Design method of flat-top radiation transmission array antenna

Abstract

The invention discloses a design method of a flat-top radiation transmission array antenna. The method comprises the following steps: step 1, designing an amplitude-phase independent adjustable transmission array antenna unit; 2, arranging the designed # imgabs0 # transmission array antenna units according to a periodic array to form a transmission array surface, and calculating the distance between the transmission array surface and a feed source antenna according to a transmission array antenna radiation theory; and step 3, surface amplitudes and phase distribution of corresponding transmission array antenna units in different flat-top radiation modes are calculated through a maximum power transmission efficiency method, and structural parameters of the antenna units are determined based on the surface amplitudes and the phase distribution of the antenna units. The method mainly pays attention to an amplitude phase distribution algorithm of flat-top radiation, obtains a mathematical optimal solution without iteration, and reduces the calculation amount.

Description

Technical Field

[0001] The invention belongs to the technical field of microwaves and antennas, and in particular relates to a design method for a flat-top radiation transmission array antenna. Background Art

[0002] In recent years, with the rapid development of metasurface technology, the research on transmission array antennas has received more and more attention. The transmission array antenna consists of a feed antenna and a planar transmission array, which focuses or redistributes the radiation energy of the directional feed antenna. With the deepening of metasurface research, the planar transmission array composed of metasurface units with independently adjustable transmission amplitude and phase can generate electromagnetic wave radiation in a specific direction and shape in space, realizing beam focusing, scanning, scattering, tracking and other functions to meet the needs of different communication systems and radar applications.

[0003] Currently, solving the amplitude and phase distribution of flat-top radiation transmission arrays requires relying on optimization algorithms. Due to the huge number of transmission array antenna units, it is very time-consuming to obtain its radiation characteristics through full-wave simulation or iterative optimization algorithms. Summary of the invention

[0004] In order to solve the above technical content, the present invention provides a design method for a flat-top radiation transmission array antenna. The transmission array surface is composed of transmission array surface units (transmission or reflection units) whose amplitude and phase can be independently controlled, and the transmission array surface amplitude and phase distribution corresponding to the flat-top radiation mode are calculated by the maximum power transmission efficiency method (MMPTE), thereby realizing the design of transmission array antennas with different flat-top radiation modes.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for designing a flat-top radiation transmission array antenna, the method comprising:

[0007] Step 1, designing an amplitude-phase independent adjustable transmission array antenna unit;

[0008] Step 2: Design The transmission array antenna units are arranged in a periodic array to form a transmission array surface. According to the transmission array antenna radiation theory, the distance between the transmission array surface and the feed antenna is calculated.

[0009] Step 3: Calculate the surface amplitude and phase distribution of the transmission array antenna unit corresponding to different flat-top radiation modes by using the maximum power transfer efficiency method, and determine the structural parameters of the antenna unit based on the surface amplitude and phase distribution of the antenna unit.

[0010] The beneficial effects of the present invention are:

[0011] The present invention mainly focuses on the amplitude phase distribution algorithm of flat-top radiation, obtains the mathematical optimal solution without iteration, and reduces the amount of calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the flat-top radiation transmission array antenna structure;

[0013] Figure 2 This is a schematic diagram of the radiation principle of the flat-top radiation transmission array antenna;

[0014] Figure 3 Schematic diagram of the flat-top radiation transmission array antenna unit structure, where (a) is the 3D structure diagram and (b) is the top view;

[0015] Figure 4 Figure 1 is a diagram showing the relationship between the unit structural parameters of the flat-top radiation transmission array antenna and the transmission amplitude phase, where (a) is a schematic diagram showing the relationship between the unit structural parameters of the transmission array antenna and the transmission phase, (b) is a schematic diagram showing the relationship between the unit structural parameters of the transmission array antenna and the transmission amplitude, and (c) is a schematic diagram showing the relationship between the unit structural angle of the transmission array antenna and the rotation angle.

