Millimeter wave circularly polarized wide-angle scanning phased-array antenna with double-layer FSS structure

Abstract

The invention discloses a millimeter wave circularly polarized wide-angle scanning phased-array antenna with a double-layer FSS structure, which comprises a phased-array antenna array, a first FSS structure layer and a second FSS structure layer which are sequentially arranged from bottom to top, and is characterized in that the first FSS structure layer comprises a first FSS unit, a second FSS unit, a third FSS unit and a first dielectric plate; the second FSS structure layer comprises a fourth FSS unit, a fifth FSS unit, a sixth FSS unit and a second dielectric plate. According to the technical scheme, the frequency selective surface (FSS) can more effectively compensate the phase difference between array units caused by scanning and maintain an equivalent equiphase surface of an array aperture within a large angle range, so that deterioration of the axial ratio (AR) is remarkably inhibited, the circular polarization purity under wide-angle scanning is ensured, the optimized FSS is also beneficial to improvement of impedance matching, and the frequency selective surface has a wide-angle range. And the gain and the efficiency under the large-angle scanning edge region are improved.

Description

Technical Field

[0001] This invention relates to the field of millimeter-wave antenna technology, and in particular to a millimeter-wave circularly polarized wide-angle scanning phased array antenna with a dual-layer FSS structure. Background Technology

[0002] With the development of low-orbit satellites and 6G satellite-ground converged communication technology, the demand for high speed, large capacity and low latency in satellite communication systems has increased dramatically. The millimeter-wave band, with its abundant spectrum resources, has become the key to achieving this goal. At the same time, circularly polarized antennas have become the preferred polarization method for satellite communication antennas due to their advantages in overcoming multipath fading, reducing polarization mismatch loss and adapting to changes in satellite attitude. In order to achieve continuous and stable coverage of high-speed mobile satellites, the phased array antennas on ground user terminals or satellite payloads must have wide-angle scanning capability. However, achieving stable performance of circularly polarized radiation under wide-angle scanning in the millimeter-wave band faces severe technical challenges: (1) Scanning mismatch: As the beam scanning angle increases, the effective spacing projection of array elements changes, resulting in array impedance mismatch and gain reduction. (2) Circular polarization degradation: During wide-angle scanning, the asymmetry of the element pattern intensifies, causing a sharp deterioration in the axial ratio (AR), resulting in loss of circular polarization purity and a serious decline in communication quality. (3) Structural complexity: Traditional wide-angle scanning solutions (such as curved surface arrays and waveguide slot arrays) are often structurally complex, bulky, heavy, and costly, making it difficult to meet the needs of user terminals for miniaturization and low cost.

[0003] Currently, the core bottlenecks facing wide-angle scanning technology for millimeter-wave circularly polarized antennas are: (1) how to effectively compensate for the phase difference caused by wide-angle scanning and maintain a good axial ratio; (2) how to achieve a low-profile, planar, and easily integrated structure in the millimeter-wave band; (3) how to simultaneously meet the requirements of wide bandwidth, wide scanning range, high gain efficiency, and good circular polarization performance; and (4) how to reduce the processing difficulty and cost of millimeter-wave precision structures.

[0004] Currently, the main methods for achieving wide-angle scanning of millimeter-wave circularly polarized phased array antennas on the market are: (1) Using an electromagnetic bandgap structure / artificial magnetic conductor to load a periodic structure above the array to suppress surface waves, improve the symmetry of the unit radiation pattern, and enhance scanning performance. However, this method is complex to design, and the axial ratio bandwidth and scanning bandwidth are limited; the height increases; the millimeter-wave processing accuracy requirements are extremely high, and the cost is sensitive; (2) Wide-angle matching layer, by loading a specially designed dielectric layer or metasurface layer in front of the array to compensate for the phase difference under different scanning angles and optimize the radiation pattern. The effect on improving the axial ratio is limited; however, this method increases the profile height and weight; the design depends on the scanning angle, and wide-angle bandwidth optimization is difficult; (3) Curved surface conformal array, by arranging the array units on a curved surface and using the characteristics of the curved surface itself to achieve wide-angle coverage. Calibration is difficult; manufacturing costs are high; it is difficult to integrate with planar circuits, which limits its application in miniaturized terminals. Summary of the Invention

