Wide-beam dual-circularly polarized metasurface antenna unit, implementation method, and phased array antenna

Abstract

The present invention discloses a wide-beam dual-circularly polarized metasurface antenna unit, implementation method, and phased array antenna. The antenna comprises an antenna feed structure, an antenna radiator structure, and an antenna wide-beam structure. The antenna feed structure comprises an annular stripline, a cross slot, and a metalized via. The antenna radiator structure comprises a primary metasurface and a parasitic metasurface. The antenna wide-beam structure comprises a parasitic slot and a grounding post. The present invention realizes a dual-circularly polarized antenna with a wide gain beam and a wide axial ratio beam.

Description

Technical Field

[0001] The present invention relates to the field of communications, and in particular to a wide-beam dual-circular-polarization metasurface antenna unit, an implementation method, and a phased array antenna. Background Art

[0002] With the advancement of wireless communication technology, the sub-6GHz frequency bands of 5G are gradually entering large-scale commercial use. The millimeter-wave frequency band, due to its wider bandwidth and faster speeds, has attracted widespread attention and become a research hotspot in academia and industry. One key application is satellite communications. Due to the long distance between satellites and the ground, communication latency is high, and communication capacity is very limited. To overcome this problem, the current mainstream solution is to use millimeter-wave dual-circularly polarized, wide-angle scanning phased array antennas. Dual-circularly polarized antennas effectively reduce multipath and rain fade, and have strong interference resistance, making them the primary antenna type in satellite communications. Phased array antennas typically utilize flat-panel array antennas with a low profile. They utilize components such as phase shifters to achieve electronic scanning, overcoming the inertia of traditional mechanical scanning and making them more suitable for low-latency communications between satellites and the ground. Wide-angle scanning extends the coverage area of ​​phased array antennas, effectively reducing the number of antennas required for coverage. The main indicators of the millimeter-wave dual-circular polarization wide-angle scanning phased array antenna include bandwidth, beam width, scanning angle, axial ratio, etc. The antenna unit is usually required to have a wide gain beam width and axial ratio beam width, and to be able to achieve left-hand or right-hand circular polarization, and based on this, it can be expanded into a phased array antenna with wide-angle scanning and low axial ratio.

[0003] To improve the wide-angle scanning and axial ratio performance of phased arrays, many advanced technical solutions have emerged in recent years. Among the existing solutions, the literature X. Luo et al., "A Scalable Ka-Band 1024-Element Transmit Dual-Circularly-Polarized Planar Phased Array for SATCOM Application," in IEEE Access, vol. 8, pp. 156084-156095, 2020, proposes a narrowband dual-circularly polarized phased array. The antenna unit uses two I-shaped slots and achieves dual circular polarization by exciting the stacked corner patches with equal amplitude and in-phase. This avoids the use of a 3dB bridge associated with half a wavelength, which facilitates compact array formation. At the same time, a circle of isolation columns is added around the antenna to help reduce coupling between units. This phased array measures 32×32 and consists of 1024 antenna elements with a spacing of 5mm (0.5 times the wavelength at 30GHz). Operating between 29.5 and 30GHz, the gain drops by 4.5dB when scanning at ±60°. However, the axial ratio exceeds 8dB, and generating circular polarization requires stimulating both ports simultaneously. This means that only left-hand or right-hand circular polarization can be achieved at the same time, not dual circular polarization. The antenna elements have a narrow axial ratio bandwidth. Despite the use of a rotating subarray configuration, the axial ratio exceeds 8dB during wide-angle scanning, failing to meet practical application requirements. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the object of the present invention is to provide a wide-beam dual-circularly polarized metasurface antenna unit, method and phased array antenna.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A wide-beam dual-circular-polarization metasurface antenna unit, comprising:

[0007] An antenna feed structure includes an annular stripline, a cross slot, and a metallized via, wherein the annular stripline is printed on a first dielectric substrate, a lower metal floor is provided on the lower surface of the first dielectric substrate, the cross slot is printed on a second dielectric substrate, an upper metal floor is printed on the upper surface of the second dielectric substrate, and the metallized via is located between the upper and lower metal floors;

