Wideband Circularly Polarized Metasurface Antenna

Abstract

This invention relates to the field of antenna technology and discloses a wideband circularly polarized metasurface antenna, comprising a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom. The upper surface of the first dielectric substrate has a metasurface metal structure; the upper surface of the second dielectric substrate has a patch structure, and the lower surface has a metal ground plane with a slot coupling structure; the lower surface of the third dielectric substrate has a microstrip feed structure. The metasurface metal structure includes parasitic patch units arranged around the edge of the first dielectric substrate and metal patch units arranged in an equally spaced rectangular array within the area formed by the parasitic patch units. Each parasitic patch unit has a first cutting portion, and each metal patch unit includes a first sub-metal patch with a second cutting portion and a second sub-metal patch with a third cutting portion. The first sub-metal patches are arranged in a cross shape to isolate the second sub-metal patches. This invention can achieve wideband circular polarization characteristics by synergistically broadening both the operating bandwidth and axial ratio bandwidth.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a broadband circularly polarized metasurface antenna. Background Technology

[0002] With the increasing demands for high-speed data transmission and high-quality signal reception in satellite communication systems, circularly polarized antennas have been widely used in modern satellite communication due to their superior resistance to polarization mismatch and multipath interference. Metasurface antennas, with their flexible control over the direction, phase, and polarization state of electromagnetic wave propagation, exhibit significant advantages in circularly polarized antenna design. By integrating metamaterials and metasurface technologies, effective manipulation of electromagnetic waves can be achieved within a compact structure, thereby improving circular polarization performance and meeting the stable communication requirements of satellite communication systems in complex environments. This provides crucial support for the development of high-speed, high-capacity satellite communication systems.

[0003] However, traditional metasurface circularly polarized antennas still have certain limitations, mainly in that the main radiating patch structure is relatively simple, making it difficult to excite multiple eigenmodes with adjacent frequencies, thus limiting the complete formation and stable maintenance of the rotating electric field. Summary of the Invention

[0004] This invention provides a wideband circularly polarized metasurface antenna to solve the technical problems of bandwidth expansion and low circular polarization performance of antennas in the prior art.

[0005] To address the aforementioned technical problems, this invention provides a broadband circularly polarized metasurface antenna, comprising a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom; the upper surface of the first dielectric substrate is provided with a metasurface metal structure, the upper surface of the second dielectric substrate is provided with a patch structure and the lower surface is provided with a metal ground plane with a slot coupling structure, and the lower surface of the third dielectric substrate is provided with a microstrip feed structure; the metal ground plane is attached to the upper surface of the third dielectric substrate; the metasurface metal structure includes parasitic patch units surrounding the edge of the first dielectric substrate and metal patch units arranged in a rectangular array, the metal patch units being disposed within the area formed by the parasitic patch units surrounding the first dielectric substrate; some of the parasitic patch units are provided with a first cutting portion, and the metal patch unit includes a first sub-metal patch with a second cutting portion and a second sub-metal patch with a second cutting portion. The second sub-metal patch of the three-cut section is separated from the first sub-metal patch by a cross arrangement; the metal patch unit includes several square metal patches; the first sub-metal patch is obtained by cutting squares along the first diagonal direction of the metal patch at two opposite corners of the metal patch, wherein the second cut section consists of two squares; the second sub-metal patch is obtained by cutting squares along the first diagonal direction of the metal patch at two opposite corners of the metal patch, and then cutting rectangles along the first diagonal direction at the squares; the first cut section is a square, and the ratio of the area of ​​the first cut section to the area of ​​the second cut section is 1:1; the parasitic patch unit includes three structures: the same structure is used at the same diagonal, different structures are used at different diagonals, and the same structure is used on all four opposite sides but the cutting angles of the first cut section on the four opposite sides are different.

[0006] In some embodiments, the rectangular array is 3×3, and the metal patch unit includes a plurality of square metal patches with a side length of P.

[0007] In some embodiments, the first sub-metal patch is obtained by cutting squares of side length A from two opposite corners of the metal patch along a first diagonal direction, wherein the second cut portion consists of two squares of side length A, and 0.38P <A<0.4P。

[0008] In some embodiments, the second sub-metal patch is obtained by cutting a square with side length A from two opposite corners of the metal patch along the first diagonal direction, and then cutting a rectangle with length D and width W from the square with side length A along the first diagonal direction, where D:W = 2:1, and 0.7A <D<0.9A。

[0009] In some embodiments, the spacing between any two adjacent horizontally and vertically arranged 3×3 metal patches is G, which is 2.69 mm. <G<2.71mm。

[0010] In some embodiments, the second sub-metal patch includes a connecting portion with a recess in the middle and triangular portions at opposite ends of the connecting portion.

[0011] In some embodiments, the parasitic patch unit includes a plurality of L-shaped first parasitic patches and a plurality of square second parasitic patches; the plurality of first parasitic patches and the plurality of second parasitic patches are all disposed at the periphery of the first dielectric substrate, wherein the plurality of first parasitic patches are distributed along a first diagonal direction of the first dielectric substrate, and the plurality of second parasitic patches are distributed along a second diagonal direction of the first dielectric substrate; the second diagonal direction is parallel to or coincides with the direction pointed to by the triangular portion, and the first diagonal direction is perpendicular to the second diagonal direction.

[0012] In some embodiments, the system further includes a plurality of stepped third parasitic patches; the plurality of third parasitic patches are disposed on opposite sides of the first dielectric substrate, and the plurality of third parasitic patches are spaced apart between the first parasitic patch and the second parasitic patch; the arrangement direction of the plurality of third parasitic patches is the same as the arrangement direction of the first sub-metal patch after it has been translated in a horizontal or vertical direction.

[0013] In some embodiments, the patch structure includes a 3×3 patch array composed of a plurality of sub-pattern units 211, wherein each of the sub-pattern units 211 includes two rectangular sub-patterns 2111.

[0014] In some embodiments, the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all made of F4B material with a dielectric constant of 3.5 and a loss tangent of 0.0022; the thickness of the first dielectric substrate is Hsub1, the thickness of the second dielectric substrate is Hsub2, and the thickness of the third dielectric substrate is Hsub3, wherein Hsub1=9mm, Hsub2=6mm, and Hsub3=4mm.

