Multi-beam multi-polarization transmission array antenna with randomly adjustable radiation direction and design method

Abstract

The invention discloses a multi-beam multi-polarization transmission array antenna with randomly adjustable radiation direction and a design method. The multi-beam multi-polarization transmission array antenna with the randomly adjustable radiation direction comprises a metasurface and a feed source, the feed source and the metasurface are arranged in a spaced mode, a plurality of metasurface units are periodically arranged on the metasurface to form an array structure, and the metasurface units are quasi-anisotropic metasurface units; generalized phase superposition is utilized, so that the metasurface antenna radiates four high-gain wave beams with different polarization modes at the same time, and the four polarization modes include dual-linear polarization and dual-circular polarization. The metasurface antenna can obtain stable multi-beam multi-polarization radiation characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-beam multi-polarization metasurface antennas, and in particular to a multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction and a design method thereof. Background Art

[0002] Metasurfaces have certain superior properties that natural materials do not have, enabling them to effectively modulate the propagation characteristics of electromagnetic waves. Space-fed antennas based on metasurfaces are mainly divided into two categories: transmission arrays and reflection arrays. Whether it is a transmission array or a reflection array, current research mainly focuses on single-beam design. This design can only provide signal coverage for a specific area at the same time, and cannot support wider coverage, more channels or multiple links in real time. In order to establish communication links with more terminals and achieve full-space electromagnetic coverage, multi-beam transmission arrays / reflection arrays have become an effective design solution due to their multifunctional integration capabilities. However, the existing multi-polarization array design is limited to single-polarization or dual-polarization modes, and cannot achieve richer polarization multiplexing effects. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings and defects of the prior art and to provide a multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction and a design method. The multi-beam multi-polarization metasurface antenna of the present invention can not only obtain multiple high-gain beams, but also the polarization mode of each beam can be independently adjusted, and the radiation direction of each beam can also be designed more according to requirements, which can greatly improve the application scenarios of the antenna.

[0004] A multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction comprises a metasurface and a feed source, wherein the feed source is arranged separately from the metasurface, a plurality of metasurface units are periodically arranged on the metasurface to form an array structure, and the metasurface units are quasi-anisotropic metasurface units; by utilizing generalized phase superposition, the metasurface antenna simultaneously radiates four high-gain beams with different polarization modes, including four polarization modes of dual linear polarization and dual circular polarization.

[0005] Among them, the compensation phase on the array is obtained by the following formula:

[0006]

[0007] Where k0 = 2π / λ0 is the wave number in free space, λ0 is the wavelength, φ out ,θ out is the high gain beam radiation direction, x m ,y n is the coordinate of the metasurface unit at each position on the metasurface aperture, x f ,y f ,z fis the feed antenna position coordinate, φ0 is the reference phase, which can be any value between 0°–360°.

[0008] The generalized phase superposition process is calculated as follows:

[0009]

[0010] Among them, E t (m,n) represents the transmitted electric field distribution of the metasurface unit, the subscripts t and s represent the metasurface unit parameters under all functions and the unit parameters under a single function, T is the number of superimposed functions, a(m,n) and φ(m,n) represent the amplitude and phase distribution of the metasurface unit, and j is the imaginary unit.

[0011] Among them, the transmitted electric field E of x-polarized and y-polarized waves is t x (m,n),E t y (m,n) can perform multiple functions by superposition through the following formula:

[0012]

[0013] Among them, A1, A2, and A3 represent the amplitude distribution of the metasurface unit under different functions, φ x1 ,φ y1， ,φ x2 ,φ y2 ,φ x3 ,φ y3 They represent the phase responses of the metasurface unit to x-polarized and y-polarized waves under different functions; E t x (m,n),E t y (m,n) are the transmitted electric fields of x-polarized and y-polarized waves respectively, and j is an imaginary unit.

[0014] Wherein, the transmission amplitude of the metasurface unit for x-polarized and y-polarized waves is both above -2dB.

[0015] The metasurface unit includes five layers of dielectric substrates, and the period of the unit is P; each layer of dielectric substrate has a cross-shaped metal patch at the bottom and top, with a length of l x and l y ; By independently adjusting l x and l y The size of the metasurface unit enables it to present different transmission amplitude responses to x- and y-polarized electromagnetic waves.

[0016] Among them, the dielectric substrates are all F4B, and the thickness is h t , the width w of the cross-shaped metal patchx and w y equal.

[0017] A second aspect of the present invention provides a method for designing a multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction, comprising the following steps:

[0018] Set the target phase distribution φ x (x m ,y n ), φ y (x m ,y) n ;

[0019] Establish a cell library composed of metasurface units through CST simulation:

[0020] Determine whether the transmission amplitude of the metasurface unit in the unit library for x-polarization and y-polarization waves is greater than the threshold; if so, search for the optimal phase, and after finding the optimal phase, output the optimal size of the metasurface unit and end; if not, re-establish the unit library composed of metasurface units through CST simulation.