[0008] An antenna radiator structure includes a main metasurface and a parasitic metasurface, wherein the main metasurface is printed on a third dielectric substrate, and the parasitic metasurface is printed on a fourth dielectric substrate, wherein the main metasurface and the parasitic metasurface constitute a laminated metasurface;

[0009] The antenna wide beam structure includes a parasitic slot and a grounding post, wherein the parasitic slot is printed on a fourth dielectric substrate, the parasitic metasurface is arranged in the parasitic slot, and the grounding post is located between the parasitic slot and the upper metal floor;

[0010] The first dielectric substrate, the second dielectric substrate, the third dielectric substrate and the fourth dielectric substrate are pressed together in order from bottom to top.

[0011] Furthermore, the annular stripline is bilaterally symmetrical, both ends of the annular stripline are impedance transformation segments, and the middle annular portion is a radiation segment.

[0012] Furthermore, the cross slits are formed by crossing four slits, with adjacent slits spaced 45 degrees apart, and the cross slits are a bilaterally symmetrical structure.

[0013] Furthermore, the metallized vias surround the annular stripline, and a metal floor is provided on the lower surface of the third dielectric substrate.

[0014] Furthermore, the main metasurface is composed of first metal patches arranged in a 4×4 array, and the parasitic metasurface is composed of second metal patches arranged in a 2×2 array.

[0015] Furthermore, the parasitic slot is octagonal, and the number of grounding posts on each side is n, and n is at least three.

[0016] A method for implementing the wide-beam dual-circularly polarized metasurface antenna unit, comprising:

[0017] The two ends of a bilaterally symmetrical annular stripline are set as port 1 and port 2. When one port is excited, the other port is connected to a matched load. At this time, the annular stripline generates traveling wave feeding, and the phase at each point on the annular stripline changes linearly. By adjusting the radius of the annular stripline, each point on the annular stripline generates a 45° phase difference in sequence. The excitation signal passes through each point in sequence and radiates through the cross slot to achieve sequential feeding.

[0018] The excitation signal is input to port 1, and the matched load is connected to port 2. Since each point on the annular stripline generates a 45° phase difference in sequence, the electromagnetic waves radiated by the cross slots also have a phase difference. Ultimately, the orthogonal electric fields synthesized in the far field have a 90° phase difference. By adjusting the width of the middle part of the annular stripline and the length of the cross slots, the orthogonal electric field amplitudes are equalized, forming a right-hand circular polarization beam with a wide axial ratio.

[0019] Since the structure is completely symmetrical, when port 2 is excited and port 1 is connected to a matched load, left-hand circular polarization is generated.

[0020] Furthermore, the resonant frequency of the antenna unit is changed by adjusting the size of the first metal patch of the main metasurface and the thickness of the third and fourth dielectric substrates.

[0021] A phased array antenna comprises N×M sub-arrays, wherein the sub-arrays are obtained by rotating 2×2 wide-beam dual-circularly polarized metasurface antenna units in sequence by 90° clockwise.

[0022] Furthermore, the distance between adjacent antenna units is equal to the size of the antenna unit.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) The present invention uses an annular strip line as a feed line and shields it through metallized vias, thereby reducing the transmission loss of the feed structure in the millimeter wave frequency band.

[0025] (2) The present invention adopts a laminated metasurface design to reduce the size of the antenna unit from one wavelength to less than half a wavelength, which is beneficial to reducing the unit spacing of the array, thereby achieving wide-angle scanning.

[0026] (3) The present invention adds an octagonal parasitic slot and a grounding column to increase the beam width from 90° to more than 120°, which is beneficial to reducing the problem of excessive gain drop in large-angle scanning.

