An active metasurface antenna with coordinated polarization and pattern reconstruction

Abstract

This invention proposes an active metasurface antenna with coordinated polarization and pattern reconstruction, addressing the limitation of existing active metasurface antennas that can only achieve single-function reconstruction of polarization or pattern. The antenna includes a radiator and a feed source. The radiator comprises M×N active metasurface elements, each including a dielectric substrate and metal patches printed on the upper and lower surfaces of the substrate. Two active devices are orthogonally positioned outside the metal patch on the upper surface. The two ends of each active device are connected to an external bias circuit and a metal base plate via DC-biased metallized vias penetrating the dielectric substrate and short-circuit metallized vias, respectively. By applying different voltages through the DC-biased metallized vias, the impedance distribution of the interference pattern of the active metasurface elements in the radiator is controlled, achieving both polarization and pattern reconstruction. This invention realizes an active metasurface antenna with coordinated polarization and pattern reconstruction, applicable to the field of wireless communication.

Description

Technical Field

[0001] This invention belongs to the field of microwave technology and relates to a metasurface antenna, specifically an active metasurface antenna with coordinated polarization and pattern reconstruction, which can be used in the field of wireless communication. Background Technology

[0002] Polarization is one of the most fundamental characteristics of electromagnetic waves. Common polarization methods include linear polarization and circular polarization, with circular polarization further divided into left-handed and right-handed circular polarization. Different wireless communication systems have different requirements for electromagnetic wave polarization. For example, ground-to-satellite communication uses circularly polarized electromagnetic waves, while radar systems use two orthogonal linearly polarized or two orthogonal circularly polarized electromagnetic waves for detection and scanning.

[0003] With the rapid development of technology, wireless communication systems such as satellites are becoming increasingly multifunctional and miniaturized, placing higher demands on the customization of electromagnetic control equipment. Therefore, electromagnetic devices capable of simultaneously achieving multiple polarization states and beam pointing reconfiguration are of great significance to wireless communication systems such as satellite and radar detection. Existing active metasurface array antennas typically only achieve beam pointing reconfiguration or polarization state reconfiguration, making it difficult to achieve coordinated and independent reconfiguration of both beam and polarization. For example, patent application CN113517563 A, entitled "An Active Metasurface Beam Scanning Structure," discloses a beam reconfiguration antenna based on an active metasurface, comprising: multiple levels of active metasurfaces separated by air layers; metal pads connecting the metal rings on the outer surfaces of the two outermost dielectric substrates of each active metasurface level to the inner solid metal sheet for symmetrically loading varactor diodes. Changing the bias voltage of the varactor diodes adjusts their capacitance to obtain equal phase differences in the transmitted wave, thereby achieving an effective electronically scanned beam. This active metasurface antenna can only achieve beam pointing reconfiguration and cannot achieve polarization reconfiguration. Patent application CN114336077 A, entitled "A Polarization Reconfigurable Converter Based on an Active Metasurface," discloses a polarization reconfigurable antenna based on an active metasurface. This antenna element consists of a single metasurface element and a PIN diode. Each metasurface element comprises three metal layers, three dielectric layers, and a metallized via connecting the top and bottom layers. The polarization state of the reflected wave is controlled by controlling an external voltage. This active metasurface antenna only achieves two polarization reconfigurations, and beam reconfiguration is not possible. The active metasurface antenna in the above invention can only achieve single-function reconfiguration and cannot achieve coordinated reconfiguration of polarization and beam pointing. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the existing technology by proposing an active metasurface antenna with coordinated polarization and pattern reconstruction, aiming to realize the characteristics of multi-polarization reconstruction and pattern reconstruction of active metasurface array antennas.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An active metasurface antenna with coordinated polarization and pattern reconstruction includes a radiator 1 and a feed 2 located at the center of the radiator 1; the radiator 1 includes L×N active metasurface elements 11, where L≥2, N≥2, and wherein:

[0007] The active metasurface unit 11 includes a square dielectric substrate 111, a metal base plate 112 printed on the lower surface of the dielectric substrate 111, and a square or circular radiating patch 113 on the upper surface. The radiating patch 113 is provided with a DC bias metallized via 114 connected to an external bias circuit. Two orthogonally distributed active devices 115 are also provided at the edge of the radiating patch 113. The free ends of the active devices 115 are connected to the metal base plate 112 through short-circuit metallized vias 116 penetrating the dielectric substrate 111.

