left diagonal of the substrate.

[0044] The lower right right angle is symmetrical to the upper left right angle about the upper right-lower left diagonal of the substrate.

[0045] The connection starts from the upper left right angle, passes through the upper left semicircle and the lower right semicircle, and reaches the lower right right angle, connecting the upper left right angle, the upper left semicircle, the lower right semicircle, and the lower right right angle. The connection consists of three segments: upper, middle, and lower. The upper segment is a metal strip that starts from the vertex of the upper left right angle and extends along the upper left-lower right diagonal of the substrate, with a length approximately one-third of the length of the upper left-lower right diagonal. The lower segment is symmetrical to the upper segment about the upper right-lower left diagonal of the substrate. The middle segment is serrated, with 1 to 5 serrations being ideal (the illustrated structure has 2 serrations, each serration forming a periodic rectangular wave shape). Too many serrations will result in an excessively narrow serration structure, affecting functionality. The two ends of the middle segment are connected to the upper and lower segments near the middle, respectively.

[0046] Overall, the upper left right angle, the upper left semicircle, the zigzag connecting line, the lower right semicircle, and the lower right right angle are integrated into one unit. Although they appear to be the same in Figure 1, the widths of the two right angles, the two semicircles, and the connecting line are not necessarily equal and should be determined according to the actual situation to achieve the highest possible transmittance and planned conversion rate, while minimizing reflectance.

[0047] The upper and lower F4BTMS220 media boards completely cover the upper and lower surfaces of the PVC board, respectively. Two F4BTMS220 media boards with a thickness of 0.127mm are used, and the projections of the three on the horizontal plane overlap.

[0048] The lower metal layer patch is attached to the lower surface of the substrate, and its projection on the horizontal plane coincides with that of the upper metal layer patch.

[0049] The entire system consists of multiple units arranged in an array, with a number greater than 40 (55*35 in the illustration). The conformal bend angle of the entire system is greater than 60° (120° in the illustration). The smaller the bend angle, the better the circular polarization conversion effect, but the RCS reduction effect will decrease accordingly.

[0050] The designed unit was numerically simulated across the entire frequency band using the electromagnetic simulation software CST Microwave Studio 2018. The simulation results of x-polarized and y-polarized waves after incident radiation with frequency are shown in Figure 2. Since the metal patch has a centrosymmetric structure, the transmission coefficients of the x-polarized and y-polarized waves are completely identical. The transmission coefficients and phases of the linearly polarized waves are shown in Figures 2(a) and (b). The transmittance difference between the same-polarization and cross-polarization components is less than 0.1 in the 6.7–9.85 GHz and 18.66–20.63 GHz frequency bands, respectively, with phase differences around -90° and 90°. The AR of the transmitted waves is less than 3 dB, indicating that the transmitted waves in these two frequency bands are circularly polarized waves. The total transmittance (T) of the DCT-MS unit is shown in Figure 2(c). The simulation curves show that the total transmittance can reach a maximum of 0.8 and a minimum of over 0.5 within the operating frequency range. Figure 2(d) shows the conversion rates of linearly polarized waves to circularly polarized waves in different frequency bands. As can be seen from the figure, in the range of 6.7–9.85 GHz, x-polarized waves mainly convert to LHCP waves, while y-polarized waves convert to RHCP waves. Conversely, in the range of 18.66–20.63 GHz, x-polarized waves mainly convert to RHCP waves, while y-polarized waves convert to LHCP waves. Figure 2(e) also shows the spatial electric field distribution on both sides of the metasurface at 9.6 GHz and 18.95 GHz. When a y-polarized wave is incident, the electric field vector on the right rotates counterclockwise and has the same amplitude on each xoy surface, indicating that the transmitted wave is RHCP. Similarly, at 18.95 GHz, the transmitted wave is LHCP.

[0051] Because of the bending of elements in conformal design, the incident direction and parameters will change to some extent. Therefore, it is necessary to analyze the wide-angle domain characteristics and robustness of the elements. Figure 3 Figures (a), (b), (c), and (d) present heatmaps showing the conversion rates of the incident wave to LHCP-polarized and RHCP-polarized waves as a function of phi and theta, respectively. For ease of observation, AR values ​​less than 3 dB are marked with red lines, while AR values ​​greater than 18 are not considered useful and are represented by the same color. The figures show that, with changes in Phi, the converted circularly polarized wave exhibits good wide-angle characteristics within the ranges of 0°±15°, 90°±15°, and 180°±15°. Similarly, this element exhibits good wide-angle characteristics with respect to theta.

[0052] Table 2 shows the parameters of the metal patches on the inner and outer sides of the cylindrical element after conformal design with radius and their variation range. As can be seen from the table, D3 is the parameter most significantly affected by the conformal design, while D1, L, and Rc also show slight changes. Therefore, robustness tests were conducted on these four parameters. Figures 4(a), (b), (c), and (d) show the heatmaps of AR as a function of parameters D3, D1, L, and Rc, respectively. It can be observed that the variation of these three parameters within the range has little impact on the overall AR, and the parameter variation range after bending of the actual array is smaller than the simulation range. Therefore, the element exhibits good robustness and can be used for conformal design.

