Energy distribution control method for quasi-bessel beams based on a vortex feed

Abstract

The energy distribution regulation method of the quasi-Bessel beam based on the vortex feed source comprises the following steps: step 1, setting the beam parameters of the quasi-Bessel beam generated by the electromagnetic super surface, for calculating the array scale of the electromagnetic super surface and designing the vortex feed source; step 2, designing the parameters of the vortex feed source, obtaining the vortex feed source; step 3, calculating the array scale of the electromagnetic super surface, for the design of the electromagnetic super surface; step 4, according to the phase compensation design of the set beam parameters of the quasi-Bessel beam and the parameters of the vortex feed source, constructing the super surface; step 5, exciting the vortex feed source with radio frequency, realizing the feed of the vortex wave to the electromagnetic super surface, and generating the quasi-Bessel beam with controllable energy distribution. The application controls the electric field intensity distribution of the vortex wave generated by the vortex feed source, and uses the electromagnetic super surface to compensate the phase of the generated vortex electromagnetic wave, so that the energy distribution regulation of the quasi-Bessel beam is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless transmission, and particularly relates to an energy distribution regulation method of quasi-Bessel beam based on a vortex feed source. BACKGROUND

[0002] With the development of the electronic information industry, more and more electronic devices need to use wireless transmission technology to facilitate energy and information transmission for the devices. Wireless energy transmission technology includes inductive energy transmission, resonant energy transmission and radiative wireless energy transmission. Radiative wireless energy transmission has the advantages of long working distance and easy combination with communication systems. Its common application is to use a high-gain antenna to form a high-gain beam. However, due to the divergence characteristics of the electromagnetic wave far field, a large aperture is required for the receiving antenna to ensure good transmission efficiency.

[0003] The working range of quasi-Bessel beam is in the radiation near field region, which can concentrate energy in a range of the radiation near field region, and can minimize the receiving aperture while ensuring transmission efficiency. At the same time, its transmission distance is relatively improved compared with magnetic induction and magnetic resonance.

[0004] Among them, Bessel beam is a typical non-diffracting beam, which is widely used in the field of wireless transmission. The orthogonal characteristics of different modes of high-order quasi-Bessel beam can provide a new dimension for wireless communication, further improving the spectral efficiency and channel capacity of electromagnetic waves. Currently, quasi-Bessel beam can be generated by electromagnetic super surface, lens and other methods.

[0005] A method for generating Bessel beam is disclosed in the patent document "A broadband lens for generating deflected Bessel multi-beam and regulation method" (application number: 202210146873.8, application publication number: CN 114465012A) applied by South China Institute of Technology. The method generates a spherical wave to illuminate the super surface unit by a horn feed source, and uses the super surface to compensate the phase to form multiple Bessel beams on one side of the super surface unit. However, the design method still has the following shortcomings: since the method is generated by a traditional horn feed, the energy distribution of the feed source is fixed, so it is difficult to regulate the energy distribution of the generated quasi-Bessel beam.

[0006] In the existing non-diffracting beam generation method, the energy distribution regulation of quasi-Bessel beam has not been realized. SUMMARY

[0007] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide an energy distribution regulation method of quasi-Bessel beam based on vortex feed, which controls the divergence angle of vortex wave generated by the vortex feed by adjusting the radius and mode of the vortex feed, thereby controlling the electric field intensity distribution of the vortex wave, and uses electromagnetic super surface to compensate the phase of the generated vortex electromagnetic wave, so as to realize the energy distribution regulation of quasi-Bessel beam.

[0008] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0009] The energy distribution regulation method of quasi-Bessel beam based on vortex feed comprises the following steps:

[0010] Step 1: set the beam parameters of quasi-Bessel beam generated by electromagnetic super surface, wherein the beam parameters include quasi-Bessel beam conical angle α, quasi-Bessel beam energy distribution concentrated region d1-d2, and mode value l beam , which is used for calculating the array size of electromagnetic super surface and designing vortex feed;

[0011] Step 2: design the parameters of vortex feed according to the set quasi-Bessel beam conical angle α and quasi-Bessel beam energy distribution concentrated region d1-d2, to obtain vortex feed;

[0012] Step 3: calculate the array size of electromagnetic super surface according to the set quasi-Bessel beam conical angle α and quasi-Bessel beam energy distribution concentrated region d1-d2, which is used for the design of electromagnetic super surface;

[0013] Step 4: perform phase compensation design according to the set beam parameters of quasi-Bessel beam and the designed parameters of vortex feed, to construct super surface;

[0014] Step 5: perform radio frequency excitation on vortex feed, to realize the feed of vortex wave to electromagnetic super surface, and generate quasi-Bessel beam with controllable energy distribution.

