Multi-channel switching antenna based on translation reconfigurable metasurface array

Abstract

The invention discloses a multi-channel switching antenna based on a translation reconfigurable metasurface array, and relates to a multi-channel switching antenna design technology, in particular to a function of translation regulation and control of a beam deflection angle of a translation reconfigurable metasurface. And therefore, the functions of channel switching, dual-channel output and the like can be achieved. The multi-channel switching antenna comprises a translation reconfigurable metasurface array, a mechanical driving system, a feed circuit and a horn antenna array. The main process of the design method is that phase distribution of the translation reconfigurable metasurface is solved based on the generalized Snell law, the differential equation and the Rayleigh-Sommerfeld formula, then the metasurface unit structure and the translation reconfigurable metasurface which meet the requirements are designed through electromagnetic simulation software, arraying is conducted on the translation reconfigurable metasurface, and finally the translation reconfigurable metasurface is obtained. The multi-channel switching antenna based on the translation reconfigurable metasurface array is obtained, and the functions of channel switching, dual-channel output and the like can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a multi-channel switching antenna design technology, in particular to a multi-channel switching antenna design method based on a translation reconfigurable metasurface, which can realize the function of beam deflection angle by translation control, and can realize the functions of channel switching and double-channel output by arraying and introducing multi-beam interference factors. BACKGROUND

[0002] With the increasing demand of users for high speed and low latency of data transmission, the existing wave band is increasingly difficult to meet the growing needs of users. The existing multi-channel switching antenna technology will inevitably develop towards millimeter wave, but millimeter wave antennas face problems such as high requirements for feed circuits, high complexity, low circuit efficiency, and high cost of phase shifters. Therefore, it is of great significance to design a multi-channel switching antenna with lightness, high integration, low cost, and functions such as channel switching and double-channel output.

[0003] A metasurface is a two-dimensional artificial material with a sub-wavelength thickness and arranged by sub-wavelength structure units. The metasurface can break through the physical limit encountered by traditional devices by virtue of the interaction between sub-wavelength structure units and incident electromagnetic waves to regulate the amplitude, phase, polarization and other properties of the incident electromagnetic waves. At the same time, due to the sub-wavelength thickness, the metasurface has a very light weight and high integration. Therefore, the artificially designed translation reconfigurable metasurface can realize the function of beam deflection, and the translation reconfigurable metasurface array can be obtained by linearly arranging the translation reconfigurable metasurface. In combination with the horn antenna array and the feed circuit, a multi-channel switching antenna based on the translation reconfigurable metasurface array can replace the traditional multi-channel switching antenna. SUMMARY

[0004] The present application proposes an antenna for realizing multi-channel switching through metasurface translation to solve the problems of high complexity and difficult multi-channel switching of existing millimeter wave antennas.

[0005] The technical scheme of the present application is a multi-channel switching antenna based on a translation reconfigurable metasurface array, which comprises a feed antenna, a metasurface A array and a metasurface B array. The feed antenna is located on one side of the metasurface A array and is aligned with the metasurface A array. The metasurface B array is located on the other side of the metasurface. The distance between the metasurface A array and the metasurface B array is d. The metasurface A array and the metasurface B array are both composed of hexahedral unit antennas with the same shape and size. Each unit antenna comprises a base and a metal plate. A plurality of annular slits with openings are formed on the metal plate. The number, position and opening direction of the annular slits are calculated according to actual requirements.

[0006] The channel switching is realized by translating the metasurface B in the plane of the metasurface B.

[0007] Further, the feed antenna is a horn antenna, and each unit antenna in the metasurface A corresponds to a horn antenna.

[0008] Further, the calculation method of the number, position, and opening direction of the ring-shaped slits in the metasurface A and the metasurface B is as follows:

[0009] Step 1: Establishing a translation variable 、 and a function relationship with a beam deflection angle , and deducing a phase distribution function on the metasurface B; x and y are two mutually perpendicular directions in the metasurface B; respectively represent the pitch angle and the azimuth angle of the beam;

[0010] Step 2: Calculating the outgoing wave phase distribution of the metasurface A according to the phase distribution function on the metasurface B;

[0011] Step 3: After the outgoing wave phase distribution of the metasurface A is calculated, the phase distribution of the horn antenna transmitting wave propagating to the incident end of the metasurface A is calculated, and then the phase distribution of the metasurface A is obtained by subtracting the incident wave phase distribution of the metasurface A from the outgoing wave phase distribution of the metasurface A;

[0012] Step 4: According to the phase distributions of the metasurface A and the metasurface B, the metasurface unit structure meeting the requirements is set, and the unit structure is arranged to construct the metasurface A and the metasurface B meeting the phase distribution.