[0016] Figure 5 Schematic diagram of the amplitude and phase distribution of the H-surface flat-top radiation transmission array antenna, where (a) is the schematic diagram of the phase distribution of the H-surface transmission array antenna, and (b) is the schematic diagram of the amplitude distribution of the H-surface transmission array antenna;

[0017] Figure 6 Schematic diagram of the H-plane flat-top radiation transmission array antenna model, where (a) is a top view and (b) is a top view;

[0018] Figure 7 Theoretical calculation and simulation pattern of H-surface flat-top radiation transmission array antenna;

[0019] Figure 8 Schematic diagram of amplitude and phase distribution of E-surface flat-top radiation transmission array antenna, where (a) is the schematic diagram of phase distribution of E-surface transmission array antenna, and (b) is the schematic diagram of amplitude distribution of E-surface transmission array antenna;

[0020] Fig. 9 Schematic diagram of the E-plane flat-top radiation transmission array antenna model, where (a) is a top view and (b) is a top view;

[0021] Fig.10 This is the theoretical calculation and simulation pattern of the E-surface flat-top radiation transmission array antenna. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Usually, a planar transmission array antenna includes a feed antenna and a transmission array surface (also called a transmission array plane) composed of a periodic surface unit structure. Figure 1 As shown, the transmission array surface performs secondary control on the electromagnetic waves radiated by the feed antenna to achieve energy convergence and beam control. A planar transmission array composed of metasurface units whose transmission amplitude and phase can be independently controlled can generate electromagnetic wave radiation in a specific direction and shape in space, and realize beam focusing, scanning, scattering, tracking and other functions to meet the needs of different communication systems and radar applications. The present invention combines MMPTE and transmission array antenna radiation theory to propose a flat-top radiation design method suitable for transmission array antennas, gives a theoretical calculation formula for radiation pattern prediction, and verifies the effectiveness and accuracy of the method through modeling simulation.

[0024] The radiation model of the flat-top radiation transmission array antenna is as follows: Figure 2 As shown, assuming are M surface units evenly distributed in the flat-top radiation area, all of which are located in the far field and are at a distance r from the feed antenna of the planar transmission array antenna. The direction of the mth surface unit is ( ), Represent the angular coordinates of the surface unit in the azimuth and elevation directions respectively. For the Poynting vector passing through each surface unit The integration can solve the total power passing through the M surface units. The power transmission efficiency (PTE) from the planar transmission array antenna to the surface unit can be expressed as:

[0025] (1)

[0026] in, is the total power radiated by the planar transmission array antenna, Represents the normal direction of each surface unit, Re represents the real part of the matrix, E and H denote the electric and magnetic fields at the surface unit, respectively, () represents the conjugate operation of the matrix. This formula is applicable to both near-field and far-field applications. In far-field applications, the radiated wave can be regarded as a uniform plane wave. In addition, it is assumed that the area of ​​each surface unit is the same and small, which is denoted by These approximations help to simplify equation (1).

[0027] Assume that the plane transmission array surface is composed of When each surface unit radiates with the same amplitude and phase, the surface unit P m The position index is ( ), then the surface unit P m The radiated electric field It can be expressed by the following formula:

[0028] (2)

[0029] (3)

[0030] in, Each surface unit is The radiated electric field at is the wave number, is the spacing between adjacent units on the transmission array surface, represents the direction vector of the electric field, j represents the imaginary unit, It is worth noting that the present invention only considers the case where all surface units radiate electromagnetic waves of the same linear polarization, and the other polarization is not taken into consideration.

[0031] Using complex matrices express The transmission wave distribution of each surface unit, T represents the transpose of the matrix, The electric field from the transmission array surface unit to the M surface units in the radiation area can be expressed by the matrix express:

[0032] (4)

[0033] The subscript rt in which r stands for receiving and t stands for transmitting. The magnetic field can be expressed as , is the characteristic impedance. The total power passing through M surface units It can be expressed as:

[0034] (5)

[0035] Among them, the superscript represents the conjugate operation of the matrix, and the superscript H represents the conjugate transpose operation of the matrix. It can be simplified to:

[0036] (6)

[0037] Among them, the intermediate parameters , so formula (1) can be expressed as:

[0038] (7)

[0039] The above derivation establishes the relationship between the radiation electric field of the transmission array antenna unit and the power transmission efficiency of the transmission array antenna. By adding constraints to the power transmission efficiency and solving it, the transmission wave distribution of the transmission array antenna unit corresponding to the ideal radiation mode can be obtained. The present invention adds the constraint that the power of each surface unit is the same when solving the power maximization of M surface units to obtain a flat-top radiation mode. The specific constraint expression is:

[0040] (8)

[0041] By solving equation (8) using the Lagrange multiplier method, the Lagrange function is defined as:

[0042] (9)

[0043] represents the Lagrange parameter, c represents a constant;

[0044] The optimal solution of formula (8) is as follows:

[0045] (10)

[0046] Obtained is the transmission wave distribution of the flat-top radiation of the planar transmission array antenna under this specific power distribution, that is, the optimal amplitude-phase distribution of the transmission array surface.

