A method and device for controlling spatial wave polarization based on radiation metasurface

Abstract

The present invention discloses a method and device for polarization control of space waves based on a radiating metasurface, wherein the space wave generation and polarization control device based on the radiating metasurface include a feeding structure and m*n periodically arranged metasurface units, where m and n are positive integers. The feeding structure is a monopole antenna that excites surface waves; each unit includes a dielectric substrate, a metal structure located on the upper surface of the dielectric substrate, and a metal floor covering the lower surface of the dielectric substrate. The present invention converts surface waves into space waves and controls their polarization states by flexibly designing the phases of left-handed and right-handed circularly polarized waves.

Description

Technical Field

[0001] The present invention belongs to the field of metasurfaces, and in particular relates to a method and a device for controlling spatial wave polarization based on a radiation metasurface. Background Art

[0002] Metasurface is a new type of artificial electromagnetic material composed of periodic subwavelength units, which has the advantages of low profile and easy processing. By designing the structure and arrangement of subwavelength units and introducing discontinuous phase and amplitude distribution, electromagnetic waves can be controlled in multiple dimensions to achieve functions such as abnormal reflection (refraction), electromagnetic stealth, and microwave imaging. It has high application value in the fields of antenna design, radar detection, and communication. However, at present, most of the manipulation of electromagnetic waves by metasurfaces is to control the existing space electromagnetic waves, working in the reflection area or the transmission area, and it cannot generate space electromagnetic waves itself.

[0003] The holographic artificial impedance surface can be regarded as a radiating metasurface whose unit characteristics are characterized by intrinsic impedance. This surface is generally fed by a monopole antenna. When its surface impedance satisfies a certain periodic arrangement rule, it can generate space wave radiation and is usually used to design leaky wave antennas. Studies have shown that methods for generating linearly polarized and circularly polarized space electromagnetic waves based on surface impedance design have been proposed. However, such methods usually have disadvantages such as low aperture efficiency and large cross-polarization. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for controlling spatial wave polarization based on a radiative metasurface, so as to solve the technical problems that existing metasurfaces are usually unable to generate electromagnetic waves, and holographic artificial impedance surfaces have low radiation efficiency and large cross-polarization.

[0005] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0006] A method for controlling spatial wave polarization based on a radiative metasurface, wherein the metasurface is composed of m*n periodically arranged metasurface units, where m and n are positive integers; the metasurface units provide discontinuous phase changes, radiate surface waves into spatial waves and control their polarization states; and the central opening of the metasurface is used to place a feeding structure.

[0007] With the feeding structure as the center, a phase gradient matching the surface wave propagation constant is constructed along its radial direction to convert the surface wave excited by the feeding structure into a space wave. According to the generalized Snell's law, the radiation phase at any point on the metasurface should satisfy the following formula:

[0008] Φ rad (ρ) = k SW ρ

[0009] Among them, Φ radis the radiation phase, k SW is the surface wave propagation constant, and ρ is the distance between this point and the feed source.

[0010] The radiated space wave is regarded as the superposition of left-hand circularly polarized wave and right-hand circularly polarized wave, and the transmission phase and PB geometric phase are used to achieve complete decoupling of the two orthogonal circularly polarized waves.

[0011] By designing the arrangement of metasurface units, the radiation phase distribution and polarization phase distribution of left-handed and right-handed circularly polarized waves can be simultaneously satisfied, thereby realizing polarization control of spatial waves.

[0012] For left-hand circularly polarized waves and right-hand circularly polarized waves, their radiation phases are denoted by Φ Lrad and Φ Rrad , and the polarization phases are denoted as Φ Lpol and Φ Rpol , then the reflection phase of left-hand and right-hand circularly polarized waves should satisfy the following formula:

[0013] Φ L =Φ Lrad +Φ Lpol ,Φ R =Φ Rrad +Φ Rpol

[0014] The surface waves excited by the monopole antenna can be regarded as the superposition of left-hand circularly polarized waves and right-hand circularly polarized waves, which carry and The initial phase of is the azimuth angle; therefore, the phases of the left-hand circularly polarized wave and the right-hand circularly polarized wave decoupled by the transmission phase and the PB geometric phase are:

