A low-scattering circularly polarized slot antenna loaded with a metasurface fabry-perot resonator

Abstract

This invention provides a Fabry-Perot resonant cavity low-scattering circularly polarized slot antenna with a metasurface loading system. From bottom to top, it comprises a feed plate, a copper ground layer, and a double-layer complementary checkerboard polarization conversion metasurface plate. The feed plate has a copper ground layer and a microstrip feed line at its upper and lower ends. A rectangular radiating slot is formed on the copper ground layer, and the microstrip feed line crosses the rectangular radiating slot for coupling and feeding. The double-layer complementary checkerboard polarization conversion metasurface plate includes a dielectric substrate and an upper and lower metasurface layer disposed at the upper and lower ends of the dielectric substrate. A Fabry-Perot resonant cavity is formed between the copper ground layer and the lower metasurface layer. The copper ground layer, the lower metasurface layer, and the lower metasurface layer serve as the total internal reflection lower and upper walls of the Fabry-Perot resonant cavity. The emitted wave passing through the double-layer complementary checkerboard polarization conversion metasurface plate is synthesized into a circularly polarized wave. This invention can synergistically achieve broadband impedance matching, broadband circular polarization, high gain, and low scattered radiation.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a metasurface-loaded Fabry-Perot resonator low-scattering circularly polarized slot antenna. Background Technology

[0002] A Fabry-Perot resonant cavity antenna typically consists of a feed, an air cavity above the feed, and a partial reflective surface (PRS) covering the air cavity. Electromagnetic waves radiated from the feed undergo multiple reflections between the PRS and a total reflection ground plane on the feed side. The outgoing waves passing through the PRS are superimposed in the side-firing direction. Fabry-Perot resonant cavity antennas require only a single feed to achieve high gain comparable to array antennas, eliminating the need for complex feeding networks, resulting in low feed loss, simple structure, and low profile. It is a representative high-gain antenna implementation.

[0003] Traditional Fabry-Perot resonant cavity antennas mostly employ isotropic polarimetric reflectors (PRSs). These PRSs only partially reflect the polarization without altering the polarization state. The linearly polarized wave radiated from the feed source remains linearly polarized after multiple reflections within the cavity, which is insufficient for circularly polarized applications such as satellite communication and radar detection. Cascading independent circularly polarizers outside the cavity increases the antenna profile height and introduces insertion loss. Regarding the physical conditions for polarization synthesis, the formation of a circularly polarized wave requires two orthogonal linearly polarized components with equal amplitudes and a phase difference of ±90°. Isotropic PRSs exhibit identical reflection responses to both orthogonal components, lacking the ability to separately modulate the amplitude and phase of each component, thus failing to directly generate a circularly polarized output wave at the radiation level. How to simultaneously achieve direct conversion from linear to circular polarization and compensation for cavity phase dispersion at the radiation level remains a challenge for current technologies.

[0004] Patent CN116722370A (publication date September 8, 2023) discloses a metasurface low RCS circular polarization slot array antenna, including an upper dielectric substrate with a polarization conversion metasurface cladding layer printed on the upper surface, consisting of polarization conversion units arranged in an n×n checkerboard pattern; an lower dielectric substrate with an m×m strip slot array etched along the center and rotated clockwise on the upper surface of the substrate; a microstrip feeding structure on the lower surface of the substrate, with rectangular microstrip lines perpendicularly coupled to the strip slots for feeding and coaxial line excitation; its circular polarization radiation is achieved by the slot array itself arranged clockwise (sequentially rotated) along the center; and the radar cross section reduction is achieved by the checkerboard polarization conversion metasurface cladding layer reflecting the scattered energy to the non-threat angle domain. However, this scheme has the following shortcomings: First, both circular polarization radiation and gain rely on the arraying of m×m slot arrays. The antenna's radiation aperture, number of feed points, and structural complexity increase with the array size, while the metasurface cladding does not participate in radiation or bear the function of gain enhancement. Second, the metasurface cladding only bears the function of scattering control and does not constitute part of the reflective upper wall of the Fabry-Perot resonator. The radiation function layer and the scattering control layer are separated from each other, and the gain enhancement depends on the arraying rather than the cavity resonance enhancement. Third, the metasurface is arranged in a single-layer checkerboard pattern, and scattering cancellation only occurs once between adjacent checkerboard squares, limiting the cancellation depth and bandwidth. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a metasurface-loaded Fabry-Perot resonator low-scattering circularly polarized slot antenna, which can achieve broadband impedance matching, broadband circular polarization, high gain, and low scattered radiation.

