Ultra-wideband low-RCS coding metasurface optimized by PSO algorithm

Abstract

The invention provides an ultra-wideband low-RCS (Radar Cross-Section) coding metasurface optimized by a PSO (Particle Swarm Optimization) algorithm, and belongs to the technical field of non-traditional machining and the technical field of electromagnetic metamaterials. Six 0-order units meeting a phase cancellation principle form two 1-order units to respectively realize RCS reduction of high frequency and low frequency bands; meanwhile, the arrangement of two types of 1-order units is optimized by utilizing a PSO (Particle Swarm Optimization) algorithm, RCS (Radar Cross Section) reduction of more than 10dB in a frequency band of 14-41GHz is obtained, and the relative bandwidth reaches 98.2%; in addition, the coding metasurface provided by the invention is low in total thickness, small in profile, low in cost and relatively high in practical value.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic metamaterials, and in particular relates to an ultra-wideband low RCS coding metasurface optimized by a PSO algorithm. Background Art

[0002] Radar cross section (RCS) is a physical quantity used to describe the strength of scattering of incident electromagnetic waves by a detected target. It usually refers to the scattering power of the detected target reflected in a certain direction after being irradiated by electromagnetic waves.

[0003] In the military field, reducing the RCS of weapons and equipment and reducing the probability of them being detected by radar is an important measure to improve combat effectiveness and survivability. Traditional RCS reduction methods include changing the shape of the target and applying absorbing materials, but changing the shape of the target increases the design complexity and affects the aerodynamic performance, and applying absorbing materials increases the weight of the equipment and can only achieve low RCS in a narrow frequency band.

[0004] Electromagnetic metasurfaces can regulate the propagation characteristics of electromagnetic waves and can be used to reduce RCS. The mainstream method is to design two metasurface units with a reflection phase difference of 180°±37°, arrange them in a chessboard pattern, and achieve RCS reduction through anti-phase cancellation. However, although the chessboard arrangement is simple in design, its RCS reduction and reduced bandwidth still cannot meet current technical requirements.

[0005] Therefore, there is an urgent need for an ultra-wideband low RCS coding metasurface optimized by the PSO algorithm to further achieve RCS reduction. Summary of the invention

[0006] In order to solve the shortcomings and deficiencies of the existing technology, an ultra-wideband low RCS coding metasurface optimized by a PSO algorithm is provided, thereby solving the problem that the existing RCS reduction method cannot meet the current technical requirements.

[0007] To achieve the purpose of the present invention, a PSO algorithm-optimized ultra-wideband low RCS coding metasurface is provided, the coding metasurface includes 6×6 squares, and the coding metasurface is optimized by a discrete PSO algorithm so that the 1st, 4-6th columns of the first row, the 3rd-6th columns of the second row, the 2nd, 4th, and 6th columns of the third row, the 1st, 3-4th, and 6th columns of the fourth row, the 1st, 3-6th columns of the fifth row, and the 1st, 3-6th columns of the sixth row are all first 1-order units, and the rest are second 1-order units; the first 1-order unit includes 4×4 squares, the 1st-2nd rows of the first and second columns and the 3rd-4th rows of the third and fourth columns of the first 1-order unit are all first 0-order units, and the rest are second 0-order units, and the surface size of the first 0-order unit and the second 0-order unit are both 9×9 mm 2The second 1-order unit includes 2×2 squares, the first row of the first column of the second 1-order unit is the third 0-order unit, the second row of the first column is the fifth 0-order unit, the second row of the second column is the fourth 0-order unit, and the first row of the second column is the sixth 0-order unit. The surface size of the third 0-order unit, the fourth 0-order unit, the fifth 0-order unit and the sixth 0-order unit is 18×18 mm 2 .

[0008] As a further improvement of the above scheme, the first 0-order unit includes a bottom metal ground plate, an intermediate dielectric substrate is fixed on the top of the bottom metal ground plate, a first top metal is fixed at the geometric center of the top of the intermediate dielectric substrate, the pattern of the first top metal is a square metal patch, and the side length d1 of the square metal patch is 0.4 mm.

[0009] As a further improvement of the above scheme, the second 0-order unit includes a bottom metal ground plate, a bottom dielectric substrate is fixed on the top of the bottom metal ground plate, an intermediate layer of metal is fixed on the top of the bottom dielectric substrate, and a top dielectric substrate is fixed on the top of the intermediate layer of metal.