[0015] In the step 1, the value range of α is [0°, 20°]; d1 and d2 are positive integers greater than 0; l beam is any integer.

[0016] The step 2 specifically comprises:

[0017] 1): set that the vortex feed is composed of N units, located in the xoy plane of Cartesian coordinate system, the working frequency is f0, the working wavelength is λ, set that the distance between the units of electromagnetic super surface in x and y directions is a constant value d∈[0.3λ, 0.7λ], the coordinates of the center point of vortex feed are (0, 0, Z f ), and the mode value of vortex wave generated by vortex feed is l feed .

[0018] 2) According to the set quasi-Bessel beam energy distribution concentrated area d1-d2, the divergence angle of the vortex beam generated by the vortex feed source is calculated as:

[0019]

[0020] Where arctan(.) is the inverse tan function;

[0021] 3) According to the set modal value l of the vortex beam generated by the vortex feed source feed and the calculated divergence angle θ of the vortex beam generated by the vortex feed source, the radius of the vortex feed source is calculated, which is used for the placement of the units of the vortex feed source;

[0022] r feed = χ lfeed / (ksinθ)

[0023] Where χ lfeed is the first zero point of the l feed th Bessel function, and k is the wave number;

[0024] 4) The excitation phase difference of the vortex feed source unit is calculated, which is used for the feeding of the vortex feed source:

[0025]

[0026] 5) According to the calculated r feed , the units of the vortex feed source are uniformly distributed in a circle with a radius of r feed , and the vortex feed source is obtained.

[0027] In the 1), l feed is any integer, N≥2×l feed , 40d≤Z f ≤60d;

[0028] The step 3 is specifically: according to the set quasi-Bessel beam energy distribution concentrated area d1-d2, the conical angle of the quasi-Bessel beam is α, and the spacing d of the units of the electromagnetic super surface in the x and y directions, the array size M of the electromagnetic super surface is determined, that is, the row and column number of the array, which is used for the design of the electromagnetic super surface:

[0029]

[0030] The step 4 is specifically:

[0031] 1) The electromagnetic super surface is composed of M rows and M columns of units calculated in step 3, and the coordinates of the i i th array element in the x direction and the j j th array element in the y direction of the electromagnetic super surface are set as (x i ,y j ,0);

[0032] 2):According to the set quasi-Bessel beam cone angle α, the modal value l beam , the coordinates of the center point of the vortex feed source (0, 0, Z f , the modal value l of the vortex wave generated by the vortex feed source feed , the compensation phase of each unit of the electromagnetic metasurface is calculated, which is used to adjust the state of the electromagnetic metasurface unit:

[0033]

[0034] Wherein, Φ(i,j) represents the compensation phase required by the i-th row and j-th column unit in the electromagnetic metasurface, arg(.) represents the argument operation of taking complex number, and exp(.) represents the exponential operation with natural logarithm e as the base; represents the azimuth angle of the electromagnetic metasurface unit located at (x i ,y j ,0) relative to the origin;

[0035] 3):Design the electromagnetic metasurface unit, and draw the transmission phase table and transmission amplitude table of the electromagnetic metasurface unit;

[0036] 4);According to the compensation phase required by each unit of the electromagnetic metasurface, adjust the state of each unit of the electromagnetic metasurface to obtain the electromagnetic metasurface.

[0037] The 3) in the above method;

[0038] Each of the electromagnetic metasurface units comprises a first metal grating layer, a second metal grating layer, a metal patch, a first dielectric layer, and a second dielectric layer.

[0039] The metal patch is arranged between the first dielectric layer and the second dielectric layer.

[0040] The first metal grating layer is arranged on the surface of the first dielectric layer away from the metal patch.