[0006] The technical solution of this invention is as follows: a metasurface-loaded Fabry-Perot resonator low-scattering circularly polarized slot antenna, comprising, from bottom to top, a feed plate, a copper ground layer, and a double-layer complementary checkerboard polarization conversion metasurface plate; a microstrip feed line is printed on the bottom layer of the feed plate; a copper ground layer is disposed on the feed plate; a rectangular radiating slot is formed on the copper ground layer, and the microstrip feed line crosses the rectangular radiating slot for coupling and feeding;

[0007] The dual-layer complementary checkerboard polarization conversion metasurface plate includes a dielectric substrate, and an upper metasurface layer and a lower metasurface layer disposed at the upper and lower ends of the dielectric substrate.

[0008] A Fabry-Perot resonant cavity is formed between the copper ground layer and the lower metasurface layer. The copper ground layer serves as the lower wall of the Fabry-Perot resonant cavity with total internal reflection, and the lower metasurface layer serves as the upper wall of the Fabry-Perot resonant cavity with total internal reflection. The outgoing waves transmitted through the double-layer complementary checkerboard polarization conversion metasurface plate are combined into circularly polarized waves.

[0009] Preferably, both the feed board and the dielectric substrate are Rogers RO4003C dielectric substrates.

[0010] Preferably, the long side of the rectangular radiation slot is perpendicular to the linear polarization direction of the radiation from the feed plate, the characteristic impedance of the microstrip feed line is 50Ω, and the microstrip feed line crosses the center of the rectangular radiation slot perpendicularly.

[0011] Preferably, the rectangular radiating slit forms a half-wavelength resonant slit, and the resonant length of the rectangular radiating slit is half the slit guiding wavelength.

[0012] Preferably, both the upper and lower metasurface layers are patch arrays.

[0013] Preferably, the patch array is composed of anisotropic rectangular metal patch units. The patch array includes rectangular metal patch units of two sizes, and the two sizes of metal patch units in the upper metasurface layer and the lower metasurface layer are complementary to each other in a grid-by-grid manner.

[0014] Preferably, the rectangular metal patch unit has a side length that is not equal in the intrinsic axis u direction and in the intrinsic axis v direction.

[0015] Preferably, the intrinsic axis of the rectangular metal patch unit is rotated 45° relative to the linear polarization direction of the feed plate, so that the incident linear polarized wave is decomposed into two orthogonal components with equal amplitude in the direction of the intrinsic axis, and the reflection amplitude of the two orthogonal components is equal and the reflection phase difference is ±90°.

[0016] Preferably, the resonant frequencies of the rectangular metal patch unit along the intrinsic axis u and along the intrinsic axis v are staggered and located on opposite sides of the operating frequency band. The reflection phase difference of the two orthogonal components is maintained within the range of 90°±15° in the operating frequency band, and the reflection amplitude imbalance does not exceed 20%.

[0017] Preferably, the two sizes of rectangular metal patch units include a first patch unit and a second patch unit, the first patch unit and the second patch unit have different sizes, and the first patch unit and the second patch unit form a chessboard grid, and the first patch unit and the second patch unit are arranged in a chessboard pattern.

[0018] Preferably, the first patch unit and the second patch unit of the upper metasurface layer and the lower metasurface layer are complementary in a grid-by-grid manner.

[0019] Preferably, corresponding support columns are provided at the four corners between the feed plate and the double-layer complementary checkerboard polarization conversion metasurface plate to maintain the cavity height of the Fabry-Perot resonator.

