Frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal

Abstract

The invention discloses a frequency reconfigurable high gain metasurface circularly polarized antenna array based on liquid crystal, which comprises a liquid crystal interlayer group, a non-uniform metasurface group, an upper Rogers substrate, a feed layer, a lower Rogers substrate and a corner cut square groove metal ground which are sequentially connected from top to bottom, through the non-uniform metasurface group and the corner cut square groove metal ground, extra resonance and a lowest axial ratio frequency point are generated, impedance matching of the antenna array is enhanced, the axial ratio bandwidth is expanded, and through combination of the antenna and a special liquid crystal material, when the temperature of liquid crystal is continuously changed, the frequency of the antenna array is increased. The characteristic of continuous change of relative dielectric constants can be realized, the movement of an effective working frequency band is realized, the advantages of wide bandwidth, high gain and small size of an antenna array can be effectively combined, and the characteristic of frequency reconfiguration can be realized through simple temperature regulation and control.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and particularly relates to a frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal. Background Art

[0002] In recent years, with the development of society, the demand for high-quality communication has been increasing day by day. Frequency-reconfigurable antennas have significant advantages in modern wireless communication and radio frequency systems, which can significantly improve system performance and flexibility, increase spectrum efficiency, enhance integration, and reduce costs and complexity. Thermotropic liquid crystal antennas utilize the temperature-sensitive characteristics of liquid crystal materials to adjust their electromagnetic response characteristics by changing the arrangement of liquid crystal molecules, thereby realizing the change of dielectric constant and achieving frequency reconfigurability. Circularly polarized antennas are a better choice for high-quality communication because they can maintain the phase difference between the main signal and the reflected signal, thereby reducing the impact of multipath interference on communication quality. Combining circularly polarized antennas with liquid crystal frequency-reconfigurable antennas, due to the continuity of the change in liquid crystal dielectric constant, liquid crystal antennas can achieve continuous frequency tuning, which is particularly suitable for the high demand for frequency flexibility and dynamic adaptability in modern communication systems.

[0003] Due to the flexibility and anisotropy of the liquid dielectric of liquid crystal antennas, they are widely used in adjusting the resonant frequency, phase, and directivity of antennas. Li et al. proposed an adjustable liquid crystal phase shifter based on a coplanar waveguide transmission line structure, which changed the characteristic impedance of the phase shifter by varying the 0-10v bias voltage, achieving a maximum phase shift of 180° in the frequency range of 54GHz - 66 GHz. In addition, liquid crystal antennas can also achieve frequency reconfigurability. Xia et al. proposed a liquid crystal-based filter dielectric resonator antenna, which designed a temperature-controlled antenna by utilizing the influence of the change in liquid crystal dielectric constant on the performance of a cylindrical dielectric resonator antenna. When the dielectric constant changes, the three peak resonant frequencies of the dielectric resonator antenna also shift, realizing a shift in the impedance bandwidth from 3.46 - 5.83GHz to 3.34 - 5.65GHz at most. Zhang et al. proposed a liquid crystal-based frequency-reconfigurable metasurface circularly polarized antenna array, which achieved high gain and broadband width by designing the metasurface circularly polarized antenna array. Subsequently, a layer of thermotropic liquid crystal layer was added between the dielectric substrates, and by changing the external temperature, the relative dielectric constant of the liquid crystal was regulated, realizing the frequency reconfigurability of the axial ratio bandwidth of the antenna array from 39.0% (4.51 - 6.70GHz) to 40.3% (4.61 - 6.94GHz). Summary of the Invention

[0004] The present invention provides a frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal. First, a sequential feeding network and radiation patches connected thereto are designed, and a chamfered square slot metal ground is loaded on the metal ground corresponding to the radiation patches to form the antenna array. Then, a non-uniform metasurface group is designed above the antenna array to further broaden the axial ratio bandwidth and impedance bandwidth of the antenna array. Finally, a liquid crystal sandwich group is introduced, and by changing the external temperature, the dielectric constant of the liquid crystal is changed, realizing the frequency reconfiguration of the antenna. At different temperatures, the operating bandwidth of the antenna moves from 73.72% (3.46 - 7.50 GHz) to 75.47% (3.30 - 7.30 GHz).