[0005] The main objective of this invention is to propose a millimeter-wave circularly polarized wide-angle scanning phased array antenna with a dual-layer FSS structure, aiming to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this invention proposes a millimeter-wave circularly polarized wide-angle scanning phased array antenna with a dual-layer FSS structure, comprising a phased array antenna array, a first FSS structure layer, and a second FSS structure layer arranged sequentially from bottom to top. The first FSS structure layer includes a first FSS unit, a second FSS unit, a third FSS unit, and a first dielectric substrate. The first, second, and third FSS units are all arranged in a cross-shaped structure. The first, second, and third FSS units are arranged in a matrix on the first dielectric substrate, forming a first FSS unit matrix, a second FSS unit matrix, and a third FSS unit matrix, respectively. The first FSS unit matrix is ​​located in the middle of the first dielectric substrate, the second FSS unit matrices are located on both sides of the first FSS unit matrix, and the third FSS unit matrices are located at both ends of the first dielectric substrate. The S-structure layer includes a fourth FSS unit, a fifth FSS unit, a sixth FSS unit, and a second dielectric substrate. The outer contours of the fourth, fifth, and sixth FSS units are all arranged in a block structure. Each of the fourth, fifth, and sixth FSS units has a through hole in the middle. Each of the four sides of the fourth, fifth, and sixth FSS units has a vertically arranged slot communicating with the through hole. The fourth, fifth, and sixth FSS units are arranged in a matrix on the second dielectric substrate, forming a fourth FSS unit matrix, a fifth FSS unit matrix, and a sixth FSS unit matrix, respectively. The fourth FSS unit matrix is ​​located in the middle of the second dielectric substrate, the fifth FSS unit matrix is ​​located on both sides of the fourth FSS unit matrix, and the sixth FSS unit matrix is ​​located at both ends of the second dielectric substrate.

[0007] Optionally, the thickness of the first dielectric substrate ranges from 1 mm to 1.5 mm, and the thickness of the second dielectric substrate ranges from 2 mm to 3 mm.

[0008] Optionally, the first FSS unit matrix is ​​a 4*4 matrix, the second FSS unit matrix is ​​a 6*6 matrix, and the third FSS unit matrix is ​​a 7*7 matrix.

[0009] Optionally, the fourth FSS unit matrix is ​​a 2*2 matrix, the fifth FSS unit matrix is ​​a 3*3 matrix, and the sixth FSS unit matrix is ​​a 4*4 matrix. Optionally, the width of the first FSS unit, the second FSS unit, and the third FSS unit is all in the range of 1mm to 2mm.

[0010] Optionally, the rotation angle range of the first FSS unit is 55° to 60°, the rotation angle range of the second FSS unit is 15° to 20°, and the rotation angle range of the third FSS unit is 0°.

[0011] Optionally, the distance between two adjacent first FSS units is 2mm to 2.5mm, the distance between two adjacent second FSS units is 1.4mm to 2mm, and the distance between two adjacent third FSS units is 1.2mm to 1.8mm.

[0012] Optionally, the width of the fourth FSS unit, the fifth FSS unit, and the sixth FSS unit is all in the range of 1mm to 1.5mm.

[0013] Optionally, the inner diameter of the through hole ranges from 0.5 mm to 0.8 mm.