[0015] Compared with the prior art, the broadband circularly polarized metasurface antenna of this invention has the following advantages:

[0016] In this embodiment of the invention, the physical separation between the first and second dielectric substrates creates a coupling space between the metasurface metal structure and the patch structure on the upper surface of the second dielectric substrate. Thus, the radio frequency energy transmitted from the microstrip feed structure to the patch structure excites the metasurface metal structure through the coupling space to form a stable rotating electric field, thereby improving circular polarization performance. The metal patch units are located within the region formed by the parasitic patch units, forming a center-edge multi-level electromagnetic coupling structure. This increases the effective path length of the metasurface fundamental mode resonant wavelength and reduces the fundamental mode resonant frequency, allowing radio frequency energy to be effectively excited over a wider frequency range, thereby broadening the operating bandwidth. The metasurface metal structure forms a spatial phase gradient through a periodic arrangement of multiple metal patches (first sub-metal patches and second sub-metal patches). When electromagnetic waves incident from the patch structure interact with it, by changing the geometric parameters (such as the position and size of the cut portions) on the metal patches (second and third cut portions), the phase response of the reflected or transmitted waves at different frequencies changes continuously, thereby generating an equivalent rotating electric field over a wide frequency band. In other words, by combining and arranging the various patches and cut sections, multiple different modes can be excited at different frequencies. Simultaneously, by adjusting the current path and phase response through a cross-shaped arrangement, multiple orthogonal modes can simultaneously satisfy the ±90° phase shift condition over a wide frequency range. Thus, this invention can achieve a dual broadening of both the operating bandwidth and axial ratio bandwidth, realizing wideband circular polarization characteristics. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a broadband circularly polarized metasurface antenna provided in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the upper surface of the first dielectric substrate in the broadband circularly polarized metasurface antenna provided in an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of the upper surface of the second dielectric substrate in the broadband circularly polarized metasurface antenna provided in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the metal ground plane structure in the broadband circularly polarized metasurface antenna provided in an embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the structure of the lower surface of the third dielectric substrate in the broadband circularly polarized metasurface antenna provided in an embodiment of the present invention;

[0022] Figure 6 This is a side view of the broadband circularly polarized metasurface antenna provided in an embodiment of the present invention.

[0023] Figure 7This is a simulation result diagram of the return loss of the broadband circularly polarized metasurface antenna provided in the embodiment of the present invention;

[0024] Figure 8 This is a simulation result of the axial ratio of the broadband circularly polarized metasurface antenna provided in the embodiment of the present invention;

[0025] Figure 9 This is a simulation result of the gain of the broadband circularly polarized metasurface antenna provided in an embodiment of the present invention;

[0026] Figure 10 This is a gain distribution diagram of the broadband circularly polarized metasurface antenna provided in this embodiment of the invention, with co-polarization and cross-polarization in the YOZ plane at an operating frequency of 1.207 GHz;

[0027] Figure 11 This is a gain distribution diagram of the broadband circularly polarized metasurface antenna provided in this embodiment of the invention, with co-polarization and cross-polarization in the YOZ plane at an operating frequency of 1.268 GHz;

[0028] Figure 12 This is a diagram showing the gain distribution of the same polarization and cross polarization of the YOZ plane of the broadband circularly polarized metasurface antenna provided in this embodiment of the invention at an operating frequency of 1.561 GHz;

[0029] Figure 13 This is a gain distribution diagram of the broadband circularly polarized metasurface antenna provided in this embodiment of the invention, with co-polarization and cross-polarization on the XOZ plane at an operating frequency of 1.207 GHz;

[0030] Figure 14 This is a gain distribution diagram of the broadband circularly polarized metasurface antenna provided in this embodiment of the invention, with co-polarization and cross-polarization on the XOZ plane at an operating frequency of 1.268 GHz;

[0031] Figure 15 This is a gain distribution diagram of XOZ plane co-polarization and cross-polarization of the broadband circularly polarized metasurface antenna provided in an embodiment of the present invention at an operating frequency of 1.561 GHz.

[0032] In the figure, 100 is the first dielectric substrate; 110 is the metasurface metal structure; 111 is the parasitic patch unit; 1111 is the first parasitic patch; 1112 is the second parasitic patch; 1113 is the third parasitic patch; 112 is the metal patch unit; 1121 is the first sub-metal patch; 1122 is the second sub-metal patch; 1122a is the connecting part; 1122b is the triangular part; 200 is the second dielectric substrate; 210 is the patch structure; 211 is the sub-patch unit; 2111 is the sub-patch; 220 is the metal ground plane; 221 is the slot coupling structure; 300 is the third dielectric substrate; 310 is the power supply network. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0034] In the description of this invention, it should be noted that the directional terms such as "center", "upper", "lower", "inner", and "outer" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and 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. They should not be construed as limiting the specific protection scope of this invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "at least" means one or more, unless otherwise explicitly specified.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] See again Figures 1 to 6This invention provides a broadband circularly polarized metasurface antenna, comprising a first dielectric substrate 100, a second dielectric substrate 200, and a third dielectric substrate 300 stacked sequentially from top to bottom. The upper surface of the first dielectric substrate 100 is provided with a metasurface metal structure 110. The upper surface of the second dielectric substrate 200 is provided with a patch structure 210, and the lower surface is provided with a metal ground plane 220 consisting of a slot coupling structure 221. The lower surface of the third dielectric substrate 300 is provided with a microstrip feed structure (i.e., a feed network 310). The metal ground plane 220 is attached to the upper surface of the third dielectric substrate 300. The metasurface metal structure 110 includes parasitic patch units 111 surrounding the edge of the first dielectric substrate 100 and metal patch units 112 arranged in a rectangular array. The metal patch units 112 are located in the area formed by the parasitic patch units 111 surrounding the parasitic patch units 111. Some of the parasitic patch units 111 are provided with a first cutting portion. The metal patch units 112 include a first sub-metal patch 1121 with a second cutting portion and a second sub-metal patch 1122 with a third cutting portion. The first sub-metal patch 1121 is arranged in a cross shape to isolate the second sub-metal patch 1122.

[0038] In this embodiment, three dielectric substrates of equal length and width (specifically, a first dielectric substrate 100, a second dielectric substrate 200, and a third dielectric substrate 300) are stacked sequentially from top to bottom. The first dielectric substrate 100 is disposed on the top layer, the second dielectric substrate 200 is disposed on the middle layer (that is, the second dielectric substrate 200 is located between the first dielectric substrate 100 and the third dielectric substrate 300), and the third dielectric substrate 300 is disposed on the bottom layer.

[0039] A metasurface metal structure 110 is disposed on the upper surface of the first dielectric substrate 100. This metasurface metal structure 110 includes parasitic patch units 111 arranged around the edge of the first dielectric substrate 100 and metal patch units 112 arranged in an equally spaced rectangular array. The parasitic patch units 111 and metal patch units 112 are used to regulate the propagation characteristics of electromagnetic waves. Specifically, the parasitic patch units 111 are arranged around the main radiating patch (i.e., metal patch units 112), introducing additional resonant frequency points through electromagnetic coupling. These resonant frequency points form multiple nearest-neighbor resonant peaks with the intrinsic resonant points of the metasurface metal structure 110, thereby expanding the overall operating bandwidth of the antenna. The structural and arrangement design of the metal patch units 112 breaks the geometric symmetry, allowing the two vertical polarization modes, transverse electric mode and transverse magnetic mode, to be excited simultaneously while maintaining a 90° phase difference, thus generating a well-polarized wave. This enhances the broadband characteristics and circular polarization performance.