[0013] Further, the specific method of step 1 is as follows:

[0014] Step 1.1: The surface momentum of the photon on the interface satisfies a conservation relationship, and the formula is as follows:

[0015]

[0016] wherein and are the projections of the incident light and the outgoing light wave vector on the interface, is the phase change distribution on the interface;

[0017]

[0018] wherein and are the included angles of the incident light and the axis, axis, and are the included angles of the outgoing light and the axis, axis, represents the refractive index of the incident medium, denotes the wave vector in vacuum, denotes the phase distribution function of the light wave on the interface;

[0019] Step 1.2: According to the phase distribution function of the perfect parallel wave:

[0020]

[0021] The in-plane displacement vector is introduced into the metasurface, and is associated with the beam deflection angle, so as to realize the effect of full-range beam deflection by in-plane translation in any direction;

[0022] Suppose that the electromagnetic wave emitted by the horn antenna passes through the metasurface A and produces a phase jump of , and then propagates in free space to the metasurface B, which produces a phase jump of . The additional phase produced by the translation reconfigurable metasurface to the incident electromagnetic wave is , thereby realizing the function of beam deflection of electromagnetic wave;

[0023] Since the outgoing wave of the metasurface B is a parallel wave, the phase distribution function of the outgoing wave of the metasurface B is obtained as:

[0024]

[0025] wherein , respectively represent the translation amount of the metasurface B in the in-plane axis, axis, , represent the position coordinates of the point on the metasurface B plane, , , represent the correlation coefficients, is the outgoing light phase distribution function of the metasurface B;

[0026] Step 1.3: The phase changes of the incident wave and the outgoing wave of the metasurface B should satisfy:

[0027]

[0028] wherein is the incident light phase distribution function of the metasurface B, is the phase distribution function of the metasurface B.

[0029] Further, the specific method of the step 2 is:

[0030] Step 2.1: According to the incident light phase distribution function of the metasurface B, according to the distance , the calculated phase distribution of the exit wave of the super surface A :

[0031]

[0032] wherein, denotes the complex conjugate of the scalar Green function, denotes the coordinates of the x, y, z directions when the coordinate system is established by the super surface B;

[0033] Step 2.2: Calculate the phase distribution function of the super surface A;

[0034]

[0035] wherein, is the phase distribution function of the exit light of the super surface A, is the phase distribution function of the incident light of the super surface A, is the phase distribution function of the super surface A.

[0036] The design has the following advantages;

[0037] 1. The translation reconfigurable super surface is designed based on the generalized Snell's law, which associates translation with beam deflection, realizes the function of changing the translation amount of the super surface to control the beam deflection angle, and is different from other driving modes of beam deflection. The translation amount can be controlled to realize real-time control of the beam deflection angle.

[0038] 2. The translation reconfigurable super surface array regulates the single-slit diffraction factor of the array element by translation. When the maximum value of the single-slit diffraction factor coincides with the maximum value of each order of the multi-beam interference factor between the array elements, the channel switching function can be realized in the process of translation. When the maximum value of the single-slit diffraction factor is located between the adjacent orders of the multi-beam interference factor, the double-channel output function can be realized. When the maximum value of the single-slit diffraction factor is located between the corresponding order and the intermediate point of the order and the adjacent order, the double-channel energy distribution function can be realized. Compared with the previous channel switching antenna, the channel switching mode of the design is simple, can be realized by translation only, and is diversified in function.

[0039] 3. The preparation of the translation reconfigurable super surface array adopts the PCB processing method, has low cost, and can realize mass production.