[0014] Optionally, the distance between two adjacent fourth FSS units is 4mm to 4.5mm, the distance between two adjacent fifth FSS units is 2.8mm to 3mm, and the distance between two adjacent sixth FSS units is 2.2mm to 2.5mm. The technical solution of this invention has the following beneficial effects: The technical solution of this invention achieves wide-angle scanning of millimeter-wave circularly polarized phased array antennas by using a double-layer gradient planar frequency selective surface (FSS). Compared with a single-layer frequency selective surface (FSS), the double-layer structure of the frequency selective surface provides richer design freedom. Moreover, the planar gradient frequency selective surface (FSS) design replaces the curved conformal design, which is convenient for integration. In addition, this design breaks the limitations of the traditional periodic frequency selective surface (FSS), enabling its phase compensation characteristics to adaptively match the requirements of different scanning angles, which is a fine control of phase and polarization state.

[0015] This gradient design enables the Frequency Selective Surface (FSS) to more effectively compensate for phase differences between array elements caused by scanning over a wide angle range, maintaining the equivalent equiphase surface of the array aperture. This significantly suppresses the degradation of the axial ratio (AR) and ensures the purity of circular polarization under wide-angle scanning. The optimized FSS also helps improve impedance matching and enhances gain and efficiency in the edge regions of large-angle scanning. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of a millimeter-wave circularly polarized wide-angle scanning phased array antenna with a double-layer FSS structure according to an embodiment of the present invention. Figure 2 Active VSWR curves for each port of a gradient double-layer FSS linear array; Figure 3 Port isolation (S-parameter); Figure 4 The frequency curve of the normal axis ratio of the linear array; Figure 5 Gain curves (0, 30, 70°) under 29.5GHz scanning of the linear array; Figure 6 The axial ratio curves are shown for a linear array scanning at 29.5 GHz (0, 30, 70°).

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0021] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] This invention proposes a millimeter-wave circularly polarized wide-angle scanning phased array antenna with a dual-layer FSS structure.

[0023] like Figures 1 to 6 As shown, in one embodiment of the present invention, a millimeter-wave circularly polarized wide-angle scanning phased array antenna with a dual-layer FSS structure includes a phased array antenna array 100, a first FSS structure layer 200, and a second FSS structure layer 300 arranged sequentially from bottom to top. The first FSS structure layer 200 includes a first FSS unit 201, a second FSS unit 202, a third FSS unit 203, and a first dielectric substrate 204. The first FSS unit 201, the second FSS unit 202, and the third FSS unit 203 are all arranged in a cross-shaped structure. The first FSS unit 201, the second FSS unit 202, and the third FSS unit 203 are arranged in a matrix on the first dielectric substrate 204, forming a first FSS unit matrix, a second FSS unit matrix, and a third FSS unit matrix, respectively. The first FSS unit matrix is ​​located in the middle of the first dielectric substrate 204, the second FSS unit matrices are located on both sides of the first FSS unit matrix, and the third FSS unit matrix is ​​located at both ends of the first dielectric substrate 204. The second FSS structure layer 300 is wrapped with... The system includes a fourth FSS unit 301, a fifth FSS unit 302, a sixth FSS unit 303, and a second dielectric substrate 304. The outer contours of the fourth FSS unit 301, fifth FSS unit 302, and sixth FSS unit 303 are all arranged in a block structure. A through hole 305 is provided in the middle of each of the four FSS units 301, fifth FSS unit 302, and sixth FSS unit 303. A hole perpendicular to the center of each of the four sides of the fourth FSS unit 301, fifth FSS unit 302, and sixth FSS unit 303 is provided in the middle. The through-hole connected opening slot 306, the fourth FSS unit 301, the fifth FSS unit 302 and the sixth FSS unit 303 are respectively arranged in a matrix on the second dielectric substrate 304, forming a fourth FSS unit matrix, a fifth FSS unit matrix and a sixth FSS unit matrix respectively. The fourth FSS unit matrix is ​​located in the middle of the second dielectric substrate 304, the fifth FSS unit matrix is ​​located on both sides of the fourth FSS unit matrix, and the sixth FSS unit matrix is ​​located at both ends of the second dielectric substrate 304.

