A polarization conversion wave-absorbing ultra-wideband stealth metasurface structure

Abstract

The application discloses a polarization conversion wave-absorbing ultra-wideband stealth super surface structure, which comprises, from top to bottom, a polarization conversion layer, a first filling layer, a frequency selective surface layer, a second filling layer and a wave-absorbing layer. The polarization conversion layer comprises polarization conversion patches, the polarization conversion patches comprise a plurality of 2*2 subarrays, and the angle arrangement of adjacent 2*2 units is different by 90 DEG. The frequency selective surface layer comprises, from top to bottom, a first patch, a second patch and a third patch. The wave-absorbing layer comprises a resistive film patch, and the impedance of the wave-absorbing layer is matched with the impedance of the second filling layer.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic metasurfaces, and more specifically to a polarization-conversion absorbing ultrawideband stealth metasurface structure. Background Technology

[0002] Radar Cross Section (RCS) is a crucial indicator of an aircraft's stealth performance. Reducing RCS decreases the detection range of reconnaissance systems, delays the time it takes for defense systems to detect targets, and lowers the probability of stealth aircraft being tracked and intercepted. Employing radar-absorbing materials is a key technique for reducing the RCS of stealth aircraft, as these materials dissipate absorbed electromagnetic waves by converting them into heat or other forms of energy. Traditional radar-absorbing materials typically include ferrites and carbon black, but these materials suffer from drawbacks such as narrow absorption bandwidth, high density, high weight, and a simplistic absorption mechanism. Existing radar-absorbing materials require increased thickness to improve low-frequency stealth capabilities, inevitably increasing the payload of the stealth aircraft. Using a frequency-selective surface conforming to the aircraft's shape is another effective way to reduce RCS. By designing the aircraft with a low-RCS profile, incident electromagnetic waves can be reflected to the opposite direction, effectively reducing single-station RCS. However, the effect is significantly reduced for dual-station or multi-station RCS.

[0003] Existing technology provides a radar-stealing absorbing material and its fabrication method, achieving 5dB absorption in the frequency range of 2.0GHz-12.0GHz. Existing technology also provides a broadband metamaterial absorber insensitive to incident angle, achieving an absorption rate of over 90% in the 8.0GHz-15.0GHz frequency band (relative bandwidth of 61%). However, existing technology cannot meet the stealth capability requirements above 18.0GHz. Summary of the Invention

[0004] The purpose of this invention is to provide a polarization-conversion absorbing ultrawideband stealth metasurface structure with the characteristics of low-frequency broadband diffuse scattering, high-frequency broadband absorption, and large-angle stability. The stealth frequency band covers the 8-30 GHz band and can significantly reduce bistatic RCS.

[0005] To achieve the above objectives, the present invention provides a polarization conversion absorbing ultrawideband stealth metasurface structure, comprising: a polarization conversion layer, a first filling layer, a frequency selective surface layer, a second filling layer, and an absorbing layer arranged sequentially from top to bottom;

[0006] The polarization conversion layer includes a polarization conversion patch, which contains several 2×2 subarrays, and the angle arrangement of adjacent 2×2 subarrays differs by 90°.

[0007] The frequency selective surface layer includes: a first patch, a second patch, and a third patch arranged from top to bottom;

[0008] The impedance of the absorbing layer is matched with the impedance of the second filling layer.

[0009] Optionally, each of the 2×2 subarrays consists of 4 polarization conversion units arranged in the same direction, and the period size of each polarization conversion unit is a;

[0010] Each polarization conversion unit includes: a central microstrip line arranged in parallel and two end microstrip lines, with the two end microstrip lines respectively located on both sides of the central microstrip line. The length of the central microstrip line is greater than the length of the end microstrip lines, and the width of the central microstrip line is the same as the width of the two end microstrip lines.

[0011] Optionally, the frequency selective surface layer first patch includes a plurality of square first units with a period size of b, each first unit having a square patch at its geometric center, and the period size of each square patch is smaller than the period size of the first unit, and the edge of the square patch is parallel to the edge of the first unit.

