A method for fast simulation of radiation characteristics of a large-scale array antenna

Abstract

The present application belongs to the field of electromagnetic numerical method, and relates to a kind of fast simulation solving method of the radiation characteristic of large-scale array antenna.The present application adopts regional decomposition technique in the simulation solving process of large-scale array antenna: first, select the m*n antenna units in the center of large-scale array antenna as small-scale array antenna;Then, the unit model of antenna array is established, and according to the arrangement of array, the corresponding simulation solving is carried out for small-scale array antenna;Then, the matrix equation of finite element regional decomposition solving is constructed, and the far field of small-scale antenna array is obtained by matrix reuse simulation solving;Further, the far field of large-scale array antenna is expanded;Finally, according to actual demand, the radiation far field parameter result of arbitrary amplitude phase distribution is obtained by changing the feed parameters of large-scale array antenna excitation unit.The present application only needs to carry out actual simulation calculation on a small-scale antenna array, and the radiation characteristic of large-scale array antenna can be realized quickly simulated and analyzed.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electromagnetic numerical methods, and relates to a fast simulation solving method for the radiation characteristics of a large-scale array antenna. BACKGROUND

[0002] An array antenna is an antenna system composed of multiple antenna units arranged in a certain manner, and has the advantages of high gain, high directivity and flexible beam control, thus having broad application prospects in the fields of satellite communication technology, radar detection systems and precise navigation. In the design process of an array antenna, the radiation characteristics of the array antenna are first preliminarily evaluated through antenna simulation analysis to determine whether the radiation characteristics meet the index requirements, then physical processing and microwave darkroom measurement are performed, and finally the design of the array antenna is completed. An efficient electromagnetic simulation method can significantly improve the efficiency of antenna simulation analysis, and therefore the research on the fast solving method for the radiation characteristics of an array antenna is of great significance.

[0003] However, with the development of antenna technology and the improvement of the performance requirements such as antenna gain, the array scale of the antenna gradually increases, and in practical applications, the scale of the array antenna has increased from hundreds of units to thousands or even tens of thousands of units. In order to ensure accuracy, the simulation analysis of the array antenna currently mainly adopts a full-wave numerical algorithm, and the number of unknown quantities required for solving a large-scale antenna array is huge, and the solving complexity is very high, which leads to the consumption of a large amount of calculation time and memory by the full-wave numerical algorithm, and even the full-wave numerical algorithm cannot be solved.

[0004] Although the periodic boundary condition can simulate an infinite array structure by approximating a single antenna unit simulation, the method can achieve large-scale antenna array simulation to a certain extent, but it ignores the finite array edge effect in actual engineering and cannot consider the coupling between units, resulting in a certain deviation from the actual situation.

[0005] Therefore, how to realize efficient and high-precision simulation design of a large-scale array antenna is a great difficulty in the current research on array antenna simulation technology. SUMMARY

[0006] In view of the above problems or deficiencies, in order to solve the problem that the existing large-scale array antenna simulation design cannot realize high efficiency and high precision, the application provides a kind of fast simulation solving method for the radiation characteristics of large-scale array antenna, which adopts regional decomposition technology in the simulation solving process, effectively reduces the simulation memory consumption, and improves the solving efficiency.Compared with the existing large-scale antenna array simulation technology, the advantages of the application compared with the traditional simulation solving method include: 1) only a small amount of modeling operation is needed, without overall modeling; 2) in the solving process, through matrix reuse, the memory consumption required for simulation solving is very small; 3) only a small-scale antenna array needs to be simulated and calculated, and through a certain array expansion of the radiation far field of the subarray (small-scale antenna array), the far field of the large-scale antenna array can be directly obtained, so that the fast simulation analysis of the radiation characteristics of the large-scale array antenna is realized.

[0007] A kind of fast simulation solving method for the radiation characteristics of large-scale array antenna, comprising the following steps:

[0008] Step 1, for the large-scale antenna array needing simulation analysis, extract the center small-scale subarray as the sub antenna array needed for simulation, the small-scale subarray is composed of m*n antenna units; m≥5, n≥5.