[0024] Specifically, the thickness of the first dielectric substrate 204 ranges from 1 mm to 1.5 mm, and the thickness of the second dielectric substrate ranges from 2 mm to 3 mm.

[0025] Specifically, the first FSS unit matrix is ​​a 4*4 matrix, the second FSS unit matrix is ​​a 6*6 matrix, and the third FSS unit matrix is ​​a 7*7 matrix.

[0026] Specifically, the fourth FSS unit matrix is ​​a 2*2 matrix, the fifth FSS unit matrix is ​​a 3*3 matrix, and the sixth FSS unit matrix is ​​a 4*4 matrix. Specifically, the widths of the first FSS unit 201, the second FSS unit 202, and the third FSS unit 203 are all in the range of 1mm to 2mm.

[0027] Specifically, the rotation angle range of the first FSS unit 201 is 55° to 60°, the rotation angle range of the second FSS unit 202 is 15° to 20°, and the rotation angle range of the third FSS unit 203 is 0°.

[0028] Specifically, the distance between two adjacent first FSS units 201 is 2mm to 2.5mm, the distance between two adjacent second FSS units 202 is 1.4mm to 2mm, and the distance between two adjacent third FSS units 203 is 1.2mm to 1.8mm.

[0029] Specifically, the width of the fourth FSS unit 301, the fifth FSS unit 302, and the sixth FSS unit 303 are all in the range of 1mm to 1.5mm.

[0030] Specifically, the inner diameter of the through hole 305 ranges from 0.5 mm to 0.8 mm.

[0031] Specifically, the distance between two adjacent fourth FSS units 301 is 4mm to 4.5mm, the distance between two adjacent fifth FSS units 302 is 2.8mm to 3mm, and the distance between two adjacent sixth FSS units 303 is 2.2mm to 2.5mm.

[0032] Specifically, the core of the technical solution of the present invention lies in using a non-periodic gradually changing double-layer frequency selective surface (FSS) as a spatial phase compensator to solve the phase mismatch and polarization degradation problems faced by millimeter-wave circularly polarized phased arrays during wide-angle scanning.

[0033] I. Root cause of the problem: Why does wide-angle scanning disrupt circular polarization? 1. Projected Phase Difference: In a phased array, beam scanning is achieved by controlling the feed phase of each element. When the beam deviates from the normal (scanning angle θ increases), the spatial projection distance between elements in the beam direction shortens, causing a deviation between the phase relationship of its radiation field and theoretical calculations. This deviation disrupts the equiphase surface of the antenna aperture field.

[0034] 2. Edge Truncation Effect: For a finite-size array, the edge effect becomes significant during large-angle scanning. The local environment of the edge cells is asymmetric to that of the central cells, causing changes in their radiation characteristics (including impedance and polarization).

[0035] 3. The essence of circular polarization: An ideal circularly polarized wave is synthesized from two linearly polarized orthogonal components (such as E_x and E_y) with equal amplitude and a 90° phase difference. The phase mismatch and edge effects mentioned above will disrupt the amplitude balance and accurate 90° phase difference relationship of these two components, leading to a deterioration in axial ratio and a decrease in circular polarization purity.

[0036] II. Working Principle of Double-Layer Gradient FSS Structure The FSS is a two-dimensional periodic structure that can modulate the amplitude and phase of incident electromagnetic waves. The innovative design of this invention lies in its design as a two-layer, non-periodic, and gradually changing structure.

[0037] 1. Two-layer structure: provides layered phase compensation degrees of freedom. Functional division of labor: The first FSS structure layer (near the antenna array): primarily optimizes performance for small to medium scan angles. Its function is to finely correct the phase in the near-field region, improve the impedance matching of the array, and serve as a primary phase compensation layer.