[0021] Wherein, when searching for the optimal phase, it is obtained by minimizing the following objective function:

[0022] Min||0.5×(φ x (x m ,y n )-P x (l x ,l y ))|+|0.5×(φ y (x m ,y n )-P y (l x ,l y ))||;

[0023] Where P x (l x ,l y ) and P y (l x ,l y ) represents the actual phase compensation of the metasurface unit for x-polarized and y-polarized waves.

[0024] Wherein, the threshold is -2dB.

[0025] The present invention is based on the principle of generalized phase superposition, and considers the influence of radiation direction and reference phase on the transmitted beam at the same time, so as to realize independent adjustment of the radiation direction and polarization mode of each beam of the metasurface; based on the quasi-anisotropic metasurface unit, and considering the phase compensation in two orthogonal polarization directions at the same time, the designed metasurface aperture can effectively reduce the phase compensation error. Simulation and test results show that the metasurface antenna of the present invention can obtain stable multi-beam multi-polarization radiation characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the multi-beam metasurface structure and radiation thereof of the present invention;

[0027] Figure 2A , Figure 2B They are respectively the array phase distribution diagrams of the x-polarization phase and the y-polarization phase of the metasurface antenna of the present invention;

[0028] Figure 3A , Figure 3B They are respectively a three-dimensional structure and a front view structure diagram of a super-surface unit of a super-surface antenna of the present invention;

[0029] Figure 4 It is a design flow chart of the metasurface antenna structure.

[0030] Figure 5A , Figure 5B , Figure 5C They are respectively the simulated radiation patterns of the x-polarized feed excitation, the y-polarized feed excitation, and the ±45° polarized feed excitation of the supersurface antenna of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The antenna of the present invention is arranged using simple quasi-anisotropic units. By utilizing the generalized phase superposition principle, the designed metasurface antenna can simultaneously radiate four high-gain beams with different polarization modes, including dual linear polarization and dual circular polarization.

[0033] Figure 1 The multi-beam multi-polarization metasurface antenna structure and its radiation schematic diagram of the present invention. The antenna proposed in the present invention mainly consists of two parts: a metasurface and a feed source.

[0034] In order to obtain a high-gain beam, after determining the aperture D of the metasurface and the distance F from the feed source to the metasurface, the compensation phase φ(x m ,y n ) can be calculated by the following formula:

[0035]

[0036] Among them, k0 = 2π / λ0 is the wave number in space only, λ0 is the wavelength, (φ out ,θ out ) is the radiation direction of the high-gain beam, (x m ,y n ) is the unit coordinate of each position on the metasurface aperture, (x f ,y f ,z f ) is the position coordinate of the feed antenna, φ0 is the reference phase, and any value between 0° and 360° is selected. Therefore, for a single-beam metasurface antenna, when the radiation direction (φ out ,θ out ) and the reference phase φ0 are determined, the phase distribution φ(x m ,y n ) can be determined.

[0037] In order to obtain multi-beam multi-polarization radiation characteristics, the present invention uses the generalized phase superposition principle, and the superposition process can be calculated by the following formula:

[0038]

[0039] Among them, E t (m,n) represents the transmitted electric field distribution, the subscripts t and s represent the unit parameters under all and single functions, T is the number of superimposed functions, and a(m,n) and φ(m,n) represent the amplitude and phase distribution of the unit.

[0040] In the present invention, the transmission electric field (E t x (m,n),E t y (m,n)), the two electric field components are superimposed with three high-gain beam phase distributions with different radiation directions, and the superposition process is calculated by equation (3-4).

[0041]

[0042] Among them, A i represents the amplitude distribution of units under different functions, φ xi Represents φ yi Represents the phase response of the unit to x-polarized and y-polarized waves. After the generalized phase superposition process, the target phase distribution of the array to x-polarized and y-polarized waves is as follows: Figure 2A , Figure 2B shown.

[0043] Based on the target phase distribution, the present invention adopts a quasi-anisotropic unit to form an array, and the structure of the unit is as follows: Figure 3A , Figure 3B The unit uses a 5-layer dielectric substrate, such as F4B, with a thickness of h t The period of the quasi-anisotropic unit is P. There are cross-shaped metal patches at the bottom and top of each dielectric substrate. The width of the patch is w. x and w y are equal, and their lengths are l x and l y . By independently adjusting l x and l y The quasi-anisotropic unit can present different transmission amplitude responses to x- and y-polarized electromagnetic waves. This makes the unit different from the traditional isotropic unit and has quasi-anisotropic characteristics. Since this unit cannot provide perfect phase compensation, the present invention proposes a new array scheme, and its design flow chart is as follows: Figure 4 shown.

[0044] During the design process, it is necessary to ensure that the transmission amplitude of the metasurface unit for x-polarized and y-polarized waves is above -2dB, and optimize the optimal unit size distribution at each coordinate of the array to reduce the phase compensation error of the array.

