Broadband circularly polarized metasurface antenna

Abstract

The invention relates to the technical field of antennas, and discloses a broadband circularly polarized metasurface antenna, which comprises a first dielectric substrate, a second dielectric substrate and a third dielectric substrate which are sequentially stacked 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, the lower surface of the second dielectric substrate is provided with a metal floor of a slot coupling structure, and the lower surface of the third dielectric substrate is provided with a microstrip feed structure; the metasurface metal structure comprises parasitic patch units arranged around the edge of the first dielectric substrate and metal patch units arranged in a rectangular array at equal intervals and arranged in an area formed by the parasitic patch units in an annular mode. The parasitic patch unit is provided with a first cutting part, and the metal patch unit comprises a first sub-metal patch provided with a second cutting part and a second sub-metal patch provided with a third cutting part; the first sub-metal patches are arranged in a cross shape to isolate the second sub-metal patches. According to the invention, dual broadening of the working bandwidth and the axial ratio bandwidth can be realized cooperatively, and the broadband circular polarization characteristic is realized.

Description

Technical Field

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

[0002] As satellite communication systems continue to demand high-speed data transmission and high-quality signal reception, circularly polarized antennas are widely used in modern satellite communications due to their superior resistance to polarization mismatch and multipath interference. Metasurface antennas, with their ability to flexibly control the propagation direction, phase, and polarization of electromagnetic waves, offer significant advantages in circularly polarized antenna design. By integrating metamaterial and metasurface technologies, effective electromagnetic wave manipulation 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 key support for the development of high-speed, high-capacity satellite communication systems.

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

[0004] The present invention provides a broadband circularly polarized metasurface antenna to solve the technical problems of widening bandwidth and low circular polarization performance of antennas in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a wide-band circularly polarized metasurface antenna, which includes a first dielectric substrate, a second dielectric substrate and a third dielectric substrate stacked in sequence 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 floor with a slot coupling structure, and the lower surface of the third dielectric substrate is provided with a microstrip feeding structure; the metal floor is adhered to the upper surface of the third dielectric substrate; the metasurface metal structure includes a parasitic patch unit arranged around the edge of the first dielectric substrate and a metal patch unit arranged in a rectangular array, and the metal patch unit is arranged in an area formed by the parasitic patch unit; some or all of the parasitic patch units are provided with a first cutting portion, and the metal patch unit includes a first sub-metal patch provided with a second cutting portion and a second sub-metal patch provided with a third cutting portion, and the first sub-metal patch is arranged in a cross to isolate the second sub-metal patch.

[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 a square with a side length of A at two diagonal corners of the metal patch along the first diagonal direction, wherein the second cutting portion is two squares with a side length of A, and there is, 0.38P <A<0.4P。

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

[0009] In some embodiments, the interval between any two adjacent metal patches in the horizontal and vertical directions of the 3×3 arrangement 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 provided at opposite ends of the connecting portion.

[0011] In some embodiments, the first cutting portion is square, and the ratio of the area of ​​the first cutting portion to the area of ​​the second cutting portion is 1:1; 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 arranged at the circumference 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 by the triangular portion, and the first diagonal direction is perpendicular to the second diagonal direction.

[0012] In some embodiments, a plurality of trapezoidal third parasitic patches are further included; the plurality of the third parasitic patches are arranged on opposite sides of the first dielectric substrate, and the plurality of the third parasitic patches are arranged between the first parasitic patch and the second parasitic patch at intervals; the arrangement direction of the plurality of the third parasitic patches is the same as the arrangement direction of the first sub-metal patch after translation in the horizontal or vertical direction.

[0013] In some embodiments, the patch structure includes a 3×3 patch array composed of a plurality of sub-patch units 211 , wherein each of the sub-patch units 211 includes two rectangular sub-patches 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, where Hsub1=9 mm, Hsub2=6 mm, and Hsub3=4 mm.