[0041] The second metal grating layer is arranged on the surface of the second dielectric layer away from the metal patch.

[0042] The first dielectric layer and the second dielectric layer are cuboids with equal volume and shape.

[0043] The first metal grating layer is composed of three square metal patches with equal size and equal spacing arranged in parallel along the x-axis direction of the substrate.

[0044] The second metal grating layer is composed of three square metal patches with equal size and equal spacing arranged in parallel along the y-axis direction of the substrate.

[0045] The metal patch is printed between the first dielectric layer and the second dielectric layer, the shape of the metal patch is any one of an open circular ring type or an I type, and the opening angle of the metal patch is used to control the transmission phase of the electromagnetic metasurface unit, and the transmission phase of the unit changes in a range close to or exceeding 360 degrees.

[0046] The transmission phase table of the electromagnetic metasurface unit is drawn as follows: the rotation angle of the metal patch is kept unchanged, simulation is performed when the opening angle of the metal patch changes, the transmission phase corresponding to each value of the opening angle of the metal patch is obtained, and each value of the opening angle of the metal patch and the transmission phase corresponding thereto are drawn into a transmission phase table.

[0047] The 4) is specifically:

[0048] The state of each unit of the electromagnetic metasurface is adjusted, the opening angle of the metal patch corresponding to the compensation phase of each unit of the electromagnetic metasurface is found from the transmission phase table, and the opening angle of the metal patch of each unit of the electromagnetic metasurface is adjusted accordingly.

[0049] The step 5) is specifically:

[0050] The vortex feed source and the electromagnetic metasurface are placed at the set positions, that is, the coordinates of the vortex feed source are set in the 1) of the step 2, each unit of the vortex feed source is fed with the excitation phase difference sigma calculated in the step 1, and an energy-distribution-controllable quasi-Bessel beam is generated.

[0051] The beneficial effects of the present application are:

[0052] Firstly, the vortex feed source is used instead of the traditional horn feed source in the present application, compared with the traditional horn feed source, the divergence angle of the vortex wave generated by the vortex feed source can be controlled by adjusting the radius and the mode value of the vortex feed source, so that the electric field intensity distribution of the vortex wave generated by the vortex feed source is controlled, and the energy of the generated quasi-Bessel beam is controllable.

[0053] Secondly, the electromagnetic metasurface is used to provide phase compensation for the vortex wave generated by the vortex feed source in the present application, the vortex wave generated by the vortex feed source is converted into a quasi-Bessel beam, the shortcomings of the prior art, such as complex array antenna structure and complex feed network, are overcome, and the present application has the advantages of simple structure and small loss. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 The flowchart of the present application is shown in the figure;

[0055] Figure 2 The schematic diagram of the electromagnetic metasurface unit designed in the embodiment of the present application is shown in the figure;

[0056] Figure 3A schematic diagram of the metal patch 3 in the electromagnetic super surface unit designed in the embodiment of the present application;

[0057] Figure 4 A schematic diagram of the compensation phase of each unit of the electromagnetic super surface in the simulation experiment of the present application;

[0058] Figure 5 A schematic diagram of the electric field intensity on the observation surface of the quasi-Bessel beam with the energy distribution concentrated region of 200mm-600mm obtained in the simulation experiment of the present application. DETAILED DESCRIPTION

[0059] The present application will be further described in detail below with reference to the accompanying drawings.

[0060] Reference Figure 1 The implementation steps of the embodiment of the present application will be further described in detail.

[0061] Step 1: setting the beam parameters of the quasi-Bessel beam generated by the electromagnetic super surface, wherein the beam parameters include the quasi-Bessel beam conical angle α, the energy distribution concentrated region d1-d2 of the quasi-Bessel beam, and the modal value l beam , for calculating the array size of the electromagnetic super surface and designing the vortex feed source;

[0062] Step 2: designing the parameters of the vortex feed source according to the set quasi-Bessel beam conical angle α and the energy distribution concentrated region d1-d2 of the quasi-Bessel beam;

[0063] Step 3: calculating the size of the electromagnetic super surface according to the set quasi-Bessel beam conical angle α and the energy distribution concentrated region d1-d2 of the quasi-Bessel beam, for the design of the electromagnetic super surface;

[0064] Step 4: performing phase compensation design according to the set state of the quasi-Bessel beam and the parameters of the vortex feed source, and constructing the super surface;

[0065] Step 5: performing radio frequency excitation on the vortex feed source, realizing the feed of the vortex wave to the electromagnetic super surface, and generating the quasi-Bessel beam with controllable energy distribution.