[0009] Step 2, establish a single antenna unit model needed for simulation, set the array antenna arranged in XOY plane, the distance between antenna units along x axis and along y axis is d x and d y , the rest of the array antenna units are directly obtained according to the established single antenna unit through distance relationship translation to obtain the sub antenna array information for simulation calculation;

[0010] In addition, a layer of vacuum region needs to be constructed around the small-scale subarray when calculating; for the vacuum region, first automatically generate a single corresponding entity model block, and then directly obtain the related calculation information of the rest of the vacuum region through translation according to the position relationship of the small-scale subarray.

[0011] Step 3, for the small-scale array antenna, establish the electromagnetic boundary value problem of finite element regional decomposition, and obtain the related solving equation;

[0012] Step 4, process the boundary and excitation needed for antenna simulation;

[0013] Step 5, construct the matrix equation of finite element regional decomposition solving by repeating array structure matrix reuse, and solve to obtain the radiation far field of the small-scale antenna array;

[0014] Step 6, after obtaining the far field of each unit of the small-scale array antenna excited respectively, further expand to the far field of the large-scale array antenna;

[0015] Step 7, according to the simulation requirements, by changing the excitation unit of large-scale array antenna feed parameters, the radiation far field parameters of arbitrary amplitude and phase distribution are obtained.

[0016] When solving the antenna radiation problem, the center part of the large-scale array antenna is first selected as a sub-array antenna to form a small-scale array antenna. Then, a unit model of the antenna array is established, and the position relationship of the small-scale array antenna units is determined according to the arrangement of the array. Then, for the small-scale array antenna, a finite element region decomposition electromagnetic boundary value problem is established, and the related solving equation is obtained. At the same time, the boundary and excitation required for simulation of the simulation array antenna are constructed and applied to the simulation solving. Then, the matrix equation of the finite element region decomposition solving is constructed, and the memory consumption of the array antenna simulation is reduced by matrix reuse. Through simulation solving, the far field of the small-scale antenna array is obtained. Finally, after obtaining the far field of each unit of the small-scale array antenna, the far field of the large-scale array antenna is further expanded. In addition, according to the actual simulation requirements, by changing the excitation unit of large-scale array antenna feed parameters, the radiation far field parameters of arbitrary amplitude and phase distribution are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a flowchart of the present application;

[0018] Figure 2 is a schematic diagram of the antenna array unit calculation model;

[0019] Figure 3 is a schematic diagram of matrix reuse of repeated structure

[0020] Figure 4 is a schematic diagram of the expansion of the small-scale antenna sub-array to the large-scale array antenna. DETAILED DESCRIPTION

[0021] The present application will be further described in detail below in combination with the drawings and examples.

[0022] A fast simulation solving method for the radiation characteristics of a large-scale array antenna, as shown in Figure 1 , the specific process is as follows:

[0023] Step 1, for the large-scale antenna array that needs to be simulated and analyzed, the center small-scale sub-array is extracted, which is composed of m x n antenna units (m≥5, n≥5), which is the sub-array antenna required for subsequent simulation solving by using the region decomposition method. The radiation characteristics of the final large-scale array antenna are calculated according to step 6 through the simulation results of the small-scale antenna array.

[0024] Step 2: Establish a single antenna unit model required for simulation. Assume that the array antenna is arranged in the XOY plane, and the distances between antenna units along the x-axis and y-axis are d respectively. x and d y , the remaining array antenna units directly obtain the sub-antenna array model information used in simulation calculations through distance relationship translation based on the established single antenna unit.

[0025] This embodiment is as follows Figure 2 As an example, a single antenna unit model of a large-scale array antenna is first established (e.g. Figure 2 As shown in block 5), it is assumed that the array antenna is arranged in the XOY plane, and the distances between the antenna elements along the x-axis and along the y-axis are d x and d y ,The remaining array antenna units can directly obtain the sub-antenna array information used in simulation ,calculation through distance relationship translation, without the need of complete ,modeling.