[0027] (4) The present invention adopts traveling wave sequence feeding to realize dual circular polarization technology. One port inputs the excitation signal and the other port is connected to the matching load to form traveling wave excitation. Then, four symmetrical slots are excited by the annular microstrip line, which can achieve a wider 10dB impedance bandwidth and 3dB axial ratio bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 3D structure diagram of the wide beam circularly polarized metasurface antenna unit of the present invention;

[0029] Figure 2(a) and Figure 2(b) are Figure 1 Side view and top view of the

[0030] Figure 3(a) is a top view of a 2×2 subarray of a dual circularly polarized wide-angle scanning phased array antenna;

[0031] Figure 3(b) is a top view of an 8×8 array of dual circularly polarized wide-angle scanning phased array antennas;

[0032] Figure 4 This is a schematic diagram of the principle of the traveling wave sequence feeding mechanism of the present invention;

[0033] Figure 5 This is a schematic diagram of the relationship between the number of grounding posts on each side of the octagonal parasitic slot and the directivity diagram;

[0034] Figure 6 (a) Schematic diagram of current distribution when the number of grounding posts on each side of the octagonal parasitic slot is n = 2;

[0035] Figure 6(b) Schematic diagram of current distribution when the number of grounding posts on each side of the octagonal parasitic slot is n = 3;

[0036] Figure 7 is the S-parameter diagram of the wide-beam dual-polarized metasurface antenna unit;

[0037] Figure 8 is the gain and axial ratio diagram of the wide-beam dual-polarized metasurface antenna unit;

[0038] Figure 9 is the gain pattern of the wide-beam dual-polarized metasurface antenna unit;

[0039] Figure 10 is the axial ratio pattern of the wide-beam dual-polarized metasurface antenna unit;

[0040] Figure 11 This is a schematic diagram comparing the directional patterns of an 8×8 phased array antenna;

[0041] Figure 12(a) is a schematic diagram showing the comparison of the gain patterns of an 8×8 phased array antenna scanned to 60°;

[0042] Figure 12(b) is a schematic diagram showing the comparison of the 8×8 phased array antenna’s radiation patterns when scanned to an axial ratio of 60°;

[0043] Figures 13(a), 13(b), and 13(c) are the scanning patterns of the 8×8 phased array antenna;

[0044] FIG14( a ), FIG14 ( b ), and FIG14 ( c ) are schematic diagrams of the scanning gain and axial ratio of the 8×8 phased array antenna at 27.5 GHz, 29 GHz, and 31 GHz, respectively. DETAILED DESCRIPTION

[0045] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0046] Example 1

[0047] A wide beam dual circular polarization metasurface antenna unit, the antenna unit is a symmetrical structure, the specific structure is as follows Figure 1 As shown in Figure 2(a) and Figure 2(b), it includes three parts:

[0048] Antenna feeding structure: includes an annular stripline 13, a cross slot 10, and a metalized via 14. The annular stripline 13 is a bilaterally symmetrical structure printed on the upper surface of a first dielectric substrate 15. The two ends of the annular stripline are impedance transformation sections, and the middle annular section is a radiation section.

[0049] The intersecting slits 10 are bilaterally symmetrical, etched into the second dielectric substrate 11. They can be formed by an even number of intersecting slits, each with varying lengths and widths. When there are four slits, the angle between adjacent slits is 45°; when there are two slits, the angle between adjacent slits is 90°.

[0050] The metallized vias 14 are located between the upper metal floor 9 and the lower metal floor 16, and are spaced evenly around the annular stripline 13. Their shapes can be square, hexagonal, or circular. The first dielectric substrate is located below the second dielectric substrate, and the two dielectric substrates are pressed together using a prepreg 12.

[0051] Specifically, the lower metal floor is arranged on the lower surface of the first dielectric substrate, the upper metal floor is arranged on the upper surface of the second dielectric substrate, and the metallized vias pass through the first dielectric substrate and the second dielectric substrate and are arranged between the upper and lower metal floors.

[0052] The antenna radiator structure includes a primary metasurface 6 and a parasitic metasurface 1. In this embodiment, the primary metasurface comprises a 4×4 array of first metal patches printed on a third dielectric substrate 7. The parasitic metasurface 1 comprises a 2×2 array of second metal patches printed on a fourth dielectric substrate 4. The overall dimensions of the primary metasurface and the parasitic metasurface are identical. In this embodiment, the first and second metal patches are square, with the first metal patch being smaller than the second metal patch.