[0015] Φ L =Φ L0 +Φ PG -Φ PB ,Φ R =Φ R0 +Φ PG +Φ PB

[0016] Among them, Φ L0 and Φ R0 are the initial phases, respectively and Correspondingly, the transmission phase Φ PG and PB geometric phase Φ PB Satisfy the following formulas respectively:

[0017] Φ PG =(Φ Rrad +Φ Lrad +Φ Rpol +ΦLpol ) / 2

[0018]

[0019] Furthermore, the metasurface unit satisfies the PB geometric phase condition, the transmission phase variation range covers 0 to 2π, and when an orthogonal linear polarization wave is incident, the reflection phase of the metasurface unit satisfies the following formula:

[0020]

[0021] Among them, u and v represent the polarization directions of the orthogonal linearly polarized incident waves. and represents the co-polarized reflection phase; when the metasurface unit angle β is rotated counterclockwise, the reflection phases for left-hand circularly polarized waves and right-hand circularly polarized waves are respectively and in, is the transmission phase, denoted by Φ PG , 2β is the PB geometric phase, denoted by Φ PB .

[0022] Furthermore, the aperture field superposition method is used to superimpose different deflection phases on the left-handed and right-handed circularly polarized waves, thereby realizing multi-beam radiation with different polarizations.

[0023] A device for generating spatial waves and controlling polarization thereof based on a radiation metasurface, comprising a feeding structure and a metasurface, wherein a central opening of the metasurface is used to place the feeding structure, and the metasurface is composed of m*n periodically arranged metasurface units, where m and n are positive integers;

[0024] Each of the metasurface units comprises a dielectric substrate, a metasurface unit structure and a metal floor; the metasurface unit structure is arranged on the upper surface of the dielectric substrate, and the metal floor is arranged on the lower surface of the dielectric substrate;

[0025] An SMA connector is welded on the metal floor;

[0026] The feeding structure is a monopole antenna, which is a coaxial probe that is higher than the metasurface, and the energy is input through the SMA connector to excite the surface wave;

[0027] The metasurface unit provides discontinuous phase changes, converting surface waves into spatial waves and controlling their polarization state.

[0028] Furthermore, the metasurface unit structure includes a metal strip and two arc structures connected thereto, the inner and outer radii of each unit arc structure are the same, the width w of the metal strip varies in the range of 0.1 mm to 1.1 mm, and the opening angle α of the arc structure varies in the range of 10° to 110°.

[0029] Furthermore, the dielectric substrate is made of F4BM265.

[0030] The spatial wave polarization control method and device based on the radiation metasurface of the present invention have the following advantages:

[0031] 1. The spatial wave polarization control method based on the radiative metasurface of the present invention can completely decouple left-handed and right-handed circularly polarized waves and generate spatial waves of arbitrary polarization by designing the transmission phase and PB geometric phase.

[0032] 2. The space wave generation and polarization control device based on the radiating metasurface of the present invention uses a monopole antenna as a feed source and utilizes the generalized Snell's law to construct a phase gradient along the radial direction of the feed source, thereby efficiently realizing the generation of space waves and having the advantages of low profile, miniaturization, and easy integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the spatial wave generation and polarization control device based on the radiation metasurface of the present invention;

[0034] Figure 2 It is a schematic diagram of the feeding structure of the present invention;

[0035] Figure 3 is a schematic structural diagram of a super surface unit of the present invention;

[0036] Figure 4(a) shows the metal strip width w of the metasurface unit and the arc structure angle α and the transmission phase at 15 GHz Relationship diagram;

[0037] Figure 4(b) shows the metal strip width w of the metasurface unit and the arc structure angle α and the linear polarization reflection phase difference at 15 GHz. Relationship diagram;

[0038] FIG4( c ) is a graph showing the relationship between the reflection phase and the unit structure rotation angle β of the metasurface unit with parameters w = 0.6 and α = 45° under the incidence of left-handed circularly polarized waves;

[0039] FIG4( d ) is a graph showing the relationship between the reflection phase and the unit structure rotation angle β when the metasurface unit with parameters w = 0.6 and α = 45° is incident with a right-hand circularly polarized wave;