[0010] As a further improvement of the above scheme, the third 0-order unit includes a bottom metal ground plate, an intermediate dielectric substrate is fixed on the top of the bottom metal ground plate, a third top metal is fixed at the geometric center of the top of the intermediate dielectric substrate, the pattern of the third top metal is a Jerusalem cross, the length d3 of the mutually perpendicular strips in the third top metal is 17 mm, short strips are vertically arranged at the ends of the strips, the length d4 of the short strips is 5.5 mm, and the width d6 of the strip and the width d5 ​​of the short strip are both 1 mm.

[0011] As a further improvement of the above scheme, the fourth 0-order unit includes a bottom metal ground plate, an intermediate dielectric substrate is fixed on the top of the bottom metal ground plate, four fourth top metals are symmetrically fixed on the top of the intermediate dielectric substrate, the pattern of the fourth top metal is a square, the side length d7 of the fourth top metal is 5.5 mm, and the spacing d8 between the upper and lower rows of the fourth top metal is 4.5 mm.

[0012] As a further improvement of the above scheme, the fifth 0-order unit includes a bottom metal ground plate, an intermediate dielectric substrate is fixed on the top of the bottom metal ground plate, a fifth top metal is fixed at the geometric center of the top of the intermediate dielectric substrate, and the pattern of the fifth top metal is a square ring, the inner side length d9 of the square ring is 12 mm, and the outer side length d 10 It is 16mm.

[0013] As a further improvement of the above solution, the sixth 0-order unit includes a bottom metal ground plate, an intermediate dielectric substrate is fixed on the top of the bottom metal ground plate, a sixth top metal is fixed at the geometric center of the top of the intermediate dielectric substrate, the pattern of the sixth top metal is a square, and the side length d of the sixth top metal is 11 It is 8mm.

[0014] As a further improvement of the above scheme, the intermediate dielectric substrates in the first 0-order unit, the third 0-order unit, the fourth 0-order unit, the fifth 0-order unit and the sixth 0-order unit all use F4B material with a dielectric constant of 2.14, a loss tangent of 0.0008 and a thickness of 3.76 mm, and the top dielectric substrate and the bottom dielectric substrate in the second 0-order unit all use F4B material with a dielectric constant of 2.14, a loss tangent of 0.0008 and a thickness of 1.88 mm.

[0015] As a further improvement of the above scheme, the coding metasurface uses a discrete PSO algorithm to optimize the coding sequence of the first 1-order unit and the second 1-order unit, and uses the bandwidth that achieves an RCS reduction of more than 10 dB within a specified frequency range as the fitness function. The objective function expression of the optimization algorithm is as follows:

[0016]

[0017] Where M is the total number of frequency points selected every 1 GHz in the range of 5-50 GHz, fi represents the i-th frequency point, RCS ideal conductor (fi) is the RCS of the ideal conductor at frequency fi, RCSA (fi) is the RCS of the coding metasurface at frequency fi under arrangement A, and 1 is the indicator function;

[0018] When its parameter is true (i.e., the RCS difference is greater than or equal to 10dB), the function value is 1, otherwise it is 0; the optimization goal is to find the maximum value of F(A).

[0019] As a further improvement of the above scheme, the coded metasurface reduces RCS by more than 10dB in the 14-41GHz frequency band compared with an ideal conductor, and the relative bandwidth reaches 98.2%. It also maintains excellent RCS reduction performance when the incident angle changes from 0° to 45°.

[0020] The beneficial effects of the present invention are:

[0021] Compared with the prior art, the present invention provides an ultra-wideband low RCS coding metasurface optimized by a PSO algorithm, which realizes RCS reduction in high-frequency and low-frequency bands respectively by combining six 0-order units that satisfy the phase cancellation principle into two 1-order units; at the same time, the PSO algorithm is used to optimize the arrangement of the two 1-order units, thereby obtaining an RCS reduction of more than 10 dB in the 14-41 GHz frequency band, and the relative bandwidth reaches 98.2%; in addition, the coding metasurface provided by the present invention has a low total thickness, a small cross-section, a low cost, and a high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the unit arrangement structure of the coding metasurface optimized by the PSO algorithm in the present invention;

[0023] Figure 2 Schematic diagram of the structure of the first 1-order unit in the present invention;

[0024] Figure 3 is a schematic structural diagram of the second 1-order unit in the present invention;