[0040] The upper surface of the second dielectric substrate 200 is provided with a patch structure 210. The patch structure 210 serves as a radiation element and is used to convert the received electromagnetic energy or feeding signal (the electromagnetic energy or radio frequency signal is obtained by being transmitted through the slot coupling structure 221 from the feeding network 310 on the lower third dielectric substrate 300) into electromagnetic waves radiated in space, thereby realizing the radiation function of the antenna.

[0041] As Figure 4 shown, a metal floor 220 of the slot coupling structure 221 is provided on the lower surface of the second dielectric substrate 200. The metal floor 220 is adhered to the upper surface of the third dielectric substrate 300. The width of the slot coupling structure 221 on the metal floor 220 is denoted as WM2, with the unit of millimeter (mm), and the length is denoted as LM2, with the unit of millimeter (mm). There is 84 mm < WM2 < 86 mm, 7.7 mm < LM2 < 7.9 mm. The metal floor 220 of the slot coupling structure 221 is used to receive the radio frequency signal input from the feeding network 310 below the third dielectric substrate 300. And because the metal floor 220 is adhered to the second dielectric substrate 200, the radio frequency signal can be transmitted upward to the upper patch structure 210 in an electromagnetic coupling manner through the metal floor 220 of the slot coupling structure 221. In addition, the metal floor 220 also plays a role in electromagnetic isolation and shielding to suppress reverse radiation and improve the directivity of the antenna.

[0042] As Figure 5 shown, a feeding network 310 is provided on the lower surface of the third dielectric substrate 300. The width of the feeding network 310 is denoted as WM1, and the length is denoted as LM1. There is 8.17 mm < WM1 < 8.37 mm, 114.9 mm < LM1 < 115.1 mm. The feeding network 310 is used to receive external feeding / radio frequency signals and transmit them to the metal floor 220 through the slot coupling structure 221.

[0043] In summary, since the metal ground plane 220 on the lower surface of the second dielectric substrate 200 is attached to the upper surface of the third dielectric substrate 300, and a slot coupling structure 221 is provided in the metal ground plane 220, the signal output from the feed network 310 on the lower surface of the third dielectric substrate 300 can be coupled to the patch structure 210 on the upper surface of the second dielectric substrate 200 through the slot structure. Furthermore, due to the physical distance between the second dielectric substrate 200 and the first dielectric substrate 100, the patch structure 210 and the metasurface metal structure 110 on the upper surface of the first dielectric substrate 100 form a coupling space based on the near-field electromagnetic field. This allows the radio frequency energy excited by the patch structure 210 to excite the metasurface metal structure 110 to generate a rotating electric field through the coupling space, achieving good circularly polarized electromagnetic wave radiation characteristics. Specifically, the coupling space enables the asymmetric modes or electric fields with a certain phase difference excited by the patch structure 210 to be effectively transferred to the metasurface metal structure 110. Under the action of the asymmetric patch distribution and cutting structure of the metasurface metal structure 110, they further evolve into rotating currents, thereby generating circularly polarized radiation.

[0044] It should be noted that the coupling space enables composite control in the following two ways, including but not limited to: First, the second dielectric substrate 200 and the third dielectric substrate 300 are directly bonded together to form a slot-coupled feed structure. This structure allows the feed network 310 to excite the patch structure 210 on the second dielectric substrate 200 through the slot in the metal ground plane 220, simplifying the feed channel design and reducing feed losses. Second, the first dielectric substrate 100 is suspended above the upper surface of the second dielectric substrate 200, meaning they are not directly bonded but rather form a certain vertical gap, creating a far-field coupling space between the metasurface structure and the patch structure 210. This structure can effectively control the radiation directivity and polarization characteristics of the patch structure 210 to optimize antenna performance.

[0045] Based on this, by arranging the parasitic patch unit 111 and the metal patch unit 112 in the metasurface metal structure 110, a center-edge multi-level electromagnetic coupling structure is formed, extending the frequency response range and thus achieving a widening of the working bandwidth. At the same time, by adjusting the arrangement and structural design of the first sub-metal patch 1121 and the second sub-metal patch 1122 in the metal patch unit 112, the amplitude and phase difference are controlled, and the orthogonal components are strengthened, thereby achieving a widening of the axial ratio bandwidth.

[0046] Specifically, the metasurface metal structure 110 includes parasitic patch units 111 and metal patch units 112. The parasitic patch units 111 are arranged along the edge of the first dielectric substrate 100. This arrangement of the parasitic patch units 111 creates a closed, encircling characteristic in spatial distribution, effectively limiting electromagnetic field leakage at the edge and establishing stable inductive and capacitive current channels in the edge region. Since the ring arrangement introduces multiple near-field coupling paths at the edge of the first dielectric substrate 100, it enhances the energy feedback capability of the patch structure 210 under multimode excitation, thereby improving the overall electromagnetic field coupling efficiency of the antenna. Based on this, not only is the response capability of the metasurface metal structure 110 to the electromagnetic waves excited by the patch structure 210 enhanced, but the equivalent capacitance and equivalent inductance of the antenna are also further increased, thereby improving resonance characteristics and expanding the frequency response range, enabling fine-tuning of the resonant frequency and optimization of the axial ratio performance. Furthermore, the metal patch units 112 are arranged within the area enclosed by the ring-shaped parasitic patch units 111. Thus, a center-edge multi-level electromagnetic coupling structure is formed on the first dielectric substrate 100.

[0047] More specifically, the parasitic patch unit 111 is provided with a first cutting portion to introduce an equivalent parasitic resonant channel, thereby enhancing the current path. The metal patch unit 112 is further subdivided into a first sub-metal patch 1121 and a second sub-metal patch 1122. The first sub-metal patch 1121 is provided with a second cutting portion; the second sub-metal patch 1122 is provided with a third cutting portion. In terms of arrangement, the second sub-metal patches 1122 are distributed in the four corner regions of the rectangular array, serving as current isolation and electric field modulation. The first sub-metal patches 1121 are distributed in the non-corner regions of the rectangular array (i.e., other regions outside the corners), achieving multi-mode current excitation through coupling with adjacent sub-metal patches. Furthermore, the second sub-metal patches 1122 are isolated by the first sub-metal patches 1121 arranged in a cross shape, avoiding excessive electromagnetic coupling interference while maintaining mode purity and directivity. Therefore, by adjusting the distribution and coupling strength of intrinsic modes based on the spatial layout and geometric cutting of the metal patch unit 112, efficient radiation can be achieved while working together with the parasitic patch unit 111 to expand the working bandwidth and axial ratio bandwidth of the antenna.

[0048] In one embodiment, the rectangular array is 3×3, and the metal patch unit 112 includes a plurality of square metal patches with a side length of P.