[0038] The second FSS structure layer is primarily optimized for large-angle scanning. It is responsible for further phase shaping of the waves radiated after passing through the lower FSS layer, compensating for the larger phase difference caused by large-angle scanning.

[0039] Synergistic effect: A resonant cavity-like structure is formed between the two FSS layers. By optimizing the spacing between the two layers, specific electromagnetic modes can be excited, thereby obtaining a richer phase response curve, which is difficult to achieve with a single-layer FSS.

[0040] 2. Non-periodic gradient design: Achieving spatially adaptive phase compensation This is the core innovation of this invention. Traditional periodic FSSs have a uniform response to all incident angles, while the structural parameters (unit size, shape, rotation angle) of the gradient FSS are position functions on the plane.

[0041] Phase compensation principle: The geometric parameters of the FSS cell (such as the length of the cross arm and the radius of the annular slit) determine its transmission phase. By gradually changing these parameters from the center to the edge of the array, it is equivalent to placing countless "microlenses" with different phase delays in space.

[0042] In the central region of the array, the FSS cells are designed to provide a small phase correction for waves radiated near the normal.

[0043] In the edge region of the array, the FSS cells are designed to provide greater phase compensation for waves radiating at large angles.

[0044] Phase compensation effect: This spatially varying phase compensation can dynamically "correct" the wavefront distorted by scanning, reconstructing an approximately planar equiphase surface throughout the scanning range, thereby maintaining good circular polarization characteristics and gain.

[0045] 3. Key technology for stable circular polarization: Pancharatnam-Berry Phase The rotation angle of the FSS unit mentioned in this invention is key to stable circular polarization.

[0046] Physical Mechanism: When a linearly anisotropic FSS cell (such as the cross-shaped slit in the lower layer or the annular slit in the upper layer) rotates in the plane by an angle φ, it introduces an additional transmission phase to the incident circularly polarized wave, with a value of ±2φ ("+" or "-" depending on the direction of rotation of the incident circularly polarized wave). This is called the geometric phase. Application: By carefully designing the rotation angle distribution of FSS elements at different positions on the array, a preset, spatially varying phase profile can be applied to the circularly polarized wave radiated by the antenna. This additional phase can accurately compensate for the 90° phase relationship between the two orthogonal electric field components (E_x and E_y) that is disrupted by scanning, thereby maintaining a low axial ratio throughout the entire scanning angular domain.

[0047] III. Synergistic Effects of Performance Improvement Improved impedance matching and decoupling: Applying FSS alters the array's equivalent electromagnetic environment, suppressing surface waves and reducing mutual coupling between array elements (as seen in the improved isolation curves). This helps broaden the active standing wave ratio (VSWR) scanning range, allowing the antenna to maintain good impedance matching during scanning and radiating energy more efficiently.

[0048] Gain compensation: By optimizing the size of the FSS cells in the edge region (making them larger), the radiation efficiency of the region can be improved, partially compensating for the gain decrease caused by the reduction in effective aperture during large-angle scanning.

[0049] Specifically, the principle of this invention can be summarized as follows: By designing a spatially non-uniform, parameter-gradient two-layer FSS structure and placing it in front of the antenna array, this structure utilizes the spatial distribution of its transmission phase to perform dynamic and adaptive phase compensation for the scanning beam. Simultaneously, it employs the geometric phase introduced by rotating elements to specifically correct the phase difference of the circularly polarized orthogonal components. These two mechanisms work together to ultimately achieve simultaneous stability of impedance, gain, and circular polarization performance over a wide scanning angle range.

[0050] This represents a paradigm shift from "passive periodic structures" to "active spatially varying electromagnetic surfaces," providing an efficient and easily integrated solution for millimeter-wave wide-angle scanning phased arrays.