[0020] Preferably, the cavity height h of the Fabry-Perot resonant cavity is the distance from the copper ground layer to the lower metasurface layer, and the cavity height h of the Fabry-Perot resonant cavity satisfies the Fabry-Perot resonance condition:

[0021] ;

[0022] In the formula, For free space operating wavelength; The equivalent reflection phase of the upper and lower metasurface layers; The reflected phase of the copper ground layer; The order of the cavity model.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The rectangular radiating slit of this invention is coupled with the Fabry-Perot cavity resonance to form multiple resonant concave points. Combined with a low-dielectric-constant thin substrate, this reduces the quality factor of the resonant circuit, achieving broadband impedance matching. Simulation results show S... 11 With an impedance bandwidth of 8.90-10.08GHz and a relative bandwidth of 12.4%, it effectively overcomes the problem of limited feed bandwidth in traditional FP resonant cavity antennas.

[0025] 2. This invention utilizes a 45° rotated anisotropic rectangular patch to decompose the incident linearly polarized wave into equal amplitudes, maintaining a phase difference of 90°±15° and an amplitude imbalance of ≤20% for the orthogonal components in the operating frequency band. It directly completes the linear to circular polarization conversion at the radiation aperture without the need for an external circular polarizer, thus avoiding additional profile and insertion loss. The main beam axial ratio is <3dB, the bandwidth is 9.55-10.35GHz, the relative bandwidth is 8.0%, and the minimum axial ratio is 0.84dB.

[0026] 3. This invention achieves gain enhancement by superimposing the aperture fields of multiple reflections from the Fabry-Perot resonator, eliminating the need for a complex feeding network, resulting in low feeding losses. The simulated peak gain is 13.03 dB, a 6-7 dB improvement compared to a bare slot feed source. The cascaded double-layer metasurface has an equivalent reflection coefficient of 0.78-0.82, balancing gain enhancement with electromagnetic wave transmission output. Furthermore, the double-layer patch generates a positive slope equivalent reflection phase, compensating for the negative slope dispersion of the propagation phase within the cavity, thus widening the gain operating bandwidth. The 3 dB gain corresponds to a bandwidth of 5.7%.

[0027] 4. This invention employs a dual suppression mechanism of phase cancellation within the same layer of checkerboard and complementary secondary cancellation between interlayer checkerboards. The phase difference between reflections from adjacent checkerboards in the same layer is maintained at 143°-217°, and the normal scattered fields cancel each other out. Electromagnetic waves passing through the first layer reach the complementary checkerboards in the second layer and undergo phase cancellation again. The average RCS reduction in the 7-12GHz frequency band is 3.46dB, with a maximum reduction of 15.77dB. An RCS reduction of 10.38dB is achieved at 9GHz.

[0028] 5. Within the effective operating frequency band of the antenna's circular polarization, the metasurface needs to maintain necessary transmission to ensure radiation performance, with a moderate compromise in scattering suppression, resulting in an RCS reduction of 1.32-2.89 dB. Meanwhile, significant scattering reduction is achieved outside the operating frequency band and at the band edge, meeting the practical engineering requirements of ensuring radiation capability during antenna operation and reducing radar scattering in non-operating frequency bands. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the antenna structure according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the upper metasurface layer in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the copper grounding layer in an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram illustrating the complementary correspondence between the checkerboard patterns of the upper and lower metasurface layers in an embodiment of the present invention.

[0033] Figure 5 This is a perspective view of the antenna according to an embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram illustrating the simulation performance of the antenna in an embodiment of the present invention;

[0035] Figure 7 The normalized radiation pattern of the antenna in this embodiment of the invention at 8.71 GHz is shown.

[0036] Figure 8 This is a schematic diagram showing the RCS curves of the antenna in this invention and a conventional metal-ground antenna as a function of frequency.