[0040] Figure 5(a) shows the transmission phase Φ of the first embodiment of the spatial wave generation and polarization control device based on the radiation metasurface. PG Distribution diagram, this embodiment generates x-polarized spatial waves radiating in a normal direction;

[0041] Figure 5(b) shows the PB geometric phase Φ of the first embodiment of the spatial wave generation and polarization control device based on the radiation metasurface.PB Distribution map;

[0042] FIG5( c ) is a diagram showing the three-dimensional far-field simulation results of the normally emitted x-polarized space wave generated by the first embodiment of the space wave generation and polarization control device based on the radiation metasurface;

[0043] FIG5( d ) is a partial physical diagram of a first embodiment of a device for generating spatial waves and controlling polarization thereof based on a radiation metasurface;

[0044] Figure 5(e) is a first embodiment of the spatial wave generation and polarization control device based on the radiation metasurface. x Near-field simulation results on the xoz plane;

[0045] Figure 5(f) shows the first embodiment of the spatial wave generation and polarization control device based on the radiation metasurface. x Near-field simulation results in the yoz plane;

[0046] FIG5( g ) is a diagram showing the far-field simulation and test results of the xoz plane of the first embodiment of the spatial wave generation and polarization control device based on the radiative metasurface;

[0047] FIG5(h) is a diagram showing the far-field simulation and test results of the yoz plane of the first embodiment of the spatial wave generation and polarization control device based on the radiation metasurface;

[0048] FIG6(a) shows the transmission phase Φ of the second embodiment of the spatial wave generation and polarization control device based on the radiative metasurface. PG Distribution diagram, this embodiment generates a left-handed circularly polarized space wave radiating in a normal direction;

[0049] FIG6( b ) is a second embodiment of the PB geometric phase Φ of the spatial wave generation and polarization control device based on the radiation metasurface. PB Distribution map;

[0050] FIG6( c ) is a diagram showing the three-dimensional far-field simulation results of a normally emitted left-handed circularly polarized space wave generated by the second embodiment of the space wave generation and polarization control device based on the radiative metasurface;

[0051] FIG6( d ) is a partial diagram of a second embodiment of a device for generating spatial waves and controlling polarization thereof based on a radiation metasurface;

[0052] FIG6( e ) is a diagram showing the near-field simulation results of the left-handed circularly polarized component in the xoz plane of the second embodiment of the spatial wave generation and polarization control device based on the radiative metasurface;

[0053] FIG6( f ) is a diagram showing the near-field simulation results of the left-handed circularly polarized component in the yoz plane of the second embodiment of the spatial wave generation and polarization control device based on the radiative metasurface;

[0054] FIG6( g ) is a diagram showing the far-field simulation and test results of the xoz plane of the second embodiment of the spatial wave generation and polarization control device based on the radiative metasurface;

[0055] FIG6(h) is a diagram showing the far-field simulation and test results of the yoz plane of the second embodiment of the spatial wave generation and polarization control device based on the radiation metasurface;

[0056] FIG7( a ) is a diagram showing the three-dimensional far-field simulation results of dual-beam radiation with different circular polarizations generated by the third embodiment of the device for spatial wave generation and polarization control based on a radiation metasurface;

[0057] FIG7( b ) is a diagram showing the far-field simulation and test results of the third embodiment of the spatial wave generation and polarization control device based on the radiation metasurface, which generates dual-beam radiation with different circular polarizations in the xoz plane;

[0058] FIG8( a ) is a diagram showing the three-dimensional far-field simulation results of dual-beam radiation with different linear polarizations generated by the fourth embodiment of the device for generating spatial waves based on a radiation metasurface and controlling its polarization;

[0059] FIG8( b ) is a diagram showing the far-field simulation and test results of the fourth embodiment of the spatial wave generation and polarization control device based on the radiation metasurface generating dual-beam radiation with different linear polarizations in the xoz plane;

[0060] FIG9( a ) is a simulation and test result of the reflection coefficient S11 of four embodiments of the spatial wave generation and polarization control device based on the radiation metasurface of the present invention;

[0061] FIG9( b ) is a simulation result of the radiation efficiency of four embodiments of the spatial wave generation and polarization control device based on the radiation metasurface of the present invention.