[0012] The third patch comprises several square third units with a periodic size of b, and the structure of each third unit is the same as that of the first unit.

[0013] The second patch includes a plurality of square second units with a periodic size of b. Each second unit includes a Jerusalem cross patch and a square ring patch. The Jerusalem cross patch and the square ring patch are both placed at the geometric center of the second unit, and the Jerusalem cross patch is located at the center of the square ring patch. The edges of the square ring patch are parallel to the edges of the second unit, and the two long sides of the Jerusalem cross patch are parallel to the edges of the second unit.

[0014] Optionally, the frequency selective surface layer further includes:

[0015] An upper dielectric substrate is disposed between the first patch and the second patch. The first patch and the second patch are respectively attached to both sides of the upper dielectric substrate, and their periodic dimensions are the same as those of the first patch and the second patch.

[0016] The lower dielectric substrate is disposed between the second and third patches. The third patch is attached to the lower surface of the lower dielectric substrate, and its periodic dimension is the same as that of the third patch.

[0017] Optionally, the resistive film patch is disposed below the third patch and includes a plurality of square resistive units with a periodic dimension of c; and each resistive unit has a square resistive film with the same resistance value at its geometric center, and the size of the resistive film is smaller than the periodic dimension of the resistive unit.

[0018] Optionally, the geometric center of the polarization conversion layer and the geometric center of the absorbing layer are on the same axis.

[0019] Optionally, the absorbing layer further includes: an absorbing dielectric substrate and a bottom patch, wherein the bottom patch is a metal sheet; the resistive film patch and the bottom patch are respectively attached to both sides of the absorbing dielectric substrate, and the size of the absorbing dielectric substrate is the same as the periodic size of the resistive film patch and the bottom patch.

[0020] Optionally, the thickness of both the first and second filler layers is in the range of 1-10 mm, and air or filler foam can be used.

[0021] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0022] (1) The polarization conversion layer and frequency selective surface layer of the metasurface structure described in this invention work together to effectively reduce the RCS in the low frequency band through phase cancellation between adjacent subarrays; the absorbing layer can completely absorb electromagnetic waves in the high frequency band to achieve the purpose of stealth.

[0023] (2) The metasurface structure described in this invention has a 180° reflection phase difference due to the 90° angular arrangement between adjacent 2×2 subarrays of the polarization conversion layer, and the symmetrical design of the frequency selection surface layer significantly reduces the bistatic (multistatic) RCS, and has broad application prospects in electromagnetic countermeasures and military stealth.

[0024] (3) The sub-units of the metasurface structure described in this invention are small in size, light in weight, easy to process, and have low profile. They also have good angular stability. The stealth bandwidth can be changed by changing the periodic size of the sub-units. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the polarization conversion absorbing ultrawideband stealth metasurface structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the polarization conversion unit of the polarization conversion absorbing ultrawideband stealth metasurface structure of the present invention.

[0027] Figure 3 This is a schematic diagram of several subarrays of the polarization conversion absorbing ultrawideband stealth metasurface structure of the present invention.

[0028] Figure 4 This is a schematic diagram of the first and third units of the polarization conversion absorbing ultrawideband stealth metasurface structure of the present invention.

[0029] Figure 5 This is a schematic diagram of the second unit of the polarization conversion absorbing ultrawideband stealth metasurface structure of the present invention.

[0030] Figure 6 This is a schematic diagram of the resistive unit of the polarization conversion absorbing ultrawideband stealth metasurface structure of the present invention.

[0031] Figure 7 This is a diagram showing the reflection phase of adjacent 2×2 subarrays of the metasurface structure in Example 1.

[0032] Figure 8 The simulation results show the reflection coefficient of the metasurface structure in Example 1 under TE-polarized electromagnetic wave incidence.

