A joint optimization compensation method for deformable array antenna pattern and quantization error

Abstract

The present invention discloses a method for joint optimization compensation of deformable array antenna pattern and quantization error, including calculation of ideal active phased array antenna radiation pattern and extraction of related parameters; establishment of active phased array antenna finite element model, determination of node coordinates after array surface structure deformation; calculation of far-field pattern and ideal compensation phase after array surface structure deformation; rounding down the ideal compensation phase according to the minimum phase shift phase of phase shifter; finally, optimization of the compensation phase obtained by rounding down using genetic algorithm and parameters of ideal radiation pattern, the phase adjustment value in the optimization process is an integer multiple of the minimum phase shift step, and finally the actual compensation phase is obtained. The present invention quantizes and optimizes the ideal compensation phase according to the excitation phase limitation existing in actual engineering, combined with genetic algorithm, and finally used in the actual deformation compensation process, which has important value in actual engineering.

Description

Technical Field

[0001] The invention belongs to the field of planar phased array antennas. Background Art

[0002] Antennas, as devices for transmitting and receiving electromagnetic waves, are widely used in radio communications, broadcasting, television, radar, navigation, aerospace engineering, etc., and active phased array antennas have the advantages of high gain, low side lobes, narrow beams, etc., and their application range is even wider. However, in actual engineering, the actual radiation pattern of active phased array antennas may be inconsistent with the ideal radiation pattern. This is because, on the one hand, mechanical errors may occur during the processing and assembly of active phased array antennas; on the other hand, in the actual operation of the antenna, deformation may occur due to factors such as gravity and heat. As a result, the active phased array antenna array surface becomes non-ideal, affecting the antenna radiation pattern. There are two compensation methods for the changes in radiation characteristics caused by the deformation of the active phased array antenna array surface: mechanical compensation and electrical performance compensation.

[0003] Mechanical compensation mainly controls the actuator and other force-applying devices to apply external force when the antenna array surface is deformed, so as to reduce the deformation and improve the radiation characteristics of the deformed active phased array antenna to achieve the effect of compensating the antenna performance. However, the efficiency of mechanical compensation is low, and generally, simple mechanical compensation cannot meet the requirements of actual engineering.

[0004] Electrical performance compensation mainly refers to adjusting the amplitude and phase of the excitation current to compensate for the directional pattern of the deformed array. Electrical performance compensation includes two methods: phase method and amplitude-phase method. In actual engineering, due to the limitation of the minimum phase shift of the phase shifter, electrical performance compensation without considering the quantization error of the phase shifter is not practical. Summary of the invention

[0005] In view of the above problems, the present invention realizes electrical performance compensation for the array deformation of the active phased array antenna based on the phase compensation method and the genetic algorithm while taking into account the quantization error of the phase shifter, which has important engineering value for the deformation compensation of the active phased array antenna in actual engineering.

[0006] The present invention is achieved through the following technical solutions.

[0007] A deformable array antenna pattern and quantization error joint optimization compensation method, including the following process:

[0008] (1) Based on the initial excitation and the ideal position coordinate information, the ideal radiation pattern is calculated, and the main lobe gain and side lobe level data in the horizontal and vertical planes are extracted and retained as a reference for the optimization of the genetic algorithm;

[0009] (2) Establish a finite element model based on the antenna's geometric parameters, constraints, and load information to determine the node coordinates of the corresponding radiation unit after the array structure is deformed;

[0010] (3) Calculate the far field after the array is deformed, and convert the effect of the array deformation on the radiation pattern into a phase change, so as to obtain the ideal compensation phase that compensates the deformed array radiation pattern to the ideal radiation pattern;

[0011] (4) Rounding down the ideal compensation phase uniformly;

[0012] (5) Taking the main lobe gain and side lobe level indicators of the ideal radiation pattern as compensation targets, the genetic algorithm is used to optimize the rounded-down phase compensation amount. The phase adjustment value in the optimization process is an integer multiple of the minimum phase shift step, thereby obtaining the optimal phase compensation amount considering the quantization error of the phase shifter.