[0053] In particular, in addition to the radiator being a metasurface, the radiator can also be a square metal patch or other form. The array structure and patch size of the main metasurface and the parasitic metasurface can be adjusted according to actual conditions, as long as the overall size of the two metasurfaces is equal.

[0054] The fourth dielectric substrate 4 and the third dielectric substrate 7 are pressed together by the prepreg 5 , and the third dielectric substrate 7 and the second dielectric substrate 11 are pressed together by the prepreg 8 .

[0055] The antenna's wide-beam structure includes a parasitic slot 2 and grounding posts 3. The parasitic slot is a regular octagon and is printed on a fourth dielectric substrate along with the parasitic metasurface. The parasitic slot can also be square, circular, or other shapes. The grounding posts 3 are located between the octagonal slot and the upper metal floor 9 and surround the octagonal slot at equal intervals. The number of grounding posts on each side is n, where n = 3, 4, or greater. These posts can be square, hexagonal, or circular.

[0056] The four dielectric substrates mentioned above all have a square structure.

[0057] The preferred dimensions in this embodiment are:

[0058] The proposed wide-beam dual-circularly polarized metasurface antenna structure is fabricated using PCB technology. The dielectric substrate is Rogers 4350B, with a dielectric constant of 3.48. The prepreg is 0.1 mm thick and has a dielectric constant of 3.5. The metal thickness on the dielectric substrate is 0.018 mm. The overall dimensions (length, width, and height) of the antenna unit are 4.8 mm × 4.8 mm × 1.766 mm.

[0059] The second metal patch size of the parasitic metasurface 1 is 1.16 mm, the interval is 0.12 mm, and the overall size is 2.44 mm*2.44 mm; the first metal patch size of the main metasurface 6 is 0.52 mm, the interval is 0.12 mm, and the overall size is 2.44 mm*2.44 mm.

[0060] The side length of the octagonal parasitic slot is 1.7 mm, and the spacing between the grounding posts 3 is 0.92 mm.

[0061] The thicknesses of the dielectric substrate from top to bottom are 0.422 mm, 0.508 mm, 0.1 mm, and 0.338 mm, respectively.

[0062] The lengths of the cross gaps 10 are 2.5 mm, 2.4 mm, 2.5 mm, and 1.6 mm, respectively, and the widths are all 0.2 mm.

[0063] The radius of the annular strip line 13 is 0.85 mm, and the width of the middle annular portion is 0.5 mm.

[0064] Description of the working principle of this antenna unit

[0065] The first part is the traveling wave sequence feeding mechanism. Figure 4As shown, the beginning and end of the bilaterally symmetrical annular stripline 13 are ports 1 and 2, respectively. The condition for generating a traveling wave is that when one port is excited, the other port must be connected to a matched load, preventing reflection echoes from the annular stripline 13 and forming a traveling wave feed. The phase at each point on the annular stripline 13 varies linearly. By adjusting the radius of the annular stripline 13, points A, B, C, D, E, F, and G on the annular stripline 13 can sequentially generate a 45° phase difference. For example, points B and F are anti-phase points, corresponding to points B' and F' at the zero point of the traveling wave sinusoidal curve. Four cross slots 10 are spaced 45° apart, and the excitation signal sequentially passes through each point and radiates through the slots, thus achieving sequential feeding. Taking right-hand circular polarization as an example, if an excitation signal is input to port 1 and a matched load is connected to port 2, the phase of point A on the annular stripline 13 will lead point B by 45° and point C by 90°. Similarly, the electromagnetic waves radiated through the cross slots 10 will also produce a consistent phase difference, and the orthogonal electric fields synthesized in the far field will ultimately have a 90° phase difference. By adjusting the width of the middle portion of the annular stripline 13 and the length and width of the four cross slots 10, the orthogonal electric field amplitudes can be made equal, ultimately forming a right-hand circular polarization with a wide axial ratio beam. Similarly, due to the complete symmetry of the structure, stimulating port 2 and connecting a matched load to port 1 can produce left-hand circular polarization.