[0051] Loading a specially designed wide-angle matching layer in front of the array can compensate for phase differences at different scanning angles and optimize the radiation pattern, but its effect on improving the axial ratio is limited. The gradient double-layer FSS design breaks the limitations of the traditional periodic FSS, enabling its phase compensation characteristics to adaptively match the requirements of different scanning angles, allowing for fine control of phase and polarization states.

[0052] The strong active coupling between array elements limits the scanning performance of the antenna array. Reducing the mutual coupling effect between array elements and improving the axial ratio of the circularly polarized array can help to widen the scanning angle of the circularly polarized linear array. Figure 2 The active VSWR curves for each port of the gradient double-layer FSS linear array are all below 1.55dB in the operating frequency band, indicating that the active coupling is well decoupled. Figure 3 Selecting the isolation between major ports as a reference, Figure 3 The S-parameter curves are all below -16dB, which also indicates good isolation (decoupling). Figure 4 To select the curve of normal axis ratio (scanning angle deflection of 0°) as a function of frequency (27.5-31GHz), the axis ratio range is 0.55-1.55 (dB), and the axis ratio performance is extremely excellent. Figure 5 To select the gain curve under linear array scanning at the center frequency (29.5GHz), the gain decreased by 5.8dB. This invention has compensated for the gain in the edge region under large-angle scanning, while existing methods without relying on lenses and related technologies result in an even greater gain decrease under such large-angle scanning.

[0053] Figure 4 The axial ratio curves under zero-bias scanning of the present invention are characterized to more intuitively represent the axial ratio performance under large-angle scanning. Figure 6 The axial ratio curves under the center frequency (29.5GHz) were selected. When the scanning angle was 0°, the axial ratio was 0.64dB. When the scanning angle was ±30° and ±70°, the axial ratios were 0.26dB, 0.23dB, 0.31dB and 0.24dB respectively, which were much less than 3dB. The axial ratio performance was extremely excellent. Although the gain dropped significantly at large angles (±70°), the axial ratio performance of this invention was extremely excellent.

[0054] Specifically, this invention achieves wide-angle scanning of millimeter-wave circularly polarized phased array antennas by employing a dual-layer gradient planar frequency selective surface (FSS). Compared to a single-layer FSS, the dual-layer FSS structure provides greater design freedom, and the planar gradient FSS design replaces the curved conformal design, facilitating integration. Furthermore, this design breaks through the limitations of traditional periodic FSSs, enabling its phase compensation characteristics to adaptively match the requirements of different scanning angles, allowing for precise control of phase and polarization states.

[0055] This gradient design enables the Frequency Selective Surface (FSS) to more effectively compensate for phase differences between array elements caused by scanning over a wide angle range, maintaining the equivalent equiphase surface of the array aperture. This significantly suppresses the degradation of the axial ratio (AR) and ensures the purity of circular polarization under wide-angle scanning. The optimized FSS also helps improve impedance matching and enhances gain and efficiency in the edge regions of large-angle scanning.

[0056] Specifically, the "dual-layer gradient planar frequency selective surface (FSS)" proposed in this invention provides an effective way to achieve stable circular polarization performance under high-efficiency wide-angle scanning through an innovative non-periodic gradient structure design. This solution offers a good approach to solving the current challenges of wide-angle scanning with millimeter-wave circular polarization, achieving stable low axial ratios over large scanning angles, and possesses significant theoretical value and broad application prospects. Compared to traditional solutions, it has the following advantages: 1. Periodic FSS optimizes only specific angles, while non-gradual double-layer FSS structure parameters gradually change with space, allowing for good phase correction at both large and small angles.

[0057] 2. FSS cell design: bottom layer cross-shaped cell: controls fundamental mode radiation; upper layer annular gap: introduces geometric phase difference; FSS cell rotation angle optimization: achieves compensated scanning orthogonal phase.

[0058] 3. The size of the edge region cells is increased to improve edge radiation efficiency, and the center-edge spacing gradient of the FSS is changed to achieve optimized axial ratio and gain compensation at large angles.

