Multi-beam multi-polarized transmission array antenna with arbitrary adjustable radiation direction and design method

Abstract

The application discloses a multi-beam multi-polarization transmission array antenna with an arbitrary adjustable radiation direction and a design method. The multi-beam multi-polarization transmission array antenna with an arbitrary adjustable radiation direction comprises a super surface and a feed source, the feed source is arranged separately from the super surface, a plurality of super surface units are arranged periodically on the super surface to form an array structure, and the super surface units are quasi-anisotropic super surface units. Generalized phase superposition is utilized to make the super surface antenna radiate four high-gain beams with different polarization modes simultaneously, including four polarization modes of double linear polarization and double circular polarization. The super surface antenna can obtain stable multi-beam multi-polarization radiation characteristics.

Description

TECHNICAL FIELD

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

[0002] Metasurfaces have certain superior properties that natural materials do not have, enabling them to effectively modulate electromagnetic wave propagation characteristics. 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 more 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 multi-functional integration capabilities. However, existing multi-polarization array designs are limited to single-polarization or dual-polarization modes, and cannot achieve more rich polarization multiplexing effects. SUMMARY

[0003] The purpose of the present application is to overcome the deficiencies and shortcomings of the prior art and provide a multi-beam multi-polarization transmission array antenna with an arbitrarily adjustable radiation direction and a design method. The multi-beam multi-polarization metasurface antenna of the present application not only enables multiple high-gain beams to be obtained, but also enables the polarization mode of each beam to be independently adjustable, and the radiation direction of each beam to be more demand-designed, thereby greatly improving the application scenarios of the antenna

[0004] A multi-beam multi-polarization transmission array antenna with an arbitrarily adjustable radiation direction, comprising a metasurface and a feed source, the feed source being arranged separately from the metasurface, a plurality of metasurface units being periodically arranged on the metasurface to form an array structure, the metasurface units being quasi-anisotropic metasurface units; the use of generalized phase superposition enables the metasurface antenna to simultaneously radiate four high-gain beams with different polarization modes, including double linear polarization and double circular polarization.

[0005] wherein the compensation phase on the array surface is obtained by the following formula:

[0006]

[0007] wherein 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 position coordinate of the feed antenna, and φ0 is the reference phase, which is any value in 0°-360°.

[0008] wherein the process of the generalized phase superposition is calculated by:

[0009]

[0010] wherein E t (m,n) represents the transmission 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] wherein wherein E t x (m,n) represents the transmission 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. t y (m,n) is superimposed by the following formula:

[0012]

[0013] wherein A1, A2, and A3 represent the amplitude distribution of the metasurface unit under different functions, respectively, and φ x1 , φ y1， , φ x2 , φ y2 , φ x3 , φ y3 represent the phase response of the metasurface unit to x-polarized and y-polarized waves under different functions, respectively; E t x (m,n) represents the transmission 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. t y (m,n) represents the transmission 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.

[0014] wherein the transmission amplitude of the metasurface unit to x-polarized and y-polarized waves is above -2dB.

[0015] wherein the metasurface unit comprises 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 the top, and the lengths are l x and l y ; by independently adjusting the sizes of l x and l y , the metasurface unit can exhibit different transmission amplitude responses to x and y polarized electromagnetic waves.

[0016] wherein the dielectric substrates are all F4B, and the thicknesses are all h t , and the width of the cross-shaped metal patch is wx and w y are equal.

[0017] In a second aspect, the present application provides a design method of a multi-beam multi-polarized transmission array antenna with arbitrary adjustable radiation direction, comprising the following steps:

[0018] Setting a target phase distribution φ x (x m ,y n ), φ y (x m ,y) n ;

[0019] Establishing a unit library composed of metasurface units through CST simulation:

[0020] Judging whether the transmission amplitudes of the metasurface units in the unit library to x-polarized and y-polarized waves are greater than a threshold value; if yes, searching for an optimal phase, and after finding the optimal phase, outputting the optimal size of the metasurface unit and ending; if not, re-establishing a 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] In the formula, P x (l x ,l y ) and P y (l x ,l y ) represent the actual phase compensation of the metasurface unit to x-polarized and y-polarized waves.