[0066] The second part is the radiator. Since slot radiation is non-directional radiation, it will produce severe back lobes and the radiation efficiency is very low, so a low-profile metasurface is used as the radiator. When the metasurface is used as a radiator, it is also called a grid slot patch. It is composed of periodic small patches at equal intervals and has a TM radiation pattern similar to that of the patch. In addition, the periodic metasurface has multi-mode resonance characteristics and has a larger impedance bandwidth than the patch. However, the size of a single-layer metasurface is usually larger than half a wavelength, which is not conducive to array formation. In order to achieve miniaturization of the antenna, it is necessary to load a parasitic metasurface 1. The principle is capacitive loading, increasing the equivalent capacitance, and reducing the resonant frequency, that is, achieving the same resonant frequency at a smaller size. By changing the size of the main metasurface 6, as well as the thickness of the fourth dielectric substrate 4 and the third dielectric substrate 7, the resonant frequency of the antenna can be effectively changed.

[0067] The third part is the wide-beam mechanism. This is achieved by adding octagonal parasitic slots around the parasitic metasurface and then adding grounding posts 3 on the inner edge of the octagonal parasitic slots. The wide-beam mechanism works as follows: Similar to traditional patch antennas, ordinary metasurface antennas radiate primarily through the gap between the main metasurface 6 and the metal floor 9. In the present invention, adding the octagonal parasitic slots and grounding them is equivalent to artificially raising the floor. The main radiating portion includes both the gap between the main metasurface 6 and the metal floor 9 and the gap between the parasitic metasurface 1 and the octagonal parasitic slots. The gap between the parasitic metasurface 1 and the octagonal parasitic slots reduces the effective aperture area of ​​the antenna, thereby widening the beamwidth. The smaller the size of the octagonal parasitic slot, the closer it is to the parasitic metasurface 1, the smaller the equivalent aperture area, and the larger the beamwidth. However, this also degrades the polarization isolation within the unit. The unit beamwidth needs to be determined based on the actual required scan angle to determine the size of the octagonal parasitic slot. In addition, the unit beamwidth of the antenna of the present invention is also related to the number n of grounding posts 3 on each side of the octagonal parasitic slot. Figure 5 A comparison of the directional patterns at the highest frequency point of 31 GHz for n = 2, 3, and 4 is shown. It can be seen that when n = 2, the beamwidth is very narrow, only 58°; when n = 3 or 4, the beamwidth reaches 122°, with little difference. This is because when n = 2, the grounding posts 3 are too far apart, the octagonal parasitic slot is not fully grounded, and energy leaks out from between the grounding posts 3. As shown in Figure 6(a), the current density on the grounding post 3 is much greater than the current density at the edge of the octagonal parasitic slot, making the grounding post 3 the primary radiator. When n ≥ 3, the octagonal parasitic slot is well grounded, as shown in Figure 6(b). The current density at the edge of the octagonal parasitic slot is the strongest, indicating a strong electric field between the parasitic metasurface 1 and the octagonal parasitic slot, effectively reducing the effective aperture of the antenna while also improving isolation between elements.

[0068] The advantages of the present invention are:

[0069] The present invention adopts an annular strip line as a feed line and shields it through metallized vias, thereby reducing the transmission loss of the feed structure in the millimeter wave frequency band.

[0070] The design of the laminated metasurface is used to reduce the size of the antenna unit from one wavelength to less than half the wavelength, which is beneficial to reducing the unit spacing of the array, thereby achieving wide-angle scanning; finally, the present invention also adds octagonal parasitic slots and grounding posts to increase the beam width from 90° to more than 120°, which is beneficial to reducing the problem of excessive gain drop in large-angle scanning. Since the antenna unit of the present invention is symmetrical, the results obtained by left-handed and right-handed circular polarization are not much different, and the following results are all based on right-handed circular polarization as an example. Figure 7 As shown, the S parameters of the antenna unit proposed in the present invention meet the reflection coefficient S11<-23dB and the polarization coupling degree S12 within the unit <-12dB within the in-band range (27.5GHz-31GHz). Figure 8 The gain and axial ratio vary with frequency. The in-band normal gain is 3.9dBi-4.5dBi, and the normal axial ratio is less than 1dB. Figure 9 The gain radiation patterns at the three frequency points of 27.5GHz, 29GHz and 31GHz are all greater than 120° at 3dB gain beamwidth. Figure 10 The axial ratio patterns at 27.5 GHz, 29 GHz, and 31 GHz all have 3dB axial ratio beamwidths greater than 114°. Both the gain and axial ratio patterns exhibit good symmetry in the phi = 0° and phi = 90° planes.