[0033] In the figure, Ⅰ-polarization conversion layer, Ⅱ-frequency selective surface layer, Ⅲ-absorbing layer, 1-polarization conversion patch, 11-polarization conversion unit, 12-end microstrip line, 13-middle microstrip line, 2-polarization dielectric substrate, 3-first patch, 31-first unit, 32-square patch, 4-upper dielectric substrate, 5-second patch, 51-second unit, 52-square ring patch, 53-Jerusalem cross patch, 6-lower dielectric substrate, 7-third patch, 8-resistive film patch, 81-resistive unit, 82-resistive film, 9-absorbing dielectric substrate, 10-bottom patch. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] like Figure 1 As shown, the present invention provides a polarization conversion absorbing ultra-wideband stealth metasurface structure, comprising: a polarization conversion layer I, a first filling layer, a frequency selective surface layer II, a second filling layer, and an absorbing layer III arranged from top to bottom.

[0038] The thickness of both the first and second filler layers is in the range of 1-10 mm, and air or foam can be used to improve the absorption bandwidth without increasing the weight of the material.

[0039] like Figure 1 As shown, a spatial coordinate system is established, with the plane parallel to the surface of each material layer regarded as the xoy plane, and the horizontal and vertical directions parallel to the edge of the material surface set as the y-axis and x-axis, respectively, and the z-axis established in the direction perpendicular to the surface of each material layer.

[0040] like Figure 3 As shown, the polarization conversion layer includes: a polarization conversion patch 1 and a polarization dielectric substrate 2. The polarization conversion patch 1 can achieve polarization conversion over a wide low-frequency range and includes several 2×2 sub-arrays, with the arrangement angle between adjacent 2×2 sub-arrays differing by 90°. Figure 3 As shown, when the polarization conversion layer I consists of four 2×2 subarrays, these four subarrays are labeled as subarray 0, subarray 1, subarray 2, and subarray 3 in a clockwise direction. Subarray 1 is obtained by rotating the geometric center point of subarray 0 clockwise by 90°, subarray 2 by rotating the geometric center point of subarray 1 clockwise by 90°, and subarray 3 by rotating the geometric center point of subarray 2 clockwise by 90°. Since the arrangement angles between adjacent 2×2 subarrays differ by 90°, the surface currents of adjacent 2×2 subarrays are orthogonally distributed, resulting in a 180° reflection phase difference between adjacent 2×2 subarrays, and the reflected electromagnetic wave amplitudes are equal.

[0041] like Figure 2 As shown, each 2×2 subarray consists of four polarization conversion units 11 arranged in the same direction. Each polarization conversion unit 11 has a period dimension of 'a' and is composed of three microstrip lines arranged in parallel. The three microstrip lines are metal lines, including a middle microstrip line 13 and two end microstrip lines 12, with the two end microstrip lines 12 respectively positioned on either side of the middle microstrip line 13. All three microstrip lines have the same width, and the length of the middle microstrip line 13 is greater than the length of the end microstrip lines 12.

[0042] The polarization dielectric substrate 2 serves as the carrier for the polarization conversion patch 1. The polarization conversion patch 1 is attached to the upper surface of the polarization dielectric substrate 2, and the periodic dimension of the polarization dielectric substrate 2 is the same as that of the polarization conversion patch 1.

[0043] The frequency selective surface layer II includes: a first patch 3, an upper dielectric substrate 4, a second patch 5, a lower dielectric substrate 6, and a third patch 7 arranged sequentially from top to bottom.

[0044] The first patch 3 is disposed below the polarization dielectric substrate 2 and includes a plurality of square first units 31 with a periodic dimension b, such as... Figure 4 As shown, the edges of each first unit 31 are parallel to the x-axis and y-axis respectively; a square patch 32 is provided at the geometric center of each first unit 31, and the size of each square patch 32 is smaller than the period size of the first unit 31, and the edges of the square patch 32 are parallel to the x-axis direction and the y-axis direction respectively, so that the structure of each first unit 31 is symmetrical about the x-axis direction and the y-axis direction.

[0045] The third patch 7 comprises several square third units with a periodic size of b, and the structure of each third unit is the same as that of the first unit 31.