[0013] Furthermore, in step (1), the ideal active phased array antenna radiation pattern is:

[0014]

[0015] Among them, I n is the excitation amplitude of the nth radiation unit; is its excitation phase; f n (θ, φ) is its directional pattern function in an isolated environment; For its position; is a spatial unit vector; k is an electromagnetic wave propagation constant; j is an imaginary unit; the main lobe gain and side lobe level data of the ideal radiation pattern in the horizontal and vertical planes are extracted and retained.

[0016] Furthermore, in the step (2), when determining the node coordinates after the array structure is deformed, only the displacement in the direction perpendicular to the array plane is considered, and the displacement of the array element along the array direction is ignored;

[0017] Furthermore, in step (3), the following steps are performed:

[0018] (3a) After the array structure is deformed, the radiation pattern of the active phased array antenna is:

[0019]

[0020] Among them, I nc The excitation amplitude should be applied after compensation for the nth radiating element; is the excitation phase to be applied; is the displacement of the nth array element perpendicular to the array plane;

[0021] (3b) The amplitude and phase under ideal compensation can be obtained:

[0022]

[0023] Furthermore, in step (4), the ideal compensation phase is uniformly rounded down, and the steps are as follows:

[0024] (4a) According to the number of phase shifters, the minimum phase shift is determined:

[0025] △=2π / 2 p

[0026] Among them, △ is the minimum phase shift; p is the number of phase shifters;

[0027] (4b) According to the truncation method, the ideal compensation phase is truncated:

[0028]

[0029] in, is the truncated compensation phase of the ideal compensation phase of the nth array element; [M] is rounded down, that is, the maximum integer value not exceeding M.

[0030] Furthermore, in step (5), a genetic algorithm is used to optimize the rounded-down phase compensation amount, and the steps are as follows:

[0031] (5a) When the number of array elements is N, set the number of chromosomes of length N to 10 to 20, which are all randomly composed of 0 and 1 to form a population;

[0032] (5b) Design corresponding genetic, mutation, and crossover functions to iteratively optimize the population;

[0033] (5c) Based on the known main lobe gain and side lobe level of the ideal radiation pattern, a reasonable optimization cutoff condition is designed so that the genetic algorithm can stop the optimization process when the optimization target is reached;

[0034] (5d) In the obtained optimal population, the chromosome with the best compensation effect is selected to obtain the final optimized compensation phase considering the quantization error of the phase shifter. The formula is as follows:

[0035]

[0036] Among them, φ n is the final compensation phase of the nth array element; The nth value of the ith chromosome in the optimal population.

[0037] The radiation pattern of the deformed active phased array antenna can be divided into two steps. First, the ideal phase field is calculated according to the deformation to obtain the ideal compensated phase. Then, it is optimized according to the number of phase shifter bits and the ideal compensated phase to obtain the actual compensated phase considering the phase shifter quantization error.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] 1. Based on the relationship between the deformation and excitation phase of the active phased array antenna, the present invention converts the influence of the array deformation on the radiation pattern into a change in the excitation phase, thereby realizing the connection between the array deformation, the radiation pattern change and the excitation phase change, and can effectively improve the influence of the array deformation of the active phased array antenna on the radiation pattern.

[0040] 2. Compared with the existing technical solutions, the present invention takes into account that in actual engineering, phase compensation is limited by the minimum phase shift step of the phase shifter, takes into account the quantization error of the phase shifter, and uses a genetic algorithm for optimization. The phase adjustment value in the optimization process is an integer multiple of the minimum phase shift step to achieve the optimization of phase compensation in actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of a method for joint optimization and compensation of deformable array antenna pattern and quantization error of the present invention;

[0042] Figure 2 This is a schematic diagram of the active phased array antenna layout;

[0043] Figure 3 This is the deformation diagram of the active phased array antenna surface;

[0044] Figure 4 It is a comparison diagram on the horizontal plane of an ideal directional diagram, a deformed directional diagram, and a compensated directional diagram obtained by using the compensation phase optimization of the present invention when the beam pointing of the active phased array antenna is 0°;

[0045] Figure 5 The invention is a comparison diagram on a vertical plane of an ideal directional diagram, a deformed directional diagram and a compensated directional diagram obtained by performing compensatory phase optimization using the present invention when the beam pointing of an active phased array antenna is 0°. DETAILED DESCRIPTION

[0046] The invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0047] Reference Figure 1 The present invention is a method for joint optimization and compensation of deformable array antenna pattern and quantization error. The specific process of the embodiment can be described as follows:

[0048] Step 1: Calculate the ideal radiation pattern of the active phased array antenna

[0049] According to the ideal position coordinates of the active phased array antenna and the initial excitation value, the ideal radiation pattern is calculated. The ideal active phased array antenna radiation pattern is:

[0050]

[0051] Among them, I n is the excitation amplitude of the nth radiation unit; is its excitation phase; f n (θ, φ) is its directional pattern function in an isolated environment; For its position; is the unit vector in space; k is the electromagnetic wave propagation constant; j is the imaginary unit.