[0071] Example 2

[0072] A phased array antenna includes N×M sub-arrays, wherein the sub-arrays are obtained by rotating a plurality of wide-beam dual-circularly polarized metasurface antenna units as described in Example 1 by 90 degrees clockwise.

[0073] In this embodiment, as shown in Figures 3(a) and 3(b), a phased array antenna comprises 8×8 wide-beam dual-circularly polarized metasurface antenna elements. This phased array antenna is constructed by translationally expanding a 2×2 subarray. To prevent grating lobes during wide-angle scanning, the spacing between antenna elements is equal to the antenna element size, namely 4.8 mm (half the wavelength of the highest frequency of 31 GHz).

[0074] This invention, based on wide-beam elements, first rotates a 2×2 subarray and then expands it into an 8×8 phased array. This significantly improves both wide-angle scanning gain and axial ratio. Because the antenna array is symmetrical, the results obtained with left-hand and right-hand circular polarization are similar. The following results are based on right-hand circular polarization as an example. Figure 11Figure 12(a) and (b) show the gain and axial ratio patterns of the antenna elements in an 8×8 array at the highest frequency point of 31 GHz before and after the addition of the octagonal parasitic slot. Before the addition of the octagonal parasitic slot, the pattern exhibited a significant dip. After the addition of the slot, the pattern became relatively flat due to the increased beamwidth of the antenna elements and the isolation provided by the ground post 3. Figures 12(a) and 12(b) show the changes in the gain and axial ratio patterns before and after the addition of the octagonal parasitic slot at the highest frequency point of 31 GHz, when scanning to 60°. The unscanned gains of the two were 22.64 dBi and 22.59 dBi, respectively, with minimal difference. Compared to the unscanned mode, before the addition of the octagonal parasitic slot, the gain decreased by 7.6 dB, and the axial ratio was 7 dB. After the addition of the octagonal parasitic slot, the gain decreased by only 5 dB, and the axial ratio was 2 dB. Scanning performance, including both gain and axial ratio, was significantly improved. Figures 13(a), 13(b), and 13(c) show the scanning patterns of the dual circularly polarized wide-angle scanning phased array antenna of the present invention at 27.5 GHz, 29 GHz, and 31 GHz. The results are as follows: at 27.5 GHz, the gain without scanning is 21.13 dBi, and the gain drops by 4 dB when scanning to ±60°; at 29 GHz, the gain without scanning is 22.06 dBi, and the gain drops by 4 dB when scanning to ±60°; and at 31 GHz, the gain without scanning is 22.59 dBi, and the gain drops by 5 dB when scanning to ±60°. Therefore, the gain fluctuation is within 5 dB when scanning within the band to ±60°. Finally, Figures 14(a), 14(b), and 14(c) show the gain and axial ratio changes during scanning. When scanning within the band to ±60°, the axial ratio is less than 3 dB, solving the problem of axial ratio degradation during wide-angle scanning.

[0075] The dual circularly polarized wide-angle scanning phased array antenna of the present invention can operate in the 5G millimeter wave communication frequency band and is suitable for phased array systems of satellite communication or terrestrial communication.