[0005] The present invention is realized by the following technical solutions:

[0006] First, the feeding layer of the antenna array is composed of a 270° sector microstrip line, a square loop, and four U-shaped radiation patches distributed around the square loop. And in order to change the distributed capacitance and distributed inductance of the antenna array and reduce the quality factor, a chamfered square slot is loaded at the position of the metal ground corresponding to the U-shaped radiation patch. In order to further broaden the axial ratio bandwidth and impedance bandwidth of the antenna array, a number of non-uniform metasurface groups are loaded above the antenna array, and a number of liquid crystal sandwich groups are added above the center and four corners of the non-uniform metasurface group. By changing the external temperature, the dielectric constant of the liquid crystal changes, thereby realizing the movement of the antenna operating bandwidth from 73.72% (3.46 - 7.50 GHz) to 75.47% (3.30 - 7.30 GHz).

[0007] The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal includes a liquid crystal sandwich group, a non-uniform metasurface group, an upper Rogers substrate, a feeding layer, a lower Rogers substrate, and a chamfered square slot metal ground connected in sequence from top to bottom. The non-uniform metasurface group is printed on the upper surface of the upper Rogers substrate, the feeding layer is printed on the upper surface of the lower Rogers substrate, and the chamfered square slot metal ground is printed on the lower surface of the lower Rogers substrate.

[0008] Further, the liquid crystal sandwich group is composed of a first liquid crystal sandwich and four second liquid crystal sandwiches. The liquid crystal sandwich is formed by encapsulating liquid crystal with two layers of glass on the upper and lower sides. The thickness of each of the two layers of glass is 0.2 mm, the thickness of the liquid crystal is 0.1 mm, and the liquid crystal is a nematic liquid crystal mixture composed of 4′-Pentyl-4-cyano-biphenyl, 4′-Alkyl-4-isothiocyanato-phenylcyclohexanes, and 4"-Alkyl-2′,5′fluoro-phenyl-4alkyl-biphenyl-tolanes. When the temperature continuously changes from -20°C to 50°C, the dielectric constant of this liquid crystal varies continuously between ε / / = 3.1 and ε ⊥ = 2.5.

[0009] Further, both the upper Rogers substrate and the lower Rogers substrate are Rogers RT / duroid5880 plates, with a dielectric constant of 2.2, a loss tangent value of 0.009, a length of 85 mm, a width of 85 mm, and a thickness of 1.57 mm. The upper Rogers substrate and the lower Rogers substrate are connected by nylon columns, and the air gap between them is 3.86 mm.

[0010] Further, the non-uniform metasurface group is composed of a first non-uniform metasurface and a second non-uniform metasurface. The first non-uniform metasurface and the second non-uniform metasurface are formed by cutting off four top corners of two squares with the same structure but different sizes. The widths of the side lengths of the square units are 10 mm and 9.2 mm respectively, and the cut-off corners are all 2 mm.

[0011] Further, the feeding layer is composed of a 270° sector microstrip line, a square loop, and four U-shaped radiation patches distributed around the square loop. The U-shaped radiation patch is formed by cutting off a small rectangle with a length of 6 mm and a width of 5 mm from four squares with a side length of 13 mm. The square loop is composed of a square with a cut-off angle of 1.5 mm and a side length of 12 mm. The inner radius of the 270° sector microstrip line is 3.2 mm, which can achieve phase differences of 0°, 90°, 180°, and 270° at ports 1 to 4 of the four arms of the square loop.

[0012] Further, the metal ground with a cut-corner square slot has four hexagonal slots. The hexagonal slot is formed by cutting off four top corners of a square slot with a side length of w3 = 21 mm, and the cut-off angle is c4 = 7 mm. And the position of the cut-corner square slot corresponds to the metal ground directly below the U-shaped radiation patch.

[0013] Further, the center of the lower Rogers substrate is the feeding port of the antenna, and the antenna uses the method of feeding with a coaxial probe to feed the feeding layer through the feeding point.