[0026] In addition, when calculating small-scale subarrays, a vacuum region needs to be constructed on the periphery to ensure the accuracy of the solution. For the vacuum region, four vacuum model blocks are first automatically generated for the four corners (such as Figure 2 Blocks 1, 3, 7, and 9 shown in the figure), and then generate 4 corresponding solid model blocks for the four edges (such as Figure 2 Blocks 2, 4, 6, and 8 shown in the figure) are directly obtained by translating the position relationship of the array to obtain the relevant calculation information used for all vacuum area blocks on the four sides.

[0027] Step 3: For small-scale array antennas, establish the electromagnetic boundary value problem of finite element domain decomposition and construct the relevant solution equations;

[0028] First, assume that the solution domain of the small-scale array antenna has N non-overlapping sub-regions, where a single antenna unit is located in an independent sub-region (such as Figure 2 As shown), two adjacent sub-regions i and j are connected using Robin boundary conditions, and the inner area of ​​sub-region i is connected using Ω i Indicates that Γ ij represents the interface between sub-regions i and j, then the boundary value problem of the region decomposition is:

[0029]

[0030] in is the electric field, is an external current source, ε ri is the relative dielectric constant of region i, μ ri is the relative magnetic permeability of region i, k0 is the vacuum wave number, symbol For the interface normal vector.

[0031] Then, the finite element weak form is constructed by the Galerkin method, and the vector basis function is used inside the finite element Test, the interface between the regions, that is, the Robin boundary part, respectively uses the basis function And Test. It can be obtained that:

[0032]

[0033] Where

[0034] Further, by replacing the area integral (4) with half of the area integral (3), a symmetric form matrix is constructed, and combined with (5), the solving equation of the finite element region decomposition method can be obtained:

[0035]

[0036] Step 4, for small-scale array antennas, the boundary and excitation processing required for small-scale antenna array simulation are performed;

[0037] In the process of antenna simulation, corresponding boundary conditions and excitations need to be set to realize simulation solving. The boundaries required in antenna simulation include: ideal electric conductor boundary Ideal magnetic conductor boundary Impedance boundary Z s Surface impedance), and radiation boundary ( Z0 is the wave impedance of vacuum).

[0038] In addition, for thin-layer media that are difficult to divide into grids, the equivalent boundary of multi-layer media is also needed for solving. Assuming that there are L thin-layer media, d l The thickness of each layer of medium is d, and its form is:

[0039]

[0040] After assuming that the multi-layer medium structure is equivalent to an infinite thin equivalent boundary, the magnetic fields on both sides of the boundary are And The relationship between the electric field and the magnetic field of the boundary is:

[0041]

[0042] Further, the finite element area integral formula of the related boundary can be expressed as:

[0043]

[0044] In addition, in the aspect of excitation, the waveguide port excitation mode is adopted in the embodiment to ensure the solution accuracy (voltage gap or current feed excitation can also be adopted). Assuming that the excitation electric field on the port is Only the main mode excitation is considered, and Z p is the mode impedance of the port p, the relationship between the electric field and the magnetic field at the port p is:

[0045]

[0046] The finite element area integral form at the corresponding port is:

[0047]

[0048] The boundary and excitation required for small-scale antenna array simulation are added to the area decomposition solution equation (6) established in step 3 to complete the boundary and excitation processing required for small-scale antenna array simulation.

[0049] Step 5, by repeatedly array structure matrix reuse, the matrix equation of the finite element area decomposition solution is constructed and solved to obtain the radiation far field of the small-scale antenna array;

[0050] The area decomposition solution equation (6) is written in the matrix form, and M i represents the finite element area decomposition submatrix block of the subarea i part, G ij represents the submatrix block of the interface part between the subarea i and the subarea j, x represents the electric field unknown quantity to be solved, and y represents the port excitation of the antenna array.

