CN108511925B - A mirrored 3D MIMO half-wave antenna array and array establishment method - Google Patents

Abstract

The embodiment of the present invention discloses a mirrored 3D MIMO half-wave antenna array and a method for establishing the array. The mirrored 3D MIMO half-wave antenna array includes: a 2D MIMO half-wave antenna array and a reflector; the 2D MIMO half-wave antenna array is arranged in a The mirror side of the reflector; wherein, the virtual image of the 2D MIMO half-wave antenna array in the reflector and the 2D MIMO half-wave antenna array form a mirrored 3D MIMO half-wave antenna array. In the embodiment of the present invention, a mirror is added on the basis of the 2D MIMO half-wave antenna array by using the mirroring technology, so that the 2D MIMO half-wave antenna array can generate a virtual image behind the mirror surface to form a mirrored 3D MIMO half-wave antenna array , the cost, technology, volume and weight are almost the same as 2D MIMO half-wave antenna arrays, but beamforming is far superior to 2D MIMO half-wave antenna arrays.

Description

A mirrored 3D MIMO half-wave antenna array and array establishment method

technical field

Embodiments of the present invention relate to the field of communications technologies, and in particular, to a mirrored 3D MIMO half-wave antenna array and a method for establishing the array.

Background technique

The traditional 2D MIMO half-wave antenna array technology is mature, but the side lobe of the shaped beam generated by the antenna is generally larger than the main lobe in the propagation direction, which not only loses the radiated energy, but also may cause interference. The existing 3D MIMO half-wave antenna arrays have good beamforming and directivity effects. Even for a 3D MIMO half-wave antenna array with only two elements in the transmission direction, the beamforming also has three distances between adjacent elements. Parameters such as three phase differences and three phase differences can be adjusted by the system. In terms of beamforming and other functional processing, it still has excellent adjustability. However, due to the need for three-dimensional array element control and the large number of array elements, the control technology and hardware architecture more complicated.

In the process of implementing the embodiments of the present invention, the inventor found that the beamforming effect of the existing 2D MIMO half-wave antenna array is not ideal, while the existing 3D MIMO half-wave antenna array is technically difficult, expensive, and expensive. Large in size and weight.

SUMMARY OF THE INVENTION

Because the beamforming effect of the existing 2D MIMO half-wave antenna array is not ideal, and the existing 3D MIMO half-wave antenna array has the problems of high technical difficulty, high cost, and large volume and weight, the embodiments of the present invention A mirrored 3D MIMO half-wave antenna array and an array establishment method are proposed.

In a first aspect, an embodiment of the present invention further provides a mirrored 3D MIMO half-wave antenna array, including: a 2D MIMO half-wave antenna array and a reflector;

The 2D MIMO half-wave antenna array is arranged on the mirror side of the reflector;

Wherein, the virtual image of the 2D MIMO half-wave antenna array in the reflector and the 2D MIMO half-wave antenna array form a mirrored 3D MIMO half-wave antenna array.

Optionally, the distance between the 2D MIMO half-wave antenna array and the reflector is less than 0.5λ, where λ is the wavelength of the electromagnetic wave in the 2D MIMO half-wave antenna array.

Optionally, the distance between the 2D MIMO half-wave antenna array and the reflector is 0.125λ.

Optionally, the virtual image and the 2D MIMO half-wave antenna array are simulated by a finite difference time domain method (FDTD) to form a mirrored 3D MIMO half-wave antenna array.

Optionally, the reflector is a metal mirror.

In a second aspect, an embodiment of the present invention provides a method for establishing a mirrored 3D MIMO half-wave antenna array, including:

determining the distance between the 2D MIMO half-wave antenna array and the mirror;

setting the 2D MIMO half-wave antenna array and the mirror according to the distance;

The virtual image and the 2D MIMO half-wave antenna array are simulated to establish a mirrored 3D MIMO half-wave antenna array.

Optionally, the determining the distance between the 2D MIMO half-wave antenna array and the reflector specifically includes:

The distance between the 2D MIMO half-wave antenna array and the reflector is determined according to the maximum value of the main lobe and the included angle of the main lobe.

Optionally, the virtual image is simulated with the 2D MIMO half-wave antenna array to establish a mirrored 3D MIMO half-wave antenna array, which specifically includes:

The virtual image and the 2D MIMO half-wave antenna array are simulated by using the FDTD, and a mirrored 3D MIMO half-wave antenna array is established.

It can be seen from the above technical solutions that in the embodiment of the present invention, a mirror is added on the basis of the 2D MIMO half-wave antenna array by using the mirroring technology, so that the 2D MIMO half-wave antenna array can generate a virtual image behind the mirror surface to form a mirror image. 3D MIMO half-wave antenna arrays are similar in cost, technology, volume and weight to 2D MIMO half-wave antenna arrays, but beamforming is far superior to 2D MIMO half-wave antenna arrays.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a mirrored 3D MIMO half-wave antenna array according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an element antenna of a basic vibrator according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an element antenna of a linear antenna radiation field at P according to an embodiment of the present invention;

4 is a schematic diagram of a mirror image of a mirror first half-wave antenna provided by an embodiment of the present invention;

5 is a schematic diagram of propagation and a schematic diagram of a direction of a 2×1×2 mirrored 3D MIMO half-wave antenna array provided by an embodiment of the present invention with α _x =0°, α _y =-60°, α _z =0°;

6 is a schematic diagram of the relationship between the lobe and _dy of a 2×1×2 mirrored 3D MIMO half-wave antenna array provided by an embodiment of the present invention when α _x =0°, α _y =-60°, and α _z =0° ;

7 is a schematic diagram of the relationship between the lobe and _dy of the 2×1×2 mirrored 3D MIMO half-wave antenna array provided by an embodiment of the present invention when α _x =100°, α _y =-60°, and α _z =0° ;