[0047] The radiation pattern of a planar transmission array antenna can be calculated using antenna array theory:

[0048] (11)

[0049] in, , They are The modulus and angle of the (p,q)th surface unit in the transmission array antenna correspond to the transmission amplitude and phase of the (p,q)th surface unit in the transmission array antenna.

[0050] According to the theoretical derivation of MMPTE in the transmission array antenna, the design of the transmission array antenna in the flat-top radiation mode can be realized. To verify the effectiveness of this method, the present invention will design the surface unit of the transmission array antenna with independent amplitude and phase adjustment and use the surface unit to design the transmission array antenna. It should be noted that the surface unit of the transmission array antenna can be arbitrarily replaced by a transmission or reflection unit with independent amplitude and phase adjustment.

[0051] The present invention selects a single dielectric layer metasurface with metal attached on both sides as a transmission array antenna surface unit to achieve independent control of the amplitude and phase of polarization conversion transmission. The transmission array antenna surface unit is composed of a dielectric layer and symmetrical S-shaped metal patches distributed above and below the dielectric layer. Amplitude and phase modulation are achieved through polarization conversion. The unit structure is as follows Figure 3 As shown in (a)-(b), the dielectric substrate is F4B ( ), dielectric layer thickness = 2mm. The upper and lower layers of the dielectric substrate are both attached with S-shaped metal patches. The lower metal layer is rotated 90° clockwise and is symmetrical with the upper metal layer about the y-axis. The surface unit can convert the y-polarized incident wave polarization into the x-polarized transmitted wave. The parameter adjustment of the surface unit structure includes two parts: the S-shaped metal structure parameter g, The adjustment can achieve the transmission wave 0 ~ Phase control is achieved by flipping the surface unit symmetrically about the yoz plane. Phase control of ~ 0; rotation angle parameters of S-shaped metal The polarization conversion ratio of the incident wave, i.e. the amplitude of the transmitted wave, can be controlled (parameter w is the width of the S-shaped metal structure, parameter g is the radius of the S-shaped metal structure, parameter α is the angle of the S-shaped structure, and parameter β is the rotation angle of the S-shaped structure). The relationship between the surface unit structure parameters g, α, β and the transmission amplitude at 12.2GHz is as follows: Figure 4 As shown in (a)-(c) in the figure, by adjusting the unit structure parameters, the amplitude of the transmitted wave can be adjusted from 0.2 to 0.85 and 2 The phase control within the range basically satisfies the transmission wave amplitude phase control required by the transmission array antenna design. Therefore, the surface unit is selected in the present invention to verify the design method of the flat-top radiation transmission array antenna.

[0052] In this design, a patch antenna operating at 12.2GHz is selected as the feed source. The transmission array surface is composed of 19×19 units, and the side length D of the transmission array surface is 247mm. According to the transmission array antenna radiation theory, the total radiation efficiency of the antenna reaches the maximum when F / D = 0.43. Therefore, in this design, the focal length of the transmission array antenna is F = 106mm, that is, the transmission array surface is 106mm away from the feed antenna and is directly above the feed antenna. According to the transmission array antenna radiation principle and the above method, when the transmission array unit and antenna model are determined, the amplitude and phase distribution of the transmission array surface under the corresponding radiation mode can be solved. The present invention designs flat-top radiation transmission array antennas on the H and E surfaces respectively to verify the effectiveness of this method.

[0053] In the H-surface flat-top radiation design, the radiation plane range is selected as (30°, 30°) ~ (30°, 60°), and four surface units evenly distributed in the radiation plane with an angle interval of 10° are selected for calculation. The amplitude and phase distribution of the transmission array surface obtained by solving the solution are as follows: Figure 5 As shown in (a)-(b) in the figure, the corresponding model is established by using Matlab-CST studio joint simulation. Figure 6 As shown in (a)-(b) in the figure. Figure 7 For the comparison between the theoretical calculation and the simulated radiation pattern of the transmission array antenna, the amplitude difference between the theoretical calculation and the simulated radiation pattern in the target radiation plane range of (30°, 30°) ~ (30°, 60°) is within 1dB. The results show that the radiated power is evenly distributed in the expected area, and the slight gain fluctuation may be caused by the coupling between the transmission array antenna elements.