[0046] The second patch 5 includes several square second units 51 with a periodic dimension b, and the edges of each second unit 51 are parallel to the x-axis and y-axis directions, respectively. Each second unit 51 includes a Jerusalem cross patch 53 and a square ring patch 52. The Jerusalem cross patch 53 and the square ring patch 52 are both placed at the geometric center of the second unit 51, and the Jerusalem cross patch 53 is located at the center of the square ring patch 52. The edges of the square ring patch 52 are parallel to the x-axis and y-axis directions, respectively, and the two long sides of the Jerusalem cross patch 53 are parallel to the x-axis and y-axis directions, respectively, so that the structure of each second unit 51 is symmetrical about the x-axis and y-axis directions. Since the structures of the first unit 31, the second unit 51, and the third unit are all symmetrical about the x-axis and y-axis directions, the frequency selective surface layer II can reflect horizontally polarized and vertically polarized low-frequency electromagnetic waves, and can achieve broadband wave transmission in a wide frequency range at high frequencies, with good steep cutoff characteristics.

[0047] The upper dielectric substrate 4 serves as the carrier for the first patch 3 and the second patch 5. The first patch 3 and the second patch 5 are respectively attached to both sides of the upper dielectric substrate 4, providing support for the first patch 3 and the second patch 5. The periodic dimension of the upper dielectric substrate 4 is the same as that of the first patch 3 and the second patch 5. The lower dielectric substrate 6 is disposed between the second patch 5 and the third patch 7, serving as the carrier for the third patch 7. The third patch 7 is attached to the lower surface of the lower dielectric substrate 6, providing support for the third patch 7. The periodic dimension of the lower dielectric substrate 6 is the same as that of the third patch 7. Furthermore, the upper dielectric substrate 4 and the lower dielectric substrate 6 are made of the same material and have the same thickness.

[0048] The absorbing layer III includes, from top to bottom, a resistive film patch 8, an absorbing dielectric substrate 9, and a bottom patch 10. For example... Figure 6 As shown, the resistive film patch 8 is disposed below the third patch 7, and can provide a resistance value of 100-1000Ω. It includes several resistive units 81, each of which is a square with a period size of c. Each resistive unit 81 has a square resistive film 82 with the same resistance value at its geometric center, and the size of the resistive film 82 is smaller than the period size of the resistive unit 81. By reducing the impedance Z of the resistive film patch 8... ω The difference between the impedance Z0 of the second filling layer between the frequency-selective surface layer II and the absorbing layer III makes the reflection coefficient Γ of the resistive film patch 8 approach 0, as shown in Equation 1. This ultimately matches the impedance of the absorbing layer III with the impedance of the second filling layer, enabling the absorption of electromagnetic waves incident on the resistive film patch 8. The bottom patch 10 is a metal sheet disposed at the bottom of the metasurface structure. Its size is the same as that of the resistive film patch 8, and it can absorb high-frequency electromagnetic waves that the resistive film patch 8 cannot completely absorb. The absorbing dielectric substrate 9 serves as the carrier for the resistive film patch 8 and the bottom patch 10. The resistive film patch 8 and the bottom patch 10 are respectively attached to both sides of the absorbing dielectric substrate 9, providing support for the resistive film patch 8 and the bottom patch 10. The size of the absorbing dielectric substrate 9 is the same as the periodic size of the resistive film patch 8 and the bottom patch 10.

[0049]

[0050] Among them, the impedance Z of the resistive film patch 8 ω The calculation method is as follows:

[0051]

[0052] In the formula, μ ω ε is the permeability of the resistive film patch. ω The conductivity of the resistive film patch.

[0053] Furthermore, the metasurface structure of the present invention has the same number of periods in the x-axis and y-axis directions, and the period size a of the polarization conversion unit 11 in the polarization conversion layer I and the period size c of the absorbing layer III are the same, both being twice the period size b of the frequency selective surface layer II. Moreover, the geometric center of the polarization conversion layer I coincides with the geometric center of the absorbing layer III in the z-axis direction.