[0052] Step 2: Determine the node coordinates of the corresponding radiation unit after the array structure is deformed

[0053] A finite element model is established according to the geometric parameters, constraints and load information of the antenna to determine the node coordinate information of the radiating unit after the array structure is deformed. When studying the deformation of the antenna, only the displacement change perpendicular to the antenna array direction is considered.

[0054] Step 3: Calculate the radiation pattern and ideal compensation phase of the deformed active phased array antenna

[0055] According to the position information of the active phased array antenna elements after the array surface structure is deformed, only the displacement in the direction perpendicular to the array plane is considered to calculate the radiation pattern and ideal compensation phase of the deformed active phased array antenna. The calculation is performed according to the following steps:

[0056] (3a) After the array structure is deformed, the radiation pattern of the active phased array antenna is:

[0057]

[0058] Among them, I nc The excitation amplitude should be applied after compensation for the nth radiating element; is the excitation phase to be applied; is the displacement of the nth array element perpendicular to the array plane.

[0059] (3b) The amplitude and phase under ideal compensation can be obtained:

[0060]

[0061] Step 4: Round down the ideal compensation phase

[0062] The ideal compensation phase is uniformly rounded down and the steps are as follows:

[0063] (3a) According to the number of phase shifters, the minimum phase shift is determined:

[0064] △=2π / 2 p

[0065] Among them, △ is the minimum phase shift; p is the number of phase shifters.

[0066] (3b) According to the truncation method, the ideal compensation phase is truncated:

[0067]

[0068] in, is the truncated compensation phase of the ideal compensation phase of the nth array element after rounding down; [M] is rounded down, that is, it takes an integer value not exceeding M.

[0069] Step 5: Optimize the rounded-down compensation phase

[0070] Combined with the main lobe gain and side lobe level data of the ideal radiation pattern in the horizontal and vertical planes obtained in step 1, as the optimization reference of the genetic algorithm, the rounded-down compensation phase is optimized as follows:

[0071] (5a) When the number of array elements is N, set the number of chromosomes of length N to 10 to 20, which are all randomly composed of 0 and 1 to form a population;

[0072] (5b) Design corresponding genetic, mutation, and crossover functions to iteratively optimize the population;

[0073] (5c) Based on the known main lobe gain and side lobe level of the ideal radiation pattern, a reasonable optimization cutoff condition is designed so that the genetic algorithm can stop the optimization process when the optimization target is reached;

[0074] (5d) In the obtained optimal population, the chromosome with the best compensation effect is selected to obtain the final optimized compensation phase considering the quantization error of the phase shifter. The formula is as follows:

[0075]

[0076] Among them, φ n is the final compensation phase of the nth array element; The nth value of the ith chromosome in the optimal population.

[0077] The advantages of the present invention can be further illustrated by the following simulation case:

[0078] 1. Determine the parameters of the active phased array antenna

[0079] Taking the X-band 10GHz active phased array antenna as an analysis case, the deformation compensation effect is analyzed. The array element of the active phased array antenna is a patch antenna, the array element spacing is half a wavelength, the number of array elements is 256, and its arrangement is as follows Figure 2 As shown, the excitation distribution adopts Taylor distribution in the transverse direction and uniform distribution in the longitudinal direction, and the initial excitation phase is 0°.

[0080] 2. Simulation content and structure analysis

[0081] Figure 3 The figure shows the deformation of the array. Figure 4 and Figure 5 The ideal radiation pattern in the horizontal plane and the vertical plane, the radiation pattern of the deformed array, and the compensation pattern obtained by optimizing the compensation phase while considering the quantization error of the phase shifter are compared. It can be seen from the comparison diagram that the deformation is symmetrical, so the obtained deformed pattern is also symmetrical. In terms of the compensation results, good compensation effects were achieved in the main lobe and near side lobe areas of the two cross sections. From the data in Table 1, considering the quantization error of the phase shifter, the compensation achieved a good effect, and the maximum error between the compensation value and the ideal value did not exceed 0.1dB. Therefore, the method proposed in the present invention can play an important role in practical engineering.