8 is a schematic diagram illustrating the relationship between the lobe and _dy of a 2×1×2 mirrored 3D MIMO half-wave antenna array provided by an embodiment of the present invention when α _x =0°, α _y =-60°, and α _z =100° ;

FIG. 9 is a schematic diagram of an architecture of a mirrored 3D MIMO half-wave antenna array provided by an embodiment of the present invention;

10 is a schematic diagram of a Yee cell in the FDTD algorithm provided by an embodiment of the present invention;

11 is a schematic diagram of propagation and a schematic diagram of a direction of a 2×2×2 3D MIMO half-wave antenna array with α _x =0°, α _y =0°, and α _z =0° according to an embodiment of the present invention;

FIG. 12 is a schematic diagram of propagation and a schematic diagram of a direction of a 2×2×2 3D MIMO half-wave antenna array with α _x =0°, α _y =-120°, α _z =0°, provided by an embodiment of the present invention;

13 is a schematic flowchart of a method for establishing a mirrored 3D MIMO half-wave antenna array according to an embodiment of the present invention;

FIG. 14 is a logical block diagram of an electronic device in one embodiment of the present invention.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

FIG. 1 shows a schematic structural diagram of a mirrored 3D MIMO half-wave antenna array provided in this embodiment, including: a 2D MIMO half-wave antenna array 101 and a reflector 102;

The 2D MIMO half-wave antenna array 101 is arranged on the mirror side of the reflector 102;

The virtual image of the 2D MIMO half-wave antenna array 101 in the reflector 102 and the 2D MIMO half-wave antenna array 101 form a mirrored 3D MIMO half-wave antenna array.

Among them, the 2D MIMO half-wave antenna array is a two-dimensional multiple-input multiple-output half-wave antenna array; the 3D MIMO half-wave antenna array is a three-dimensional multiple-input multiple-output half-wave antenna array.

点的电场可简化为E_r、E_θ、

三个分量。Specifically, a half-wave antenna array means that the array element is a half-wave antenna. The so-called half-wave antenna refers to a symmetrical linear antenna with an antenna length of half a wavelength, and the radiation field of a linear antenna with a finite length at a certain point in space can be regarded as is the superposition of the radiated fields by the infinite element antenna there. The so-called element antenna refers to an antenna whose length is d _z and the element current of Id _z acts on a uniformly distributed current of I. Because the element current is small, the element antenna is short, and the receiving area is relatively far away, the element antenna can be regarded as a basic radiating oscillator. Figure 1 shows the situation of the element antenna in the rectangular coordinate system and the spherical coordinate system. It is not difficult to find that the element antenna is far away.

The electric field at a point can be simplified to E _r , E _θ ,

three components.

According to antenna theory, the analysis basis of half-wave antenna array is half-wave antenna, the analysis basis of half-wave antenna is linear antenna, the analysis basis of linear antenna is element antenna, and element antenna is the analysis basis of all antenna systems.

According to the electromagnetic field theory, in the coordinate system of Figure 2, the vector potential (vector potential) generated at P by the element current I along the Z axis in the element antenna can be expressed as:

The vector A can also be decomposed in the spherical coordinate system as

Since the transformation matrix between spherical coordinates and rectangular coordinates is:

It can be seen from FIG. 2A that the rectangular coordinate component of the vector position of the element antenna at P is A _x =A _y =0, and according to formula (2), the spherical coordinate component of the vector position of the element antenna at P can be obtained as A _r = _Az cos θ, A _θ = _Az sin θ,

And because the relationship between the electric field E and the magnetic field H and the vector potential A is:

According to formula (3), the spherical coordinate component of the electromagnetic field of the element antenna at P can be obtained as:

真空介电常数ε₀＝8.854×10^-12F/m，磁导率μ₀＝4π×10^-7H/m，波数k＝2π/λ，介质波阻η＝√(μ/ε)，真空波阻η₀＝120πΩ。in the formula

Vacuum permittivity ε ₀ =8.854×10 ^-12 F/m, magnetic permeability μ ₀ =4π×10 ^-7 H/m, wave number k=2π/λ, dielectric wave resistance η=√(μ/ε), Vacuum wave resistance η ₀ =120πΩ.

和E_θ两个分量，E_r分量忽略不计，即：Since formula (4) is relatively complicated, only the far-field region is used to simplify the approximate analysis. The so-called far-field region means that the position of P satisfies the condition of kr>>1. At this time, only the 1/r term needs to be retained in the electromagnetic field component, and other terms can be ignored. Therefore, in the far-field region, only

and E _θ two components, E _r component is ignored, namely:

两项分量，将对称直线天线视为由无穷个元天线累加，如图3所示，求远场处

点的电场E_θ。若P点位于远场区，且天线信号激励电流的波长为λ、幅值为I_m，且指向Z轴正向，根据天线理论，这时的对称直线天线上的电流可以近似为三角形分布，即z≥0时信号的激励电流为I(z)＝I_msink(l-z)、z<0时信号的激励电流为I(z)＝I_msink(l+z)，根据公式(9)，对称直线天线上的电流元(或元天线)Id_z在远场区P点的辐射电场可以表示为：According to equation (5), the electromagnetic field of the element antenna in the far-field region is only E _θ and

Two components, consider the symmetrical linear antenna as the accumulation of infinite element antennas, as shown in Figure 3, find the far field

The electric field E _θ at the point. If point P is located in the far-field region, and the excitation current of the antenna signal has a wavelength of λ and an amplitude of _Im , and points to the positive direction of the Z-axis, according to the antenna theory, the current on the symmetrical linear antenna at this time can be approximated as a triangular distribution, That is, the excitation current of the signal when z≥0 is I(z)=I _m sink(lz), and the excitation current of the signal when z<0 is I(z)=I _m sink(l+z), according to formula (9) , the radiated electric field of the current element (or element antenna) Id _z on the symmetric linear antenna at point P in the far-field region can be expressed as:

Among them, the distance between the element antenna Id _z and the point P in the far field area is:

对r值用二项式展开，取前两项近似，则r≈R-z'cosθ。对于距离，远场区有r≈R成立，对于相位，远场区有r≈R-z'cosθ成立，将其代入(6)式得：Since R ² =x ² +y ² +z ² , z=Rcosθ, the distance r can be expressed as:

Expand the value of r with binomial, take the first two approximations, then r≈R-z'cosθ. For the distance, r≈R is established in the far-field region, and for the phase, r≈R-z'cosθ is established in the far-field region. Substitute it into equation (6) to get:

Obviously, the radiated electric field of the element antenna in the far-field region is only related to the inclination angle θ and the distance R of the antenna. Integrating the antenna length 2L, the electric field of the symmetric linear antenna at point P in the far-field region can be expressed as:

式中f(θ)为对称直线天线在远场区的方向图函数，可表示为：If we take the modulo value of E(θ), we have

where f(θ) is the pattern function of the symmetric linear antenna in the far-field region, which can be expressed as:

Assuming that the maximum value of the pattern function of the symmetric linear antenna is f _m , the normalized pattern function of the symmetrical linear antenna is: Fθ)=f(θ)/f _m , or:

When the length of the symmetrical linear antenna is 2L=λ/2, it is called a half-wave antenna or a half-wave oscillator, at this time kL=π/2, taking f _m =1, the half-wave antenna pattern function is:

If the half-wave antenna is placed in front of the metal mirror, a virtual image of the half-wave antenna will be generated behind the mirror, as shown in Figure 4. It can be seen that the electromagnetic field at point P in front of the mirror is generated by the superposition of the half-wave antenna and the virtual image of the half-wave antenna. If the vibration source current of the half-wave antenna is I, the distance from the mirror surface dy in the Y-axis direction, and the initial phase of the vibration source α _y , according to the electromagnetic field theory, not only the distance between the vibration source and the virtual image of the vibration source is _2dy , but also the vibration source and the vibration source are 2d _y . The phase difference of the source virtual image is also 2α _y . Therefore, if the XYZ coordinate system is made on the mirror surface as shown in Figure 3, and ψ _y =α _y +kd _y sinθsinφ, the electric field of the vibration source at P can be expressed as E=Ie ^{+αx+jkdysinθsinφ} =Ie ^+jψy , If the reflective surface has no loss, the electric field of the virtual image of the vibration source at P can be expressed as E`=I`e- ^{αx-jkdysinθsinφ} =Ie ^{-αx-jkdysinθsinφ} =Ie- ^jψy .

Similarly, if the two-dimensional half-wave antenna array is placed at _dy in front of the metal mirror, a virtual image of the two-dimensional half-wave antenna array can also be obtained at _dy behind the mirror (as shown in Figure 1), forming a physical It is a two-dimensional, logically three-dimensional mirrored three-dimensional half-wave antenna array. Although the mirrored three-dimensional half-wave antenna array has only two array elements on the Y-axis, by adjusting the distance dy between the vibration source and the mirror surface and the initial phase α _y of the vibration source on the _Y -axis, it is also possible to obtain the same three-dimensional half-wave antenna. The same beamforming effect in the Y-axis direction as the wave antenna array. The difference is that the values of the _{dy and α y parameters} of the mirrored three-dimensional half-wave antenna array are half of those of the three-dimensional half-wave antenna array.

The following first analyzes the two-dimensional physical half-wave antenna array on the _XZ plane at dy in front of the mirror:

Assume that the phase difference of the excitation current of the adjacent antennas on the X axis is α _x , the initial phase of the excitation current of the Y axis antenna is α _y , and the phase difference of the excitation current of the adjacent antennas on the Z axis is α _z . _y , so the excitation current of the first array element in the first row on the X axis is I ₁₁ e ^+jψy , the excitation current of the second array element in the first row is I ₁₂ =I ₁₁ e ^jαx+jψy ,..., the first row The excitation current of the n _xth array element is I _1nx =I ₁ e ^{j(nx-1)αx+jψy} , the excitation current of the first array element of the second row is I ₂₁ =I ₁₁ e ^jαz+jψy , the second row of the first array element is I 21 =I 11 e jαz+jψy , The excitation current of the two array elements is I ₂₂ =I ₂₁ e ^jαx ₌ I ₁₁ e ^{j(αx+αz)+ jψy} _{, .} ^-1)αx =I ₁₁ e ^{j[(nx-1)αx+αz]+jψy} ,..., the excitation current of the first array element in the n _z row is I _nz1 =I ₁₁ e ^{j(nz-1)αz+ jψy} , the excitation current of the second array element in the n _z th row is I _nz2 =I _nz1 e ^jαx =I ₁₁ e ^{j[(nz-1)αz+αx]+jψy} ,..., the n _z th row of the n _x array The element excitation current is I _nznx =I _nz1 e ^j(nx-1)αx =I ₁₁ e ^{j[(nx-1)αx+(nz-1)αz]+jψy} , then the electric field independently generated by each array element can be expressed as :

Since r>>Nd, its Taylor expansion, taking the first-order approximation, can define the median value of complex numbers:

Similarly, the median value of the denominator real numbers can also be defined

r ₁₂ ≈…≈r _1nx ≈…≈r ₂₁ ≈…≈r _2nx ≈…≈r _nznx ≈r ₁₁ (14)

Substitute (13) and (14) into (12) to get:

definition:

ψ _z = α _z +kd _z cosθ (17)

Superimpose equation (15) and substitute equations (16) and (17) to get:

Since I ₂₁ =I ₁₁ e ^jαz , ..., I _nz1 =I ₁₁ e ^j(nz-1)αz , in the denominator r ₂₁ ≈...≈r _nz1 ≈r ₁₁ , in the complex number r ₂₁ ≈r ₁₁ -d _z cosθ, ..., r _nz1 ≈r ₁₁ -(nz-1)d _z cosθ, then:

The electric field at P of all elements in the superimposed half-wave antenna array:

E=E ₁ +E ₂ +…

+E _nz =E ₁₁ [(1-e ^jNxψx )e ^jψy /(1-e ^jψx )]+E ₂₁ [(1-e ^jNxψx )e ^jψy /(1-e ^jψx )]+…

+E _nz1 [(1-e ^jNxψx )e ^jψy /(1-e ^jψx )]

=E ₀ I ₁₁ /r ₁₁ e ^-jkr11 [cos(π/2cosθ)/sinθ][(1-e ^jNxψx )/(1-e ^jψx )]e ^jψy [(1-e ^jNzψz )/(1-

e ^jψz )] (20)

Then analyze the virtual image of the two-dimensional half-wave antenna array on the XZ plane _dy behind the metal mirror.