[0008] When different voltages are applied to the DC bias metallized via 114, the active device 115 will exhibit different operating states. The active metasurface element 11 will simultaneously possess a surface impedance that varies with the operating state of the active device 115, enabling adjustment of the interference pattern impedance distribution of the radiator 1, thereby achieving polarization and pattern reconstruction of the active metasurface antenna. Specifically, during the coordinated polarization and pattern reconstruction, the surface impedance Z of the active metasurface element 11 is present in the interference pattern impedance distribution of the reconstructed x-polarized pattern, y-polarized pattern, left-hand circularly polarized pattern, and right-hand circularly polarized pattern. co-x (x,y),Z cro-y (x,y),Z LCP (x,y) and Z RCP The formulas for calculating (x, y) are as follows:

[0009]

[0010] Where x and y represent the horizontal and vertical coordinates of the center of the active metasurface unit 11 relative to the feed source 2, respectively. s Let M be the average impedance of the active metasurface unit 11 under different operating states, and let M be the maximum impedance of the active metasurface unit 11 under different operating states and X be the average impedance of the active metasurface unit 11 under different operating states. s The difference, where k0 is the propagation constant in free space. θ0 represents the azimuth and elevation angles of the beam pointing, and k tLet φ(x,y) be the wave number of the surface wave propagating on the antenna surface, and let φ(x,y) be the angle between the active metasurface element 11 and the feed 2 in the azimuth plane.

[0011] In the above-mentioned active metasurface antenna with coordinated polarization and pattern reconstruction, the feed source 2 adopts a monopole antenna structure, and the center of the cylindrical conductor of the monopole antenna coincides with the center normal of the radiator 1.

[0012] In the aforementioned active metasurface antenna with coordinated polarization and pattern reconstruction, the active device 115 employs a varactor diode or a PIN diode.

[0013] In the aforementioned active metasurface antenna with coordinated polarization and pattern reconstruction, the DC bias metallized via 114 is located at the center of the radiating patch 113.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. This invention designs an active scalar metasurface unit using a metal patch with a circular or square upper surface patch, ensuring that the phase shift of the surface wave remains consistent in the orthogonal direction. This guarantees that the active metasurface unit is insensitive to the polarization state of electromagnetic waves, thereby enabling the reconstruction of four polarization states.

[0016] 2. In this invention, the surface impedance of the active metasurface unit is controlled by changing the voltage across the active device. The surface impedance of the active metasurface unit 11 in the interference pattern impedance distribution is calculated using the beam scanning formula for each polarization state. This enables the reconstruction of four polarization states and beam pointing of the active metasurface array antenna, solving the problem that existing active metasurface antennas can only achieve single-function reconstruction. It realizes the coordinated reconstruction of polarization and beam pointing of the active metasurface antenna. Attached Figure Description

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 (a) is a schematic diagram of the active metasurface unit structure of the present invention;

[0019] Figure 2 (b) is a schematic diagram of the upper surface of the active metasurface unit of the present invention;

[0020] Figure 3 (a) is the simulation result of x-polarized beam scanning of the present invention;

[0021] Figure 3 (b) shows the simulation results of the y-polarized beam scanning of the present invention;

[0022] Figure 4(a) is the simulation result of the left-hand circularly polarized beam scanning of the present invention;

[0023] Figure 4 (b) shows the simulation results of the left-handed circular polarization axial ratio of the present invention;

[0024] Figure 4 (c) shows the simulation results of the right-hand circularly polarized beam scanning of the present invention;

[0025] Figure 4 (d) is the simulation result of the right-hand circular polarization axial ratio of the present invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Reference Figure 1 The present invention includes a radiator 1 and a feed 2 located at the center of the radiator 1. The radiator 1 includes 20×20 active metasurface elements 11, and the feed 2 is a monopole antenna.