[0082] Table 1 Comparison of ideal, deformed and compensation data considering phase shifter quantization error

[0083]

[0084]

[0085] The present invention is not limited to the above cases. On the basis of the technical solution disclosed in the present invention and according to the disclosed technical content, some technical processes in the present invention can be changed without making any creative work, and these changes are within the protection scope of the present invention.

Claims

1. A method for joint optimization and compensation of deformable array antenna pattern and quantization error, characterized in that: (1) Calculate the ideal radiation pattern based on the position coordinates and excitation distribution of the active phased array antenna in the undeformed state, and extract and retain the main lobe gain and side lobe level data in the horizontal and vertical planes; (1a) Calculate the radiation pattern of the ideal active phased array antenna, which is: Where, In is the excitation amplitude of the nth radiation unit; is its excitation phase; fn(θ,φ) is its directional pattern function in an isolated environment; For its position; is the unit vector in space; k is the electromagnetic wave propagation constant; j is the imaginary unit; (1b) extracting and retaining the main lobe gain and side lobe level data of the ideal radiation pattern in the horizontal and vertical planes; (2) Establish a finite element model based on the antenna's geometric parameters, constraints, and load information to determine the node coordinates of the corresponding radiation unit after the array structure is deformed; (3) Calculate the far field after the array is deformed, convert the effect of the array deformation on the radiation pattern into a phase change, and obtain the ideal compensation phase that compensates the deformed array radiation pattern to the ideal radiation pattern; (3a) After the array surface is deformed, the radiation pattern of the active phased array antenna is: Among them, I nc The excitation amplitude should be applied after compensation for the nth radiating element; is the excitation phase to be applied; is the displacement of the nth array element perpendicular to the array plane; (3b) Amplitude and phase under ideal compensation: (4) rounding down the ideal compensation phase according to the minimum phase shift step of the phase shifter; (5) Taking the main lobe gain and side lobe level indicators of the ideal radiation pattern as compensation targets, the genetic algorithm is used to optimize the rounded-down phase compensation amount. The phase adjustment value in the optimization process is an integer multiple of the minimum phase shift step, thereby obtaining the optimal phase compensation amount considering the quantization error of the phase shifter.

2. The method for joint optimization and compensation of deformable array antenna pattern and quantization error according to claim 1, characterized in that: The step (2) includes: when determining the node coordinates after the array surface structure is deformed, only considering the displacement in the direction perpendicular to the array plane, and ignoring the displacement of the array elements along the array direction.

3. The method for joint optimization and compensation of deformable array antenna pattern and quantization error according to claim 2, characterized in that: In the step (4), rounding down the ideal compensation phase uniformly includes: (4a) According to the number of phase shifters, the minimum phase shift is determined: Δ=2π / 2 p ; Where Δ is the minimum phase shift; p is the number of bits of the phase shifter; (4b) According to the truncation method, the ideal compensation phase is truncated: in, is the truncated compensation phase of the ideal compensation phase of the nth array element; [M] is rounded down, that is, the maximum integer value not exceeding M.

4. The method for joint optimization and compensation of deformable array antenna pattern and quantization error according to claim 3, characterized in that: In the step (5), optimizing the rounded-down phase compensation amount by using a genetic algorithm includes: (5a) When the number of array elements is N, set the number of chromosomes of length N to 10 to 20, which are all randomly composed of 0 and 1 to form a population; (5b) Design corresponding genetic, mutation, and crossover functions to iteratively optimize the population; (5c) Based on the known main lobe gain and side lobe level of the ideal radiation pattern, a reasonable optimization cutoff condition is designed so that the genetic algorithm stops the optimization process when the optimization target is reached; (5d) In the obtained optimal population, the chromosome with the best compensation effect is selected to obtain the final optimized compensation phase considering the quantization error of the phase shifter. The formula is as follows: Among them, φ n is the final compensation phase of the nth array element; The nth value of the ith chromosome in the optimal population.

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