[0049] In this embodiment, a rectangular array is composed of 3×3 metal patches with a side length of P. Among them, the metal patches of each square in the rectangular array are arranged at equal intervals. The 3×3 rectangular array structure can support the excitation of eigenmodes at multiple adjacent frequencies, provide multiple coupling channels for the rotation of the circularly polarized electric field, enhance the consistency of the electric field rotation, and is beneficial to expanding the axial ratio bandwidth. In addition, the square metal patch has good geometric adjustability. Combined with the equal-spacing arrangement, the frequency can be conveniently adjusted and the bandwidth can be controlled by changing the size or cutting structure.

[0050] Specifically, the value range of P is 33.4mm < P < 33.6mm. Controlling the patch side length between 33.4mm and 33.6mm can make the radiation frequency of the metal patch unit accurately cover the target communication frequency band, that is, the typical frequency bands of Beidou satellites: 1.207 gigahertz (GHz), 1.268 GHz, and 1.561 GHz. Thus, the broadband circularly polarized metasurface antenna in the present invention adopts aperture-coupled microstrip technology and a 3×3 metasurface antenna array and can be applied to Beidou satellite communication.

[0051] In one embodiment, as Figure 2 shown, the first sub-metal patch 1121 is obtained by cutting two squares with a side length of A from the two diagonals of the metal patch along the first diagonal direction. Among them, the second cutting part is two squares with a side length of A, and 0.38P < A < 0.4P.

[0052] In this embodiment, the first sub-metal patch 1121 is arranged in other regions (i.e., non-corner regions) outside the four corners of the rectangular array. That is, for the 3×3 rectangular array structure, the number of the first sub-metal patches 1121 is 5. The first sub-metal patch 1121 is arranged in the non-corner region, which can enhance the symmetry and stability of the overall radiation pattern and axial ratio performance.

[0053] Based on the aforementioned rectangular array composed of metal patches with side length P, the structural setting of a first sub-metal patch 1121 will be taken as an example for illustration. The first sub-metal patch 1121 is obtained by cutting off squares with side length A (the unit of A is mm) at the lower left corner and the upper right corner respectively along the first diagonal direction of the square metal patch, where the first diagonal direction is from the lower left corner to the upper right corner. Therefore, the area where the "square with side length A" is cut off is also the second cutting part. By cutting off the small square area with side length A along the diagonal direction and adjusting A within a preset range (0.38P < A < 0.4P), an asymmetric perturbation can be introduced on the basis of the square metal patch, enabling the metasurface metal structure 110 to excite more eigenmodes (especially the high-order modes in adjacent frequency points), which helps the formation of the rotation of the circularly polarized electric field. In addition, the geometric asymmetry generated by the chamfered corners adjusts the current distribution at the edges of the first sub-metal patch 1121, making the superposition of different modes in the radiation field have an appropriate phase difference, which is conducive to the formation of stable right-handed or left-handed circularly polarized waves.

[0054] It can be understood that in a 3×3 rectangular array, for the 5 square metal patches with side length P in the non-peripheral angle region, after cutting off squares with side length A at their lower left corners and upper right corners respectively, the remaining part is the first sub-metal patch 1121. For these 5 square metal patches in the non-peripheral angle region, each square metal patch is cut along the first chamfered corner direction, and the remaining part after that is the first sub-metal patch 1121.

[0055] In one embodiment, as Figure 2 shown, the second sub-metal patch 1122 is obtained by cutting off squares with side length A at the two diagonals of the metal patch along the first diagonal direction, and then cutting a rectangle with length D and width W along the first diagonal direction at the square with side length A, where D:W = 2:1, and 0.7A < D < 0.9A.

[0056] In this embodiment, the second sub-metal patches 1122 are arranged in the four peripheral angle regions of the 3×3 rectangular array. That is, for the 3×3 rectangular array structure, the number of the second sub-metal patches 1122 is 4. Arranging the second sub-metal patches 1122 in the four peripheral angle regions of the 3×3 rectangular array helps to adjust the equivalent impedance distribution of the metasurface structure, thereby improving the radiation efficiency and pattern symmetry of the antenna boundary, and suppressing edge reflection and unnecessary coupled waves.

[0057] Based on the aforementioned 3×3 rectangular array composed of square metal patches with side length P, the structural setting method of a second sub-metal patch 1122 will be described by way of example. First, make a first cut along the first diagonal direction of the square metal patch at its lower left corner and upper right corner respectively (specifically, cut off a square with side length A), obtaining the first sub-metal patch 1121. Then, make a second cut at the second cut portion of the first sub-metal patch 1121 (specifically, cut off a rectangle with length D and width W along the direction perpendicular to the first diagonal direction). The remaining part is the second sub-metal patch 1122. Here, the first diagonal direction is from the lower left corner to the upper right corner; the direction perpendicular to the first diagonal direction is from the lower right corner to the upper left corner. Therefore, the vacant area after the second cut at the lower left corner and upper right corner of the square metal patch is the third cut portion. Here, the units of both length D and width W are mm.

[0058] Cut off the A×A square area along the lower left corner to the upper right corner (the first diagonal direction) to construct the first sub-metal patch 1121, which can break the mirror symmetry and prompt the metasurface metal structure 110 to excite multiple eigenmodes with adjacent frequencies, thereby enhancing the frequency response width (i.e., the operating bandwidth) of the antenna. Make a second cut along the vertical direction at the second cut portion to further enhance the geometric asymmetry of the second sub-metal patch 1122, causing the current path to change complexly, thereby strengthening the fine control of the electric field rotation speed, direction, and axial ratio. In addition, the geometric structure formed by the second cut improves the modal distribution density and multimode interference efficiency, which is beneficial to broadening the axial ratio bandwidth and enhancing the circular polarization bandwidth performance.

[0059] It can be understood that the second sub-metal patch 1122 is obtained by making a second cut based on the first sub-metal patch 1121.

[0060] Specifically, for the rectangle with cutting length D, the ratio of the cutting length to the width is 2:1 and 0.7A < D <  0.9A. With such a design, firstly, it is ensured that the cutting scale is not too large relative to the area of the original patch (the square metal patch with side length P), so as not to cause the interruption of the current path or the decrease of the radiation intensity. Secondly, a highly asymmetric geometric perturbation is formed at the third cut portion, which breaks the symmetry of the patch structure 210, changes the distribution path of the current, and the unbalanced current path can more effectively generate differences in the electric field components in different directions, which is beneficial to forming a rotating electric field, thereby enhancing the circular polarization performance and helping to maintain a low axial ratio within a wide frequency band.

[0061] In one embodiment, as Figure 2As shown, regardless of the vertical or horizontal direction, the interval between any two adjacent first sub-metal patches 1121 is G, and the interval between an adjacent first sub-metal patch 1121 and a second sub-metal patch 1122 is also G, where 2.69 mm < G < 2.71 mm.