[0062] Description of the marks in the figure: 1. Feeding structure; 2. Metasurface unit; 11. Coaxial probe; 12. SMA connector; 21. Metasurface unit structure. DETAILED DESCRIPTION

[0063] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a spatial wave polarization control method based on a radiation metasurface and a device thereof in conjunction with the accompanying drawings.

[0064] like Figure 1As shown, a device for generating spatial waves and polarization control thereof based on a radiative metasurface includes a feeding structure 1 and a metasurface. The central opening of the metasurface is used to place the feeding structure 1. The metasurface is composed of metasurface units 2 arranged in 21*21 periods. Each metasurface unit 2 includes a dielectric substrate, a metasurface unit structure 21 and a metal floor; the metasurface unit structure 21 is arranged on the upper surface of the dielectric substrate, the metal floor is arranged on the lower surface of the dielectric substrate, the dielectric substrate material is selected as F4BM265, and the device operating frequency is 15GHz.

[0065] The metasurface unit 2 is characterized by satisfying the PB geometric phase condition, and the transmission phase variation range covers 0 to 2π. Its specific structure includes but is not limited to the metasurface unit structure 21, the dielectric substrate material includes but is not limited to F4BM265, and the operating frequency is determined by the metasurface unit characteristics, including but not limited to 15 GHz.

[0066] like Figure 2 As shown, the feeding structure 1 is a monopole antenna, and the central opening of the metasurface is used to place the feeding structure. The monopole antenna is actually a coaxial probe 11 that is higher than the metasurface, and the energy is input by the SMA (small radio frequency coaxial connector) connector 12 welded to the metal floor of the metasurface. With the monopole antenna of the feeding structure 1 as the center, a phase gradient matching the surface wave propagation constant is constructed along its radial direction to convert the surface wave excited by the monopole antenna into a space wave. According to the generalized Snell's law, the radiation phase at any point on the metasurface satisfies the following formula:

[0067] Φ rad (ρ) = k SW ρ

[0068] Among them, Φ rad is the radiation phase, k SW is the surface wave propagation constant, and ρ is the distance between the point and the feed source. In this embodiment, the operating frequency of the space wave generating device based on the metasurface is 15 GHz, k SW =1.14k0, k0 is the propagation constant of electromagnetic waves in free space.

[0069] The radiated space wave is regarded as the superposition of left-hand circularly polarized wave and right-hand circularly polarized wave. The transmission phase and PB geometric phase are used to completely decouple the two orthogonal circularly polarized waves so that they can respectively satisfy the radiation phase distribution and polarization phase distribution of left-hand and right-hand circularly polarized waves, thereby realizing polarization control of the space wave.

[0070] For left-hand circularly polarized waves and right-hand circularly polarized waves, their radiation phases are denoted by Φ Lrad and Φ Rrad , and the polarization phases are denoted as Φ Lpol and Φ Rpol, then the reflection phase of left-hand and right-hand circularly polarized waves should satisfy the following formula:

[0071] Φ L =Φ Lrad +Φ Lpol ,Φ R =Φ Rrad +Φ Rpol

[0072] The surface wave excited by the monopole antenna can also be regarded as the superposition of left-hand circularly polarized wave and right-hand circularly polarized wave, and they carry and The initial phase of is the azimuth angle. The phases of the left-hand circularly polarized wave and the right-hand circularly polarized wave decoupled by the transmission phase and the PB geometric phase are:

[0073] Φ L =Φ L0 +Φ PG -Φ PB ,Φ R =Φ R0 +Φ PG +Φ PB

[0074] Among them, Φ L0 and Φ R0 are the initial phases, respectively and Correspondingly, the transmission phase Φ PG and PB geometric phase Φ PB Satisfy the following formulas respectively:

[0075] Φ PG =(Φ Rrad +Φ Lrad +Φ Rpol +Φ Lpol ) / 2

[0076]

[0077] like Figure 3 As shown, the period p of the metasurface unit structure 21 is 5 mm, and the dielectric thickness h is 2 mm. The metal structure on the upper surface of the unit includes a metal strip and two arc structures connected thereto. The inner diameter r1 of each unit arc structure is 1.7 mm, and the outer diameter r2 is 2.1 mm. The width w of the metal strip and the opening angle α of the arc structure are adjusted to meet the reflection phase requirements. In the figure, uov is a local coordinate system describing the unit, in which the u-axis and the v-axis are perpendicular and parallel to the middle metal strip, respectively. β is the angle of counterclockwise rotation of the metal structure in the uov plane.