[0015] Compared with the prior art, the broadband circularly polarized metasurface antenna according to the embodiment of the present invention has the following advantages: In this embodiment of the present invention, the physical separation between the first and second dielectric substrates creates a coupling space between the patch structure and the metasurface metal structure on the upper surface of the second dielectric substrate. Consequently, RF energy transmitted from the microstrip feed structure to the patch structure excites the metasurface metal structure through the coupling space, forming a stable rotating electric field, thereby enhancing circular polarization performance. The metal patch units are arranged within the region formed by the ring of parasitic patch units, forming a center-edge multi-level electromagnetic coupling structure. This increases the effective path length of the metasurface's fundamental mode resonant wavelength and lowers the fundamental mode resonant frequency, effectively exciting RF energy 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 (a first sub-metal patch and a second sub-metal patch). When an electromagnetic wave incident on the patch structure interacts with it, the phase response of the reflected or transmitted wave at different frequencies continuously changes by varying the geometric parameters (such as the position and size) of the cutouts (the second and third cutouts) on the metal patches, thereby generating an equivalent rotating electric field across a wide frequency band. In other words, the combination and arrangement of the patches and cutouts allows multiple different modes to be excited at different frequencies. Furthermore, by adjusting the current path and phase response through a cross-shaped arrangement, multiple orthogonal modes can simultaneously meet the ±90° phase shift requirement across a wide frequency range. This approach achieves both a coordinated operating bandwidth and an axial ratio bandwidth, achieving broadband circular polarization characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic structural diagram of a broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 2 2 is a schematic structural diagram of the upper surface of the first dielectric substrate in the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 3 2 is a schematic structural diagram of the upper surface of the second dielectric substrate in the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 4 Schematic diagram of the structure of the metal floor in the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 5 2 is a schematic structural diagram of the lower surface of the third dielectric substrate in the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 6 1 is a schematic side view of the structure of a broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 7 1 is a diagram showing the simulation results of the return loss of the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 8 1 is a diagram showing the axial ratio simulation results of the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 9 1 is a graph showing the gain simulation results of a broadband circularly polarized metasurface antenna provided by an embodiment of the present invention; Figure 10 The following are the co-polarization and cross-polarization gain distribution diagrams of the wideband circularly polarized metasurface antenna provided by an embodiment of the present invention at a YOZ plane operating frequency of 1.207 GHz; Figure 11 The following are the co-polarization and cross-polarization gain distribution diagrams of the wideband circularly polarized metasurface antenna provided by an embodiment of the present invention at a YOZ plane operating frequency of 1.268 GHz; Figure 12 The YOZ plane co-polarization and cross-polarization gain distribution diagrams of the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention at an operating frequency of 1.561 GHz are shown; Figure 13 The following are the co-polarization and cross-polarization gain distribution diagrams of the broadband circularly polarized metasurface antenna provided by an embodiment of the present invention at an XOZ plane operating frequency of 1.207 GHz; Figure 14 The following are the co-polarization and cross-polarization gain distribution diagrams of the wideband circularly polarized metasurface antenna provided by an embodiment of the present invention at an XOZ plane operating frequency of 1.268 GHz; Figure 15 This is the XOZ plane co-polarization and cross-polarization gain distribution diagram of the wideband circularly polarized metasurface antenna provided by an embodiment of the present invention at an operating frequency of 1.561 GHz.

[0017] In the figure, 100 is a first dielectric substrate; 110 is a metasurface metal structure; 111 is a parasitic patch unit; 1111 is a first parasitic patch; 1112 is a second parasitic patch; 1113 is a third parasitic patch; 112 is a metal patch unit; 1121 is a first sub-metal patch; 1122 is a second sub-metal patch; 1122a is a connecting portion; 1122b is a triangular portion; 200 is a second dielectric substrate; 210 is a patch structure; 211 is a sub-patch unit; 2111 is a sub-patch; 220 is a metal floor; 221 is a slot coupling structure; 300 is a third dielectric substrate; 310 is a feeding network. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings and embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be noted that, for directional words, such as the terms "middle", "upper", "lower", "inside", "outside", etc., the directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present invention.

[0020] 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. Therefore, the terms "first" and "second" may explicitly or implicitly include one or more of these features. Throughout the description of the present invention, "at least" means one or more than one, unless otherwise specifically defined.