[0051] In addition, assuming that the antenna excitation unit has P in total, to obtain the corresponding directional diagram by adjusting the amplitude and phase of the feed source in real time, each port excitation needs to be solved in sequence, and therefore P right end terms need to be solved in total, and the matrix form of the final finite element area decomposition solution equation is:

[0052]

[0053] Since the antenna unit (single antenna unit) has a repeated structure, the antenna subdomain matrix M i and G ij do not need to be calculated in total, and only the matrices (partial matrices) of different structures need to be calculated, and the antenna subdomain matrix of the repeated structure is directly reused. As shown in Figure 3 , assuming that a 49-area antenna array calculation model is adopted, after reuse, only 9 subarea corresponding matrices and 18 interface corresponding connection matrices need to be stored when solving the matrix (12), and all matrices do not need to be stored.

[0054] Then, the electric field solution of each antenna element is obtained by solving matrix (12). After obtaining the electric field solution of matrix (12), the far field of each antenna element is obtained by near-far field extrapolation

[0055] Let I p represent the amplitude and phase of the antenna element excitation, and the total far field distribution of the small-scale antenna array is:

[0056]

[0057] Step 6, after obtaining the far field of each element of the small-scale array antenna, further expand the far field of the large-scale array antenna.

[0058] The previous process has obtained the far field of the small-scale antenna array, and this step mainly derives the far field of the large-scale array from the far field information of the small-scale array.

[0059] For the small-scale antenna array m x n (in this embodiment, m and n are both odd numbers and m = n = 5, so that the small-scale antenna array is completely centered relative to the large-scale array antenna, and the accuracy is higher), the array of the large-scale array antenna whose far field needs to be solved is M x N (M > m, N > n). According to the principle of active pattern, the active pattern of the center part of the large-scale array is basically the same, so through the subarray expansion method, the center element of the small-scale array antenna is expanded by copying as the center element of the large-scale array antenna, and the edge element is used as the edge element of the large-scale array antenna, so that the small-scale array antenna is expanded from m x n to M x N. The specific expansion method is as shown in the embodiment Figure 4 The method is also applicable when the number of rows and columns is different.

[0060] Through the above method, the far field of the large-scale array antenna can be obtained by the far field of the small-scale subarray antenna , let m and n be the row number (x-axis direction) and column number (y-axis direction) of the small-scale antenna array whose far field distribution has been solved, and the specific calculation method is:

[0061]

[0062] Through this method, the far field of the large-scale array can be directly obtained by a small amount of calculation.

[0063] Step 7, according to the simulation requirements, by changing the feed parameters of the excitation element of the large-scale array antenna, the radiation far field parameters of any amplitude and phase distribution are obtained.

[0064] The array antenna can obtain corresponding beam pointing by adjusting the excitation amplitude and phase distribution of each antenna unit. According to simulation requirements, the excitation I ij (An amplitude and phase marker of the excitation unit (i, j)), which is substituted into (14), can be used to re-stackingly calculate the far field and quickly obtain the radiation characteristics of the large-scale array under different excitation amplitudes and phases.

[0065] As can be seen from the above embodiments, the application adopts the region decomposition technique in the simulation solving process of the large-scale array antenna: firstly, m*n antenna units in the center of the large-scale array antenna are selected as a small-scale array antenna; then, a unit model of the antenna array is established, and according to the arrangement of the array, a finite element region decomposition electromagnetic boundary value problem is established for the small-scale array antenna, a corresponding boundary and excitation are constructed, and then applied to the simulation solving; next, a matrix equation of the finite element region decomposition solving is constructed, and the matrix reuse is applied to reduce the memory consumption of the array antenna simulation, and the far field of the small-scale antenna array is obtained through the simulation solving; after obtaining the far field of each unit excitation of the small-scale array antenna, the far field is expanded to the far field of the large-scale array antenna. Finally, according to actual simulation requirements, the excitation unit of the large-scale array antenna is changed to obtain the radiation far field parameter results of the arbitrary amplitude and phase distribution. The application only needs to perform actual simulation calculation on a small-scale antenna array, and the far field of the large-scale antenna array can be directly obtained through the subarray expansion, so that the fast simulation analysis of the radiation characteristics of the large-scale array antenna is realized.