[0040] 4. The multi-channel switching antenna adopts the translation reconfigurable super surface array, has high integration, and the device is light, thin and small in volume. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is the structure and working principle schematic diagram of the multi-channel switching antenna based on the translation reconfigurable super surface array in the present application example.

[0042] Figure 2 is a structural schematic diagram of a PB phase-based translational reconfigurable metasurface in the example of the present application.

[0043] Figure 3 is a structural schematic diagram of a horn antenna in the example of the present application.

[0044] Figure 4 is a working principle diagram of a translational reconfigurable metasurface in the example of the present application.

[0045] Figure 5 is a single-slit diffraction factor diagram of a translational reconfigurable metasurface array in the example of the present application.

[0046] Figure 6 is a multi-beam interference factor diagram of a translational reconfigurable metasurface array in the example of the present application.

[0047] Figure 7 is a channel switching schematic diagram based on a translational reconfigurable metasurface array in the example of the present application.

[0048] Figure 8 is a dual-channel output schematic diagram based on a translational reconfigurable metasurface array in the example of the present application. DETAILED DESCRIPTION

[0049] The scheme proposed in this project is to design a multi-channel switching antenna based on a translational reconfigurable metasurface array. By driving the translational reconfigurable metasurface B array, channel switching, dual-channel output and other functions are realized. The requirement for the feed circuit is low, and the high capacity target in the field of wireless communication can be realized, and the cost is reduced.

[0050] Figure 1 is a structural schematic diagram and working principle schematic diagram of a multi-channel switching antenna based on a translational reconfigurable metasurface array in the example of the present application, which mainly consists of three parts: a translational reconfigurable metasurface array, a horn antenna array, and a feed circuit. The feed circuit mainly provides radio frequency signals for the horn antenna array. The horn antenna array emits electromagnetic waves to propagate to the metasurface A array. With the phase response of the metasurface A, the metasurface A array focuses the incident electromagnetic waves. The focused electromagnetic waves propagate in free space to the incident end of the metasurface B, and by translating the metasurface B array, multi-channel switching, dual-channel output and other functions can be realized. The design of the multi-channel switching antenna is divided into two parts: 1) the design of the translational reconfigurable metasurface; and 2) the design of the multi-channel switching antenna based on the translational reconfigurable metasurface array.

[0051] (1) Design principle of translational reconfigurable metasurface

[0052] The design method of the translation reconfigurable metasurface is to combine the generalized Snell's law, differential equation and Rayleigh-Sommerfeld formula, introduce the in-plane displacement vector into the metasurface, and establish the function relationship between the displacement vector and the beam deflection angle, so as to deduce the phase distribution of the translation reconfigurable metasurface, and finally design the translation reconfigurable metasurface to realize the function of beam deflection. According to the physical meaning of the generalized Snell's law, the surface momentum of the photon on the interface satisfies the conservation relationship, and the formula is as follows:

[0053]

[0054] and are the projections of the incident light and the outgoing light wave vector on the interface respectively, is the phase change distribution on the interface;

[0055]

[0056] and are the angles between the incident light and the axis and the axis respectively, and are the angles between the outgoing light and the axis and the axis respectively.

[0057] According to the required function, the phase distribution function on the metasurface can be deduced by means of the generalized Snell's law, so as to realize many functions such as beam deflection, perfect focusing and the like, wherein the phase distribution function of the perfect parallel wave is as follows:

[0058]

[0059] The in-plane displacement vector is introduced into the metasurface, and the correlation with the beam deflection angle is established, so as to realize the effect of full-range beam deflection by any direction translation in the plane. The specific derivation process is as follows: the translation reconfigurable metasurface is composed of two metasurfaces, assuming that one of them is metasurface A and the other is metasurface B, as shown in Figure 2 The electromagnetic wave emitted by the horn antenna will produce a phase mutation of after passing through metasurface A, and then propagates in free space to metasurface B, and then produces a phase mutation of through metasurface B, so that the translation reconfigurable metasurface produces an additional phase of to the incident electromagnetic wave, and thus realizes the function of beam deflection of the electromagnetic wave. Since the outgoing wave of the metasurface B is a parallel wave, the phase distribution function of the outgoing wave of the metasurface B should satisfy: ​​

[0060]

[0061] wherein , respectively represent the translation of the super surface B in-plane axis, axis, is the phase distribution function of the exit light of the super surface B.