[0062] In this embodiment, since the rectangular array composed of metal patch units 112 is an equidistant rectangular array, the intervals between the metal patches in the rectangular array are the same in both the vertical and horizontal directions. That is, regardless of the vertical or horizontal direction, the interval between an adjacent first sub-metal patch 1121 and a second sub-metal patch 1122 is also G. The equal spacing between the first sub-metal patch 1121 and the second sub-metal patch 1122 in both directions (horizontal and vertical) not only helps to form a symmetric rotating electric field distribution but also supports the multi-mode resonance mechanism, further expanding the effective operating bandwidth and axial ratio bandwidth of the circularly polarized antenna.

[0063] Specifically, 2.69 mm < G < 2.71 mm. This design can improve the accuracy of the return loss of the broadband circularly polarized metasurface antenna in the present invention in the operating frequency band (specifically 1.11 GHz - 1.69 GHz).

[0064] In one embodiment, as Figure 2 shown, the second sub-metal patch 1122 includes a connecting portion 1122a with a depression in the middle and triangular portions 1122b provided at opposite ends of the connecting portion 1122a.

[0065] In this embodiment, the second sub-metal patch 1122 is generally in the shape of a double-headed arrow, and a connecting portion 1122a with an inward depression is provided in the middle of the second sub-metal patch 1122. The connecting portion 1122a makes the second sub-metal patch 1122 in the form of a "waist-clamped" structure through a local notch. The depression structure in the middle can extend the current path, regulate the inductance and capacitance distribution without increasing the overall footprint, thus facilitating the simultaneous occurrence of resonances at multiple frequency points, that is, supporting the excitation of multiple eigenmodes and the realization of broadband response.

[0066] Triangular portions 1122b are symmetrically arranged at opposite ends of the connecting portion 1122a. Regarding the second sub-metal patch 1122, the base of each triangular portion 1122b faces the connecting portion 1122a, and its apex extends outward (or, the apex faces away from the connecting portion 1122a), forming an arrowhead-like end feature. Regarding the first dielectric substrate 100, the direction pointed by the apex of the triangular portion 1122b coincides with or is parallel to the direction from the upper left corner to the lower right corner of the first dielectric substrate 100. The combined structure of the connecting portion 1122a and the triangular portions 1122b extends the current path and can effectively widen the frequency range with an axis ratio of less than 3 dB.

[0067] In one embodiment, the first cut portion is square, and the ratio of the area of ​​the first cut portion to the area of ​​the second cut portion is 1:1;

[0068] The parasitic patch unit 111 includes a plurality of L-shaped first parasitic patches 1111 and a plurality of square second parasitic patches 1112; the plurality of first parasitic patches 1111 and the plurality of second parasitic patches 1112 are all disposed at the periphery of the first dielectric substrate 100, wherein the plurality of first parasitic patches 1111 are distributed along a first diagonal direction of the first dielectric substrate 100, and the plurality of second parasitic patches 1112 are distributed along a second diagonal direction of the first dielectric substrate 100; the second diagonal direction is parallel to or coincides with the direction pointed to by the triangular portion 1122b, and the first diagonal direction is perpendicular to the second diagonal direction.

[0069] In this embodiment, the cut areas of each parasitic patch (specifically the first parasitic patch 1111 and the third parasitic patch 1113) in the parasitic patch unit 111 all belong to the first cut portion. Since the parasitic patch unit 111 is obtained by translating the first sub-metal patch 1121 horizontally or vertically to the edge of the first dielectric substrate 100, this has two advantages: first, arranging along the edge can form a stable reflection or coupling boundary field at the periphery, and with the help of the metal patch unit 112, a better rotating electric field distribution is formed, thereby enhancing the axial ratio characteristics; second, it is beneficial to expand the operating bandwidth, and by adjusting the edge electromagnetic behavior through edge parasitic modes, improve the frequency response characteristics. Therefore, the area of ​​the first cut portion on a single parasitic patch is the same as the area of ​​the second cut portion on a single first sub-metal patch 1121, that is, the area ratio of the two is 1:1. Consistent areas can achieve similar resonant frequency distributions, which helps to form a synergistic resonance effect between the parasitic patch and the first sub-metal patch 1121, thereby improving the circular polarization performance.

[0070] Specifically, since the first dielectric substrate 100 is rectangular, it has four corners. Since both the first parasitic patch 1111 and the second parasitic patch 1112 are located at the corners of the first dielectric substrate 100, the total number of these four parasitic patches is also four. Furthermore, since both the first parasitic patch 1111 and the second parasitic patch 1112 are distributed along the diagonal direction of the first dielectric substrate 100, and as is well known, a rectangle has two pairs of diagonals, and each pair of diagonals has two angles, the number of the first parasitic patch 1111 and the second parasitic patch 1112 is two each. This diagonal symmetrical distribution enhances the overall electromagnetic symmetry and structural stability, facilitating the formation of orthogonal diagonal coupling paths and effectively exciting two sets of orthogonal mode currents.

[0071] The first parasitic patch 1111 is distributed along a first diagonal direction of the first dielectric substrate 100, and the second parasitic patch 1112 is distributed along a second diagonal direction of the first dielectric substrate 100; the second diagonal direction is parallel to or coincides with the direction pointed to by the triangular portion 1122b, and the first diagonal direction is perpendicular to the second diagonal direction. Figure 2 It can be seen that the direction pointed to by the triangular portion 1122b coincides with or is parallel to the direction from the upper left corner to the lower right corner of the first dielectric substrate 100. Therefore, the second diagonal direction is the diagonal direction from the upper left corner to the lower right corner of the first dielectric substrate 100, and the first diagonal direction is the diagonal direction from the lower left corner to the upper right corner of the first dielectric substrate 100. Thus, it can be seen that the first parasitic patch 1111 is distributed at the lower left corner and the upper right corner of the first dielectric substrate 100, and the second parasitic patch 1112 is distributed at the upper left corner and the lower right corner of the first dielectric substrate 100.

[0072] Furthermore, the opening of the L-shaped first parasitic patch 1111 faces the third cut-out portion. This opening facing the third cut-out portion forms a coupling channel or electric field discharge path, enhancing the coupling between the first parasitic patch 1111 and the second sub-metal patch 1122. In addition, the L-shaped structure naturally provides current guiding and folding-back paths, and the opening direction facing the third cut-out portion strengthens directional radiation control, helps form a current concentration region, further improves high-frequency performance, and enhances the antenna's bandwidth consistency and circular polarization stability.

[0073] In summary, by symmetrically arranging the parasitic patch units 111 along the edge of the first dielectric substrate 100 in different diagonal directions, and making their structural features (such as the area of ​​the cut portion, the shape direction, and the orientation of the opening) correspond and couple with the central metal patch unit 112, the modal coupling relationship between the patches can be effectively enhanced, the working bandwidth and axial ratio bandwidth of the antenna can be expanded, and the stability and consistency of the circular polarization performance can be significantly improved.