[0037] In the diagram, 1-feed plate; 2-copper grounding layer; 3-double-layer complementary checkerboard polarization conversion metasurface plate; 4-microstrip feeder;

[0038] 21- Rectangular radial slot;

[0039] 31-Dielectric substrate; 32-Upper metasurface layer; 33-Lower metasurface layer; 34-First patch unit; 35-Second patch unit. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0041] like Figure 1 , 5 As shown, this embodiment provides a Fabry-Perot resonator low-scattering circularly polarized slot antenna with a metasurface loading, which includes, from bottom to top, a feed plate 1, a copper ground layer 2, and a double-layer complementary checkerboard polarization conversion metasurface plate 3.

[0042] In this embodiment, as Figure 1 As shown, the feed board 1 is located at the bottom layer of the antenna. The feed board 1 uses a Rogers RO4003C dielectric substrate, and a microstrip feed line 4 is printed on the bottom layer of the feed board 1. The characteristic impedance of the microstrip feed line 4 is 50Ω. A copper ground layer 2 is provided on the feed board 1, and a rectangular radiating slot 21 is formed on the copper ground layer 2. The microstrip feed line 4 crosses the rectangular radiating slot 21 for coupling and feeding. In this embodiment, the rectangular radiating slot 21 is formed in the center of the copper ground layer 2.

[0043] In this embodiment, as Figure 3 As shown, the long side of the rectangular radiation slot 21 is perpendicular to the linear polarization direction of the feed plate 1, and the microstrip feed line 4 crosses the center of the rectangular radiation slot 21 perpendicularly.

[0044] In this embodiment, the rectangular radiation slit 21 constitutes a half-wavelength resonant slit, and the resonant length of the rectangular radiation slit 21 is half of the slit guiding wavelength.

[0045] In this embodiment, as Figure 2 , 4 As shown, the dual-layer complementary checkerboard polarization conversion metasurface plate 3 includes a dielectric substrate 31, and an upper metasurface layer 32 and a lower metasurface layer 33 disposed at the upper and lower ends of the dielectric substrate 31. The dielectric substrate is also a Rogers RO4003C dielectric plate.

[0046] In this embodiment, a Fabry-Perot resonant cavity is formed between the copper ground layer 2 and the lower metasurface layer 33. The copper ground layer 2 serves as the lower wall of the Fabry-Perot resonant cavity with total internal reflection, and the lower metasurface layer 33 serves as the upper wall of the Fabry-Perot resonant cavity with total internal reflection. The outgoing waves transmitted through the double-layer complementary checkerboard polarization conversion metasurface plate 3 are combined into circularly polarized waves.

[0047] In this embodiment, both the upper metasurface layer 32 and the lower metasurface layer 33 are patch arrays.

[0048] In this embodiment, the patch array is composed of anisotropic rectangular metal patch units.

[0049] In this embodiment, the equivalent amplitude reflection coefficient of the rectangular metal patch unit of the upper metasurface layer 32 and the lower metasurface layer 33 is 0.78 to 0.82. The equivalent reflection phase increases with increasing frequency in the working frequency band and changes with a positive slope, which compensates for the negative slope change of the propagation phase in the Fabry-Perot resonant cavity.

[0050] In this embodiment, the intrinsic axis of the rectangular metal patch unit is rotated by 45° relative to the linear polarization direction of the feed plate 1, so that the incident linear polarized wave is decomposed into two orthogonal components with equal amplitude in the direction of the intrinsic axis. The reflection amplitudes of the two orthogonal components are equal and the reflection phase difference is ±90°.

[0051] In this embodiment, the resonant frequency of the rectangular metal patch unit along the intrinsic axis u direction is staggered with the resonant frequency along the intrinsic axis v direction and located on both sides of the working frequency band. The reflection phase difference of the two orthogonal components is maintained within the range of 90°±15° in the working frequency band, and the reflection amplitude imbalance does not exceed 20%.