According to the principle of mirror image, with the help of formula (20), the total electric field at P of all elements of the virtual image of the two-dimensional half-wave antenna array can be expressed as:

E`=E ₀ I ₁₁ /r ₁₁ e ^-jkr11 [cos(π/2cosθ)/sinθ][(1-e ^jNxψx )/(1-e ^jψx )]e ^-jψy [(1-e ^jNzψz )/

(1-e ^jψz )] (21)

Finally, the common total field at P of the two-dimensional half-wave antenna array and the virtual image of the two-dimensional half-wave antenna array can be expressed as:

Es=E+E`=E ₀ I ₁₁ /r ₁₁ e ^-jkr11 [cos(π/2cosθ)/sinθ][(1-e ^jNxψx )/(1-e ^jψx )]

[(1-e ^jNzψz )/(1-e ^jψz )](e ^jψy +e ^-jψy ) (22)

According to the formula e ^jθ =cosθ+jsinθ, e ^-jθ =cosθ-jsinθ, formula (26) can be expressed as:

Es=E ₀ I ₁₁ /r ₁₁ e ^-jkr11 [cos(π/2cosθ)/sinθ][(1-e ^jNxψx )/(1-e ^jψx )][(1-e ^jNzψz )/(1-e

^jψz )][2cosψ _y ]

Taking the absolute value, we get:

|E|＝|E ₀ I ₁₁ /r ₁₁ e ^-jkr11 |[cos(π/2cosθ)/sinθ][sin(N _x ψ _x /2)/sin(ψ _x /2)][sin(N _z ψ _z

/2)/sin(ψ _z /2)]2cosψ _y (23)

Therefore, the pattern function of the mirrored three-dimensional half-wave antenna array can be expressed as:

The normalized pattern function of the mirrored 3D half-wave antenna array is:

Obviously, [cos(π/2cosθ)/sinθ] is the pattern function of the half-wave antenna, and [sin(N _x ψ _x /2)/sin(ψ _x /2)] is the array factor of the parallel oscillator along the X axis , [sin(N _z ψ _z /2)/sin(ψ _z /2)] is the array factor of the coaxial oscillator along the Z axis, [2cosψ _y ] is the array factor of the array element and the virtual image of the array element on the Y axis. It should be noted that the distance between two adjacent array elements in the Y-axis array factor is 2d _y , that is to say, the thickness of the two-dimensional half-wave antenna array converted into the mirrored three-dimensional half-wave antenna array by mirror reflection is only three-dimensional. Half wave antenna array thickness.

In addition, the pattern function of the three-dimensional half-wave antenna array is:

As in Equation (25), the normalized pattern function of the three-dimensional half-wave antenna array is:

In fact, the three-dimensional half-wave antenna array pattern function can be used to derive the mirror image three-dimensional half-wave antenna array pattern function. Take N _y =2, dy =2d _y `, α <sub>y</sub> =2α <sub>y</sub> `, then ψ _y =α _y +kd _y sinθsinφ=2α _y `+k2d <sub>y</sub> `sinθsinφ _{=2ψ y `} , and substitute it into (26) In the formula, the second term of the Y-axis matrix factor [sin(N _y ψ _y /2)/sin(ψ _y /2)] can be obtained:

[sin(N _y ψ _y /2)/sin(ψ _y /2)]=[sin(2ψ _y `)/sin(ψ <sub>y</sub> `)]=2cos(ψ _y `) (28)

Substitute equation (28) into equation (26) to obtain equation (24). Therefore, from the analytical point of view, the mirrored three-dimensional half-wave antenna array is actually a three-dimensional half-wave antenna array with only two elements in the _Y -axis, and the parameters dy and αy of the mirrored three-dimensional half-wave antenna array, only the Y-axis has only two elements. Half of the parameters corresponding to a three-dimensional half-wave antenna array with two elements.

Let the frequency of the electromagnetic wave be f=6GHz, the wavelength be λ=c/f, and c=3×10 ⁸ is the speed of light in vacuum. Let the number of elements of the 3D MIMO half-wave antenna array elements on the X, Y, and Z axes be Nx=2, Ny=2, Nz=2, and the spacing between adjacent array elements is dx ₌ λ/2, dy =λ/4, d _z =0.6λ, the phase difference of each adjacent array element is α _x =0°, α _y =0°～−120°, α _z =0°. According to formula (27), the normalized pattern of the 3D MIMO half-wave antenna array can be obtained analytically, as shown in Figs. 5D and 11D.

If the space step length D _x =D _y =D _z =λ/24, and the time step length Dt=Dx/(2c), then the array element spacing d _x =12 cells, _{dy =6 cells, d z =} 14 cells. Assuming 8 cells in the PML area and 42 cells in the active area of the array element and the total field interval, the cell numbers of the FDTD in the three-dimensional space are s _x =112, s _y =106, and s _z =114, respectively. Considering the microcomputer memory space and CPU performance, the number of time iterations is 400. According to formulas (29) and (30), the electromagnetic radiation pattern and pattern of the 3D MIMO half-wave antenna array can be obtained by FDTD and fully matched absorption boundary PML simulation, as shown in Figures A to C in Figures 5 and 11.

