CN113420484A - Deformation array antenna directional pattern and quantization error combined optimization compensation method - Google Patents
Deformation array antenna directional pattern and quantization error combined optimization compensation method Download PDFInfo
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Abstract
The invention discloses a deformation array antenna directional diagram and quantization error combined optimization compensation method, which comprises the steps of calculating an ideal active phased array antenna radiation directional diagram and extracting related parameters; establishing an active phased array antenna finite element model, and determining the node coordinates of the array surface structure after deformation; calculating a far-field directional diagram and an ideal compensation phase of the array surface structure after deformation; rounding down the ideal compensation phase according to the minimum phase shift phase of the phase shifter; and finally, optimizing the compensation phase obtained by rounding downwards by utilizing a genetic algorithm and parameters of an ideal radiation directional diagram, wherein the phase adjustment value in the optimization process is integral multiple of the minimum phase shift step, and finally obtaining the actual compensation phase. The method is used for quantifying and optimizing the ideal compensation phase by combining a genetic algorithm according to the excitation phase limit existing in the actual engineering, is finally used in the actual deformation compensation process, and has important value in the actual engineering.
Description
Technical Field
The invention belongs to the field of planar phased array antennas.
Background
The antenna is used as an electromagnetic wave transmitting and receiving device and has wide application in the aspects of radio communication, broadcasting, television, radar, navigation, aerospace engineering and the like, and the active phased array antenna has the advantages of high gain, low side lobe, narrow beam and the like and has wider application range. However, in practical engineering, the actual directional diagram of the active phased array antenna is inconsistent with the ideal directional diagram, because on one hand, mechanical errors occur in the processes of processing and assembling the active phased array antenna; on the other hand, in actual operation of the antenna, deformation may occur due to gravity, heat, and the like. Therefore, the array surface of the active phased array antenna is changed into a non-ideal state, and an antenna directional diagram is influenced. For the radiation characteristic change caused by the array surface deformation of the active phased array antenna, there are two compensation methods: i.e. mechanical compensation and electrical compensation.
The mechanical compensation mainly applies external force under the condition that an antenna array surface is deformed by controlling force application devices such as an actuator, so that the deformation is reduced, the radiation characteristic of the deformed active phased array antenna is improved, and the effect of compensating the antenna performance is achieved. However, the mechanical compensation efficiency is low, and the requirement of actual engineering cannot be met by common pure mechanical compensation.
The electrical property compensation mainly refers to adjusting the amplitude and the phase of the excitation current to compensate the directional diagram of the deformation array. The electrical property compensation includes both phase and amplitude methods. In practical engineering, the phase shifter has no practical applicability because of the limitation of the minimum phase shift phase, and the electrical performance compensation without considering the quantization error of the phase shifter.
Disclosure of Invention
Aiming at the problems, the invention realizes the electrical property compensation of the array surface deformation of the active phased array antenna under the condition of considering the quantization error of the phase shifter based on the phase compensation method and the genetic algorithm, and has important engineering value for the deformation compensation of the active phased array antenna in the actual engineering.
The invention is realized by the following technical scheme.
A deformation array antenna directional pattern and quantization error combined optimization compensation method comprises the following processes:
(1) calculating an ideal radiation directional diagram according to the initial excitation and position coordinate information under an ideal condition, and extracting and reserving main lobe gain and side lobe level data of a horizontal plane and a vertical plane as an optimization reference of a genetic algorithm;
(2) establishing a finite element model according to the geometric parameters, constraint conditions and load information of the antenna, and determining the node coordinates of the corresponding radiation unit after the array surface structure is deformed;
(3) calculating the far field of the deformed array surface, converting the influence of the deformation of the array surface on the directional diagram into phase change, and obtaining an ideal compensation phase for compensating the deformed array radiation directional diagram to an ideal radiation directional diagram;
(4) uniformly rounding down the ideal compensation phase;
(5) and (3) taking the main lobe gain and side lobe level indexes of an ideal directional diagram as compensation targets, optimizing the phase compensation quantity after downward rounding by utilizing a genetic algorithm, wherein the phase adjustment value in the optimization process is an integral multiple of the minimum phase shift step, so that the optimal phase compensation quantity considering the quantization error of the phase shifter is obtained.