[0052] In this embodiment, the phase difference between the reflections of adjacent checkerboard patterns within the patch arrays of the upper metasurface layer 32 and the lower metasurface layer 33 to the incident wave is within the range of 143° to 217°, and the scattered fields of adjacent checkerboard patterns cancel each other out in the normal direction. The scattered energy is redirected to the four oblique quadrants, and the normal RCS reduction is greater than 10 dB. The incident wave passing through the lower metasurface layer 33 encounters a complementary checkerboard pattern in the upper metasurface layer 32, and the phase cancellation relationship is re-established, constituting double cancellation. Within the effective operating frequency band of circular polarization, the upper metasurface layer 32 and the lower metasurface layer 33 must maintain controlled transmission to perform radiation functions.

[0053] In this embodiment, the rectangular metal patch unit has a side length that is not equal in the intrinsic axis u direction and in the intrinsic axis v direction.

[0054] In this embodiment, the two sizes of rectangular metal patch units include a first patch unit 34 and a second patch unit 35. The first patch unit 34 and the second patch unit 35 have different sizes, and the first patch unit 34 and the second patch unit 35 form the grid of a chessboard. The first patch unit 34 and the second patch unit 35 are arranged in a chessboard pattern.

[0055] In this embodiment, the first patch unit 34 and the second patch unit 35 of the upper metasurface layer 32 and the lower metasurface layer 33 are complementary in a grid-by-grid manner.

[0056] In some embodiments, see Figure 4As shown, both the upper metasurface layer 32 and the lower metasurface layer 33 are 8×8 patch arrays, and the first patch unit 34 and the second patch unit 35 are arranged in a checkerboard pattern with adjacent 2×2 patch units of the same size forming a grid. No metal isolation layer is provided between the upper metasurface layer 32 and the lower metasurface layer 33, and neither the upper metasurface layer 32 nor the lower metasurface layer 33 is provided with metallized vias.

[0057] In this embodiment, corresponding support columns are provided at the four corners between the feed plate 1 and the double-layer complementary checkerboard polarization conversion metasurface plate 3, and the cavity height of the Fabry-Perot resonator is maintained by the support columns.

[0058] In some embodiments, the support column is a nylon column.

[0059] In this embodiment, the cavity height h of the Fabry-Perot resonant cavity is the distance from the copper ground layer 2 to the lower metasurface layer 33, and the cavity height h of the Fabry-Perot resonant cavity satisfies the Fabry-Perot resonance condition:

[0060] ;

[0061] In the formula, For free space operating wavelength; The equivalent reflection phase of the upper metasurface layer 32 and the lower metasurface layer 33; The reflected phase of copper grounding layer 2; The order of the cavity model.

[0062] In this embodiment, the rectangular radiating slot 21 itself forms a resonance, and its equivalent circuit is an RLC parallel resonant circuit. The rectangular radiating slot 21 is embedded in the Fabry-Perot resonant cavity, forming multiple adjacent resonant dimples within the impedance band. The synergy of multiple resonances keeps the input impedance within the matching range over a wide frequency band, thereby widening the impedance bandwidth. Correspondingly, the trajectory of the antenna input impedance changing with frequency remains within the matching circle on the Smith chart over a wide frequency band. Adjusting the length and width of the rectangular radiating slot 21 controls the slot resonant point, and adjusting the width of the microstrip feed line 4 and the extension length through the slot controls the coupling strength. Therefore, the impedance matching window is adjusted by the parameters of the slot and the microstrip feed line 4, and is not coupled to the cavity gain window or the metasurface plate axis ratio window.

[0063] like Figure 6 As shown, Figure 6 (a) in the figure shows the simulated S11 frequency curve of the antenna; from the figure... Figure 6As can be seen from (a) above, the impedance bandwidth of antenna S11 below -10dB is 8.90-10.08GHz, and the minimum value of S11 is -46.5dB (9.67GHz). The impedance curve shows three adjacent resonant dips at 9.11GHz, 9.67GHz and 9.89GHz, which is direct evidence of the mutual coupling between the slot feed resonance and the cavity resonance, and the synergistic widening of the impedance bandwidth by multiple resonances.