[0074] It should be noted that, in this invention, the direction from the top left corner to the bottom right corner and the direction from the bottom right corner to the top left corner refer to the same diagonal direction; similarly, the direction from the bottom left corner to the top right corner and the direction from the top right corner to the bottom left corner refer to the same diagonal direction. That is, this invention does not specifically limit the directionality to whether it is from top to bottom or from bottom to top.

[0075] In one embodiment, such as Figure 1 and Figure 2 As shown, it also includes a plurality of stepped third parasitic patches 1113; the plurality of third parasitic patches 1113 are disposed on opposite sides of the first dielectric substrate 100, and the plurality of third parasitic patches 1113 are spaced apart between the first parasitic patch 1111 and the second parasitic patch 1112; the arrangement direction of the plurality of third parasitic patches 1113 is the same as the arrangement direction of the first sub-metal patch 1121 after being translated in a horizontal or vertical direction.

[0076] In this embodiment, the plurality of third parasitic patches 1113 arranged on opposite sides in the vertical direction can be obtained by translating the first sub-metal patch 1121 horizontally to the left and right and then cutting them. Since the intervals between the plurality of first sub-metal patches 1121 and second sub-metal patches 1122 in the rectangular array are the same, the intervals between two adjacent third parasitic patches 1113 obtained after translating to opposite sides are also the same. Thus, by translating and cutting the plurality of third parasitic patches 1113 on opposite sides from the first sub-metal patch 1121, and making the spacing between adjacent third parasitic patches 1113 the same as the spacing between adjacent first sub-metal patches 1121, the overall periodicity and symmetry of the antenna can be effectively maintained, the consistency of edge electromagnetic response and intrinsic mode excitation can be improved, the rotating electric field structure can be optimized, the working bandwidth and axial ratio bandwidth of the antenna can be expanded, and the circular polarization performance can be improved.

[0077] Specifically, the lower left and upper right corners of the first sub-metal patch 1121 are the second cut portions after being cut. For the vertical left opposite side, after horizontally shifting the first sub-metal patch 1121 to the left to the opposite side, the left portion of the first sub-metal patch 1121 is cut off, and the remaining portion is the third parasitic patch 1113. The first cut portion at the upper right corner of the third parasitic patch 1113 has the same area as the second cut portion at the upper right corner of the first sub-metal patch 1121. For the vertical right opposite side, after horizontally shifting the first sub-metal patch 1121 to the right to the opposite side, the right portion of the first sub-metal patch 1121 is cut off, and the remaining portion is the third parasitic patch 1113. The first cut portion at the lower left corner of the third parasitic patch 1113 has the same area as the second cut portion at the lower left corner of the first sub-metal patch 1121. Thus, the arrangement direction of the third parasitic patch 1113 on this side is the same as the arrangement direction of the first sub-metal patch 1121 after it has been translated horizontally.

[0078] Similarly, for the upper opposite side in the horizontal direction, after the first sub-metal patch 1121 is vertically moved upwards to the opposite side, the upper part of the first sub-metal patch 1121 is cut off, and the remaining part is the third parasitic patch 1113. The area of ​​the first cut portion on the left side of the third parasitic patch 1113 is the same as the area of ​​the second cut portion at the lower left corner of the first sub-metal patch 1121. For the lower opposite side in the horizontal direction, after the first sub-metal patch 1121 is vertically moved downwards to the opposite side, the lower part of the first sub-metal patch 1121 is cut off, and the remaining part is the third parasitic patch 1113. The area of ​​the first cut portion on the right side of the third parasitic patch 1113 is the same as the area of ​​the second cut portion at the upper right corner of the first sub-metal patch 1121. Thus, the arrangement direction of the third parasitic patch 1113 on this side is the same as the arrangement direction of the first sub-metal patch 1121 after being vertically translated.

[0079] Maintaining a consistent arrangement direction is beneficial for achieving isotropic mode excitation or phase commonality enhancement in the arrangement direction, and also helps the third parasitic patch 1113 to maintain the same frequency response as the first sub-metal patch 1121 in terms of electromagnetic behavior, thereby enhancing coupling efficiency.

[0080] In summary, the parasitic patches can be understood as employing three different structures: the same structure is used on the same diagonal, different structures are used on different diagonals, and the same structure is used on all four opposite sides, but the tangent directions (arrangement directions of the first cut portion) are different. By adjusting the area of ​​the diagonal patches and changing the tangent directions, the axial ratio bandwidth of circular polarization is broadened. Specifically, the principle behind this broadening is as follows: the parasitic patches employ three different structures (first parasitic patch 1111, second parasitic patch 1112, and third parasitic patch 1113), each possessing different electromagnetic response characteristics, enabling resonance in different frequency bands. The rational spatial arrangement of these patches with different structures excites multiple eigenmodes with adjacent frequencies, simultaneously generating multiple overlapping circular polarization operating ranges. Based on the superposition effect of multimode resonance, this effectively broadens the frequency bandwidth of circular polarization. Setting the same structure on one diagonal and different structures on different diagonals helps to form an asymmetric phase distribution on the antenna surface. The asymmetric structure guides the current to generate a non-uniform distribution, which makes the electromagnetic wave form a more stable and directionally continuous rotating electric field during propagation, thereby improving the circular polarization stability of the antenna. The arrangement direction of the third parasitic patch 1113 will change the equivalent current path and local reflection phase of the metal boundary, thereby introducing a certain phase difference. This artificially designed phase difference can complement the metal patch unit 112, forming a ±90° phase difference suitable for circular polarization in multiple frequency points, thereby improving the axial ratio performance.

[0081] Thus, compared with the setting method in which the traditional metasurface antenna unit structure is a complete structure, the metasurface antenna in the present invention makes the most of the area of the first dielectric substrate 100, covers the unit structure (the parasitic patch unit 111 and the metal patch unit 112) on the upper surface of the first dielectric substrate 100, realizes circular polarization in a wider frequency band, covers three frequency bands of Beidou satellites (1.207 GHz, 1.268 GHz, 1.561 GHz, and the axial ratio of each frequency band is less than 3 dB). At the same time, the second sub-metal patch 1122 is cut twice to increase the surface current path, broaden the working frequency band, and supplemented by adding 3 kinds of parasitic patch structures 210 at the edge to further broaden the axial ratio bandwidth.

[0082] In one embodiment, as Figure 3 shown, the patch structure 210 includes a 3×3 patch array composed of several sub-patch units 211. Among them, each sub-patch unit 211 includes two rectangular sub-patches 2111.