[0062] At the same time, the phase change of the incident wave and the exit wave of the super surface B should satisfy:

[0063]

[0064] wherein is the phase distribution function of the incident light of the super surface B, is the phase distribution function of the super surface B.

[0065] The solving process of the phase change equation is as follows: firstly, the differential of , on both ends of the above formula is solved, after obtaining the result of the first order differential, the differential of , on both ends of the first order differential equation is solved again, and finally the derivative of , of the second order differential equation is solved, so that the functions of , can be obtained as follows:

[0066]

[0067] wherein , , , , , , , , are all constants.

[0068] Substitute , into the formula:

[0069] , the calculation can obtain:

[0070]

[0071]

[0072]

[0073] According to the generalized Snell's law, we can derive:

[0074]

[0075]

[0076]

[0077]

[0078] in For the wave vector of light, , They are respectively exist axis, Components on the axis, , These are the elevation and azimuth angles of the beam.

[0079] make , Simplifying, we get:

[0080]

[0081]

[0082] The incident wave phase distribution of metasurface B can be obtained through the above steps. Since there is a distance between metasurface A and metasurface B... Therefore, the Rayleigh-Sommerfeld formula can be used to derive the phase distribution of the emitted wave from metasurface A:

[0083]

[0084]

[0085] in Let be the phase distribution function of the emitted light from metasurface A. Let be the incident light phase distribution function of metasurface A. Let be the phase distribution function of metasurface A.

[0086] At this point, the phase distribution functions of both metasurface A and metasurface B have been obtained. Based on these phase distribution functions, the appropriate unit structure can be selected to design a translationally reconfigurable metasurface, such as... Figure 2 As shown. In During the change, that is, the metasurface B translates, and the beam pitch angle... Changes can occur, therefore, translational reconfigurable metasurfaces can achieve beam deflection effects, such as... Figure 4 As shown.

[0087] (2) Design principle of multi-channel switched antenna based on translation reconfigurable metasurface array

[0088] After obtaining the translation reconfigurable metasurface, the translation reconfigurable metasurfaces are linearly arranged, and the equal-interval translation reconfigurable metasurface array can be realized while keeping the intervals of different translation reconfigurable metasurfaces equal. Then, a horn antenna is placed under each metasurface to form a horn antenna array, as shown in Figure 3 . Then, the feed circuit is connected under the horn antenna array, and the design of the multi-channel switched antenna based on the translation reconfigurable metasurface array is completed, which can realize multi-channel switching, dual-channel output, etc.

[0089] Seven translation reconfigurable metasurfaces are linearly arranged in this design to obtain a translation reconfigurable metasurface array with seven array elements. The intervals of different translation reconfigurable metasurfaces are equal to the size of the metasurface , that is, the linear dense packing of translation reconfigurable metasurfaces. At this time, a translation reconfigurable metasurface can be regarded as an array element in a linear array, and an array element can be regarded as a point source when calculating the far-field light intensity, with an interval of the size of the metasurface . When the incident electromagnetic wave passes through the translation reconfigurable metasurface array composed of seven array elements, it can be regarded as multi-slit diffraction, and the far-field light intensity of the outgoing wave of a single array element can be regarded as a single-slit diffraction factor in multi-slit diffraction. The far-field light intensity of the outgoing wave of different array elements interferes to introduce a multi-beam interference factor. In the translation reconfigurable metasurface array, the far-field light intensity of a single array element can be adjusted by the translation metasurface B array, that is, the single-slit diffraction factor is adjusted, while the multi-beam interference factor is always the same when the interval of different array elements is fixed. Therefore, the multi-channel switching, dual-channel output, etc. can be realized by the translation metasurface B array. The electric field distribution and light intensity distribution of the multi-channel switched antenna based on the translation reconfigurable metasurface array with seven array elements are as follows:

[0090]

[0091]

[0092] wherein is the far-field light intensity distribution of a single array element, is the single-slit diffraction factor of the translation reconfigurable metasurface array, as shown in Figure 5 , is the multi-beam interference factor of the translation reconfigurable metasurface array, as shown in Figure 6 . By changing through the translation metasurface B array, the deflection angle of the beam This allows for the translation of the single-slit diffraction factor while maintaining a fixed multi-beam interference factor. During the translation of the metasurface B array, multi-channel switching is achieved when the maximum value of the single-slit diffraction factor coincides with the maximum values ​​of each order of the multi-beam interference factor; dual-channel output is achieved when the maximum value of the single-slit diffraction factor is located in the middle of adjacent orders of the multi-beam interference factor; and dual-channel energy distribution is achieved when the maximum value of the single-slit diffraction factor is located between the corresponding order and the midpoint between that order and adjacent orders.