It can be seen from Figures 5 and 11 that in the 3D MIMO half-wave antenna array, the phase difference α _y between the Y-axis elements determines the beam distribution on the Y-axis. When α _y = 0°, the main and side lobes are the same, Distributed at both ends of the Y-axis; when α _y =-120°, the side lobes are extremely small, and the main lobes are distributed in the positive direction of the Y-axis, see Figures 5 and 11. Therefore, the directivity of the 3D MIMO half-wave antenna array is excellent, and the beamforming can be easily adjusted through six parameters of d _x , _dy , d _z , α _x , α _y , and α _z .

Assuming that the number of elements of the 2D MIMO half-wave antenna array element on the X and Z axes is N _x =2, N _z =2, the distance between adjacent array elements is dx=λ/2, d _z =0.6λ, the phase The phase differences of adjacent array elements are α _x =0° and α _z =0°, respectively. Assume that the distance between the 2D MIMO half-wave antenna array and the back metal silver mirror is dy = λ/8, and the initial phase of the array element on the Y axis is α _{y =} -60°. According to formula (25), the normalized pattern of the mirrored 3D MIMO half-wave antenna array is analytically obtained, as shown in Fig. 12D.

According to the same space step as above, the array element spacing is d _x =12 cells, d _z =14 cells, and the distance between the 2D MIMO half-wave antenna array and the mirror surface is _dy =3 cells. Taking metallic silver as the mirror, conductivity σ _Ag =6.25×10 ⁷ Siemens/m, copper σ _Cu =5.88×10 ⁷ and aluminum σ _Al =3.72×10 ⁷ can also be used to reduce cost. According to formulas (29) and (30), the electromagnetic radiation pattern and pattern of the mirrored 3D MIMO half-wave antenna array can be obtained by FDTD and fully matched absorption boundary PML simulation, as shown in Figures 5A to 5C.

The structure of the mirror 3D MIMO half-wave antenna array from top to bottom mainly includes: protective casing, array unit, array element support surface, bracket between array element surface and reflector surface, metal-coated reflector surface, substrate, phased power amplifier and other components Components such as the integrated surface and the bottom plate as the back of the shell, among which the array element support surface, brackets and other components are reinforced engineering plastic parts. The interface between the bracket and the support surface is connected with non-metal screw-free interface cards. Except for the array element and the information connection line, they are all reinforced plastic parts. The connection between all the array elements on the support surface of the array element and the integrated components behind the mirror reflection surface is an integrated parallel data line, which is laid out through the edge of the antenna shell. , except for a small amount of non-metallic brackets between the support surface of the array element and the mirror reflection surface, there are no other metal parts that can interfere with electromagnetic waves, so as to ensure the mirror reflection effect of the mirror on the array element.

In the embodiment of the present invention, a mirror is added on the basis of the 2D MIMO half-wave antenna array by using the mirroring technology, so that the 2D MIMO half-wave antenna array can generate a virtual image behind the mirror surface to form a mirrored 3D MIMO half-wave antenna array , the cost, technology, volume and weight are almost the same as 2D MIMO half-wave antenna arrays, but beamforming is far superior to 2D MIMO half-wave antenna arrays.

Further, based on the above embodiment, the distance between the 2D MIMO half-wave antenna array and the reflector is less than 0.5λ, where λ is the wavelength of the electromagnetic wave in the 2D MIMO half-wave antenna array.

Specifically, the main technical index of the mirrored 3D MIMO half-wave antenna array is the distance _dy between the 2D MIMO half-wave antenna array and the reflector. The performance of the mirrored 3D MIMO half-wave antenna array is mainly the effect of the lobes, that is, the larger the main lobe strength, the better, the smaller the main lobe angle, the better, and the smaller the side lobe, the better. The beam effect of the half-wave antenna array is related to the azimuth and inclination of the beam. When the azimuth is 90° or α _x = 0°, the side lobe of the horizontal lobe is almost 0; when the inclination is 90° or α _z = 0 At °, the sidelobe of the vertical lobe is almost zero, as shown in Figure 6C. When α _x ≠ 0° or α _z ≠ 0°, both horizontal lobes or vertical lobes produce side lobes, and the larger the absolute value of the angle, the greater the intensity of the side lobes, the greater the number of side lobes, and even the greater the number of side lobes. The lobe strength exceeds the main lobe. However, by adjusting the spacing _dy appropriately, the azimuth angle and inclination angle of the array beam are within an appropriate adjustment range, and a better lobe effect can be obtained.

Take the basic array parameters f=6GHz, Nx=2, Nz=2, α _x =0°～100°, α _y =-60°, α _z =0°～100°, d _x =λ/2, d _z =0.6λ, when the distance between the 2D MIMO half-wave antenna array and the mirror surface is d _y =0～0.5λ, according to formula (25), the difference between the horizontal lobe and the vertical lobe of the main lobe of the mirrored three-dimensional MIMO half-wave antenna array is obtained. The relationship between the normalized maximum value and beam angle and _dy , as well as the normalized pattern of the horizontal lobe and vertical lobe at _dy corresponding to the maximum beam intensity, are shown in Figures 6-8 to analyze The relationship of the array to the mirror spacing. The reason why only the range of dy = _0-0.5λ is analyzed is not only to consider reducing the thickness of the array antenna, but also because this range is just the main range of the array performance variation.

Figure 6 shows the variation of the maximum value and included angle of the lobe with _dy when α _x = 0°, α _y = -60°, and α _z = 0° for a 2×1×2 mirrored 3D MIMO half-wave antenna array. Relationship curve, and the pattern curve for dy = _0.167λ . It can be seen that in the curve of the maximum beam value changing with _dy , the horizontal lobe and the vertical lobe curve completely coincide, because the horizontal lobe and the vertical lobe are the curves taken by the same beam at different sections. The normalized maximum value corresponds to dy = _0.167λ , and the optimal value range is 0 to _0.3λ ; in the curve of the beam angle changing with dy, the difference between the horizontal lobe and the vertical lobe is large, because the horizontal The lobe array elements are distributed in parallel by the half-wave antenna, and the vertical lobe array elements are distributed axially by the half-wave antenna. Therefore, not only the vertical lobe angle is smaller than the horizontal lobe, but also the change of the vertical lobe angle is higher than that of the horizontal lobe. The flap angle changes slowly. The optimal value range of the two is still 0~0.3λ.