[0083] In this embodiment, the patch structure 210 on the upper surface of the second dielectric substrate 200 forms a patch array composed of 3×3 sub-patch units 211. Among them, 2 rectangular sub-patches 2111 form a group to constitute a sub-patch unit 211. The part of the metal patch unit 112 perpendicular to the feeding line direction and with both side lengths of B (the value of B is 4.9 mm < B < 5.1 mm) is reserved as the sub-patch 2111. Thus, adding the sub-patch 2111 and the 3×3 patch array on the upper surface of the second-layer dielectric substrate can not only excite multiple adjacent resonant modes, but also optimize the coupling path between the patches, improve the flexibility of the current distribution and the feeding matching efficiency, thereby significantly expanding the impedance matching bandwidth of the antenna.

[0084] In one embodiment, as Figure 1 shown, the first dielectric substrate 100, the second dielectric substrate 20 and the third dielectric substrate 300 all adopt F4B material with a dielectric constant of 3 and a loss tangent of 0.0022; the thickness of the first dielectric substrate 100 is Hsub1, the thickness of the second dielectric substrate 200 is Hsub2, and the thickness of the third dielectric substrate 300 is Hsub3, and there are Hsub1 = 9 mm, Hsub2 = 6 mm, Hsub3 = 4 mm.

[0085] In this embodiment, the first dielectric substrate 100, the second dielectric substrate 20 and the third dielectric substrate 300 are of equal length and equal width to each other (that is, the boundaries of the three-layer dielectric substrates are aligned), which helps to enhance the mechanical stability and coplanarity of the antenna structure and avoid coupling anomalies or polarization distortions caused by inconsistent dimensions. <0000Among them, the length of the first dielectric substrate 100 is Lsub1, the width of the first dielectric substrate 100 is Wsub1, 149 mm < Lsub1 < 151 mm, and 149 mm < Wsub1 < 151 mm. The thickness of the first dielectric substrate 100 is Hsub1, the thickness of the second dielectric substrate 200 is Hsub2, and the thickness of the third dielectric substrate 300 is Hsub3, where Hsub1 = 9 mm, Hsub2 = 6 mm, and Hsub3 = 4 mm.

[0087] In a specific embodiment, the size of the antenna of the present invention is set to 150 mm × 150 mm × 19 mm. The three-layer dielectric substrates are stacked from top to bottom using F4B material with a dielectric constant of 3.5 and a loss tangent of 0.0022.

[0088] It should be noted that the thickness of the three-layer dielectric substrates can have a deviation of 0.1 mm, that is, 8.9 mm < Hsub1 < 9.1 mm, 5.9 mm < Hsub2 < 6.1 mm, and 3.9 mm < Hsub3 < 4.1 mm. The three-layer dielectric substrates are stacked from top to bottom using F4B material with a dielectric constant of 3.5 and a loss tangent of 0.0022, which can save costs.

[0089] In summary, by setting the three-layer dielectric substrates in a structure with equal length and width, not only the alignment and assembly process between the antenna layers is simplified, but also the structural symmetry and the stability of the radiation pattern are improved. The dielectric substrates with different thicknesses are arranged in layers, making the coupling space and gap coupling between the layers more efficient, which helps to improve the bandwidth and circular polarization performance of the antenna. At the same time, the unified use of low-loss and stable F4B dielectric materials can effectively reduce dielectric losses and improve the working efficiency and signal integrity of the antenna in high-frequency communication.

[0090] In addition, it should be noted that the electromagnetic simulation software (Computer Simulation Technology, CST) is used to simulate and optimize the various structural parameters of the broadband circularly polarized metasurface antenna in the present invention to obtain the simulation results of return loss (that is, the value obtained by taking the logarithm of the absolute value of the scattering parameter S11), axial ratio, and gain. Among them, in the Figure 7 The scattering parameter S11 (Scattering Parameter S11) in the specification drawings, that is, the input reflection coefficient, represents the ratio of the reflected signal measured from port 1 to the input signal when the excitation signal is input from port 1. The scattering parameter S11 is a commonly used setting in the art and will not be explained here.

[0091] In the specification drawings Figures 10-12In this context, Gain represents the antenna's radiation capability in the YOZ plane (where YOZ represents the plane passing through the Y and Z axes in a three-dimensional coordinate system, also known as the longitudinal section / plane), measured in dB; copolar indicates co-polarization; and crosspolar indicates cross-polarization. Figure 10 In this context, F=1.207GHz indicates that the operating frequency / operating frequency band is 1.207GHz; Figure 11 In the code F=1.268GHz, it means the operating frequency / operating frequency band is 1.207GHz; Figure 12 In the figure, F=1.561GHz indicates that the operating frequency / operating frequency band is 1.207GHz.

[0092] In the attached diagram of the instruction manual Figures 13-15 In this context, Gain represents the antenna's radiation capability in the XOZ plane (where XOZ represents the plane passing through the X and Z axes in a three-dimensional coordinate system, also known as the transverse section / plane), measured in dB; copolar indicates co-polarization; and crosspolar indicates cross-polarization. Figure 13 In this context, F=1.207GHz indicates that the operating frequency / operating frequency band is 1.207GHz; Figure 14 In the code F=1.268GHz, it means the operating frequency / operating frequency band is 1.207GHz; Figure 15 In the figure, F=1.561GHz indicates that the operating frequency / operating frequency band is 1.207GHz.

[0093] like Figures 7 to 15 As shown, simulation results demonstrate that the broadband circularly polarized metasurface antenna of this invention exhibits a return loss of less than -10dB in the frequency range of 1.11GHz to 1.69GHz, demonstrating excellent impedance matching characteristics and meeting the requirements for broadband operation. Further details can be found in [reference needed]. Figure 10 and Figure 15 ,Depend on Figures 10 to 15 As can be seen, in the three core operating frequency bands of the BeiDou Navigation Satellite System (1.207GHz, 1.268GHz, and 1.561GHz), the axial ratio of the antenna is less than 3dB, indicating that it can stably radiate circularly polarized electromagnetic waves within these frequency bands. In summary, the broadband circularly polarized metasurface antenna of this invention not only achieves broadband impedance matching but also possesses excellent circular polarization performance, effectively meeting the requirements of satellite communication, navigation, and positioning for highly stable and reliable circularly polarized signals.