[0053] Table 2 Changes after conformal unit design

[0054]

[0055] Further RCS comparison analysis was conducted between the conformal metasurface and a metal plate with the same projected area in the xOy plane, as shown in Figure 5. For x-polarized waves, the metasurface exhibits good RCS reduction. On one hand, the conformal metasurface itself has the effect of diverging the scattered wave beam; on the other hand, PVC has a high loss tangent, enabling the metasurface to have a certain absorption effect while meeting transmission requirements, thus achieving a good RCS reduction effect. However, for y-polarized waves, the reduction effect is slightly inferior to that of x-polarized waves. Compared to the case of x-polarized wave incidence, the dielectric loss does not change when y-polarized waves are incident, but the divergence effect on the scattered wave beam is poor. This is due to the geometric structure of the fan-shaped cylindrical surface.

[0056] Finally, the object was measured in a microwave anechoic chamber, such as... Figure 6 As shown, the measurement results are consistent with expectations.

Claims

1. A metasurface unit, hereinafter referred to as "unit", characterized in that, The unit comprises an upper metal layer patch, an upper F4BTMS220 dielectric plate, an intermediate PVC dielectric substrate, a lower F4BTMS220 dielectric plate, and a lower metal layer patch from top to bottom. Wherein The substrate is a thin cuboid with square upper and lower surfaces. The upper metal layer patch is attached to the upper surface of the substrate and is symmetric about the left upper-right lower diagonal of the substrate; from the upper left corner to the lower right corner, the upper metal layer patch comprises an upper left right angle, an upper left semicircle, a zigzag line, a lower right semicircle, and a lower right right angle. The upper left right angle is formed by two metal strips extending along the two adjacent edges of the upper left corner of the substrate and forming a right angle with each other; the two metal strips meet at the upper left corner of the substrate to form a whole; the lengths and widths of the two metal strips are equal, and the outer edges of the two metal strips are at a certain distance from the corresponding edges of the substrate. The upper left semicircle is a semicircular ring with its back facing the upper left right angle and opening towards the center of the substrate; the upper left semicircle is symmetric about the left upper-right lower diagonal of the substrate. The lower right semicircle is symmetric about the right upper-left lower diagonal of the substrate with the upper left semicircle. The lower right right angle is symmetric about the right upper-left lower diagonal of the substrate with the upper left right angle. The line starts from the upper left right angle, passes through the upper left semicircle and the lower right semicircle, and reaches the lower right right angle; the line connects the upper left right angle, the upper left semicircle, the lower right semicircle, and the lower right right angle; the line comprises an upper segment, a middle segment, and a lower segment; the upper segment is a metal strip starting from the top point of the upper left right angle and extending along the left upper-right lower diagonal of the substrate; the length of the upper segment is one third of the length of the left upper-right lower diagonal of the substrate; the lower segment is symmetric about the right upper-left lower diagonal of the substrate with the upper segment; the middle segment is zigzag-shaped, and the two ends of the middle segment are connected to the end points of the upper segment and the lower segment close to the middle segment. The upper and lower F4BTMS220 dielectric plates completely cover the upper and lower surfaces of the PVC plate, respectively, and the projections of the three on the horizontal plane overlap. The lower metal layer patch is attached to the lower surface of the substrate and coincides with the projection of the upper metal layer patch on the horizontal plane.

2. The metasurface unit of claim 1, wherein, The upper metal layer patch is integrally formed.

3. The metasurface unit of claim 1, wherein, The dielectric constant of the substrate is in the range of 2-3, and the loss tangent is in the range of 0.01-0.06; the size of the unit is in the range of 8-12 mm, and the thickness is less than 5 mm; the metal patch accounts for 10%-20%, and the thickness of the metal patch is in the range of 0.01-0.02 mm.

4. The metasurface unit of claim 1, wherein, The size of the unit is 8*8 mm, and the substrate is a PVC plate with a thickness of 3 mm; the thickness of the lower F4BTMS220 dielectric plate is 0.127 mm, and the thickness of the metal patch is 0.035 mm.

5. The metasurface unit of claim 1, wherein, The number of zigzags in the middle segment of the line is 1-5, and each zigzag is in the shape of a periodic rectangular wave.

6. A low-RCS conformal dual-band dual-circularly polarized transmission metasurface system, characterized in that, The overall shape of the system is a fan-shaped cylindrical surface; if the overall curvature of the system is not considered, the system is composed of a plurality of super-structured surface unit arrays as claimed in any one of claims 1-5.

7. The low-RCS, conformal dual-band, dual-circularly polarized transmission meta-surface system of claim 6, wherein, The number of units is greater than 40, and the conformal bending angle of the entire system is greater than 60°.

8. The low-RCS conformal dual-band dual-circular polarized transmission meta-surface system of claim 6, wherein, The conformal bending angle of the entire system is 120°; two F4BTMS220 dielectric plates with a thickness of 0.127 mm are used.

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