[0021] In the present invention, unless otherwise specified or limited, the terms "assemble," "connect," and "connect" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integral connection; mechanical connection; direct connection, connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0022] See again Figures 1 to 6An embodiment of the present 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 in sequence from top to bottom. The first dielectric substrate 100 has a metasurface metal structure 110 provided on its upper surface, the second dielectric substrate 200 has a patch structure 210 provided on its upper surface, and a metal floor 220 having a slot coupling structure 221 provided on its lower surface. The third dielectric substrate 300 has a microstrip feeding structure (i.e., a feeding network 310) provided on its lower surface. The metal floor 220 is attached to the upper surface of the third dielectric substrate 300. The metasurface metal structure 110 includes a parasitic patch unit 111 arranged around the edge of the first dielectric substrate 100 and a metal patch unit 112 arranged in a rectangular array. The metal patch unit 112 is arranged in an area formed by the parasitic patch unit 111. 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 provided with a second cutting portion and a second sub-metal patch 1122 provided with a third cutting portion. The first sub-metal patch 1121 is arranged in a cross to isolate the second sub-metal patch 1122.

[0023] In this embodiment, three layers of 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 in sequence 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 (i.e., 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.

[0024] A metasurface metal structure 110 is provided on the upper surface of the first dielectric substrate 100. The metasurface metal structure 110 includes a parasitic patch unit 111 arranged around the edge of the first dielectric substrate 100 and a metal patch unit 112 arranged in an equidistant rectangular array. The parasitic patch unit 111 and the metal patch unit 112 are used to control the propagation characteristics of electromagnetic waves. Specifically, the parasitic patch unit 111 is arranged on the periphery of the main radiating patch (i.e., the metal patch unit 112) and introduces additional resonant frequency points through electromagnetic coupling. These resonant frequency points form multiple adjacent resonant peaks with the intrinsic resonant points of the metasurface metal structure 110, thereby expanding the overall operating bandwidth of the antenna. The structural design and arrangement design of the metal patch unit 112 break the geometric symmetry, allowing the two perpendicular polarization modes, the transverse electric mode and the transverse magnetic mode, to be excited simultaneously while maintaining a 90° phase difference, thereby generating a good circularly polarized wave. In this way, the broadband characteristics and circular polarization performance can be enhanced.

[0025] On the upper surface of the second dielectric substrate 200, there is a patch structure 210. The patch structure 210 serves as a radiation unit 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.

[0026] As Figure 4 shown, on the lower surface of the second dielectric substrate 200, there is a metal floor 220 of the slot coupling structure 221, and 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, and the unit of WM2 is millimeter (mm). The length is denoted as LM2, and the unit of LM2 is millimeter (mm). There is 84mm < WM2 < 86mm, 7.7mm < LM2 < 7.9mm. 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 of electromagnetic isolation and shielding to suppress reverse radiation and improve the directivity of the antenna.

[0027] As Figure 5 shown, on the lower surface of the third dielectric substrate 300, there is a feeding network 310. The width of the feeding network 310 is denoted as WM1, and the length is denoted as LM1. There is 8.17mm < WM1 < 8.37mm, 114.9mm < LM1 < 115.1mm. 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.

[0028] In summary, because the metal floor 220 provided on the lower surface of the second dielectric substrate 200 is bonded to the upper surface of the third dielectric substrate 300, a slot coupling structure 221 is provided in the metal floor 220. This allows the signal output by the feed network 310 on the lower surface of the third dielectric substrate 300 to 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, a coupling space based on a near-field electromagnetic field is formed between the patch structure 210 and the metasurface metal structure 110 on the upper surface of the first dielectric substrate 100. This allows the RF energy excited by the patch structure 210 to excite the metasurface metal structure 110 through the coupling space to generate a rotating electric field, thereby achieving excellent circularly polarized electromagnetic wave radiation characteristics. Specifically, the coupling space enables the asymmetric mode or electric field with a certain phase difference excited by the patch structure 210 to be effectively transmitted to the metasurface metal structure 110, and under the action of the asymmetric patch distribution and cutting structure of the metasurface metal structure 110, it further evolves into a rotating current, thereby generating circularly polarized radiation.