[0093] Based on the characteristic of translationally reconfigurable metasurface arrays that can control the single-slit diffraction factor through translation, different functions can be achieved when the maximum value of the single-slit diffraction factor is located at different positions of the multi-beam interference factor. The calculation method is as follows:

[0094]

[0095]

[0096] in This represents the location of the maximum single-slit diffraction factor. This represents the location of the maxima of each order of the multibeam interference factor.

[0097] when From 0 As it gradually increases, It will increase, at that time They are respectively At this time, the maxima of the single-slit diffraction factor coincide with the zeroth, first, second, and third orders of the multi-beam interference factor, respectively, to achieve channel switching, such as... Figure 7 As shown; when When the maximum value of the single-slit diffraction factor is located in the middle of an adjacent order of the multi-beam interference factor, a dual-channel output effect can be achieved, such as... Figure 8 As shown; when When the value is other, the maximum value of the single-slit diffraction factor is located between the corresponding order and the midpoint between that order and the adjacent order, enabling dual-channel energy distribution. Therefore, the multi-channel switching antenna based on the translation-reconfigurable metasurface array can achieve channel switching and dual-channel output functions when the metasurface B array is translated.

[0098] Metasurfaces are two-dimensional artificial materials composed of subwavelength structural units. By cleverly designing these subwavelength structural units to interact with incident electromagnetic waves, the amplitude, phase, polarization, and other properties of the incident electromagnetic waves can be arbitrarily controlled. Currently, metasurfaces are widely studied, and various high-transmittance... Subwavelength structure units of phase coverage range are proposed and verified, so that the metasurface has mature design technology. In addition, the metasurface structure has high integration characteristics due to its own subwavelength thickness characteristics, and as a passive device, it does not need control circuit, and the preparation method is compatible with the existing PCB process, which can realize mass production and low cost.

[0099] The design of the metasurface mainly lies in the design of the subwavelength structure unit and the arrangement of the subwavelength structure unit. The subwavelength structure unit can be designed and optimized using electromagnetic simulation software such as COMSOL, CST STUDIO SUITE, FDTD, etc., aiming to design a subwavelength structure unit with a transmittance of more than 80%, a phase coverage of 2π range and working in Ka band. The subwavelength structure unit of this design adopts PB phase structure unit. PB phase structure unit is a common control method for controlling the phase of incident wave, which can realize the phase control from 0 to 2π by rotating the structure unit. At the same time, PB phase structure unit has the characteristics of high transmittance, accurate phase control, easy to control dispersion, etc., which can improve the control accuracy of wavefront. Based on the phase control characteristics of PB phase structure unit and setting the center of metasurface A and metasurface B as the phase zero point, arranging PB phase structure unit according to the phase distribution of the following two formulas, metasurface A and metasurface B that meet the required phase response can be designed.

[0100]

[0101]

[0102] After that, metasurface A and metasurface B are linearly arranged in an equal interval to form a translation reconfigurable metasurface array, and a horn antenna array and a feeding circuit are placed below the metasurface A array, so that it can emit electromagnetic waves when the feeding circuit is powered on. At this point, the design of the multi-channel switching antenna based on the translation reconfigurable metasurface array is completed, and it can realize the functions of channel switching, double-channel output, etc. required.