[0025] Figure 4 is a schematic structural diagram of the first 0-order unit in the present invention;

[0026] Figure 5 is a schematic structural diagram of the second 0-order unit in the present invention;

[0027] Figure 6 is a schematic structural diagram of the third 0-order unit in the present invention;

[0028] Figure 7 is a schematic structural diagram of the fourth 0-order unit in the present invention;

[0029] Figure 8 is a schematic structural diagram of the fifth 0-order unit in the present invention;

[0030] Fig. 9 is a schematic structural diagram of the sixth 0-order unit in the present invention;

[0031] Fig.10 is a reflection amplitude and reflection phase curve diagram of the first and second 0-order units in the present invention;

[0032] Fig.11 is a RCS comparison curve of the first 1-order unit and the ideal electrical conductor in the present invention;

[0033] Fig.12 Graphs showing the reflection amplitude and reflection phase of the third, fourth, fifth and sixth 0-order units in the present invention;

[0034] Fig.13is a RCS comparison curve of the second 1-order unit B and the ideal electrical conductor in the present invention;

[0035] Fig.14 The RCS comparison curve of the coding metasurface of the present invention and the ideal electrical conductor when the incident angle increases from 0° to 45°;

[0036] Fig.15 : RCS scattering diagrams of the coding metasurface of the present invention and an ideal electric conductor at 19 GHz when the incident angles are 0°, 15°, 30° and 45° respectively;

[0037] Fig.16 Schematic diagram of the coding metasurface structure without PSO algorithm optimization;

[0038] Fig.17 Schematic diagram of the RCS reduction comparison curve between the coding hypersurface optimized using the PSO algorithm and the coding hypersurface not optimized using the PSO algorithm.

[0039] Among them, 1-first 0-order unit, 2-second 0-order unit, 3-third 0-order unit, 4-fourth 0-order unit, 5-fifth 0-order unit, 6-sixth 0-order unit, 100-bottom metal ground plate, 101-first top metal, 102-middle dielectric substrate, 201-top dielectric substrate, 202-bottom dielectric substrate, 203-middle metal, 301-third top metal, 401-fourth top metal, 501-fifth top metal, 601-sixth top metal. DETAILED DESCRIPTION

[0040] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings:

[0041] according to Figure 1-3 As shown, the present invention provides an ultra-wideband low RCS coding metasurface optimized by a PSO algorithm, the coding metasurface includes 6×6 squares, and after the coding metasurface is optimized by a discrete PSO algorithm, the 1st, 4-6th columns of the first row, the 3rd-6th columns of the second row, the 2nd, 4th, and 6th columns of the third row, the 1st, 3-4th, and 6th columns of the fourth row, the 1st, 3-6th columns of the fifth row, and the 1st, 3-6th columns of the sixth row are all first 1-order units, and the rest are second 1-order units; the first 1-order unit includes 4×4 squares, and the 1st-2nd rows of the first and second columns and the 3rd-4th rows of the third and fourth columns of the first 1-order unit are all first 0-order units 1, and the rest are second 0-order units 2, and the surface size of the first 0-order unit 1 and the second 0-order unit 2 are both 9×9 mm 2The second 1-order unit includes 2×2 squares. The first row of the first column of the second 1-order unit is the third 0-order unit 3, the second row of the first column is the fifth 0-order unit 5, the second row of the second column is the fourth 0-order unit 4, and the first row of the second column is the sixth 0-order unit 6. The surface size of the third 0-order unit 3, the fourth 0-order unit 4, the fifth 0-order unit 5 and the sixth 0-order unit 6 is 18×18 mm. 2 .

[0042] Among them: Figure 4 As shown, the first 0-order unit 1 includes a bottom metal ground plate 100, an intermediate dielectric substrate 102 is fixed on the top of the bottom metal ground plate 100, a first top metal layer 101 is fixed at the geometric center of the top of the intermediate dielectric substrate 102, and the pattern of the first top metal layer 101 is a square metal patch, and the side length d1 of the square metal patch is 0.4 mm.

[0043] like Figure 5 As shown, the second 0-order unit 2 includes a bottom metal ground plane 100 , a bottom dielectric substrate 202 is fixed on the top of the bottom dielectric substrate 202 , an intermediate metal layer 203 is fixed on the top of the intermediate metal layer 203 , and a top dielectric substrate 201 is fixed on the top of the intermediate metal layer 203 .