Claims

1. A method for rapidly simulating and solving the radiation characteristics of a large-scale array antenna, comprising the following steps: Step 1: For the large-scale antenna array that needs to be simulated and analyzed, extract the small-scale sub-array at its center as the sub-antenna array required for simulation. The small-scale sub-array consists of m×n antenna units. m≥5, n≥5; Step 2: Establish a single antenna unit model required for simulation. Assume that the array antenna is arranged in the XOY plane, and the distances between antenna units along the x-axis and y-axis are d respectively. x and d y , the remaining array antenna units directly obtain the sub-antenna array information used in simulation calculations through distance translation based on the established single antenna unit; In addition, a vacuum region needs to be constructed around the small-scale subarray during calculations. For this vacuum region, a single corresponding solid model block is automatically generated. Then, similarly, the positional relationship of the small-scale subarray is used to directly obtain the relevant calculation information for the remaining vacuum regions through translation. Step 3: For small-scale array antennas, establish an electromagnetic boundary value problem using finite element domain decomposition and obtain the relevant solution equations; Step 4: For small-scale array antennas, perform boundary and excitation processing required for antenna simulation; Step 5: Repeat the array structure matrix reuse to construct the matrix equation solved by finite element domain decomposition and solve it to obtain the radiation far field of the small-scale antenna array; Write the solution equation of the domain decomposition obtained in step 3 into matrix form, let M i represents the finite element domain decomposition submatrix block of the subregion i, G ir represents the sub-matrix block at the interface between sub-region i and sub-region r, X represents the unknown quantity of the electric field to be calculated, and Y represents the port excitation of the antenna array; In addition, assuming that there are a total of P antenna excitation units, in order to adjust the feed amplitude and phase in real time to obtain the corresponding radiation pattern, it is necessary to solve the excitation of each port in turn. Therefore, a total of P right-hand terms need to be solved. The matrix form of the final finite element domain decomposition solution equation is: Where K is the total number of non-overlapping sub-regions. Since the antenna unit has a repeated structure, the antenna sub-domain matrix M i and G ir No need to calculate all, only the matrices of different structures are calculated, and the antenna sub-domain matrices of repeated structures are directly reused; After that, by solving the matrix (12), the electric field solution of the antenna excitation unit is obtained. After obtaining the electric field solution of the matrix (12), the far field of each antenna unit under the excitation is obtained by extrapolation of the near and far fields. Order I p Represents the amplitude and phase of the antenna unit excitation, and the total far-field distribution of the final small-scale antenna array is: Step 6: After obtaining the far field of each unit of the small-scale array antenna, further expand it into the far field of the large-scale array antenna; For a small-scale array antenna with an array size of m×n, the large-scale array antenna in the far field needs to be M×N, where M>m and N>n. Based on the active pattern principle and the subarray expansion method, the central unit of the small-scale array antenna is replicated and expanded to serve as the central unit of the large-scale array antenna, and the edge units are used as the edge units of the large-scale array antenna, expanding from m×n to M×N. The far field of the final large-scale array antenna Far field using small-scale subarray antennas Let m and n be the row number x-axis direction and column number y-axis direction of the small-scale antenna array whose far-field distribution has been solved. The specific calculation method is: Among them I i1j1 represents the amplitude and phase of the excitation of the antenna element in the i1th row and j1th column, and ultimately directly obtains the far field of the large-scale array; Step 7: According to the simulation requirements, by changing the feed parameters of the large-scale array antenna excitation unit, the radiation far-field parameters of arbitrary amplitude and phase distribution are obtained.

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