Figure 7 shows the change of the maximum value and included angle of the lobe with _dy when α _x = 100°, α _y = -60°, α _z = 0° for a 2×1×2 mirrored 3D MIMO half-wave antenna array Relationship curve, and the pattern curve when dy = _0.201λ . It can be seen that the curve of the maximum value of the horizontal lobe and the vertical lobe changing with dy completely coincides, the normalized maximum value corresponds to dy _{= 0.201λ} , and the optimal value range is 0.1λ～0.3λ; the horizontal lobe There is a big difference between the included angle and the vertical lobe angle as a function of _dy . Since only the phase difference between adjacent array elements on the X-axis is α _x = 100°, only the horizontal lobe changes greatly, not only the azimuth angle is 124°, but also two larger secondary lobes on both sides of the main lobe. lobe, which affects the energy distribution of the main lobe and changes the curve shape of the angle between the horizontal lobe and _dy . The included angle of the vertical lobe becomes larger with the change of _{dy, and the included angle and inclination of the beam hardly change, indicating that the change of α x has} little effect on the vertical lobe.

Figure 8 shows the variation of the maximum value and included angle of the lobe with _dy when α _x = 0°, α _y = -60°, α _z = 100° for a 2×1×2 mirror 3D MIMO half-wave antenna array Relationship curve, and the pattern curve for dy = _0.176λ . It can be seen that the curve of the maximum value of the horizontal lobe and the vertical lobe changing with dy coincides, the normalized maximum value corresponds to dy _{= 0.176λ} , and the optimal value range is 0.1λ～0.3λ; the horizontal lobe clamps The curves of the angle and the vertical lobe angle with _dy vary greatly. This is mainly because only the phase difference between adjacent array elements on the Z axis is α _z = 100°, so the inclination of the vertical lobe is 109°, and a side lobe is generated, which affects the energy distribution of the vertical main lobe. Of course, To change the vertical lobe angle and _dy curve shape. The azimuth angle of the horizontal lobe is still 90°, and the curve shape of the horizontal lobe angle and _{dy is basically unchanged, which also shows that the change of α z has} little effect on the horizontal lobe.

According to the comparison of all the curves in Figure 6-8, considering the maximum value of the main lobe and the angle between the main lobes, the optimal spacing of the mirrored 3DMIMO half-wave antenna array is d _y =0.1λ～0.2λ, in general, take d _y = 0.125λ, that is, the distance between the 2D MIMO half-wave antenna array and the metal mirror is λ/8, which is also half of the value of λ/4 between the adjacent elements on the Y-axis in a typical 3D MIMO half-wave antenna array, so we The distance between the mirrored 3D MIMO half-wave antenna array and the metal mirror is designed to be _{dy =} λ/8. It can be seen from the directional diagram that when the horizontal adjacent array elements differ by α _x to change the beam azimuth, the effect on the beam inclination has little effect. On the contrary, when the vertical adjacent array elements differ by α _z to change the beam inclination, the influence on the beam azimuth It is not too big. Considering the size of the array, we still design the 2D MIMO half-wave antenna array so that the distance between adjacent array elements on the X axis is d _x =λ/2, and the distance between adjacent array elements on the Z axis is d _z =0.6λ, see Figure 9 shown.

Further, on the basis of the above embodiment, the virtual image and the 2D MIMO half-wave antenna array are simulated by the finite difference time domain method FDTD to form a mirrored 3D MIMO half-wave antenna array.

Specifically, the FDTD (Finite Difference Time Domain, finite difference time domain) is a time and space-based, finite difference discretization of Maxwell's curl equation, with two-order precision, and a central finite difference format instead of differential form approximation. Iterative numerical calculation method. FDTD differentiates Maxwell's differential equations simultaneously in the two domains of space and time, alternately calculates the electric and magnetic fields in the space domain by leapfrog leaps, and simulates changes in field strength by updating in the time domain. FDTD analysis of the electromagnetic field requires consideration of the geometric parameters, material parameters, calculation accuracy, complexity and stability of the research object, and the simulation accuracy is high. The parameters of FDTD simulating space electromagnetic properties are given according to the space grid, and complex electromagnetic structures can be simulated only by giving the medium parameters of the corresponding space points. FDTD solves finite difference equations under appropriate boundary and initial conditions, describes complex physical processes with clear images, can directly reflect the time domain characteristics of electromagnetic waves, and can represent very rich time domain information of electromagnetic fields. It is an important part of modern electromagnetic field research. method.

The FDTD meshing adopts the structure method proposed by Yee that the space and time are different by half a step. Through the leapfrog step, the magnetic and electric field values of the previous moment are used to obtain the electric and magnetic field values at the current moment. Calculate the process over the entire space, so as to obtain the time domain solution of the time-varying electric and magnetic fields in the entire space. If Fourier transform is applied to the time domain solution, the corresponding frequency domain solution can be obtained. Although the action area of the electromagnetic field is infinite, the calculation space of FDTD is limited, that is, the number of Yee grids composed of Yee cells (as shown in Figure 10) is limited, and an electromagnetic field absorption area must be set at the boundary of the total field area of FDTD, such as approximate absorption The boundary MUR and the perfectly matched absorption boundary PML, in which the complete matching of the PML absorption boundary makes the electromagnetic field propagating to the total field boundary almost completely absorbed, and the electromagnetic wave propagation effect in the simulated infinite space is very real. Using the FDTD and PML boundaries to analyze the electromagnetic field propagation between the simultaneous frequency transceiver antennas that meet the needs of 5G, the ideal effect can be obtained.