[0028] Reference Figure 2 (a) The active metasurface unit 11 includes a dielectric substrate 111, a first metal patch 112 printed on the lower surface of the dielectric substrate 111, and a radiating patch 113 on the upper surface; wherein the relative permittivity of the dielectric substrate is 2.2 and the thickness h = 3 mm.

[0029] Reference Figure 2 (b) The radiating patch 113 is provided with a DC bias metallized via 114 connected to an external bias circuit. Two varactor diodes are also provided at the edge of the radiating patch 113. The free ends of the varactor diodes are connected to the metal base plate 112 through a short-circuit metallized via 116 penetrating the dielectric substrate 111. The period of the active metasurface unit 21 is p = 10 mm, and the diameter of the metallized via is d1 = 0.3 mm. The DC bias metallized via 114 is located at the center of the square patch in the radiating patch 113, and its structural parameters are w1 = 0.5 mm, w2 = 2.5 mm, and w3 = 0.6 mm.

[0030] The working principle of the present invention is:

[0031] An active scalar metasurface unit was designed using a circular or square metal patch on its upper surface. This design ensures that the phase shift of the surface wave remains consistent in orthogonal directions, guaranteeing the insensitivity of the active metasurface unit to the electromagnetic wave polarization state. The active device is a varactor diode with a capacitance value ranging from 0.032 pF to 0.144 pF. The dispersion curves of the active scalar metasurface unit under different capacitance values ​​were calculated using intrinsic modes, and the surface impedance of the active scalar metasurface unit under different capacitance values ​​was then calculated. The formula for calculating the surface impedance of the metasurface unit is as follows:

[0032]

[0033] Where η0 is the free-space wave impedance, φ is the surface wave phase shift of the active metasurface unit 11, c is the speed of light, and w is the angular frequency of the antenna operation. Therefore, based on the relationship between the capacitance of the varactor diode and the voltage, the relationship between the applied voltage (in volts) and the surface impedance of the active scalar metasurface unit can be obtained.

[0034] Assuming that only the beam direction is considered when calculating the impedance distribution of the interferogram of the radiator, the surface impedance of each metasurface unit is calculated using the following formula:

[0035]

[0036] At this point, the metasurface will generate vector vortex waves under the excitation of monopoles. Therefore, by introducing the superposition of antiphase states when calculating the impedance of the metasurface units in half of the metasurface region, the linear polarization can be reconstructed; by superimposing the phases of the vortex waves on the metasurface, the left and right circular polarizations can be reconstructed.

[0037] Therefore, when performing polarization and pattern co-reconstruction, the surface impedance Z of the active metasurface unit is present in the impedance distribution of the interference pattern reconstructed from the x-polarization pattern, y-polarization pattern, left-hand circular polarization pattern, and right-hand circular polarization pattern. x (x,y),Z y (x,y),Z LCP (x,y) and Z RCP The formulas for calculating (x, y) are as follows:

[0038]

[0039] In this invention, four linearly related surface impedance values ​​are calculated by varying the capacitance of a varactor diode, corresponding to four different voltage changes. Therefore, based on the surface impedance of the active metasurface unit, by discretizing it to the impedance closest to its own surface impedance value, the corresponding voltage can be obtained, thus realizing the polarization and pattern reconstruction of the active metasurface antenna.

[0040] The technical effects of the present invention will be further illustrated by the following simulation experiments.

[0041] 1. Simulation conditions and content.

[0042] The simulation experiments conducted below based on the embodiments of the present invention were all completed using CST MICROWAVE STUDIO simulation software.