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

[0025] The application is based on the generalized phase superposition principle, and the influence of the radiation direction and the reference phase on the transmission beam is considered, so that the radiation direction and the polarization mode of each beam of the metasurface are independently adjusted; based on the quasi-anisotropic metasurface unit, and considering the phase compensation in two orthogonal polarization directions, the designed metasurface aperture can effectively reduce the phase compensation error. The simulation and test results show that the metasurface antenna of the application can obtain stable multi-beam and multi-polarization radiation characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a multi-beam metasurface structure and its radiation schematic diagram of the application;

[0027] Figure 2A 、 Figure 2B are respectively the x-polarization phase and the y-polarization phase of the metasurface antenna of the application.

[0028] Figure 3A 、 Figure 3B are respectively the three-dimensional structure and the front view structure diagram of the metasurface unit of the metasurface antenna of the application.

[0029] Figure 4 is a design flowchart of the metasurface antenna structure.

[0030] Figure 5A 、 Figure 5B 、 Figure 5C are respectively the simulation radiation patterns of the x-polarization feed excitation, the y-polarization feed excitation and the ±45° polarization feed excitation of the metasurface antenna of the application. DETAILED DESCRIPTION

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

[0032] The antenna of the application arranges simple quasi-anisotropic units, and uses the generalized phase superposition principle, so that the designed metasurface antenna can radiate four high-gain beams with different polarization modes, including double linear polarization and double circular polarization.

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

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

[0035]

[0036] where k0=2π / λ0 is the wave number in free space, 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 at each position on the metasurface aperture, (x f ,y f ,z f ) is the position coordinate of the feed antenna, and φ0 is the reference phase, which is selected as any value from 0° to 360°. 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] To obtain the multi-beam and multi-polarization radiation characteristics, the generalized phase superposition principle is used in the present application, and the superposition process can be calculated by the following formula:

[0038]

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

[0040] In the present application, the transmission electric fields (E t x (m,n), E t y (m,n)) of x-polarized and y-polarized waves are considered simultaneously, and the two electric field components are superimposed with three high-gain beam phase distributions having different radiation directions, respectively, and the superposition process is calculated by equations (3-4).

[0041]

[0042] where A i represents the amplitude distribution of the unit 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 shown in equations (5-6). Figure 2A 、 Figure 2B

[0043] Based on the target phase distribution, the present application uses a quasi-anisotropic unit to form an array, and the structure of the unit is as shown in​Figure 3A , Figure 3B As shown. This unit uses a 5-layer dielectric substrate, such as F4B, with a thickness of h. t The period of the quasi-anisotropic cell is P. Each dielectric substrate has cross-shaped metal patches at the bottom and top, with a patch width w. x and w y They are equal, and their lengths are l respectively. x and l y By independently adjusting l x and l y The size of this quasi-anisotropic element allows it to exhibit different transmission amplitude responses to x- and y-polarized electromagnetic waves. This distinguishes it from traditional isotropic elements, giving it quasi-anisotropic characteristics. Since this element cannot provide perfect phase compensation, this invention proposes a novel array scheme, the design flowchart of which is shown below. Figure 4 As shown.

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

[0045] The antenna in this embodiment of the invention is formed by an array of quasi-anisotropic metasurface elements. The transmission amplitude and phase response of the independently controlled elements to orthogonally linearly polarized electromagnetic waves are controlled. Then, according to the generalized phase superposition principle, the phase distribution of the array surface corresponding to the multi-beam multi-polarization radiation pattern is solved. Based on the target phase distribution on the array surface, a suitable metasurface element array is selected to reduce the phase error on the array surface. Finally, a linearly polarized feed antenna is selected and placed at 45° to the array surface. The designed metasurface antenna can simultaneously radiate four high-gain beams with different polarization modes, meeting the requirements of complex mobile communication networks with multiple polarizations and multiple user terminals.

[0046] Figure 5A , Figure 5B , Figure 5C The radiation patterns of the designed metasurface under different polarization feed excitations are shown. In the simulation, the metasurface used a five-layer dielectric substrate, model F4B, with a dielectric constant of 2.65, a loss tangent of 0.001, and a thickness of 0.762 mm. The focal diameter ratio (F / D) of the antenna was 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, with the four beams having x-polarization, y-polarization, left-hand circular polarization, and right-hand circular polarization, respectively, exhibiting excellent polarization multiplexing capability.