其中D＝εE、B＝μH、J＝σE、J_m＝σ_mH。若将矢量方程展开为直角坐标系标量方程，对时域和空域的一阶偏导数取中心差分近似离散，整理后便可得到FDTD方程，其中电场E_x方程为：Maxwell's curl equation is composed of Ampere's loop law and Faraday's law of electromagnetic induction, and the vector formula is

where D=εE, B=μH, J= _σE , Jm= _σmH . If the vector equation is expanded into a scalar equation in a rectangular coordinate system, and the first-order partial derivatives in the time domain and space domain are approximated by the central difference, the FDTD equation can be obtained after sorting, and the electric field E _x equation is:

Because E _y , E _z and _Ex have complete duality and xyz subscript cyclicity, they can be derived and obtained according to formula (29).

Similarly, the magnetic field H _x equation of the FDTD equation is:

Also, because _{Hy, H z and} H _x have complete duality and xyz subscript cyclicity, they can be derived and obtained according to formula (30).

The coefficients in equations (29) and (30) are: C _a (m)={1-[σ(m)Δt]/[2ε(m)]}/{1+[σ(m)Δt]/[ 2ε(m)]}, C _b (m)={Δt/ε(m)}/{1+[σ(m)Δt]/[2ε(m)]}, C _p (m)={1- [σ _m (m)Δt]/[2μ(m)]}/{1+[σ _m (m)Δt]/[2μ(m)]}, C _q (m)={Δt/μ(m) }/{1+[σ _m (m)Δt]/[2μ(m)]}, where m takes values throughout the Yee cell subscripts of each computational region. Obviously, formulas (29) and (30) are iterative formulas in the time domain to calculate the next moment from the previous moment, each moment is superimposed in the air domain, and the characteristics of the Yee cell are determined by the ε of the location of each Yee cell. (m), μ(m), σ(m) and σm ( _m ). When the total field is a vacuum and the scatterer is a metal surface, except that the Yee cell parameter σ(m) corresponding to the scatterer is different, ε(m)=ε ₀ , μ(m)=μ ₀ , σ(m)= 0, σ _m (m)=0, the FDTD equation at this time is very simple. In addition, the space step Δx, Δy, Δz and time step Δt must satisfy the Courant stability condition, that is, Δx, Δy, Δz≦λ/12, Δt≦min(Δx, Δy, Δz)/c, in order to ensure the iteration of the FDTD equation The convergence of , generally take Δx=Δy=Δz=λ/20, Δt=Δx/(2c), λ is the wavelength of the electromagnetic field, and c is the speed of light in vacuum.

Since FDTD modeling can be highly consistent with the real scene, under the premise of computing resources, when the values of space step Δx, Δy, Δz and time step Δt are small enough, and the number of time iterations is large enough, FDTD simulation three-dimensional The electromagnetic field propagation of the half-wave antenna array is very close to the real scene. Not only can qualitatively visualize the electromagnetic field propagation, but also quantitatively obtain data that is close to reality. However, due to the limited computing resources and the number of FDTD cells, the dynamic transmission analysis area of the electromagnetic field can only be a small electrical environment. It is used to analyze the dynamic transmission distribution of the electromagnetic field in the near-field area of the antenna, so that the analytical formula and FDTD can complement each other in the far-field and near-field areas of the antenna.

From the analytical patterns in Figures 5 and 12 to the FDTD propagation pattern and pattern, the difference between the two is very small. The lobe angle of the FDTD pattern is larger than that of the analytical pattern, because the analytical pattern is suitable for the far-field region. FDTD accommodates the near field region. By comparing Figure 5 and Figure 12, it can be seen that the FDTD propagation diagram of Figure 12 has sidelobes in the negative Y-axis direction, but the FDTD propagation diagram of Figure 5 has no sidelobes in the negative Y-axis direction, indicating that the mirror image 3D MIMO half A wave antenna array can not only achieve the same effect as a 3D MIMO half-wave antenna array, but may be better in some ways.

Further, on the basis of the above embodiment, the reflecting mirror is a metal mirror.

Among them, the mirror surface of the metal mirror is an important component for generating the mirror image array elements. The higher the reflectivity, the higher the similarity of the mirror image array elements, and the better the mirror three-dimensional effect. One of the advantages of the mirror 3D MIMO antenna array is that it is thin. In order to facilitate the installation of the two-dimensional array and the metal mirror, the mirror material needs to meet the characteristics of lightness, thinness, flatness and high reflectivity. We design the mirror to be silver-coated organic material, because The high-frequency skin effect is strong, the electromagnetic wave incident on the metal is very shallow, and the high-frequency electromagnetic wave can be reflected in the silver coating, which can not only improve the reflection performance, save the cost, reduce the weight, but also facilitate the selection of the reflection material. with installation. Since the distance between the 2D MIMO half-wave antenna array and the metal mirror is very small, the control components such as the weight and phase of the array elements can be placed behind the metal mirror, or directly integrated on the other side of the metal mirror. Connect the control array element and send and receive the vibration element signal.

In the array element control system, since there are only two array elements in the Y-axis direction, the half-wave antenna and the half-wave antenna virtual image, it is only necessary to add an initial phaser in the Y-axis direction to the array element. Although the initial phaser can adjust the initial value, But the function is single and the structure is simple. In addition, the phase difference between adjacent array elements in the X-axis and Z-axis in the 2D MIMO half-wave antenna array is given by the respective phase shift controllers. In order to better control the beamforming, it is also necessary to use a weight controller to control the amplitude of the transmitted signal on each array element. Since these controllers are all mature technology components, the integration and standardization are very high, and they can be integrated on the other side of the mirror surface material to make it a whole with the mirror surface, or the controller and the mirror surface can be formed to support four and more For modules with more than 4 array elements, the entire array is composed of multiple modules, which can save space and weight, facilitate installation and maintenance, and reduce technical difficulty and cost.