[0078] Figure 4(a) shows the metal strip width w of the metasurface unit and the arc structure angle α and the transmission phase at 15 GHz. Figure 4(b) shows the relationship between w and α and the reflected phase difference at 15Hz. The solid black line marks the relationship between To achieve that the metasurface unit satisfies the PB geometric phase condition Transmission Phase The variation range covers 0~2π, the width w of the metal strip varies from 0.1mm to 1.1mm, and the angle α of the arc structure varies from 10° to 110°. Figure 4(c) and Figure 4(d) respectively show the reflection characteristics of the metasurface unit with parameters w=0.6 and α=45° when the left-handed and right-handed circularly polarized waves are incident. It can be seen that the PB geometric phase Φ of the unit PB -2β and 2β respectively.

[0079] Figure 5 shows the first embodiment of the spatial wave generation and polarization control device based on the radiation metasurface, which generates linearly polarized spatial waves. For left-hand circularly polarized waves and right-hand circularly polarized waves, their radiation phases are equal, Φ Lrad =Φ Rrad =1.14k0ρ; polarization phases are opposite to each other, is the angle between the linear polarization direction and the x-axis. Correspondingly, the PB geometric phase and transmission phase are:

[0080] Φ PG =1.14k0ρ,

[0081] In this embodiment, the linear polarization direction is x polarization. Φ PG and Φ PB The phase distribution is shown in Figure 5(a) and Figure 5(b) respectively. Figure 5(c) is the three-dimensional far-field simulation result of the x-polarized wave, which is a pencil-shaped beam radiating along the normal direction of the metasurface. Figure 5(d) is a partial view of the metasurface. x The near-field simulation results in the xoz plane and yoz plane are shown in Figure 5(e) and Figure 5(f), respectively. The results show that the space wave generating device proposed in the present invention successfully converts the surface wave into a space plane wave. The far-field simulation and test results of the space wave in the xoz plane and yoz plane are shown in Figure 5(g) and Figure 5(h), respectively. The x-polarized wave gain generated by the device is as high as 22.8dB, and the cross-polarization is less than 25dB.

[0082] FIG6 shows a second embodiment of a spatial wave generation and polarization control device based on a radiation metasurface, generating a circularly polarized spatial wave. This embodiment generates a left-hand circularly polarized wave with normal radiation, while suppressing the generation of a right-hand circularly polarized wave. Therefore, the radiation phase Φ of the left-hand circularly polarized wave is Lrad =1.14k0ρ, polarization phase Φ Lpol =0, and the radiation phase of the right-hand circularly polarized wave Φ Rrad = 0. Since the space wave generating device in this embodiment does not radiate right-hand circularly polarized waves, its polarization phase is not important, and its value is arbitrarily taken as Correspondingly, the PB geometric phase and transmission phase are:

[0083]

[0084] The Φ of this embodiment PG and Φ PB The phase distribution is shown in Figure 6(a) and Figure 6(b) respectively. Figure 6(c) shows the three-dimensional far-field diagram of the left-handed circularly polarized wave, which is a pencil-shaped beam radiating along the normal direction of the metasurface. Figure 6(d) is a partial diagram of the actual metasurface. The near-field simulation results of the left-handed circularly polarized component in the xoz plane and the yoz plane are shown in Figure 6(e) and Figure 6(f) respectively. The results show that the surface wave is well converted into a left-handed circularly polarized plane wave. The far-field simulation and test results of the space wave in the xoz plane and the yoz plane are shown in Figure 6(g) and Figure 6(h) respectively. The left-handed circularly polarized wave gain generated by the device is as high as 22dB, the axial ratio is much lower than 3dB, and the cross-polarization is lower than 20dB.