Claims

1. A multi-channel switched antenna based on a translational reconfigurable metasurface array, the antenna comprising: A feed antenna, a metasurface A array, a metasurface B array; The feed antenna is located on one side of the metasurface A array and is aligned with the metasurface A array, and the metasurface B array is located on the other side of the metasurface, and the distance between the metasurface A array and the metasurface B array is d; the metasurface A array and the metasurface B array are both composed of hexahedral unit antennas with the same shape and size; each unit antenna comprises a substrate and a metal plate, and a plurality of annular slits with openings are formed on the metal plate, and the number, position and opening direction of the annular slits are calculated according to actual requirements; The switching of the channel is realized by translating the metasurface B in the plane of the metasurface B.

2. A multi-channel switched antenna based on a reconfigurable metasurface array as claimed in claim 1, characterized in that, The feed antenna is a horn antenna, and each unit antenna in the metasurface A corresponds to a horn antenna.

3. A multi-channel switched antenna based on a reconfigurable metasurface array as claimed in claim 1, wherein, The calculation method of the number, position and opening direction of the annular slits in the metasurface A and the metasurface B is as follows: Step 1: Establishing the translation variable 、 and the function relationship with the beam deflection angle , the phase distribution function on the metasurface B is derived; x, y are two mutually perpendicular directions within the metasurface B; respectively represent the pitch angle and azimuth angle of the beam; Step 2: calculate the phase distribution of the outgoing wave of the metasurface A according to the phase distribution function on the metasurface B; Step 3: after the phase distribution of the outgoing wave of the metasurface A is calculated, the phase distribution of the horn antenna transmitting wave propagating to the incident end of the metasurface A is calculated, and then the phase distribution of the metasurface A is obtained by subtracting the phase distribution of the incident wave of the metasurface A from the phase distribution of the outgoing wave of the metasurface A; Step 4: according to the phase distribution of the metasurface A and the metasurface B, set the metasurface unit structure meeting the requirements, and arrange the unit structure to construct the metasurface A and the metasurface B meeting the phase distribution.

4. A multi-channel switched antenna based on a reconfigurable metasurface array as claimed in claim 3, characterized in that, The specific method of step 1 is as follows: Step 1.1: the surface momentum of the photon on the interface satisfies the conservation relationship, and the formula is as follows: ； wherein with are the projections of the incident and emergent light wavevectors on the interface, respectively, is the phase change distribution on the interface; ； wherein and is the angle between the incident light and the axis, is the angle between the incident light and the axis, and is the angle between the exit light and the axis, denotes the refractive index of the incident medium, denotes the wave vector in vacuum, denotes the phase distribution function of the light wave at the interface; Step 1.2: according to the phase distribution function of the perfect parallel wave: ； Introduce the in-plane displacement vector into the metasurface, and establish a correlation with the beam deflection angle, so as to realize the effect of full-range beam deflection by translating in any direction in the plane; Suppose that the electromagnetic waves emitted by the horn antenna will produce [something] after passing through the metasurface A. The phase abrupt change propagates in free space to metasurface B, where it generates... The phase abrupt change, the translationally reconfigurable metasurface produces an effect on the incident electromagnetic wave. The additional phase enables the beam deflection function of electromagnetic waves; Since the outgoing wave of the metasurface B is a parallel wave, the phase distribution function of the outgoing wave of the metasurface B is obtained as follows: ； wherein , respectively represent the translation of the super surface B in the plane of the axis, axis, , represent the position coordinates of the point on the plane of the super surface B, , , represent the correlation coefficient, is the exit light phase distribution function of the super surface B; Step 1.3: the phase change of the incident wave and the outgoing wave of the metasurface B should satisfy: ； wherein is the phase distribution function of the incident light for the super surface B, is the phase distribution function of the super surface B.

5. A multi-channel switched antenna based on a reconfigurable metasurface array as claimed in claim 3, wherein, The specific method of step 2 is as follows: Step 2.1: According to the incident light phase distribution function of the super surface B, the exit wave phase distribution of the super surface A is calculated according to the distance between the super surface A and the super surface B : 0.5 * (1 - (x - 0.5)2) : ； wherein denotes the complex conjugate of the scalar Green function, denotes the coordinates in x, y, z directions when a coordinate system is established with the super surface B; Step 2.2: calculate the phase distribution function of the metasurface A; ； wherein is an exit light phase distribution function of the metasurface A, is an exit light phase distribution function of the metasurface A, is a phase distribution function of the metasurface A.

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