[0045] The antenna of the embodiment of the present invention is formed based on a quasi-anisotropic metasurface unit array, and independently controls the transmission amplitude and phase response of the unit to orthogonal linearly polarized electromagnetic waves; then, according to the generalized phase superposition principle, the array phase distribution corresponding to the multi-beam multi-polarization radiation pattern is solved, and the target phase distribution on the array is further considered, and a suitable metasurface unit array is selected to reduce the phase error on the array; finally, a linearly polarized feed antenna is selected and placed at 45° to the array. The designed metasurface antenna can simultaneously radiate four high-gain beams with different polarization modes, meeting the needs of complex mobile communication networks with multi-polarization and multi-user terminals coexisting.

[0046] Figure 5A , Figure 5B , Figure 5C The radiation patterns of the designed metasurface under different polarization feed excitations are shown. In the simulation process, the metasurface uses a five-layer dielectric substrate, model F4B, with a dielectric constant of 2.65, a loss tangent of 0.001, a thickness of 0.762mm, and a focal diameter ratio (F / D) of 0.78.

[0047] When the metasurface is excited by an x-polarized feed antenna, the antenna can radiate three x-polarized high-gain beams. When the metasurface is excited by a y-polarized feed antenna, the antenna can radiate three y-polarized high-gain beams. When the metasurface is excited by a ±45° polarized feed antenna, the antenna can radiate four high-gain beams, and the polarization modes of the four beams are x-polarization, y-polarization, left-hand circular polarization, and right-hand circular polarization, respectively, with excellent polarization multiplexing capability.

[0048] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0049] Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is therefore intended that all changes falling within the meaning and range of equivalent elements of the claims are included in the present invention.

[0050] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction, characterized in that: It includes a metasurface and a feed source, wherein the feed source is arranged separately from the metasurface, and a plurality of metasurface units are periodically arranged on the metasurface to form an array structure, and the metasurface units are quasi-anisotropic metasurface units; by utilizing generalized phase superposition, the metasurface antenna simultaneously radiates four high-gain beams with different polarization modes, including four polarization modes of dual linear polarization and dual circular polarization.

2. The multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 1, characterized in that: The compensation phase on the array is obtained by the following formula: Where k0 = 2π / λ0 is the wave number in free space, λ0 is the wavelength, φ out ,θ out is the high gain beam radiation direction, x m ,y n is the coordinate of the metasurface unit at each position on the metasurface aperture, x f ,y f ,z f is the feed antenna position coordinate, φ0 is the reference phase, which can be any value between 0°–360°.

3. The multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 2, characterized in that: The generalized phase superposition process is calculated as follows: Among them, E t (m,n) represents the transmitted electric field distribution of the metasurface unit, the subscripts t and s represent the metasurface unit parameters under all functions and the unit parameters under a single function, T is the number of superimposed functions, a(m,n) and φ(m,n) represent the amplitude and phase distribution of the metasurface unit, and j is the imaginary unit.

4. The multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 3, characterized in that: in, Transmitted electric field E of x-polarized and y-polarized waves t x (m,n),E t y (m,n) can perform multiple functions by superposition through the following formula: Among them, A1, A2, and A3 represent the amplitude distribution of the metasurface unit under different functions, φ x1 ,φ y1， ,φ x2 ,φ y2 ,φ x3 ,φ y3 They represent the phase responses of the metasurface unit to x-polarized and y-polarized waves under different functions; E t x (m,n),E t y (m,n) are the transmitted electric fields of x-polarized and y-polarized waves respectively, and j is an imaginary unit.

5. The multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 1, characterized in that: The transmission amplitude of the metasurface unit to x-polarized and y-polarized waves is both above -2dB.

6. The multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 1, characterized in that: The metasurface unit comprises five layers of dielectric substrates, and the period of the unit is P; the bottom and top of each layer of dielectric substrate are provided with cross-shaped metal patches, and the lengths are l x and l y ; By independently adjusting l x and l y The size of the metasurface unit enables it to present different transmission amplitude responses to x- and y-polarized electromagnetic waves.

7. The multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 6, characterized in that: The dielectric substrates are all F4B, and the thickness is h t , the width w of the cross-shaped metal patch x and w y equal.

8. A design method for a multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction, characterized in that: The steps include: Set the target phase distribution φ x (x m ,y n ), φ y (x m ,y) n ; Establish a cell library composed of metasurface units through CST simulation: Determine whether the transmission amplitude of the metasurface unit in the unit library for x-polarization and y-polarization waves is greater than the threshold; if so, search for the optimal phase, and after finding the optimal phase, output the optimal size of the metasurface unit and end; if not, re-establish the unit library composed of metasurface units through CST simulation.

9. The design method of the multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 8 is characterized in that: When searching for the optimal phase, the following objective function is minimized: Min||0.5×(φ x (x m ,y n )-P x (L x ,L y ))|+|0.5×(φ y (x m ,y n )-P y (L x ,L y ))||; Where P x (l x ,l y ) and P y (l x ,l y ) represents the actual phase compensation of the metasurface unit for x-polarized and y-polarized waves.

10. The design method of the multi-beam multi-polarization transmission array antenna with arbitrarily adjustable radiation direction according to claim 8, characterized in that: The threshold is -2dB.

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