[0066] The step 2 specifically includes:

[0067] 1): setting that the vortex feed source is composed of N units, located in the xoy plane of the Cartesian coordinate system, the working frequency is f0, the working wavelength is λ, setting that the distance between the units of the electromagnetic super surface in the x and y directions is a constant value d∈[0.3λ, 0.7λ], the coordinates of the center point of the vortex feed source are (0, 0, Z f ), and the modal value of the vortex wave generated by the vortex feed source is l feed ;

[0068] 2): The divergence angle of the vortex beam generated by the vortex feed is calculated based on the set energy distribution concentration area d1~d2 of the quasi-Bessel beam.

[0069]

[0070] Where arctan(.) is the inverse tan function;

[0071] 3): Based on the set modal values ​​l of the vortex wave generated by the vortex feed source feed The divergence angle θ of the vortex beam generated by the calculated vortex feed is used to calculate the radius of the vortex feed and to place the elements of the vortex feed.

[0072] r feed =χ lfeed / (ksinθ)

[0073] Where, χ lfeed For the l feed The first zero of the order Bessel function, Wave number;

[0074] 4): Calculate the excitation phase difference of the vortex feed element for feeding the vortex feed:

[0075]

[0076] 5): Based on the calculated r feed The element of the vortex feed source has a radius of r. feed The vortex feed source is obtained by uniformly distributing the feed around the circumference.

[0077] Step 3 specifically involves:

[0078] Based on the defined energy distribution concentration regions d1~d2 of the quasi-Bessel beam, the cone angle α of the quasi-Bessel beam, and the spacing d of the electromagnetic metasurface elements in the x and y directions, the array size of the electromagnetic metasurface is determined for its design.

[0079]

[0080] Step 4 specifically involves:

[0081] 1): The electromagnetic metasurface is composed of M rows and M columns of elements calculated in step 3. The coordinates of the i-th element in the x-direction and the j-th element in the y-direction of the electromagnetic metasurface are set as (x...). i ,y j ,0);

[0082] 2): Based on the set quasi-Bessel beam conic angle α, the modal value l beam The coordinates of the center point of the vortex feed are (0,0,Z). f), the mode value l of the vortex wave generated by the vortex feed feed , calculating the compensation phase of each unit of the electromagnetic super surface, for adjusting the state of the electromagnetic super surface unit:

[0083]

[0084] wherein, Φ(i,j) represents the compensation phase required by the i-th row and j-th column unit in the electromagnetic super surface, arg(.) represents the argument operation of the complex number, exp(.) represents the exponential operation with the natural logarithm e as the base, represents the azimuth angle of the electromagnetic super surface unit located at (x i ,y j ,0) relative to the origin;

[0085] 3) designing the electromagnetic super surface unit, and drawing the transmission phase table and the transmission amplitude table of the electromagnetic super surface unit;

[0086] 4) adjusting the state of each unit of the electromagnetic super surface according to the compensation phase required by each unit of the electromagnetic super surface, to obtain the electromagnetic super surface.

[0087] in the step 3);

[0088] The design of the electromagnetic super surface unit refers to that, except the metal patch 3, all structures of each electromagnetic super surface unit are the same, and each electromagnetic super surface unit comprises a first metal grating layer 1, a second metal grating layer 5, a metal patch 3, a first dielectric layer 2, and a second dielectric layer 4.

[0089] The metal patch 3 is arranged between the first dielectric layer 2 and the second dielectric layer 4.

[0090] The first metal grating layer 1 is arranged on the surface of the first dielectric layer 2 away from the metal patch 3.

[0091] The second metal grating layer 5 is arranged on the surface of the second dielectric layer 4 away from the metal patch 3.