[0029] It should be noted that the coupling space can be implemented in two specific ways, including but not limited to the following two forms. The first form is that the second dielectric substrate 200 and the third dielectric substrate 300 are directly bonded to form a slot-coupled feeding structure. This structure allows the feeding network 310 to excite the patch structure 210 on the second dielectric substrate 200 through the gap in the metal floor 220, which not only simplifies the feeding channel design but also reduces feeding losses. The second form is that the first dielectric substrate 100 is suspended above the upper surface of the second dielectric substrate 200. That is, the two are not directly bonded, but rather form a certain vertical spacing, so that a far-field coupling space is formed between the metasurface structure and the patch structure 210. This structure can effectively control the radiation directionality and polarization characteristics of the patch structure 210 to optimize antenna performance.

[0030] On this basis, through the arrangement and setting of 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 to extend the frequency response range, thereby achieving widening of the working bandwidth; at the same time, through the respective 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 widening of the axial ratio bandwidth.

[0031] Specifically, the metasurface metal structure 110 includes a parasitic patch unit 111 and a metal patch unit 112. The parasitic patch unit 111 is arranged along the edge of the first dielectric substrate 100. The structural arrangement of the parasitic patch unit 111 forms a closed surround characteristic in terms of spatial distribution, effectively limiting the edge electromagnetic field leakage and establishing stable inductive and capacitive current channels in the edge area. Since the annular arrangement can introduce multiple near-field coupling paths at the edge of the first dielectric substrate 100, the energy feedback capability of the patch structure 210 under multi-mode excitation is enhanced, 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 further increased, thereby improving the resonance characteristics and expanding the frequency response range, achieving fine adjustment of the resonant frequency and optimization of the axial ratio performance. In addition, the metal patch unit 112 is arranged in the area surrounded by the annular parasitic patch unit 111. Thus, a center-edge multi-level electromagnetic coupling structure is formed on the first dielectric substrate 100 .

[0032] More specifically, the parasitic patch unit 111 is provided with a first cutout, which introduces 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 cutout, while the second sub-metal patch 1122 is provided with a third cutout. The second sub-metal patches 1122 are arranged at the four corners of the rectangular array, providing current isolation and electric field regulation. The first sub-metal patches 1121 are located in the non-corner regions of the rectangular array (i.e., areas outside the corners), achieving multimodal current excitation through coupling with adjacent sub-metal patches. Furthermore, the cross-shaped arrangement of the first sub-metal patches 1121 isolates the second sub-metal patches 1122, preventing excessive electromagnetic coupling interference while maintaining mode purity and directionality. Therefore, the distribution and coupling strength of the eigenmode are adjusted based on the spatial layout and geometric cutting of the metal patch unit 112, so as to achieve efficient radiation while cooperating with the parasitic patch unit 111 to expand the working bandwidth and axial ratio bandwidth of the antenna.

[0033] 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.

[0034] In this embodiment, a rectangular array is composed of 3×3 metal patches in the shape of squares with side length 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 conducive to expanding the axial ratio bandwidth. In addition, the metal patches in the shape of squares have 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.

[0035] Specifically, the value range of P is 33.4 mm < P < 33.6 mm. Controlling the side length of the patch between 33.4 mm and 33.6 mm 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.

[0036] In one embodiment, as Figure 2 shown, the first sub-metal patch 1121 is obtained by cutting two squares with side length A from the two diagonals of the metal patch along the first diagonal direction. Among them, the second cutting part is two squares with side length A, and 0.38P < A < 0.4P.

[0037] 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.

[0038] Based on the aforementioned rectangular array composed of metal patches with side length P, the structural setting method 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 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 a 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 beneficial to the formation of stable right-handed or left-handed circularly polarized waves.

[0039] 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 the lower left corner and upper right corner 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.

[0040] 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.

[0041] 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. [[ID=

[0042] 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, perform the first cut along the first diagonal direction of the square metal patch and 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, perform a secondary cut on 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 secondary cut at the lower left corner and upper right corner of the square metal patch is the third cut portion. The units of both length D and width W are mm.

[0043] 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. Perform a secondary cut in the vertical direction again 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 secondary 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.

[0044] It can be understood that the second sub-metal patch 1122 is obtained by performing a secondary cut on the basis of the first sub-metal patch 1121.

[0045] Specifically, for the rectangle with a cutting length of D, the ratio of the cutting length to the width is 2:1 and 0.7A < D < 0.9A. With such a design, first, 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. Second, a highly asymmetric geometric perturbation is formed in 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.