[0059] 4. Compared to metasurface solutions that require nanoscale processing, this design retains a feature size >0.1λ (0.3mm in the millimeter-wave band), making it compatible with PCB manufacturing processes.

[0060] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A millimeter wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure, characterized in that, The application relates to a phased array antenna array, a first FSS structure layer and a second FSS structure layer arranged in sequence from bottom to top, the first FSS structure layer comprises first FSS units, second FSS units, third FSS units and a first dielectric plate, the first FSS units, the second FSS units and the third FSS units are arranged in a cross structure, the first FSS units, the second FSS units and the third FSS units are arranged in a matrix on the first dielectric plate respectively, and first FSS unit matrices, second FSS unit matrices and third FSS unit matrices are formed respectively, the first FSS unit matrix is located in the middle of the first dielectric plate, the second FSS unit matrices are located on both sides of the first FSS unit matrix respectively, and the third FSS unit matrices are located at both ends of the first dielectric plate respectively, the second FSS structure layer comprises fourth FSS units, fifth FSS units, sixth FSS units and a second dielectric plate, the fourth FSS units, the fifth FSS units and the sixth FSS units are arranged in a square structure, a through hole is arranged in the middle of each of the fourth FSS units, the fifth FSS units and the sixth FSS units, and an open slot in communication with the through hole is vertically arranged in the middle of each of the four edges of the fourth FSS units, the fifth FSS units and the sixth FSS units, the fourth FSS units, the fifth FSS units and the sixth FSS units are arranged in a matrix on the second dielectric plate respectively, and fourth FSS unit matrices, fifth FSS unit matrices and sixth FSS unit matrices are formed respectively, the fourth FSS unit matrix is located in the middle of the second dielectric plate, the fifth FSS unit matrices are located on both sides of the fourth FSS unit matrix respectively, and the sixth FSS unit matrices are located at both ends of the second dielectric plate respectively, the first FSS unit matrix is a 4*4 matrix, the second FSS unit matrix is a 6*6 matrix, the third FSS unit matrix is a 7*7 matrix, the fourth FSS unit matrix is a 2*2 matrix, the fifth FSS unit matrix is a 3*3 matrix, and the sixth FSS unit matrix is a 4*4 matrix.

2. The millimeter wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure according to claim 1, characterized in that, The thickness of the first dielectric plate ranges from 1mm to 1.5mm, and the thickness of the second dielectric plate ranges from 2mm to 3mm.

3. The millimeter wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure according to claim 1, characterized in that, The width of each of the first FSS units, the second FSS units and the third FSS units ranges from 1mm to 2mm.

4. The millimeter wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure according to claim 1, characterized in that, The rotation angle of each of the first FSS units ranges from 55 degrees to 60 degrees, the rotation angle of each of the second FSS units ranges from 15 degrees to 20 degrees, and the rotation angle of each of the third FSS units is 0 degree.

5. The millimeter wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure according to claim 1, characterized in that, The distance between two adjacent first FSS units ranges from 2mm to 2.5mm, the distance between two adjacent second FSS units ranges from 1.4mm to 2mm, and the distance between two adjacent third FSS units ranges from 1.2mm to 1.8mm.

6. The millimeter-wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure according to claim 1, characterized in that, The width of the fourth FSS unit, the fifth FSS unit and the sixth FSS unit ranges from 1mm to 1.5mm.

7. The millimeter-wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure according to claim 1, characterized in that, The inner diameter of the through hole ranges from 0.5mm to 0.8mm.

8. The millimeter-wave circularly polarized wide-angle scanning phased array antenna with double-layer FSS structure according to claim 1, characterized in that, The distance between two adjacent fourth FSS units ranges from 4mm to 4.5mm, the distance between two adjacent fifth FSS units ranges from 2.8mm to 3mm, and the distance between two adjacent sixth FSS units ranges from 2.2mm to 2.5mm.

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