[0064] Figure 6 Figure (b) shows the simulated axial ratio-frequency curve of the antenna. Figure 6 As can be seen from (b), the frequency band with an axial ratio of less than 3dB in the main beam direction is 9.55-10.35GHz, and the lowest axial ratio is 0.84dB (9.72GHz).

[0065] Figure 6 In the diagram, (c) shows the antenna's gain-frequency simulation curve. Figure 6 As can be seen from (c), the peak side-fire gain of the antenna is 13.03 dBi (9.17 GHz), and the 3 dB gain bandwidth is 8.92-9.44 GHz. The gain is the total gain including all polarization components. In this embodiment, the effective operating frequency band formed by the overlap of the impedance matching frequency band and the axial ratio frequency band is 9.55–10.08 GHz, the in-band gain is 5.78-9.22 dBi, and the 3 dB gain window (8.92-9.44 GHz) is distributed adjacent to the effective operating frequency band.

[0066] Figure 7 This is the normalized radiation pattern of the antenna in this embodiment at 8.71 GHz; where, Figure 7 (a) in the diagram represents plane E. Figure 7 (b) in the figure represents the H-plane. As can be seen from the figure, the main beams of both the E-plane and H-plane point towards the side (θ=0°), exhibiting a pencil-shaped beam pattern. The main polarization level is much higher than the cross-polarization, resulting in good cross-polarization suppression. There are some sidelobes, but no obvious grating lobes. (8×8 metasurface array period) It suppresses spatial grating lobes; the FP resonator homogenizes the aperture field, forming a high-gain side-firing beam.

[0067] Figure 8The figure shows the RCS curves of the antenna in this embodiment and the existing metal-ground antenna as a function of frequency. As can be seen from the figure, after loading the metasurface, the RCS is significantly reduced in most frequency bands; a deep scattering dip appears at 7.25 GHz, with a maximum reduction of 15.77 dB; at 9 GHz, the reduction is 10.38 dB; in the effective operating frequency band of circular polarization 9.55-10.08 GHz, the RCS reduction is only 1.32-2.89 dB, indicating a weaker reduction effect. Due to the phase difference between adjacent checkerboard reflections falling between 143° and 217° and the complementary dual phase cancellation between the upper and lower metasurface layers, the normal scattered field cancels out, resulting in a significant decrease in RCS. The metasurface must retain sufficient transmitted power for radiation, and a trade-off is made for scattering cancellation performance, resulting in limited RCS reduction. This verifies that the antenna in this embodiment has both radiation and scattering reduction functions. The single-site RCS reduction before and after loading the double-layer metasurface plate is statistically analyzed by frequency band as shown in the following table:

[0068] frequency band Reduction 7–12 GHz Average reduction of 3.46 dB 7–9 GHz Average reduction of 4.82 dB Impedance operating frequency band 8.90–10.08 GHz Average reduction of 4.25 dB Effective frequency band with circular polarization: 9.55–10.08 GHz Reduced by 1.32–2.89 dB

[0069] The peak RCS decreased from +4.31 dBsm in the uncoated state to +1.17 dBsm after loading the double-layer metasurface plate, a reduction of 3.14 dB. The maximum reduction across the entire frequency band was 15.77 dB, occurring at 7.25 GHz, corresponding to an RCS reduction from +0.32 dBsm to −15.45 dBsm. The reduction was 10.38 dB at 9.00 GHz. The continuous frequency bands with a reduction of not less than 3 dB were 7.05–7.85 GHz, 8.7–9.35 GHz, and 10.6–12 GHz.