[0046] In one embodiment, as Figure 2As shown, regardless of whether it is in the vertical direction or the 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.

[0047] In this embodiment, since the rectangular array composed of the metal patch units 112 is an equally spaced 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 whether it is in the vertical direction or the 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.

[0048] 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).

[0049] 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.

[0050] In this embodiment, the second sub-metal patch 1122 is generally in an approximate double-arrow structure, 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 a "waist-clamped" structure in terms of morphology 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 occupied size, 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.

[0051] Triangular portions 1122b are symmetrically arranged at opposite ends of the connecting portion 1122a. In the second sub-metal patch 1122, the base of each triangular portion 1122b faces the connecting portion 1122a, and the top corners flare outward (or, in other words, point away from the connecting portion 1122a), forming an arrow-shaped end feature. In the first dielectric substrate 100, the top corners of the triangular portions 1122b point in a direction that 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, effectively broadening the frequency range with an axial ratio of less than 3 decibels.

[0052] In one embodiment, the first cutting portion is a square, and the ratio of the area of ​​the first cutting portion to the area of ​​the second cutting portion is 1:1; 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 disposed at corners of the first dielectric substrate 100. 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 indicated by the triangular portion 1122b, and the first diagonal direction is perpendicular to the second diagonal direction.

[0053] In this embodiment, the cutout areas of each parasitic patch in the parasitic patch unit 111 (specifically, the first parasitic patch 1111 and the third parasitic patch 1113) are all considered first cutouts. Since the parasitic patch unit 111 is formed by horizontally or vertically translating the first sub-metal patch 1121 to the edge of the first dielectric substrate 100, this arrangement, firstly, forms a stable reflection or coupling boundary field at the periphery, which, combined with the metal patch unit 112, creates a better rotating electric field distribution, thereby enhancing the axial ratio characteristics. Secondly, it helps expand the operating bandwidth, modulates the edge electromagnetic behavior through edge parasitic modes, and improves the frequency response characteristics. Therefore, the first cutout on a single parasitic patch and the second cutout on a single first sub-metal patch 1121 have the same area, meaning their area ratio is 1:1. This consistent area achieves a similar resonant frequency distribution, which helps to create a synergistic resonance effect between the parasitic patch and the first sub-metal patch 1121, thereby improving circular polarization performance.

[0054] Specifically, since the first dielectric substrate 100 is rectangular, the number of corners around the first dielectric substrate 100 is four. Since both the first parasitic patch 1111 and the second parasitic patch 1112 are disposed at the corners around the first dielectric substrate 100, the total number of first parasitic patches 1111 and second parasitic patches 1112 is four. Furthermore, since both the first parasitic patches 1111 and second parasitic patches 1112 are distributed diagonally along the first dielectric substrate 100, and since a rectangle has two pairs of diagonals, each pair of diagonals has two corners, the number of first parasitic patches 1111 and second parasitic patches 1112 is two each. This diagonally symmetrical distribution enhances overall electromagnetic symmetry and structural stability, facilitating the formation of orthogonal diagonal coupling paths and effectively exciting two sets of orthogonal mode currents.

[0055] The first parasitic patch 1111 is distributed along the first diagonal direction of the first dielectric substrate 100, and the second parasitic patch 1112 is distributed along the second diagonal direction of the first dielectric substrate 100; the second diagonal direction is parallel to or coincides with the direction pointed 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 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. Therefore, it can be seen that the first parasitic patch 1111 is distributed at the lower left corner and upper right corner of the first dielectric substrate 100, and the second parasitic patch 1112 is distributed at the upper left corner and lower right corner of the first dielectric substrate 100.

[0056] Furthermore, the opening of the L-shaped first parasitic patch 1111 faces the third cutout. This opening toward the third cutout 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. Furthermore, the L-shaped structure naturally provides current guidance and return paths. The opening toward the third cutout enhances directional radiation control, helps form a current concentration area, further improves high-frequency performance, and enhances the antenna's bandwidth consistency and circular polarization stability.

[0057] In summary, by arranging the parasitic patch units 111 symmetrically in different diagonal directions along the edge of the first dielectric substrate 100 and making their structural features (such as the cutting area, shape direction, and opening orientation) correspond to and couple with the central metal patch unit 112, the modal coupling relationship between the patches can be effectively enhanced, the operating 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.