[0094] The working process of this invention is as follows: In this embodiment, due to the physical separation between the first dielectric substrate 100 and the second dielectric substrate 200, a coupling space is formed between the metasurface metal structure 110 and the patch structure 210 on the upper surface of the second dielectric substrate 200. Thus, the radio frequency energy on the patch structure 210 excites the metasurface metal structure 110 through the coupling space to form a stable rotating electric field, thereby improving circular polarization performance. The metal patch unit 112 is disposed within the region formed by the parasitic patch unit ring, thereby forming a center-edge multi-level electromagnetic coupling structure. This increases the effective path length of the metasurface fundamental mode resonant wavelength and reduces the fundamental mode resonant frequency, allowing the radio frequency signal to be effectively excited over a wider frequency range, thereby broadening the operating bandwidth. The metasurface metal structure 110 forms a spatial phase gradient through a periodic arrangement of multiple metal patches (first sub-metal patch 1121 and second sub-metal patch 1122). When an incident electromagnetic wave interacts with it, the local electromagnetic response is modulated by changing the geometric parameters (such as the position and size of the cut sections) on the metal patch (the second and third cut sections). This causes a continuous change in the phase response of the reflected or transmitted wave at different frequencies, thereby generating an equivalent rotating electric field over a wide frequency band. In other words, the combination and arrangement of the patches and cut sections allow multiple different modes to be excited at different frequencies. Simultaneously, by adjusting the current path and phase response through a cross-shaped arrangement, multiple orthogonal modes simultaneously satisfy the ±90° phase difference condition within the frequency band corresponding to the BeiDou satellite. Thus, this invention can achieve a dual broadening of both the working bandwidth and axial ratio bandwidth, realizing wideband circular polarization characteristics.

[0095] In summary, this embodiment of the invention provides a broadband circularly polarized metasurface antenna, comprising a first dielectric substrate 100, a second dielectric substrate 200, and a third dielectric substrate 300 stacked sequentially from top to bottom; the upper surface of the first dielectric substrate 100 is provided with a metasurface metal structure 110; the upper surface of the second dielectric substrate 200 is provided with a patch structure 210 and the lower surface is provided with a metal ground plane 220 with a slot coupling structure 221; the lower surface of the third dielectric substrate 300 is provided with a microstrip feeding structure; the metal ground plane 220 is attached to the upper surface of the third dielectric substrate 300; the metasurface... The surface metal structure 110 includes parasitic patch units 111 arranged around the edge of the first dielectric substrate 100 and metal patch units 112 arranged in a rectangular array. The metal patch units 112 are disposed within the area formed by the parasitic patch units 111 surrounding the surface. Some or all of the parasitic patch units 111 are provided with a first cutting portion. The metal patch unit 112 includes a first sub-metal patch 1121 with a second cutting portion and a second sub-metal patch 1122 with a third cutting portion. The first sub-metal patches 1121 are arranged in a cross shape to isolate the second sub-metal patches 1122. This invention can achieve wideband circular polarization characteristics by synergistically broadening both the working bandwidth and the axial ratio bandwidth.

[0096] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A broadband circularly polarized metasurface antenna, characterized in that, The device includes a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked sequentially from top to bottom; the upper surface of the first dielectric substrate is provided with a metasurface metal structure, the upper surface of the second dielectric substrate is provided with a patch structure and the lower surface is provided with a metal ground plane with a slot coupling structure, and the lower surface of the third dielectric substrate is provided with a microstrip feeding structure; the metal ground plane is attached to the upper surface of the third dielectric substrate. The metasurface metal structure includes parasitic patch units surrounding the edge of the first dielectric substrate and metal patch units arranged in a rectangular array. The metal patch units are located in the area formed by the parasitic patch units surrounding the substrate. Some of the parasitic patch units are provided with a first cutting portion. The metal patch unit includes a first sub-metal patch with a second cutting portion and a second sub-metal patch with a third cutting portion. The first sub-metal patch is arranged in a cross shape to isolate the second sub-metal patch. The metal patch unit includes several square metal patches; the first sub-metal patch is obtained by cutting squares from the metal patch along the first diagonal direction at two opposite corners of the metal patch, wherein the second cut portion consists of two squares; the second sub-metal patch is obtained by cutting squares from the metal patch along the first diagonal direction at two opposite corners of the metal patch, and then cutting rectangles at the squares along the first diagonal direction; the first cut portion is a square, and the ratio of the area of ​​the first cut portion to the area of ​​the second cut portion is 1:1; the parasitic patch unit includes three structures: the same structure is used at the same diagonal, different structures are used at different diagonals, and the same structure is used on all four opposite sides, but the cutting angle direction of the first cut portion on the four opposite sides is different.

2. The broadband circularly polarized metasurface antenna according to claim 1, characterized in that, The rectangular array is 3×3, and the metal patch unit includes several square metal patches with a side length of P.

3. The broadband circularly polarized metasurface antenna according to claim 2, characterized in that, The first sub-metal patch is obtained by cutting squares with side length A from two opposite corners of the metal patch along the first diagonal direction, wherein the second cut portion consists of two squares with side length A, and 0.38P <A<0.4P。 4. The broadband circularly polarized metasurface antenna according to claim 3, characterized in that, The second sub-metal patch is obtained by cutting squares of side length A from the metal patch along the first diagonal direction at two opposite corners, and then cutting rectangles of length D and width W from the squares of side length A along the first diagonal direction, where D:W = 2:1, and 0.7A <D<0.9A。 5. The broadband circularly polarized metasurface antenna according to claim 2, characterized in that, The spacing between any two adjacent horizontally and vertically arranged 3×3 metal patches is G, which is 2.69mm. <G<2.71mm。 6. The broadband circularly polarized metasurface antenna according to claim 1, characterized in that, The second sub-metal patch includes a connecting portion with a recess in the middle and triangular portions at opposite ends of the connecting portion.

7. The broadband circularly polarized metasurface antenna according to claim 6, characterized in that, The parasitic patch unit includes a plurality of L-shaped first parasitic patches and a plurality of square second parasitic patches; the plurality of first parasitic patches and the plurality of second parasitic patches are all disposed at the periphery of the first dielectric substrate, wherein the plurality of first parasitic patches are distributed along a first diagonal direction of the first dielectric substrate, and the plurality of second parasitic patches are distributed along a second diagonal direction of the first dielectric substrate; the second diagonal direction is parallel to or coincides with the direction pointed to by the triangular portion, and the first diagonal direction is perpendicular to the second diagonal direction.

8. The broadband circularly polarized metasurface antenna according to claim 7, characterized in that, It also includes a plurality of third parasitic patches in a stepped shape; the plurality of third parasitic patches are disposed on opposite sides of the first dielectric substrate, and the plurality of third parasitic patches are spaced apart between the first parasitic patch and the second parasitic patch; the arrangement direction of the plurality of third parasitic patches is the same as the arrangement direction of the first sub-metal patch after being translated in a horizontal or vertical direction.

9. The broadband circularly polarized metasurface antenna according to claim 1, characterized in that, The patch structure includes a 3×3 patch array composed of several sub-pattern units, wherein each sub-pattern unit includes two rectangular sub-patterns.

10. The broadband circularly polarized metasurface antenna according to claim 1, characterized in that, The first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all made of F4B material with a dielectric constant of 3.5 and a loss tangent of 0.0022; the thickness of the first dielectric substrate is Hsub1, the thickness of the second dielectric substrate is Hsub2, and the thickness of the third dielectric substrate is Hsub3, with Hsub1=9mm, Hsub2=6mm, and Hsub3=4mm.

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