[0043] Simulation 1 simulates the linearly polarized beam scanning of the active metasurface antenna in this embodiment of the invention. The simulation results are as follows: Figure 3 As shown in (a) and 3(b);

[0044] Simulation 2 simulates the circularly polarized beam scanning of the active metasurface antenna in this embodiment of the invention. The simulation results are as follows: Figure 4 As shown in (a), 4(b), 4(c) and 4(d);

[0045] 2. Simulation Result Analysis

[0046] Reference Figure 3 (a) In this embodiment of the invention, by changing the impedance distribution of the radiator interferogram, the beam pointing simulation of the x-polarization pattern at 0 degrees and 30 degrees is realized at the working frequency.

[0047] Reference Figure 3 (b) In this embodiment of the invention, by changing the impedance distribution of the radiator interferogram, the beam pointing simulation of the y-polarization pattern at 0 degrees and 30 degrees is realized at the operating frequency.

[0048] Reference Figure 4 In embodiments (a) and (b), by changing the impedance distribution of the radiator interferogram, left-hand circular polarization beam pointing simulation at 0 degrees and 30 degrees is achieved at the operating frequency, and the axial ratio at the beam pointing point is less than 3dB.

[0049] Reference Figure 4 (c) and 4(d) In the embodiments of the present invention, by changing the impedance distribution of the radiator interferogram, right-hand circular polarization beam pointing simulation at 0 degrees and 30 degrees is achieved at the working frequency, and the axial ratio at the beam pointing is less than 3dB.

[0050] The above description is only a preferred embodiment of the present invention and does not constitute a limitation on the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the innovative concept of the present invention, but these changes all fall within the protection scope of the present invention.

Claims

1. An active metasurface antenna with coordinated polarization and pattern reconstruction, comprising a radiator (1) and a feed (2) located at the center of the radiator (1); the radiator (1) comprises L×N active metasurface elements (11), where L≥2 and N≥2, characterized in that: The active metasurface unit (11) includes a dielectric substrate (111) with a square surface, a metal base plate (112) printed on the lower surface of the dielectric substrate (111), and a radiating patch (113) with a square or circular shape on the upper surface. The radiating patch (113) is provided with a DC bias metallized via (114) connected to an external bias circuit. Two orthogonally distributed active devices (115) are also provided at the edge of the radiating patch (113). The free ends of the active devices (115) are connected to the metal base plate (112) through short-circuit metallized vias (116) that penetrate the dielectric substrate (111). When different voltages are applied to the DC bias metallized via (114), the active device (115) will exhibit different operating states. The active metasurface unit (11) will also have a surface impedance that varies with the operating state of the active device (115), which can adjust the interference pattern impedance distribution of the radiator (1), thereby realizing the polarization and pattern reconstruction of the active metasurface antenna. Among them, the surface impedance Z of the active metasurface unit (11) is in the interference pattern impedance distribution of the x-polarized pattern, y-polarized pattern, left-hand circularly polarized pattern and right-hand circularly polarized pattern during the coordinated reconstruction of polarization and pattern. co-x (x,y),Z cro-y (x,y),Z LCP (x,y) and Z RCP The formulas for calculating (x, y) are as follows: Where x and y represent the horizontal and vertical coordinates of the center of the active metasurface unit (11) relative to the feed source (2), respectively. s M represents the average impedance of the active metasurface unit (11) under different operating states, and M represents the maximum impedance of the active metasurface unit (11) under different operating states and X. s The difference, where k0 is the propagation constant in free space. θ0 and θ0 are the azimuth and elevation angles of the beam pointing, respectively, and k t φ is the wave number of the surface wave propagating on the antenna surface, and φ(x,y) is the angle between the active metasurface element (11) and the feed (2) in the azimuth plane.

2. The active metasurface antenna with coordinated polarization and pattern reconstruction according to claim 1, characterized in that, The feed source (2) adopts a monopole antenna structure, and the center of the cylindrical conductor of the monopole antenna coincides with the center normal of the radiator (1).

3. The active metasurface antenna with coordinated polarization and pattern reconstruction according to claim 1, characterized in that, The active device (115) is a varactor diode or a PIN diode.

4. The active metasurface antenna with coordinated polarization and pattern reconstruction according to claim 1, characterized in that, The DC bias metallized via (114) is located at the center of the radiating patch (113).

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