[0054] When electromagnetic waves irradiate the metasurface structure described in this invention, low-frequency electromagnetic waves are diffusely scattered on the polarization conversion layer I. These low-frequency electromagnetic waves, passing through the polarization conversion layer I, then irradiate the frequency selective surface layer II. Simultaneously, the frequency selective surface layer II reflects the low-frequency electromagnetic waves, completely intercepting them. High-frequency electromagnetic waves pass through the polarization conversion layer I and the frequency selective surface layer II, reaching the absorbing layer III, where they are completely absorbed, achieving complete electromagnetic wave interception and a stealth effect.

[0055] Example 1

[0056] This embodiment will construct a structure with overall dimensions of 360×360×9.2mm. 3 A stealthy metasurface structure with dimensions of (length × width × height).

[0057] The polarization conversion patch 1 in the polarization conversion layer I is designed as a patch layer consisting of four 2×2 sub-arrays with different orientations, and each polarization conversion unit 11 is square. The three microstrip lines in each polarization conversion unit 11 are parallel to the diagonal of the polarization conversion unit 11, and each microstrip line is made of copper foil. The width W1 of each microstrip line is 0.5 mm, the length L1 of the middle microstrip line 13 is 9.0 mm, the length L2 of the two end microstrip lines 12 is 4.0 mm, and the spacing W2 between adjacent microstrip lines is 1.0 mm. The polarization dielectric substrate 2 is Rogers 5880, with a dielectric constant of 2.2, a loss tangent of 0.005, and a substrate thickness of 0.2 mm.

[0058] The square patch 32 in the first patch 3 and the third patch 7 of the frequency selective surface layer II has a side length L3 of 1.2 mm. The Jerusalem cross patch 53 in the second patch 5 has a long side length L4 of 1.7 mm, a short side length L5 of 0.6 mm, and a linewidth W3 of 0.2 mm; the square ring patch 52 in the second patch 5 has a linewidth W4 of 0.8 mm. The square patch 32 in the first patch 3 and the third patch 7, and the square ring patch 52 and Jerusalem cross patch 53 in the second patch 5 are all made of copper foil. Both the upper dielectric substrate 4 and the lower dielectric substrate 6 are made of Arlon AD350, with a dielectric constant of 3.5, a loss tangent of 0.003, and a substrate thickness of 1.5 mm.

[0059] The resistive film 82 in the resistive unit 81 of the resistive film patch 8 has a size L5 of 8.5 mm, and the resistance R of the resistive film patch 8 is 200 Ω. The bottom patch 10 is a copper foil and is attached to the surface of the absorbing dielectric substrate 9. The absorbing dielectric substrate 9 is made of Arlon AD350, with a thickness of 1.5 mm, a dielectric constant of 3.5, and a loss tangent of 0.003.

[0060] Furthermore, in this embodiment, the period size a of the polarization conversion unit 11 of the polarization conversion layer I and the period size c of the absorbing layer III are both set to 9 mm, and the period size b of the frequency selective surface layer II is set to 4.5 mm.

[0061] Both the first and second filler layers are made of air. The thickness of the first filler layer is 2.0 mm and the thickness of the second filler layer is 2.5 mm.

[0062] Figure 7 The diagram shows the reflection phase results of adjacent 2×2 subarrays of polarization conversion layer I in this embodiment, proving that there is a 180° reflection phase difference between adjacent 2×2 subarrays.

[0063] Figure 8 The simulation results of the metasurface structure of this embodiment under TE (Transverse Electric) polarized electromagnetic wave incident show that the reflected electromagnetic wave and the incident electromagnetic wave undergo polarization rotation in the frequency range of 8.0 to 18.0 GHz, and the electromagnetic wave is absorbed in the frequency range of 18.0 to 30 GHz. This confirms that the metasurface structure of this embodiment can reduce RCS (Rich Communication Services) in the frequency range of 8.0 to 18.0 GHz through phase cancellation between adjacent polarization conversion subarrays, and reduce RCS in the frequency range of 18 to 30 GHz through absorption of electromagnetic wave energy by the absorbing layer, thus achieving stealth coverage in the frequency range of 8.0 to 30.0 GHz.

[0064] The metasurface structure described in this embodiment is for ultra-wideband stealth in the microwave band. By changing the period size of the sub-units, the metasurface structure described in this invention can be adapted to stealth in other frequency bands.