[0085] Figure 7 shows a third embodiment of a spatial wave generation and polarization control device based on a radiation metasurface, which generates dual-beam radiation with different circular polarizations. To achieve dual-beam radiation, a deflection phase is introduced into the control phase of the left-handed and right-handed circularly polarized waves so that their reflected phases satisfy the following formula:

[0086] Φ L =Φ Lrad +Φ Lpol +Φ Ldef ,Φ R =Φ Rrad +Φ Rpol +Φ Rdef

[0087] Among them, Φ Ldef =-k0sinθ L (xcosφ L +ysinφ L ), Φ Rdef =-k0sinθ R (xcosφ R +ysinφ R), are the deflection phases of left-handed and right-handed circularly polarized waves, θ L(R) and φ L(R) Describes the direction of deflection. Take Φ Lpol =Φ Rpol =0,Φ Lrad =Φ Rrad =1.14k0ρ,φ L =φ R 0=0,θ L =20°,θ R =-20°, two circularly polarized beams with opposite rotation directions can be generated, and the deflection directions are (θ L =20°,φ L =0) and (θ R =-20°,φ R =0). The simulated 3D far-field pattern is shown in Figure 7(a), and the far-field simulation and test results in the xoz plane are shown in Figure 7(b).

[0088] By using the aperture field superposition method, more complex multi-beam radiation with different polarizations can be achieved. Figure 8 shows the fourth embodiment of the spatial wave generation and polarization control device based on the radiation metasurface, which generates dual-beam radiation with different linear polarizations. PG and Φ PB Satisfy the following formulas respectively:

[0089]

[0090]

[0091] Where N represents the number of beams. When N = 2, Φ Ldef1 =Φ Rdef1 =-k0sinθ1(xcosφ1+ysinφ1), Φ Ldef2 =Φ Rdef2 =-k0sinθ2(xcosφ2+ysinφ2), two beams with deflection directions of (θ1, φ1) and (θ2, φ2) can be generated. Lpol1 =Φ Rpol1 =0, Φ Lpol2 =-π / 2,Φ Rpol2 =π / 2, beam 1 and beam 2 are x-polarized and y-polarized, respectively. When the deflection directions are designed to be (θ1=30°, φ1=0) and (θ2=-30°, φ2=0), the 3D far-field pattern and the far-field pattern in the xoz plane are shown in Figure 8(a) and Figure 8(b), respectively.

[0092] The reflection coefficient S11 and radiation efficiency of the above four embodiments are shown in Figure 9(a) and Figure 9(b) respectively. The results show that the S11 simulation and test results are lower than -18dB and -12dB respectively, and the radiation efficiency is higher than 95%, indicating that the efficiency of generating space waves is very high.

[0093] The present invention proposes a method and device for controlling the polarization of space waves based on a radiating metasurface. The surface waves excited by a monopole antenna are efficiently converted into space waves by designing the radiation phase arrangement. The polarization phases of left-handed and right-handed circularly polarized waves are designed to control the polarization of the space waves. This is a design method that uses a metasurface to generate space waves and control the polarization state of the beam in a simple and flexible manner. The present invention has the advantages of low profile, high efficiency, and easy integration, and has potential application prospects in the fields of antenna design and system-on-chip integration.