[0092] The first dielectric layer 2 and the second dielectric layer 4 are cuboids with equal volume and same shape; the first metal grating layer 1 is composed of three square metal pieces with same size and equal interval arranged in parallel along the x-axis direction of the substrate; the second metal grating layer 5 is composed of three square metal pieces with same size and equal interval arranged in parallel along the y-axis direction of the substrate; the metal patch 3 is printed between the first dielectric layer 2 and the second dielectric layer 4, and the shape of the metal patch 3 is any one of an open circular ring type and an I type; the opening angle of the metal patch 3 is used for controlling the transmission phase of the electromagnetic super surface unit, and the transmission phase of the unit changes in a range close to or exceeding 360°.

[0093] Referring to Figure 2 and Figure 3Further description is made to the electromagnetic metasurface unit structure in the embodiment of the present application.

[0094] The metal patch 3 of the electromagnetic metasurface unit in the embodiment of the present application is in C shape, Figure 2 The structure of the electromagnetic metasurface unit is shown in the figure, and the structure of the unit comprises a first metal grating layer 1, a second metal grating layer 5, a metal patch 3, a first dielectric layer 2 and a second dielectric layer 4; wherein the first dielectric layer 2 and the second dielectric layer 4 are cuboids with equal volume and same shape; the first metal grating layer 1 and the second metal grating layer 5 are respectively printed on the upper and lower ends of the first dielectric layer 2 and the second dielectric layer 4; the first metal grating is composed of three square metal patches with same size and equal interval arranged in parallel along the x-axis direction of the substrate; the second metal grating is composed of three square metal patches with same size and equal interval arranged in parallel along the y-axis direction of the substrate.

[0095] The metal patch 3 is printed between the first dielectric layer 2 and the second dielectric layer 4, and the shape of the metal patch 3 is C shape.

[0096] The first dielectric layer 2 and the second dielectric layer 4 have the same structure, and are both cuboids with length of 7.5 mm, width of 7.5 mm and height of 2 mm, which are composed of F4B board material with relative dielectric constant of 2.65 and loss tangent of 0.0015.

[0097] The first metal grating layer 1 is composed of three square metal patches with same size, which are arranged in parallel along the x-axis direction in turn and uniformly, and the interval between the two metal patches is 1.1 mm.

[0098] The second metal grating layer 5 is composed of three square metal patches with same size, which are arranged in parallel along the y-axis direction in turn and uniformly, and the interval between the two metal patches is 1.1 mm.

[0099] Figure 3 The figure is a top view of the metal patch 3 in the electromagnetic metasurface unit.

[0100] The metal patch 3 is an open C-shaped patch with opening size of α and angle of 45° between the central axis and the x-axis. The value range of α is [10°, 190°].

[0101] The method for drawing the transmission phase table of the electromagnetic metasurface unit is as follows: keeping the rotation angle of the metal patch 3 unchanged, when the opening angle of the metal patch 3 is changed, simulation is performed to obtain the transmission phase corresponding to each value of the opening angle of the metal patch 3, and each value of the opening angle of the metal patch 3 and the transmission phase corresponding thereto are drawn into a transmission phase table.

[0102] The step 4) is specifically as follows:

[0103] The state of each unit of the adjustable electromagnetic super surface is adjusted by searching for the opening angle of the metal patch 3 corresponding to the compensation phase of each unit of the electromagnetic super surface from a transmission phase table, and adjusting the opening angle of the metal patch 3 of each unit of the electromagnetic super surface accordingly.

[0104] The step 5 is specifically:

[0105] The vortex feed source and the electromagnetic super surface are placed in the set position, that is, the coordinates of the vortex feed source are set in 1) of step 2, each unit of the vortex feed source is fed with the excitation phase difference σ calculated in step 1 respectively, and a quasi-Bessel beam with adjustable energy distribution is generated.

[0106] The technical effects of the present application are further described in combination with simulation experiments and sampling result analysis.

[0107] 1. Simulation experiment conditions:

[0108] The hardware platform of the simulation experiment of the present application is: the processor is Intel(R) Core(TM) i7-10700 CPU, the main frequency is 2.90 GHz, and the memory is 16 GB.

[0109] The software platform of the simulation experiment of the present application is: Windows 10 operating system, Ansys HFSS2021 and MATLAB R2020b.