[0070] The embodiments and descriptions above are merely illustrative of the principles and preferred embodiments of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A metasurface-loaded Fabry-Perot resonator low-scattering circularly polarized slot antenna, characterized in that, From bottom to top, the components include a feed plate (1), a copper grounding layer (2), and a double-layer complementary checkerboard polarization conversion metasurface plate (3); the bottom layer of the feed plate (1) has a microstrip feed line (4); the feed plate (1) has a copper grounding layer (2); a rectangular radiation slot (21) is opened on the copper grounding layer (2), and the microstrip feed line (4) crosses the rectangular radiation slot (21) for coupling and feeding; The dual-layer complementary checkerboard polarization conversion metasurface plate (3) includes a dielectric substrate (31), and an upper metasurface layer (32) and a lower metasurface layer (33) disposed at the upper and lower ends of the dielectric substrate (31). A Fabry-Perot resonant cavity is formed between the copper ground layer (2) and the lower metasurface layer (33). The copper ground layer (2) serves as the lower wall of the Fabry-Perot resonant cavity with total internal reflection. The lower metasurface layer (33) and the lower metasurface layer (33) serve as the upper wall of the Fabry-Perot resonant cavity with total internal reflection. The outgoing waves through the double-layer complementary checkerboard polarization conversion metasurface plate (3) are combined into circularly polarized waves. The upper metasurface layer (32) and the lower metasurface layer (33) are both patch arrays; the patch array is composed of anisotropic rectangular metal patch units, the patch array includes rectangular metal patch units of two sizes, and the two sizes of metal patch units of the upper metasurface layer (32) and the lower metasurface layer (33) are complementary in grid order; the intrinsic axis of the rectangular metal patch unit is rotated 45° relative to the linear polarization direction of the feed plate (1), so that the incident linear polarization wave is decomposed into two orthogonal components with equal amplitude in the direction of the intrinsic axis, the reflection amplitude of the two orthogonal components is equal and the reflection phase difference is ±90°.

2. The antenna according to claim 1, characterized in that: The long side of the rectangular radiation slot is perpendicular to the linear polarization direction of the feed plate (1), and the microstrip feed line (4) crosses the center of the rectangular radiation slot (21) perpendicularly.

3. The antenna according to claim 2, characterized in that: The rectangular radiating slit (21) constitutes a half-wavelength resonant slit, and the resonant length of the rectangular radiating slit (21) is half the slit guiding wavelength.

4. The antenna according to claim 1, characterized in that: The rectangular metal patch unit has a side length that is not equal in the intrinsic axis u direction and in the intrinsic axis v direction.

5. The antenna according to claim 4, characterized in that: The resonant frequencies of the rectangular metal patch unit along the intrinsic axis u and along the intrinsic axis v are staggered and located on opposite sides of the operating frequency band. The reflection phase difference of the two orthogonal components is maintained within the range of 90°±15° in the operating frequency band, and the reflection amplitude imbalance does not exceed 20%.

6. The antenna according to claim 1, characterized in that: The two sizes of rectangular metal patch units include a first patch unit (34) and a second patch unit (35). The first patch unit (34) and the second patch unit (35) have different sizes, and the first patch unit (34) and the second patch unit (35) form the grid of a chessboard. The first patch unit (34) and the second patch unit (35) are arranged in a chessboard pattern.

7. The antenna according to claim 6, characterized in that: The first patch unit (34) and the second patch unit (35) of the upper metasurface layer (32) and the lower metasurface layer (33) are complementary to each other.

8. The antenna according to claim 1, characterized in that: The cavity height h of the Fabry-Perot resonant cavity is the distance from the copper ground layer (2) to the lower metasurface layer (33), and the cavity height h of the Fabry-Perot resonant cavity satisfies the Fabry-Perot resonance condition: ； In the formula, For free space operating wavelength; The equivalent reflection phase of the upper metasurface layer (32) and the lower metasurface layer (33); The reflected phase of the copper ground layer (2); The order of the cavity model.

9. The antenna according to claim 1, characterized in that: Both the feed board (1) and the dielectric substrate (31) are Rogers RO4003C dielectric substrates.

10. The antenna according to claim 1, characterized in that: The four corners between the feed plate (1) and the double-layer complementary checkerboard polarization conversion metasurface plate (3) are provided with corresponding support columns, which maintain the cavity height of the Fabry-Perot resonator.

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