[0044] like Figure 6 As shown, the third 0-order unit 3 includes a bottom metal ground plate 100, an intermediate dielectric substrate 102 is fixed on the top of the bottom metal ground plate 100, a third top metal layer 301 is fixed at the geometric center of the top of the intermediate dielectric substrate 102, the pattern of the third top metal layer 301 is a Jerusalem cross, the length d3 of the mutually perpendicular strips in the third top metal layer 301 is 17 mm, short strips are vertically arranged at the ends of the strips, the length d4 of the short strips is 5.5 mm, and the width d6 of the strips and the width d5 ​​of the short strips are both 1 mm.

[0045] like Figure 7 As shown, the fourth 0-order unit 4 includes a bottom metal ground plate 100, an intermediate dielectric substrate 102 is fixed on the top of the bottom metal ground plate 100, four fourth top metal layers 401 are symmetrically fixed on the top of the intermediate dielectric substrate 102, the pattern of the fourth top metal layers 401 is a square, the side length d7 of the fourth top metal layers 401 is 5.5 mm, and the spacing d8 between the upper and lower rows of the fourth top metal layers 401 is 4.5 mm.

[0046] like Figure 8As shown, the fifth 0-order unit 5 includes a bottom metal ground plate 100, an intermediate dielectric substrate 102 is fixed on the top of the bottom metal ground plate 100, and a fifth top metal 501 is fixed at the geometric center of the top of the intermediate dielectric substrate 102. The pattern of the fifth top metal 501 is a square ring, and the inner side length d9 of the square ring is 12 mm, and the outer side length d 10 It is 16mm.

[0047] like Fig. 9 As shown, the sixth 0-order unit 6 includes a bottom metal ground plane 100, an intermediate dielectric substrate 102 is fixed on the top of the bottom metal ground plane 100, a sixth top metal 601 is fixed at the geometric center of the top of the intermediate dielectric substrate 102, the pattern of the sixth top metal 601 is a square, and the side length d of the sixth top metal 601 is 11 It is 8mm.

[0048] The intermediate dielectric substrate 102 in the above-mentioned first 0-order unit 1, the third 0-order unit 3, the fourth 0-order unit 4, the fifth 0-order unit 5 and the sixth 0-order unit 6 all adopt F4B material with a dielectric constant of 2.14, a loss tangent of 0.0008 and a thickness of 3.76 mm, and the top dielectric substrate 201 and the bottom dielectric substrate 202 in the second 0-order unit 2 all adopt F4B material with a dielectric constant of 2.14, a loss tangent of 0.0008 and a thickness of 1.88 mm.

[0049] like Fig.10 As shown, the simulation conditions of the first 0-order unit 1 and the second 0-order unit 2 are set to simulate infinite periodic boundary conditions. When the electromagnetic wave is irradiated vertically, the amplitude of the reflection coefficient is close to 0dB, and the phase difference is 180°±37° within 16-39GHz. According to the principle of phase cancellation, if they are arranged reasonably, RCS reduction can be achieved.

[0050] like Fig.11 As shown, the simulation condition of the first 1-order unit composed of the first 0-order unit 1 and the second 0-order unit 2 is set to simulate an infinite periodic boundary condition. When the electromagnetic wave is irradiated vertically, compared with an ideal conductor, its RCS is reduced by more than 10dB within 20-40GHz.

[0051] like Fig.12As shown, the simulation conditions of the third 0-order unit 3, the fourth 0-order unit 4, the fifth 0-order unit 5 and the sixth 0-order unit 6 are respectively set to simulate infinite periodic boundary conditions. When the electromagnetic wave is irradiated vertically, the amplitude of the reflection coefficient is close to 0dB. In the 9-24GHz frequency band, the third 0-order unit 3, the fifth 0-order unit 5 and the sixth 0-order unit 6 have a phase difference of 180°±37° with the fourth 0-order unit 4. According to the principle of phase cancellation, if they are arranged reasonably, RCS reduction can be achieved.

[0052] like Fig.13 As shown, the simulation conditions of the second 1-order unit composed of the third 0-order unit 3, the fourth 0-order unit 4, the fifth 0-order unit 5 and the sixth 0-order unit 6 are set to simulate infinite periodic boundary conditions. When the electromagnetic wave is irradiated vertically, compared with the ideal conductor, its RCS is reduced by more than 10dB in the two frequency bands of 10-16GHz and 40-45GHz.