[0014] Compared with the prior art, the significant advantages of the present invention are as follows:

[0015] (1) By the chamfered square slot metal ground and the non-uniform metasurface group, the present invention generates additional resonances and the lowest axial ratio frequency points, broadening the axial ratio bandwidth and impedance bandwidth of the antenna array.

[0016] (2) By combining liquid crystal with the antenna, and taking advantage of the characteristic that the nematic liquid crystal mixture will continuously deflect during continuous temperature change, the present invention realizes the continuous change of the relative permittivity of the liquid crystal material. By regulating the dielectric constant of the liquid crystal with temperature, the present invention realizes that the impedance bandwidth and axial ratio bandwidth are respectively moved from 3.20 - 7.50 GHz and 3.46 - 7.65 GHz to 3.29 - 7.30 GHz and 3.30 - 7.53 GHz, and the effective working bandwidth can be moved from 73.72% (3.46 - 7.50 GHz) to 75.47% (3.30 - 7.30 GHz).

[0017] (3) By cleverly combining the material characteristics of the nematic liquid crystal mixture with the antenna and using simple temperature regulation, the present invention realizes the movement of the effective working frequency band of the antenna. The design of this liquid crystal-based frequency reconfigurable high-gain metasurface circularly polarized antenna array enables the antenna of the present invention to have the advantages of frequency reconfigurability, wide bandwidth, high gain, and small size, and can meet the stringent requirements of modern communication systems for antennas. Description of the Drawings

[0018] Figure 1 Is a perspective view of a liquid crystal-based frequency reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0019] Figure 2 Is a side view of a liquid crystal-based frequency reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0020] Figure 3 Is a plan view of a liquid crystal-based frequency reconfigurable high-gain metasurface circularly polarized antenna array, a liquid crystal sandwich group, and a non-uniform metasurface group according to an embodiment of the present invention.

[0021] Figure 4 Is a plan view of the feeding layer of a liquid crystal-based frequency reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0022] Figure 5It is a metal ground plane diagram with chamfered square slots of a liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0023] Figure 6 It is the |S 11 spectrum of a liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0024] Figure 7 It is the axial ratio spectrum of a liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0025] Figure 8 It is the gain spectrum of a liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0026] Figure 9 It is the radiation pattern of a liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array according to an embodiment of the present invention.

[0027] In the figure: 1 - glass; 2 - liquid crystal; 3 - non-uniform metasurface group; 4 - upper Rogers substrate; 5 - feeding layer; 6 - lower Rogers substrate; 7 - metal ground with chamfered square slots; 8 - nylon column. Specific Embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] Next, in conjunction with Figures 1 to 9 a liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array provided by the present invention will be described.

[0030] Embodiment: This embodiment provides a liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array, including a liquid crystal sandwich group, a non-uniform metasurface group 3, an upper Rogers substrate 4, a feeding layer 5, a lower Rogers substrate 6, a metal ground 7 with chamfered square slots, and a nylon column 8. The liquid crystal sandwich group includes a first liquid crystal sandwich and a second liquid crystal sandwich. The liquid crystal sandwich is formed by encapsulating the liquid crystal 2 with upper and lower layers of glass 1. In the present invention, the frequency reconfiguration of the antenna is realized by changing the dielectric constant of the liquid crystal 2 using the change in temperature.

[0031] Specifically, the liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array, as Figure 1As shown in the figure, the liquid crystal sandwich group and the non-uniform metasurface group 3 are placed on the upper surface of the upper Rogers substrate 4. The feeding layer 5 composed of a feeding network and radiation patches is on the upper surface of the lower Rogers substrate 6. There is a metal ground 7 with a chamfered square slot. The feeding port 9 is on the lower surface of the lower Rogers substrate 6. The upper Rogers substrate 4 and the lower Rogers substrate 6 are connected by four nylon columns 8.