[0110] The parameter setting of the simulation experiment of the present application is: the range of the quasi-Bessel beam is set to 200mm-600mm, the modal value l beam =0, the coordinates of the center point of the vortex feed source are set to (0, 0, 200mm), the working frequency of the vortex feed source is set to f=10GHz, and the working wavelength is set to λ=30mm. The vortex feed source is composed of 8 units, the modal value l feed of the vortex wave generated by the vortex feed source is +1, and the cone angle of the generated Bessel beam is α=10°.

[0111] 2. Simulation content and result analysis:

[0112] The simulation experiment of the present application is carried out by using the method proposed in the present application, and the compensation phase diagram and the control amplitude diagram required by the electromagnetic super surface are calculated by the simulation software MATLAB R2020b. Among them, the compensation phase diagram is as shown in Figure 4 , wherein the abscissa represents the position coordinates of the unit in the x direction, the ordinate represents the position coordinates of the unit in the y direction, and the phase distribution is between 0° and 360°.

[0113] The vortex feed source is excited by the simulation software Ansys HFSS2021, and an observation surface is added in the beam propagation direction, so that the electric field intensity distribution diagram of the beam can be obtained, as shown inFigure 5 are shown.

[0114] The effects of the present application are further described below. Figure 5 The effects of the present application are further described below.

[0115] Figure 5 is an electric field intensity map in the propagation direction of the quasi-Bessel beam in the simulation experiment of the present application, wherein the side axis represents the size of the electric field intensity. Figure 5 As can be seen from the figure, the quasi-Bessel beam is successfully generated, and there is a region with relatively strong electric field energy at 200mm-600mm, which indicates that the present method can regulate the energy distribution of the quasi-Bessel beam, and the beam effect is good.

[0116] The above simulation analysis shows that the energy distribution regulation of the quasi-Bessel beam can be achieved by using the method of the present application.

Claims

1. A method for energy distribution control of a quasi-Bessel beam based on a vortex feed, characterized in that, The method comprises the following steps; Step 1: set the beam parameters of the quasi-Bessel beam generated by the electromagnetic metasurface, the beam parameters include the quasi-Bessel beam conical angle α, the region where the quasi-Bessel beam energy is concentrated d1~d2, and the mode value l beam ; for calculating the array size of the electromagnetic metasurface and designing the vortex feed source; Step 2: According to the set quasi-Bessel beam cone angle alpha and the energy distribution concentrated area d1-d2 of the quasi-Bessel beam, the parameters of the vortex feeder are designed to obtain the vortex feeder; Step 3: According to the set quasi-Bessel beam cone angle alpha and the energy distribution concentrated area d1-d2 of the quasi-Bessel beam, the array size of the electromagnetic super surface is calculated for the design of the electromagnetic super surface; Step 4: According to the set quasi-Bessel beam parameters and the designed vortex feeder parameters, the phase compensation design is carried out to construct the super surface; Step 5: The vortex feeder is excited by radio frequency to realize the feeding of the vortex wave to the electromagnetic super surface, and a quasi-Bessel beam with controllable energy distribution is generated; The step 2 is specifically: 1) : set the vortex feed source consists of N units, located in the xoy plane of the Cartesian coordinate system, the operating frequency is f0, the operating wavelength is λ, set the unit spacing of the electromagnetic super surface in x and y direction is a constant value d ∈ [0.3λ, 0.7λ], the coordinate of the vortex feed center point is (0, 0, Z f ), the mode value of the vortex wave generated by the vortex feed source is l feed ; 2) According to the set quasi-Bessel beam energy distribution concentrated area d1-d2, the divergence angle of the vortex beam generated by the vortex feeder is calculated as: Wherein, arctan(.) is the inverse tan function; 3) : Mode value, I, of the vortex wave generated by the vortex feed set feed and the calculated divergence angle, Θ, of the vortex wave beam generated by the vortex feed, the radius of the vortex feed is calculated for the placement of the elements of the vortex feed; wherein is the first zero of the l feed th Bessel function of the first kind, is the wave number; 4): The excitation phase difference of the vortex feeder unit is calculated for the feeding of the vortex feeder: 5) : the vortex feed source is uniformly arranged according to the calculated uniform distribution of the circumference with radius r feed of a circle, and the vortex feed source is obtained; l feed N is any integer, N > 2 x l feed 40d < Z f ≤ 60 x d; The step 3 is specifically: According to the set quasi-Bessel beam energy distribution concentrated area d1-d2 and the quasi-Bessel beam cone angle alpha, the array size M of the electromagnetic super surface is determined, that is, the row and column number of the array, which is used for the design of the electromagnetic super surface: D is the spacing of the electromagnetic super surface unit; The step 4 is specifically: 1): The electromagnetic metasurface is composed of M rows and M columns of units calculated in step 3, and the coordinates of the i-th element in the x direction and the j-th element in the y direction of the electromagnetic metasurface are set as (x i ,y j ,0); 2) : the mode value l according to the set quasi-Bessel beam cone angle a beam , the coordinate (0, 0, Z f ) of the center point of the vortex feed source feed , the mode value l of the vortex wave generated by the vortex feed source feed , the compensation phase of each unit of the electromagnetic metasurface is calculated, and the state of the electromagnetic metasurface unit is adjusted: where Φ(i,j) represents the compensation phase required for the i-th row and j-th column unit in the electromagnetic super surface, arg(.) represents the argument operation of a complex number, exp(.) represents the exponential operation with the base of natural logarithm e, represents the azimuth angle of the electromagnetic super surface unit located at (x i ,y j ,0) relative to the origin. 3): The electromagnetic super surface unit is designed, and the transmission phase table and transmission amplitude table of the electromagnetic super surface unit are drawn; 4): According to the required compensation phase of each unit of the electromagnetic super surface, the state of each unit of the electromagnetic super surface is adjusted to obtain the electromagnetic super surface.