[0094] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A method for controlling spatial wave polarization based on a radiative metasurface, characterized in that: The metasurface is composed of m*n periodically arranged metasurface units (2), where m and n are positive integers; the metasurface units (2) provide discontinuous phase changes, radiate surface waves excited by a feeding structure (1) into space waves and control their polarization states; and the central opening of the metasurface is used to place the feeding structure (1); With the feeding structure (1) as the center, a phase gradient matching the surface wave propagation constant is constructed along its radial direction to convert the surface wave excited by the feeding structure (1) into a space wave. According to the generalized Snell's law, the radiation phase at any point of the metasurface should satisfy the following formula: F rad (p)=k SW r Among them, Φ rad is the radiation phase, k SW is the surface wave propagation constant, ρ is the distance between any point of the surface wave and the feed source; The radiated spatial wave is regarded as the superposition of left-hand circularly polarized wave and right-hand circularly polarized wave, and the transmission phase and PB (Pancharatnam–Berry) geometric phase are used to achieve complete decoupling of the two orthogonal circularly polarized waves. By designing the arrangement of the metasurface units (2), the radiation phase distribution and polarization phase distribution of left-handed and right-handed circularly polarized waves are simultaneously satisfied, thereby realizing polarization control of the space wave; For left-hand circularly polarized waves and right-hand circularly polarized waves, their radiation phases are denoted by Φ Lrad and Φ Rrad , and the polarization phases are denoted as Φ Lpol and Φ Rpol , then the reflection phase of left-hand and right-hand circularly polarized waves should satisfy the following formula: F L =Φ Lrad +F Lpol ,F R =Φ Rrad +F Rpol The surface waves excited by the feeding structure (1) can be regarded as the superposition of left-hand circularly polarized waves and right-hand circularly polarized waves, each carrying and The initial phase of is the azimuth angle; therefore, the phases of the left-hand circularly polarized wave and the right-hand circularly polarized wave decoupled by the transmission phase and the PB geometric phase are: F L =Φ L0 +F PG -F PB ,F R =Φ R0 +F PG +F PB Among them, Φ L0 and Φ R0 are the initial phases, respectively and Correspondingly, the transmission phase Φ PG and PB geometric phase Φ PB Satisfy the following formulas respectively: F PG =(Φ Rrad +F Lrad +F Rpol +F Lpol ) / 2 2. The spatial wave polarization control method based on the radiation metasurface according to claim 1 is characterized in that: The metasurface unit (2) satisfies the PB geometric phase condition, the transmission phase variation range covers 0 to 2π, and when an orthogonal linear polarization wave is incident, the reflection phase of the metasurface unit (2) satisfies the following formula: Among them, u and v represent the polarization directions of the orthogonal linearly polarized incident waves. and represents the co-polarized reflection phase; when the metasurface unit (2) is rotated counterclockwise by an angle β, the reflection phases for left-hand circularly polarized waves and right-hand circularly polarized waves are respectively and in, is the transmission phase, denoted by Φ PG , 2β is the PB geometric phase, denoted by Φ PB .

3. The spatial wave polarization control method based on the radiation metasurface according to claim 2 is characterized in that: The aperture field superposition method is used to superimpose different deflection phases on left-handed and right-handed circularly polarized waves to achieve multi-beam radiation with different polarizations.

4. A device for generating spatial waves and controlling polarization thereof based on a radiative metasurface, characterized in that: A method for controlling spatial wave polarization based on a radiative metasurface as claimed in any one of claims 1 to 3 is used, wherein the device comprises a feeding structure (1) and a metasurface, wherein a central opening of the metasurface is used to place the feeding structure (1), and the metasurface is composed of m*n periodically arranged metasurface units (2), where m and n are positive integers; Each of the metasurface units (2) comprises a dielectric substrate, a metasurface unit structure (21) and a metal floor; the metasurface unit structure (21) is arranged on the upper surface of the dielectric substrate, and the metal floor is arranged on the lower surface of the dielectric substrate; The metal floor is welded with an SMA connector (12); The feeding structure (1) is a monopole antenna, which is a coaxial probe (11) higher than the metasurface, and energy is input through an SMA connector (12) to excite surface waves; The metasurface unit (2) provides discontinuous phase changes, converts surface waves into space waves and controls their polarization states.

5. The device for generating spatial waves and controlling polarization thereof based on a radiation metasurface according to claim 4, characterized in that: The super surface unit structure (21) comprises a metal strip and two arc structures connected thereto, the inner and outer radii of each unit arc structure are the same, the width w of the metal strip varies in the range of 0.1 mm to 1.1 mm, and the opening angle α of the arc structure varies in the range of 10° to 110°.

6. The device for generating spatial waves and controlling polarization thereof based on a radiation metasurface according to claim 5, characterized in that: The dielectric substrate material is F4BM265.

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