[0032] The liquid crystal sandwich group, the upper Rogers substrate 4, and the lower Rogers substrate 6 are as Figure 2 shown. The liquid crystal sandwich group is encapsulated by upper and lower glass layers 1 with liquid crystal 2. The liquid crystal sandwich group includes a first liquid crystal sandwich and four second liquid crystal sandwiches. The first liquid crystal sandwich and the second liquid crystal sandwiches have the same structure. The thickness of the upper and lower glass layers 1 is d1 = 0.2 mm. The liquid crystal 2 is a nematic liquid crystal mixture composed of 4′-Pentyl-4-cyano-biphenyl, 4′-Alkyl-4-isothiocyanato-phenylcyclohexanes, and 4"-Alkyl-2′,5′fluoro-phenyl-4alkyl-biphenyl-tolanes. When the temperature continuously changes from -20°C to 50°C, the dielectric constant of the liquid crystal 2 can continuously vary between ε / / = 3.1 and ε ⊥ = 2.5. The thickness of the liquid crystal 2 is d2 = 0.1 mm. The upper Rogers substrate 4 and the lower Rogers substrate 6 are both Rogers RT / duroid 5880 plates with a dielectric constant of 2.2, a loss tangent value of 0.009, and a thickness of h1 = 1.57 mm. The upper Rogers substrate 4 and the lower Rogers substrate 6 are connected by four nylon columns 8, and the air gap h2 between the two is 3.86 mm.

[0033] The plan views of the upper Rogers substrate 4, the liquid crystal sandwich group, and the non-uniform metasurface group 3 are as Figure 3As shown in the figure, the upper Rogers substrate 4 has a length of l1 = 85 mm and a width of w1 = 85 mm. The liquid crystal sandwich group is composed of a first liquid crystal sandwich and a second liquid crystal sandwich. The first liquid crystal sandwich is located at the center of the upper Rogers substrate 4 and is a square with a side length of l2 = 20 mm. The second liquid crystal sandwich is arranged at the four corners of the upper Rogers substrate 4 and is a hexagon formed by cutting off four top corners from a square with a side length of l3 = 7 mm, and the cut-off angle c1 = 2 mm. The non-uniform metasurface group 3 is on the upper surface of the upper Rogers substrate 4 and is composed of a first non-uniform metasurface and a second non-uniform metasurface with side lengths of l4 = 10 mm and l5 = 9.2 mm respectively, and the cut-off angles are both c2 = 2 mm. The first non-uniform metasurface includes 20 first metasurface units, among which 12 first metasurface units are distributed around the first liquid crystal sandwich, and the remaining 8 first metasurface units and 8 second non-uniform metasurface units are distributed along the side length of the upper Rogers substrate 4.

[0034] The feeding layer 5, whose plan view is as Figure 4 shown, is on the upper surface of the lower Rogers substrate 6 and is composed of a square ring with an external side length of w2 = 12 mm and a cut-off angle of c3 = 1.5 mm and a 270° sector microstrip line with an internal radius of r1 = 3.2 mm connecting four U-shaped radiation patches. The 270° sector microstrip line provides a 90° phase difference, realizing a phase difference of 0°, 90°, 180°, and 270° from port 1 to port 4 at the four arms of the square ring. The four U-shaped radiation patches are composed of four squares with a side length of k1 = 13 mm, from which small rectangles with a length of k3 = 6 mm and a width of k2 = 5 mm are cut off. The 270° sector microstrip line is directly connected to the U-shaped radiation patch and is placed on the upper surface of the lower substrate.

[0035] The metal ground 7 with a cut-off square slot, whose plan view is as Figure 5 shown, is on the lower surface of the lower Rogers substrate 6. Four hexagonal slots are opened on the metal ground corresponding to the four U-shaped patches. The hexagonal slot is composed of a square slot with a cut-off angle of c4 = 7 mm and a side length of w3 = 21 mm. The feeding port of the antenna is at the center of the lower Rogers substrate 6, and the feeding layer 5 can be fed through the feeding point by using a coaxial probe for feeding.