[0058] It should be noted that in the present invention, the diagonal direction from the upper left corner to the lower right corner refers to the same diagonal direction as the diagonal direction from the lower right corner to the upper left corner; similarly, the diagonal direction from the lower left corner to the upper right corner refers to the same diagonal direction as the diagonal direction from the upper right corner to the lower left corner. In other words, the present invention does not specifically limit the directionality from top to bottom or bottom to top.

[0059] In one embodiment, if Figure 1 and Figure 2 As shown, the present invention further includes a plurality of trapezoidal third parasitic patches 1113; the plurality of the third parasitic patches 1113 are arranged on opposite sides of the first dielectric substrate 100, and the plurality of the third parasitic patches 1113 are arranged between the first parasitic patch 1111 and the second parasitic patch 1112 at intervals; the arrangement direction of the plurality of the third parasitic patches 1113 is the same as the arrangement direction of the first sub-metal patch 1121 after translation in the horizontal or vertical direction.

[0060] In this embodiment, the plurality of third parasitic patches 1113 disposed on opposite sides in the vertical direction can be obtained by horizontally translating the first sub-metal patch 1121 to the left and right and then cutting. Since the spacing between the plurality of first sub-metal patches 1121 and the second sub-metal patch 1122 in the rectangular array is the same, the spacing between two adjacent third parasitic patches 1113 obtained after translating to the opposite sides is also the same. In this way, by translating the plurality of third parasitic patches 1113 on the opposite sides from the first sub-metal patch 1121 and then cutting them, 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 between the edge electromagnetic response and the eigenmode excitation can be improved, and it is beneficial to optimize the rotating electric field structure, expand the antenna's operating bandwidth and axial ratio bandwidth, and improve the circular polarization performance.

[0061] Specifically, the lower left and upper right corners of the first sub-metal patch 1121 are the second cutout portions that have been cut. For the left opposite side in the vertical direction, after the first sub-metal patch 1121 is horizontally translated to the left to the opposite side, the left portion of the first sub-metal patch 1121 is cut away, and the remaining portion of the patch is the third parasitic patch 1113. The first cutout portion in the upper right corner of the third parasitic patch 1113 has the same area as the second cutout portion in the upper right corner of the first sub-metal patch 1121. For the right opposite side in the vertical direction, after the first sub-metal patch 1121 is horizontally translated to the right to the opposite side, the right portion of the first sub-metal patch 1121 is cut away, and the remaining portion of the patch is the third parasitic patch 1113. The first cutout portion in the lower left corner of the third parasitic patch 1113 has the same area as the second cutout portion in the lower left corner of the first sub-metal patch 1121. In this way, 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 translated along the horizontal direction.

[0062] Similarly, for the upper opposite side in the horizontal direction, after the first sub-metal patch 1121 is vertically translated upward to the opposite side, the upper portion of the first sub-metal patch 1121 is cut off, and the remaining portion becomes the third parasitic patch 1113. The first cut portion on the left side of the third parasitic patch 1113 has the same area as the second cut portion in 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 translated downward to the opposite side, the lower portion of the first sub-metal patch 1121 is cut off, and the remaining portion becomes the third parasitic patch 1113. The first cut portion on the right side of the third parasitic patch 1113 has the same area as the second cut portion in the upper right corner of the first sub-metal patch 1121. In this way, 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 vertical translation.

[0063] The setting method of maintaining consistency in the arrangement direction is conducive to achieving isotropic modal excitation or phase commonality enhancement in the arrangement direction, and helps the third parasitic patch 1113 maintain consistency in frequency response with the first sub-metal patch 1121 in electromagnetic behavior, thereby enhancing coupling efficiency.