This embodiment uses the 2D MIMO half-wave antenna array as the technical basis to realize the effect of the 3D MIMO half-wave antenna array. better than microstrip patch antenna arrays. Due to the mature technology of the two-dimensional half-wave antenna array, the design scheme is simple in structure, easy to implement, and has certain feasibility and practicability.

FIG. 13 shows a schematic flowchart of a method for establishing a mirrored 3D MIMO half-wave antenna array provided in this embodiment, including:

S1301. Determine the distance between the 2D MIMO half-wave antenna array and the reflector;

S1302. Set the 2D MIMO half-wave antenna array and the reflector according to the distance;

S1303. Simulate the virtual image and the 2D MIMO half-wave antenna array to establish a mirrored 3D MIMO half-wave antenna array.

In the embodiment of the present invention, a mirror is added on the basis of the 2D MIMO half-wave antenna array by using the mirroring technology, so that the 2D MIMO half-wave antenna array can generate a virtual image behind the mirror surface to form a mirrored 3D MIMO half-wave antenna array , the cost, technology, volume and weight are almost the same as 2D MIMO half-wave antenna arrays, but beamforming is far superior to 2D MIMO half-wave antenna arrays.

Further, on the basis of the foregoing method embodiments, S1301 specifically includes:

The distance between the 2D MIMO half-wave antenna array and the reflector is determined according to the maximum value of the main lobe and the included angle of the main lobe.

Further, on the basis of the above method embodiments, S1303 specifically includes:

The virtual image and the 2D MIMO half-wave antenna array are simulated by using the FDTD, and a mirrored 3D MIMO half-wave antenna array is established.

The method for establishing a mirrored 3D MIMO half-wave antenna array described in this embodiment can be used to implement the foregoing apparatus embodiments, and the principles and technical effects thereof are similar, and details are not described herein again.

14, the electronic device includes: a processor (processor) 1401, a memory (memory) 1402 and a bus 1403;

in,

The processor 1401 and the memory 1402 communicate with each other through the bus 1403;

The processor 1401 is configured to call program instructions in the memory 1402 to execute the methods provided by the above method embodiments, for example, including:

determining the distance between the 2D MIMO half-wave antenna array and the mirror;

setting the 2D MIMO half-wave antenna array and the mirror according to the distance;

The virtual image and the 2D MIMO half-wave antenna array are simulated to establish a mirrored 3D MIMO half-wave antenna array.

This embodiment discloses a computer program product, the computer program product includes a computer program stored on a non-transitory computer-readable storage medium, the computer program includes program instructions, and when the program instructions are executed by a computer, the computer program The methods provided by the above method embodiments can be performed, for example, including:

determining the distance between the 2D MIMO half-wave antenna array and the mirror;

setting the 2D MIMO half-wave antenna array and the mirror according to the distance;

The virtual image and the 2D MIMO half-wave antenna array are simulated to establish a mirrored 3D MIMO half-wave antenna array.

This embodiment provides a non-transitory computer-readable storage medium, where the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the methods provided by the foregoing method embodiments, for example, including :

determining the distance between the 2D MIMO half-wave antenna array and the mirror;

setting the 2D MIMO half-wave antenna array and the mirror according to the distance;

The virtual image and the 2D MIMO half-wave antenna array are simulated to establish a mirrored 3D MIMO half-wave antenna array.

Those of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by program instructions related to hardware, the aforementioned program can be stored in a computer-readable storage medium, and when the program is executed, execute It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

The device embodiments described above are only illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed over multiple network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution in this embodiment. Those of ordinary skill in the art can understand and implement it without creative effort.

From the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and certainly can also be implemented by hardware. Based on this understanding, the above-mentioned technical solutions can be embodied in the form of software products in essence or the parts that make contributions to the prior art, and the computer software products can be stored in computer-readable storage media, such as ROM/RAM, magnetic A disc, an optical disc, etc., includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in various embodiments or some parts of the embodiments.

It should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be used for The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (6)

1. a mirrored 3D MIMO half-wave antenna array, is characterized in that, comprising: 2D multiple-input multiple-output MIMO half-wave antenna array and reflector; The 2D MIMO half-wave antenna array is arranged on the mirror side of the reflector; Wherein, the virtual image of the 2D MIMO half-wave antenna array in the reflector and the 2D MIMO half-wave antenna array form a mirrored 3D MIMO half-wave antenna array; determining the distance between the 2D MIMO half-wave antenna array and the mirror; setting the 2D MIMO half-wave antenna array and the mirror according to the distance; Simulate the virtual image and the 2D MIMO half-wave antenna array to establish a mirrored 3D MIMO half-wave antenna array; The determining the distance between the 2D MIMO half-wave antenna array and the reflector specifically includes: The distance between the 2D MIMO half-wave antenna array and the reflector is determined according to the maximum value of the main lobe and the included angle of the main lobe. 2. The mirrored 3D MIMO half-wave antenna array according to claim 1, wherein the distance between the 2D MIMO half-wave antenna array and the reflector is less than 0.5λ, where λ is the 2D MIMO half-wave The wavelength of electromagnetic waves in an antenna array. 3 . The mirrored 3D MIMO half-wave antenna array according to claim 2 , wherein the distance between the 2D MIMO half-wave antenna array and the reflector is 0.125λ. 4 . 4 . The mirrored 3D MIMO half-wave antenna array according to claim 1 , wherein the virtual image and the 2D MIMO half-wave antenna array are simulated by the finite difference time domain method (FDTD) to form a mirrored 3D MIMO half-wave antenna array. 5 . 5. The mirrored 3D MIMO half-wave antenna array according to claim 1, wherein the reflector is a metal mirror. 6. The mirrored 3D MIMO half-wave antenna array according to claim 5, wherein the virtual image and the 2D MIMO half-wave antenna array are simulated to establish a mirrored 3D MIMO half-wave antenna array, which specifically includes : The virtual image and the 2D MIMO half-wave antenna array are simulated by FDTD to establish a mirrored 3D MIMO half-wave antenna array.

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