[0036] Figure 6 is the |S 11 | curve of the liquid crystal-based frequency-reconfigurable high-gain metasurface circularly polarized antenna array of this embodiment, Figure 7 and is the axial ratio curve of the reconfigurable metasurface high-gain circularly polarized antenna array. In the range of -20 to 50 °C, the dielectric constant ε of the liquid crystal used in the antenna array LcIt is regulated within 2.5 - 3.1, and at the same time, the frequency band of this metasurface high-gain circularly polarized antenna array will gradually shift from high frequency to low frequency. In the range of 3.5 - 7.5 GHz, as the dielectric constant of the liquid crystal changes, the operating bandwidth of the antenna shifts towards low frequency in turn, and the resonant frequency points of the antenna change significantly. When ε Lc is 2.5, the impedance bandwidth and axial ratio bandwidth of the antenna are 3.20 - 7.50 GHz and 3.46 - 7.65 GHz respectively, and the overlapping effective operating bandwidth is 73.72% (3.46 - 7.50 GHz). When ε Lc is 3.1, the impedance bandwidth and axial ratio bandwidth of the antenna are 3.29 - 7.30 GHz and 3.30 - 7.53 GHz respectively, and the overlapping effective operating bandwidth is 75.47% (3.30 - 7.30 GHz). Compared with the liquid crystal with ε Lc being 2.5, the liquid crystal with ε Lc = 3.1 can shift the low-frequency cut-off frequency of the operating frequency of the antenna towards low frequency by 0.16 GHz and the high-frequency cut-off frequency towards low frequency by 0.2 GHz.

[0037] Figure 8 is the antenna gain curve diagram of the array antenna based on different dielectric constants. There is also a certain frequency shift phenomenon in the overall gain of the antenna at 3.2 - 7.5 GHz. When the dielectric constant is 2.5, the maximum gain is 11.86 dBi at 5.6 GHz. When the dielectric constant is 3.1, the maximum gain is 11.93 dBi at 5.6 GHz.

[0038] Figure 9 is the radiation pattern of the array antenna based on different dielectric constants. Figure (a) corresponds to the radiation patterns at 5 GHz and 6 GHz when the dielectric constant ε Lc of the liquid crystal is 2.5, and Figure (b) corresponds to the radiation patterns at 5 GHz and 6 GHz when ε Lc is 3.1. It can be seen that the main polarization of this circularly polarized antenna is RHCP and the cross polarization is LHCP. When ε Lc is 2.5, at 5 GHz, the maximum polarization isolation degrees of the left and right spins on the main lobe in the xoz plane and the yoz plane can reach 25.49 dB and 32.74 dB respectively, and the 3 dB axial ratio beam widths reach 44.86° and 44.82° respectively. At 6 GHz, the maximum polarization isolation degrees of the left and right spins on the main lobe in the xoz plane and the yoz plane can reach 30.83 dB and 22.03 dB respectively, and the 3 dB axial ratio beam widths reach 26.89° and 26.57° respectively. When ε LcWhen ε = 3.1, at 5 GHz, the maximum polarization isolation degrees of the left - hand and right - hand circular polarizations on the main lobe in the xoz plane and yoz plane can reach 24.07 dB and 29.19 dB respectively, and the 3 - dB axial - ratio beam widths reach 47.87° and 44.49° respectively. At 6 GHz, the maximum polarization isolation degrees of the left - hand and right - hand circular polarizations on the main lobe in the xoz plane and yoz plane can reach 26.22 dB and 21.2 dB respectively, and the 3 - dB axial - ratio beam widths reach 24.84° and 27.5° respectively.