[0064] In summary, the parasitic patches employ three different structures: the same structure for the same diagonal corner, different structures for different diagonals, and the same structure for all four opposite sides, but with different cut angle directions (the arrangement direction of the first cutouts). By varying the area of ​​the diagonal patches and the cut angle directions, the circular polarization axial ratio bandwidth is broadened. The specific principle behind this broadening is that the parasitic patches employ three different structures (first parasitic patch 1111, second parasitic patch 1112, and third parasitic patch 1113), each with distinct electromagnetic response characteristics, enabling resonance in different frequency bands. These patches are rationally arranged in space, exciting multiple eigenmodes with adjacent frequencies and generating multiple overlapping circular polarization operating ranges. This creates a superposition effect based on multi-mode resonance, effectively broadening the circular polarization frequency bandwidth. Using the same structure at the same diagonal angle and different structures at different diagonals helps create an asymmetric phase distribution on the antenna surface. The asymmetric structure guides the current to produce a non-uniform distribution, resulting in a more stable and directionally continuous rotating electric field during electromagnetic wave propagation, thereby improving the circular polarization stability of the antenna. The arrangement direction of the third parasitic patch 1113 changes the equivalent current path and local reflection phase at the metal boundary, thereby introducing a certain phase difference. This artificially designed phase difference complements the metal patch unit 112, forming a ±90° phase difference suitable for circular polarization at multiple frequency points, thereby improving axial ratio performance.

[0065] 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 with 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 operating frequency band, and supplemented by adding 3 types of parasitic patch structures 210 at the edge to further broaden the axial ratio bandwidth.

[0066] 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.

[0067] 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 with a length of B on both sides (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.

[0068] In one embodiment, as Figure 1 shown, the first dielectric substrate 100, the second dielectric substrate 200, and the third dielectric substrate 300 all adopt F4B materials with a dielectric constant of 3.5 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.

[0069] In this embodiment, the first dielectric substrate 100, the second dielectric substrate 200, 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.

[0070] Among 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.

[0071] 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.

[0072] 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.

[0073] In summary, by setting the three-layer dielectric substrates in an equal-length and equal-width structural form, not only simplifies the alignment and assembly process between the antenna layers, but also improves the structural symmetry and the stability of the radiation pattern. The layered setting of the dielectric substrates with different thicknesses makes the coupling space and slot coupling between the layers more efficient, which helps to improve the bandwidth and circular polarization performance of the antenna. At the same time, uniformly using 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.

[0074] 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, Figure 7 The scattering parameter S11 (Scattering Parameter S11) in the specification drawings is the input reflection coefficient, which 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.

[0075] In the specification drawings Figure 10-12The Gain in the formula represents the radiation capability of the antenna in the YOZ plane (where YOZ represents the plane passing through the Y and Z axes in the three-dimensional coordinate system, also known as the longitudinal section / plane), and is expressed in dB; copolar represents co-polarization; and crosspolar represents cross-polarization. Figure 10 F=1.207GHz means the operating frequency / operating frequency band is 1.207GHz; Figure 11 F=1.268GHz means the operating frequency / operating frequency band is 1.207GHz; Figure 12 F=1.561GHz means the operating frequency / operating frequency band is 1.207GHz.

[0076] In the drawings of the specification Figure 13-15 The Gain in the formula represents the radiation capability of the antenna in the XOZ plane (where XOZ represents the plane passing through the X-axis and Z-axis in the three-dimensional coordinate system, also known as the transverse section / plane), and is expressed in dB; copolar represents co-polarization; and crosspolar represents cross-polarization. Figure 13 F=1.207GHz means the operating frequency / operating frequency band is 1.207GHz; Figure 14 F=1.268GHz means the operating frequency / operating frequency band is 1.207GHz; Figure 15 F=1.561GHz means the operating frequency / operating frequency band is 1.207GHz.

[0077] like Figures 7 to 15 As shown in the simulation results, the broadband circularly polarized metasurface antenna of the present invention has a return loss of less than -10dB in the frequency range of 1.11GHz to 1.69GHz, showing good impedance matching characteristics and meeting the broadband working requirements. 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 satellite navigation system (1.207 GHz, 1.268 GHz, and 1.561 GHz), the antenna's axial ratio is less than 3 dB, demonstrating its ability to stably radiate circularly polarized electromagnetic waves within these frequency bands. In summary, the broadband circularly polarized metasurface antenna of the present invention not only achieves broadband impedance matching but also exhibits excellent circular polarization performance, effectively meeting the requirements of satellite communications, navigation, and positioning for highly stable and reliable circularly polarized signals.