[0076] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A wide-beam dual-circular-polarization metasurface antenna unit, characterized in that: include: An antenna feed structure includes an annular stripline, a cross slot, and a metallized via, wherein the annular stripline is printed on a first dielectric substrate, a lower metal floor is provided on the lower surface of the first dielectric substrate, the cross slot is printed on a second dielectric substrate, an upper metal floor is printed on the upper surface of the second dielectric substrate, and the metallized via is located between the upper and lower metal floors; The annular stripline is bilaterally symmetrical, with both ends of the annular stripline being impedance transformation segments and the middle annular portion being a radiation segment; The cross slits are bilaterally symmetrical structures, etched on the second dielectric substrate, and are composed of an even number of cross slits, with each slit having a different length and width; By adjusting the width of the middle part of the ring microstrip line and the length and width of the cross gap, the orthogonal electric field amplitudes are made equal, and finally a right-handed or left-handed circular polarization of a wide axial ratio beam is formed; An antenna radiator structure includes a main metasurface and a parasitic metasurface, wherein the main metasurface is printed on a third dielectric substrate, and the parasitic metasurface is printed on a fourth dielectric substrate, wherein the main metasurface and the parasitic metasurface constitute a laminated metasurface; The antenna wide beam structure includes a parasitic slot and a grounding post, wherein the parasitic slot is printed on a fourth dielectric substrate, the parasitic metasurface is arranged in the parasitic slot, and the grounding post is located between the parasitic slot and the upper metal floor; The parasitic slot is an octagonal slot, and the inner edge of the octagonal slot is loaded with grounding posts, and the number of the loaded grounding posts is n ≥ 3; After adding the octagonal parasitic slot, the radiation portion of the present invention includes the gap between the main metasurface and the metal floor and the gap between the parasitic metasurface and the octagonal parasitic slot. The smaller the size of the octagonal parasitic slot, the closer the distance to the parasitic metasurface, the smaller the equivalent aperture area, and the larger the beam width. However, this will also deteriorate the polarization isolation within the unit. The unit beam width needs to be determined according to the actual required scanning angle to determine the size of the octagonal parasitic slot. The first dielectric substrate, the second dielectric substrate, the third dielectric substrate and the fourth dielectric substrate are pressed together in order from bottom to top.

2. The wide-beam dual-circular-polarization metasurface antenna unit according to claim 1, characterized in that: The metallized vias surround the annular strip line, and a metal floor is provided on the lower surface of the third dielectric substrate.

3. The wide-beam dual-circular-polarization metasurface antenna unit according to claim 1, characterized in that: The main metasurface is composed of first metal patches arranged in a 4×4 array, and the parasitic metasurface is composed of second metal patches arranged in a 2×2 array.

4. A method for implementing a wide-beam dual-circular-polarization metasurface antenna unit according to any one of claims 1 to 3, characterized in that: include: The two ends of a bilaterally symmetrical annular stripline are set as port 1 and port 2. When one port is excited, the other port is connected to a matched load. At this time, the annular stripline generates traveling wave feeding, and the phase at each point on the annular stripline changes linearly. By adjusting the radius of the annular stripline, each point on the annular stripline generates a 45° phase difference in sequence. The excitation signal passes through each point in sequence and radiates through the cross slot to achieve sequential feeding. The excitation signal is input to port 1, and the matched load is connected to port 2. Since each point on the annular stripline generates a 45° phase difference in sequence, the electromagnetic waves radiated by the cross slots also have a phase difference. Ultimately, the orthogonal electric fields synthesized in the far field have a 90° phase difference. By adjusting the width of the middle part of the annular stripline and the length of the cross slots, the orthogonal electric field amplitudes are equalized, forming a right-hand circular polarization beam with a wide axial ratio. Since the structure is completely symmetrical, when port 2 is excited and port 1 is connected to a matched load, left-hand circular polarization is generated.

5. The implementation method according to claim 4, characterized in that: The resonant frequency of the antenna unit is changed by adjusting the size of the first metal patch of the main metasurface and the thickness of the third and fourth dielectric substrates.

6. A phased array antenna, characterized in that: The invention comprises N×M sub-arrays, wherein the sub-arrays are obtained by rotating 2×2 wide-beam dual-circular-polarization metasurface antenna units according to any one of claims 1 to 3 by 90° in a clockwise direction.

7. The phased array antenna according to claim 6, wherein: The distance between adjacent antenna elements is equal to the size of the antenna element.

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