2. The method of claim 1, wherein the energy distribution of the quasi-Bessel beam based on a vortex feed source is controlled by adjusting the phase of the vortex feed source. The step 1, the value range of a is [0°, 20°], d1 and d2 are positive integers greater than 0; l beam is any integer.

3. The method of claim 1, wherein the method is performed by a processor. The 3) in the above; Each electromagnetic super surface unit comprises a first metal grating layer (1), a second metal grating layer (5), a metal patch (3), a first dielectric layer (2) and a second dielectric layer (4); The metal patch (3) is arranged between the first dielectric layer (2) and the second dielectric layer (4); The first metal grating layer (1) is arranged on the surface of the first dielectric layer (2) away from the metal patch (3); The second metal grating layer (5) is arranged on the surface of the second dielectric layer (4) away from the metal patch (3); The first dielectric layer (2) and the second dielectric layer (4) are cuboids with equal volume and same shape.

4. The method of claim 3, wherein the method is performed by a processor. The first metal grating layer (1) is composed of three square metal pieces with same size and equal spacing arranged in parallel along the x-axis direction of the substrate; The second metal grating layer (5) is composed of three square metal pieces with same size and equal spacing arranged in parallel along the y-axis direction of the substrate; The metal patch (3) is printed between the first dielectric layer (2) and the second dielectric layer (4), and the shape of the metal patch (3) is any one of an open circular ring type and an I type. The opening angle of the metal patch (3) is used to control the transmission phase of the electromagnetic super surface unit, and the transmission phase of the unit changes in a range close to or exceeding 360°.

5. The method of claim 3, wherein the method is performed by a processor. The method for drawing the transmission phase table of the electromagnetic super surface unit is as follows: keeping the rotation angle of the metal patch (3) unchanged, simulating when the opening angle of the metal patch (3) changes, obtaining the transmission phase corresponding to each value of the opening angle of the metal patch (3), and drawing each value of the opening angle of the metal patch (3) and the transmission phase corresponding thereto into a transmission phase table.

6. The method of claim 3, wherein the energy distribution of the quasi-Bessel beam based on a vortex feed source is controlled by adjusting the radius of the vortex feed source. The step 4) is specifically: The step 5) is specifically:

7. The method of claim 3, wherein the method is performed by a computer system. The vortex feed source and the electromagnetic super surface are placed at the set positions, that is, the coordinates of the vortex feed source are set in the step 2), each unit of the vortex feed source is respectively fed with the excitation phase difference σ calculated in the step 1), and the quasi-Bessel wave beam with adjustable energy distribution is generated. ​

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