[0054] In the E-surface flat-top radiation design, the radiation plane range is selected as (10°, 30°) ~ (40°, 30°), and four surface units evenly distributed in the radiation plane with an angle interval of 10° are selected for calculation. The amplitude and phase distribution of the transmission array surface obtained by solving the solution are as follows: Figure 8 As shown in (a)-(b) in the figure, the corresponding transmission array model is as follows Fig. 9 As shown in (a)-(b) in the figure. Fig.10 Comparing the theoretical calculation and simulation patterns in this case, it can be seen that the radiation power is concentrated within the target range and the gain fluctuation within the target range is less than 1.5dB.

[0055] In the above two examples, the theoretical calculation results are basically consistent with the simulation results and the flat-top radiation within the target range is achieved, which is sufficient to prove the effectiveness of this method.

[0056] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A design method for a flat-top radiation transmission array antenna, characterized in that: The method comprises: Step 1, designing an amplitude-phase independent adjustable transmission array antenna unit; Step 2: Design The transmission array antenna units are arranged in a periodic array to form a transmission array surface. According to the transmission array antenna radiation theory, the distance between the transmission array surface and the feed antenna is calculated. Step 3: Calculate the surface amplitude and phase distribution of the transmission array antenna unit corresponding to different flat-top radiation modes by using the maximum power transfer efficiency method, and determine the structural parameters of the antenna unit based on the surface amplitude and phase distribution of the antenna unit.

2. A method for designing a flat-top radiation transmission array antenna according to claim 1, characterized in that: In the step 1, the transmission array antenna unit realizes amplitude and phase modulation through polarization conversion.

3. A method for designing a flat-top radiation transmission array antenna according to claim 2, characterized in that: In step 2, the side length D of the transmission array surface is calculated. The transmission array surface is directly above the feed antenna. According to the transmission array antenna radiation theory, the total radiation efficiency of the antenna reaches the maximum when F / D = 0.43, and the focal length F of the transmission array antenna is designed.

4. The method for designing a flat-top radiation transmission array antenna according to claim 1, characterized in that: The step 3 includes: There are transmission array antenna surface units. When each surface unit radiates with the same amplitude and phase, the surface unit P m The position index is , , then the surface unit P m The radiated electric field It is expressed by the following formula: （2） （3） in, Each surface unit is The radiated electric field at is the wave number, is the spacing between adjacent antenna elements on the transmission array surface, represents the direction vector of the electric field, j represents the imaginary unit, represents the phase of the radiated electric field, Respectively represent the angular coordinates of the surface unit in the azimuth and elevation directions; Using complex matrices express The transmission wave distribution of antenna elements, T represents the transpose of the matrix, The electric field from the transmission array antenna element to the M surface elements in the radiation area is given by the matrix express: （4） The r in the subscript rt stands for receiving, t stands for transmitting, and the magnetic field is expressed as , is the characteristic impedance, and the total power passing through M surface units It is expressed as: （5） Among them, the superscript represents the conjugate operation of the matrix, and the superscript H represents the conjugate transpose operation of the matrix. represents the same area for each surface unit, Simplified to: （6） Among them, the intermediate parameters , so the power transmission efficiency from the planar transmission array antenna to the surface unit is expressed as: （7） When solving the power maximization of M surface units, the constraint that the power of each surface unit is the same is added to obtain a flat-top radiation pattern. The constraint expression is: （8） By solving equation (8) using the Lagrange multiplier method, the Lagrange function is defined as: （9） represents the Lagrange parameter, c represents a constant; The optimal solution of formula (8) is as follows: （10） Obtained is the transmission wave distribution of the flat-top radiation of the planar transmission array antenna under a specific power distribution, that is, the optimal amplitude-phase distribution on the transmission array surface; The radiation pattern of the planar transmission array antenna is calculated using antenna array theory: （11） in, , They are The modulus and angle of the (p,q)th surface unit in the transmission array antenna correspond to the transmission amplitude and phase of the (p,q)th surface unit in the transmission array antenna.

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