[0053] In addition, the coded metasurface uses a discrete PSO algorithm to optimize the coding sequence of the first 1-order unit and the second 1-order unit, and uses the bandwidth that achieves an RCS reduction of more than 10 dB within the specified frequency range as the fitness function. The objective function expression of the optimization algorithm is as follows:

[0054]

[0055] Where M is the total number of frequency points selected every 1 GHz in the range of 5-50 GHz, fi represents the i-th frequency point, RCS ideal conductor (fi) is the RCS of the ideal conductor at frequency fi, RCSA (fi) is the RCS of the coding metasurface at frequency fi under arrangement A, and 1 is the indicator function;

[0056] When its parameter is true (i.e., the RCS difference is greater than or equal to 10dB), the function value is 1, otherwise it is 0; the optimization goal is to find the maximum value of F(A).

[0057] like Fig.14 As shown, when the plane wave is incident at 0°, 15°, 30° and 45°, compared with the ideal conductor of the same size and the same simulation conditions, the coded metasurface designed by the present invention has an RCS reduction of more than 10 dB in the 14-41 GHz frequency band, and a relative bandwidth of 98.2%. Moreover, when the incident angle changes from 0° to 45°, it still maintains excellent RCS reduction performance, which indicates that the present invention has good dual-station RCS reduction performance.

[0058] like Fig.15As shown in the figure, at 19 GHz, when the incident wave is incident on the coding metasurface designed by the present invention and the ideal electric conductor surface of the same size at 0°, 15°, 30° and 45°, the reflection wave capability of the ideal electric conductor is mainly concentrated in the main lobe; while the coding metasurface designed by the present invention scatters the reflected wave in multiple directions, the amplitude of the main beam is significantly suppressed, and its RCS value is significantly lower than that of the ideal electric conductor of the same size.

[0059] In order to highlight the superiority of the coded metasurface obtained by the PSO algorithm optimization in the present invention, the RCS value of the coded metasurface is compared with that of a metasurface of the same size that is not optimized by the PSO algorithm. Fig.16 As shown in , this arrangement is the best arrangement obtained by comparing the RCS performance of possible traditional arrangements. Fig.17 As shown, the maximum RCS reduction value of the coding metasurface designed by the present invention is 24.9dB, and it reaches a reduction of more than 10dB in the range of 14-41GHz. The maximum RCS reduction value of the metasurface not optimized by the PSO algorithm is 19.5dB, and the 10dB reduction bandwidth is 13.7-20.3GHz and 36.2-42.2GHz, which is about 16GHz narrower than the absolute bandwidth of the coding metasurface designed by the present invention.

[0060] In summary, the present invention has ultra-wideband low RCS performance, and can achieve an RCS reduction of more than 10 dB within 14-41 GHz, with a relative bandwidth of 98.2% and a maximum reduction of 24.9 dB. The coded metasurface designed by the present invention has the advantages of low profile and low cost, and has high practicality.

[0061] The above embodiments are not limited to the technical solutions of the embodiments themselves, and the embodiments can be combined with each other to form new embodiments. The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention shall be included in the scope of the technical solutions of the present invention.

Claims

1. An ultra-wideband low RCS coding metasurface optimized by a PSO algorithm, the coding metasurface comprising 6×6 squares, characterized in that: The coding metasurface is optimized by using a discrete PSO algorithm so that the 1st, 4-6th columns of the first row, the 3rd-6th columns of the second row, the 2nd, 4th, and 6th columns of the third row, the 1st, 3-4th, and 6th columns of the fourth row, the 1st, 3-6th columns of the fifth row, and the 1st, 3-6th columns of the sixth row are all first 1-order units, and the rest are second 1-order units; the first 1-order unit includes 4×4 squares, the 1st-2nd rows of the first and second columns and the 3rd-4th rows of the third and fourth columns of the first 1-order unit are all first 0-order units (1), and the rest are second 0-order units (2), and the surface size of the first 0-order unit (1) and the second 0-order unit (2) is 9×9 mm 2 The second 1-order unit includes 2×2 squares, the first row of the first column of the second 1-order unit is the third 0-order unit (3), the second row of the first column is the fifth 0-order unit (5), the second row of the second column is the fourth 0-order unit (4), and the first row of the second column is the sixth 0-order unit (6), and the surface size of the third 0-order unit (3), the fourth 0-order unit (4), the fifth 0-order unit (5) and the sixth 0-order unit (6) are all 18×18 mm 2 .

2. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The first 0-order unit (1) comprises a bottom metal grounding plate (100), an intermediate dielectric substrate (102) is fixed on the top of the bottom metal grounding plate (100), a first top metal layer (101) is fixed at the geometric center of the top of the intermediate dielectric substrate (102), the pattern of the first top metal layer (101) is a square metal patch, and the side length d1 of the square metal patch is 0.4 mm.

3. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The second 0-order unit (2) comprises a bottom metal grounding plate (100), a bottom dielectric substrate (202) is fixed on the top of the bottom metal grounding plate (100), an intermediate metal layer (203) is fixed on the top of the bottom dielectric substrate (202), and a top dielectric substrate (201) is fixed on the top of the intermediate metal layer (203).

4. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The third 0-order unit (3) comprises a bottom metal ground plate (100), an intermediate dielectric substrate (102) is fixed on the top of the bottom metal ground plate (100), a third top metal (301) is fixed at the geometric center of the top of the intermediate dielectric substrate (102), the pattern of the third top metal (301) is a Jerusalem cross, the length d3 of mutually perpendicular strips in the third top metal (301) is 17 mm, short strips are vertically arranged at the ends of the strips, the length d4 of the short strips is 5.5 mm, and the width d6 of the strips and the width d5 ​​of the short strips are both 1 mm.

5. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The fourth 0-order unit (4) comprises a bottom metal grounding plate (100), an intermediate dielectric substrate (102) is fixed on the top of the bottom metal grounding plate (100), four fourth top metals (401) are symmetrically fixed on the top of the intermediate dielectric substrate (102), the pattern of the fourth top metal (401) is a square, the side length d7 of the fourth top metal (401) is 5.5 mm, and the spacing d8 between the upper and lower rows of the fourth top metal (401) is 4.5 mm.

6. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The fifth 0-order unit (5) comprises a bottom metal ground plate (100), an intermediate dielectric substrate (102) is fixed on the top of the bottom metal ground plate (100), a fifth top metal (501) is fixed at the geometric center of the top of the intermediate dielectric substrate (102), the pattern of the fifth top metal (501) is a square ring, the inner side length d9 of the square ring is 12 mm, and the outer side length d 10 It is 16mm.

7. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The sixth 0-order unit (6) comprises a bottom metal ground plane (100), an intermediate dielectric substrate (102) is fixed on the top of the bottom metal ground plane (100), a sixth top metal (601) is fixed at the geometric center of the top of the intermediate dielectric substrate (102), the pattern of the sixth top metal (601) is a square, and the side length d of the sixth top metal (601) is 11 It is 8mm.

8. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The intermediate dielectric substrate (102) in the first 0-order unit (1), the third 0-order unit (3), the fourth 0-order unit (4), the fifth 0-order unit (5) and the sixth 0-order unit (6) all adopt F4B material with a dielectric constant of 2.14, a loss tangent of 0.0008 and a thickness of 3.76 mm, and the top dielectric substrate (201) and the bottom dielectric substrate (202) in the second 0-order unit (2) all adopt F4B material with a dielectric constant of 2.14, a loss tangent of 0.0008 and a thickness of 1.88 mm.

9. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: The coding metasurface uses a discrete PSO algorithm to optimize the coding sequence of the first 1-order unit and the second 1-order unit, and uses the bandwidth that achieves an RCS reduction of more than 10 dB within a specified frequency range as the fitness function. The objective function expression of the optimization algorithm is as follows: Where M is the total number of frequency points selected every 1 GHz in the range of 5-50 GHz, fi represents the i-th frequency point, RCS ideal conductor (fi) is the RCS of the ideal conductor at frequency fi, RCSA (fi) is the RCS of the coding metasurface at frequency fi under arrangement A, and 1 is the indicator function; When its parameter is true (i.e., the RCS difference is greater than or equal to 10dB), the function value is 1, otherwise it is 0; the optimization goal is to find the maximum value of F(A).

10. The ultra-wideband low RCS coded metasurface optimized by a PSO algorithm according to claim 1, characterized in that: In the 14-41 GHz frequency band, the coding metasurface reduces the RCS by more than 10 dB compared with an ideal conductor, and the relative bandwidth reaches 98.2%. When the incident angle changes from 0° to 45°, it still maintains excellent RCS reduction performance.

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