[0048] The foregoing merely illustrates the principles of the application and application of its more particular aspects and embodiments. This description and the examples have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed. Modifications and variations are possible in light of the above teachings or can be acquired from practice of the application. Other embodiments and aspects of the application will offer themselves to those skilled in the art upon consideration of this description. For instance, it will be appreciated that the application is not limited to the specific embodiments described herein but includes any and all implementations which fall within the scope of the appended claims and their equivalents.

[0049] It is therefore intended that the application not be limited to the particular embodiment described and illustrated herein, but that it is being embodied in other forms without departing from the spirit or essential characteristics thereof. The particular embodiments are to be considered in their functional and / or compositional equivalents and not in a restrictive sense.

[0050] Furthermore, it is to be understood that the application can be carried out by specifically different embodiments and that each described embodiment need not have all the characteristics of the claimed application. In particular, each embodiment described in the specification of the application can be combined with other embodiments described in the specification of the application. Furthermore, it is to be understood that the application is not limited to the particular details described and / or illustrated herein. It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A multi-beam multi-polarized transmit array antenna with arbitrary steerable radiation direction, characterized in that, The application relates to a metasurface and a feed source, the feed source being arranged separately from the metasurface, a plurality of metasurface units being arranged periodically on the metasurface to form an array structure, the metasurface units being quasi-anisotropic metasurface units; the metasurface antenna radiates four high-gain beams with different polarization modes simultaneously by using generalized phase superposition, including double linear polarization and double circular polarization. The compensation phase on the array surface is obtained by the following formula: where k0= 2π / λ0 is the wave number in free space, λ0is the wavelength, φ out ,θ out are the high-gain beam radiation directions, x m ,y n are the coordinates of the metasurface unit at each position on the metasurface aperture, x f ,y f ,z f are the coordinates of the feed antenna position, φ0is the reference phase, which is any value in 0°-360°; The process of the generalized phase superposition is calculated by the following formula: where E t (m, n) represents the super surface unit transmission electric field distribution, the subscripts t and s represent the super surface unit parameters under all functions and the unit parameters under a single function, T is the number of superposed functions, a(m, n) and φ(m, n) represent the amplitude and phase distribution of the super surface unit, and j is the imaginary unit; where the transmitted electric field of the x-polarized and y-polarized waves The superposition of the various functions is performed by the following equation: where A1, A2, A3 represent the amplitude distribution of the metasurface unit under different functions, respectively x1 , φ y1， , φ x2 , φ y2 , φ x3 , φ y3 respectively represent the phase response of the metasurface unit to x-polarized and y-polarized waves under different functions; respectively represent the transmission electric field of x-polarized and y-polarized waves, and j is the imaginary unit; 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 the top, and the lengths are l x and l y ; by independently adjusting the sizes of l x and l y , the metasurface unit can present different transmission amplitude responses to x and y polarized electromagnetic waves.

2. The multi-beam multi-polarized transmit array antenna with arbitrary 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 greater than -2dB.

3. The multi-beam multi-polarized transmit array antenna with arbitrary adjustable radiation direction according to claim 1, characterized in that, The medium substrates are each F4B, and each has a thickness h t The width w of the cross-shaped metal patch x and w y are equal.

4. The method of designing a multi-beam multi-polarized transmit array antenna with arbitrary steerable radiation direction according to any one of claims 1-3, characterized in that, The application further relates to a method for designing a metasurface antenna, comprising the following steps: Setting a target phase distribution φ x (x m ,y n ), φ y (x m ,y) n ; A unit library of metasurface units is established by CST simulation; Whether the transmission amplitude of the metasurface unit in the unit library to x-polarized and y-polarized waves is greater than a threshold value is judged; if yes, the optimal phase is searched, and after the optimal phase is found, the optimal size of the metasurface unit is outputted, and the process is ended; if not, the unit library of metasurface units is re-established by CST simulation.

5. The method of claim 4, wherein the radiation direction is arbitrarily adjustable. The optimal phase is searched by minimizing the following target function: Min ||0.5 x (φ x (x m ,y n )-P x (l x ,l y ))|+|0.5 x (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 ) represent the actual phase compensation of the metasurface unit for x-polarized and y-polarized waves, respectively.

6. The method of claim 4, wherein the radiation direction is arbitrarily adjustable. The threshold value is -2dB.

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