[0078] The working process of the present invention is as follows: In this embodiment of the present invention, due to the physical separation between the first dielectric substrate 100 and the second dielectric substrate 200, a coupling space is formed between the patch structure 210 and the metasurface metal structure 110 on the upper surface of the second dielectric substrate 200. As a result, the RF 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 arranged within the region formed by the ring of parasitic patch units, thereby forming a center-edge multi-level electromagnetic coupling structure. This can increase the effective path length of the metasurface fundamental mode resonant wavelength and reduce the resonant frequency of the fundamental mode, allowing the RF 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 regulated by changing the geometric parameters (such as the position and size) of the cutouts (the second and third cutouts) on the metal patch, resulting in a continuous change in the phase response of the reflected or transmitted waves at different frequencies, thereby achieving the generation of an equivalent rotating electric field within a wide frequency band. In other words, the combination and arrangement of the patches and cutouts enables multiple different modes to be excited at different frequencies. At the same time, the current path and phase response are adjusted in a cross-arrangement, enabling multiple orthogonal modes to simultaneously meet the ±90° phase difference condition within the frequency band corresponding to the Beidou satellite. In this way, the present invention can achieve a dual widening of the collaborative working bandwidth and the axial ratio bandwidth, achieving broadband circular polarization characteristics.

[0079] In summary, an embodiment of the present invention provides a broadband circularly polarized metasurface antenna, which includes a first dielectric substrate 100, a second dielectric substrate 200, and a third dielectric substrate 300 stacked in sequence 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 floor 220 having a slot coupling structure 221; the lower surface of the third dielectric substrate 300 is provided with a microstrip feeding structure; the metal floor 220 is attached to the upper surface of the third dielectric substrate 300; the metasurface The surface metal structure 110 includes a parasitic patch unit 111 arranged around the edge of the first dielectric substrate 100 and a rectangular array of metal patch units 112. The metal patch units 112 are located within the region formed by the parasitic patch unit 111. Some or all of the parasitic patch units 111 are provided with a first cutout. The metal patch unit 112 includes a first sub-metal patch 1121 provided with a second cutout and a second sub-metal patch 1122 provided with a third cutout. The first sub-metal patches 1121 are arranged in a cross to isolate the second sub-metal patches 1122. The present invention can achieve broadband circular polarization characteristics by synergistically broadening both the operating bandwidth and the axial ratio bandwidth.

[0080] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A broadband circularly polarized metasurface antenna, characterized in that: The invention comprises a first dielectric substrate, a second dielectric substrate, and a third dielectric substrate stacked in sequence 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 floor having a slot coupling structure, and the lower surface of the third dielectric substrate is provided with a microstrip feeding structure; the metal floor is attached to the upper surface of the third dielectric substrate; The metasurface metal structure includes a parasitic patch unit arranged around the edge of the first dielectric substrate and a metal patch unit arranged in a rectangular array. The metal patch unit is arranged in an area formed by the parasitic patch unit. Some or all of the parasitic patch units are provided with a first cutting portion. The metal patch unit includes a first sub-metal patch provided with a second cutting portion and a second sub-metal patch provided with a third cutting portion. The first sub-metal patch is arranged in a cross to isolate the second sub-metal patch.

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

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

7. The broadband circularly polarized metasurface antenna according to claim 6, wherein: The first cutting portion is a square, and the ratio of the area of ​​the first cutting portion to the area of ​​the second cutting portion is 1:1; 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 arranged at the circumference 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 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, wherein: The invention also includes a plurality of trapezoidal third parasitic patches; the plurality of the third parasitic patches are arranged on opposite sides of the first dielectric substrate, and the plurality of the third parasitic patches are arranged between the first parasitic patch and the second parasitic patch at intervals; the arrangement direction of the plurality of the third parasitic patches is the same as the arrangement direction of the first sub-metal patch after translation in the horizontal or vertical direction.

9. The broadband circularly polarized metasurface antenna according to claim 1, wherein: The patch structure includes a 3×3 patch array composed of a plurality of sub-patch units, wherein each of the sub-patch units includes two rectangular sub-patches.

10. The broadband circularly polarized metasurface antenna according to claim 1, wherein: 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, where Hsub1 = 9 mm, Hsub2 = 6 mm, and Hsub3 = 4 mm.

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