[0039] In summary, as the temperature decreases, the effective impedance bandwidth and axial - ratio bandwidth of the antenna move from 73.72% (3.46 - 7.50 GHz) to 75.47% (3.30 - 7.30 GHz), and the peak gain changes from 11.86 dBi at 5.6 GHz to 11.93 dBi at 5.6 GHz. The simulated radiation patterns show that when the dielectric constant of the liquid crystal gradually changes from 2.5 to 3.1, the radiation patterns changing from high frequency to low frequency remain basically unchanged. The liquid - crystal - based frequency - reconfigurable high - gain metasurface circularly - polarized antenna array has the advantages of frequency reconfigurability, wide bandwidth, high gain and small size, providing a more competitive solution for modern communication systems.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal, capable of realizing frequency reconfiguration, comprising an upper Rogers substrate (4), a feed layer (5), a lower Rogers substrate (6) and a cut-corner square groove metal ground (7) arranged from top to bottom, characterized in that: The invention also comprises a plurality of liquid crystal interlayer groups and a plurality of non-uniform super surface groups (3) arranged on the upper surface of an upper Rogers substrate (4), wherein the liquid crystal interlayer group comprises a first liquid crystal interlayer and four second liquid crystal interlayers having the same structure, wherein the liquid crystal interlayer is formed by encapsulating liquid crystal (2) by two layers of glass (1) at the top and bottom, and the non-uniform super surface group (3) comprises a first non-uniform super surface and a second non-uniform super surface, wherein a feed layer (5) is printed on the upper surface of a lower Rogers substrate (6), and a cut-corner square groove metal ground (7) is printed on the lower surface of the lower Rogers substrate (6).

2. The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 1, characterized in that: The first liquid crystal interlayer and the second liquid crystal interlayer have the same structure, the thickness of the upper and lower layers of glass (1) are both 0.2 mm, the thickness of the liquid crystal (2) is 0.1 mm, the first liquid crystal interlayer group is placed at the center of the upper Rogers substrate (4), and the second liquid crystal interlayer is arranged at the four corners of the upper Rogers substrate (4).

3. The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 2, characterized in that: Liquid crystal (2) is a nematic phase liquid crystal mixture, composed of 4′-Pentyl-4-cyano-biphenyl, 4′-Alkyl-4-isothiocyanato-phenylcyclohexanes and 4"-Alkyl-2′,5′fluoro-phenyl-4alkyl-biphenyl-tolanes. When the temperature changes continuously from -20°C to 50°C, the dielectric constant ε of the liquid crystal changes from horizontal to vertical. / / =3.1 to the dielectric constant ε in the vertical direction ⊥ =2.5 continuously changes.

4. The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 3, characterized in that: The first liquid crystal interlayer is a square with a side length of l2 = 20 mm, and the second liquid crystal interlayer is a hexagon, which is formed by cutting off four corners of a square with a side length of l3 = 7 mm, and the cut corner c1 = 2 mm.

5. The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 4, characterized in that: The first non-uniform metasurface and the second non-uniform metasurface have the same structure but different sizes. The first non-uniform metasurface includes 20 first metasurface units, 12 of which are distributed around the first liquid crystal interlayer, and the remaining 8 first metasurface units and 8 second non-uniform metasurface units are distributed along the side length of the upper Rogers substrate (4).

6. The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 5, characterized in that: The upper Rogers substrate (4) and the lower Rogers substrate (6) are both Rogers RT / duroid 5880 plates, with a dielectric constant of 2.2, a loss tangent value of 0.009, and a thickness of h1=1.57 mm. The upper Rogers substrate (4) and the lower Rogers substrate (6) are connected by four nylon columns (8), and the air gap between the two is h2=3.86 mm.

7. The frequency reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 1, characterized in that: The feed layer (5) comprises, from the center outward, a 270° fan-shaped microstrip line, a square ring and four U-shaped radiation patches distributed around the square ring, and the 270° fan-shaped microstrip line is connected to the four U-shaped radiation patches respectively.

8. The frequency reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 7, characterized in that: The 270° fan-shaped microstrip line of the feeding layer (5) can not only act as an impedance matcher, but also provide a 90° phase difference. The microstrip line connects the inside and outside to achieve a phase difference of 0°, 90°, 180°, and 270° for the four arms of the square ring.

9. The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 7, characterized in that: The cut-corner square groove metal ground (7) has four hexagonal grooves corresponding to the metal ground positions corresponding to the four U-shaped radiation patches of the feed layer (5). The hexagonal groove is formed by cutting off the four corners of a square groove with a side length of w3=21mm, and the cut angle is c4=7mm.

10. The frequency-reconfigurable high-gain metasurface circularly polarized antenna array based on liquid crystal according to claim 1, characterized in that: The non-uniform super surface group (3), the feed layer (5) and the cut-corner square groove metal ground (7) all adopt a copper film with a thickness of 0.035 mm.

Images