[0065] In summary, the polarization conversion layer and frequency selective surface layer of the metasurface structure described in this invention work together to effectively reduce the RCS in the low-frequency band through phase cancellation between adjacent subarrays; the absorbing layer can completely absorb electromagnetic waves in the high-frequency band to achieve stealth, and can significantly reduce bistatic (multistatic) RCS, which has broad application prospects in the fields of electromagnetic countermeasures and military stealth.

[0066] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A polarization-conversion absorbing ultrawideband stealth metasurface structure, characterized in that, include: The layers arranged from top to bottom are: polarization conversion layer, first filling layer, frequency selective surface layer, second filling layer, and absorbing layer. The polarization conversion layer includes a polarization conversion patch, which comprises several 2×2 subarrays, and the angular arrangement between adjacent 2×2 subarrays differs by 90°; each 2×2 subarray consists of four polarization conversion units with the same orientation, and the period size of each polarization conversion unit is a. Each polarization conversion unit includes: a central microstrip line arranged in parallel and two end microstrip lines, with the two end microstrip lines respectively located on both sides of the central microstrip line. The length of the central microstrip line is greater than the length of the end microstrip lines, and the width of the central microstrip line is the same as the width of the two end microstrip lines. The frequency selective surface layer includes: a first patch, a second patch, and a third patch arranged sequentially from top to bottom; the first patch includes several square first units with a period size of b, each first unit has a square patch at its geometric center, and the size of each square patch is smaller than the period size of the first unit, with the edge of the square patch parallel to the edge of the first unit; the third patch includes several square third units with a period size of b, and the structure of each third unit is the same as that of the first unit; the second patch includes several square second units with a period size of b, each second unit includes: a Jerusalem cross patch and a square ring patch, both the Jerusalem cross patch and the square ring patch are placed at the geometric center of the second unit, and the Jerusalem cross patch is located at the center of the square ring patch; the edges of the square ring patch are parallel to the edges of the second unit, and the two long sides of the Jerusalem cross patch are parallel to the edges of the second unit; The impedance of the absorbing layer is matched with the impedance of the second filling layer; the absorbing layer includes a resistive film patch, an absorbing dielectric substrate, and a bottom patch; the bottom patch is a metal sheet; the resistive film patch and the bottom patch are respectively attached to both sides of the absorbing dielectric substrate, and the periodic dimension of the absorbing dielectric substrate is the same as the periodic dimension of the resistive film patch and the bottom patch.

2. The polarization-conversion absorbing ultrawideband stealth metasurface structure according to claim 1, characterized in that, The polarization conversion layer further includes a polarization dielectric substrate, wherein the polarization conversion patch is attached to the upper surface of the polarization dielectric substrate, and the periodic dimension of the polarization dielectric substrate is the same as the periodic dimension of the polarization conversion patch.

3. The polarization-conversion absorbing ultrawideband stealth metasurface structure according to claim 1, characterized in that, The frequency-selective surface layer further includes: An upper dielectric substrate is disposed between the first patch and the second patch. The first patch and the second patch are respectively attached to both sides of the upper dielectric substrate, and their periodic dimensions are the same as those of the first patch and the second patch. The lower dielectric substrate is disposed between the second and third patches. The third patch is attached to the lower surface of the lower dielectric substrate, and its periodic dimension is the same as that of the third patch.

4. The polarization-conversion absorbing ultrawideband stealth metasurface structure according to claim 1, characterized in that, The resistive film patch is disposed below the third patch and includes several square resistive units with a periodic dimension of c; and each resistive unit has a square resistive film with the same resistance value at its geometric center, and the size of the resistive film is smaller than the periodic dimension of the resistive unit.

5. The polarization-conversion absorbing ultrawideband stealth metasurface structure according to claim 1, characterized in that, The geometric center of the polarization conversion layer and the geometric center of the absorbing layer are on the same axis.

6. The polarization-conversion absorbing ultrawideband stealth metasurface structure according to claim 1, characterized in that, The thickness of both the first and second filler layers is in the range of 1-10 mm, and air or filling foam can be used.

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