Further, in the step (1), the radiation pattern of the ideal active phased array antenna is:
wherein, InExciting amplitude for the nth radiating element;
for which the phase is excited; f. ofn(θ, φ) is its directional pattern function in an isolated environment;
is its bit vector;
is a spatial unit vector; k is an electromagnetic wave propagation constant; j is an imaginary unit; and extracting and retaining main lobe gain and side lobe level data of the horizontal plane and the vertical plane of the ideal directional diagram.
Furthermore, in the step (2), when determining the coordinates of the nodes after the deformation of the array surface structure, only the displacement in the direction perpendicular to the array plane is considered, and the displacement of the array elements in the array direction is ignored;
further, in the step (3), the following steps are performed:
(3a) the radiation pattern of the active phased array antenna after the array surface structure is deformed is as follows:
wherein, IncApplying an excitation amplitude value after compensation for the nth radiation unit;
the excitation phase for which it should be applied;
displacement of the nth array element in the direction vertical to the array plane;
(3b) the amplitude and phase under ideal compensation can be obtained:
further, in the step (4), the ideal compensation phase is uniformly rounded down, and the following steps are performed:
(4a) and determining the minimum phase-shifting phase according to the number of the phase shifter bits:
△＝2π/2p
wherein Δ is a minimum phase shift phase; p is the number of phase shifter bits;
(4b) according to the tail cutting method, the tail cutting is carried out on the ideal compensation phase:
wherein,
a tail-cutting compensation phase after the tail cutting of the ideal compensation phase of the nth array element is obtained; [ M ] A]Rounded down, i.e., taking the largest integer value that does not exceed M.
Further, in the step (5), the phase compensation amount after rounding down is optimized by using a genetic algorithm, and the method includes the following steps:
(5a) under the condition that the number of array elements is N, chromosomes with the length of N are set, the number of the chromosomes is 10-20, all the chromosomes are randomly composed of 0 and 1, and a population is formed;
(5b) designing corresponding inheritance, variation and cross functions to carry out iterative optimization on the population;
(5c) designing a reasonable optimization cut-off condition according to the known main lobe gain and side lobe level of the ideal radiation directional diagram, so that the genetic algorithm can stop an optimization program when an optimization target is reached;
(5d) and selecting the chromosome with the best compensation effect from the obtained optimal population to obtain the final optimal compensation phase considering the quantization error of the phase shifter, wherein the formula is as follows:
wherein phi isnThe final compensation phase of the nth array element is obtained;
the nth value of the ith chromosome in the optimal population.
The radiation pattern of the deformed active phased array antenna can be stepped in two steps, an ideal phase field is calculated according to the deformation condition to obtain an ideal compensation phase, and then optimization is carried out according to the phase number of the phase shifter and the ideal compensation phase to obtain an actual compensation phase considering the quantization error of the phase shifter.
Compared with the prior art, the invention has the following advantages:
1. the method is based on the relation between the active phased array antenna deformation and the excitation phase, the influence of the array surface deformation on the radiation directional diagram is converted into the change of the excitation phase, the relation between the array surface deformation, the change of the radiation directional diagram and the change of the excitation phase is realized, and the influence of the array surface deformation on the directional diagram of the active phased array antenna can be effectively improved.
2. Compared with the prior art, the method considers that in the actual engineering, the phase compensation is limited by the minimum phase shifting stepping of the phase shifter, considers the quantization error of the phase shifter, and utilizes the genetic algorithm to carry out optimization, and the phase adjustment value in the optimization process is the integral multiple of the minimum phase shifting stepping so as to realize the optimization of the phase compensation in the actual engineering.
Drawings
FIG. 1 is a flow chart of a method for jointly optimizing and compensating a deformed array antenna directional pattern and a quantization error according to the present invention;
FIG. 2 is a schematic diagram of an active phased array antenna layout;
FIG. 3 is a diagram of active phased array antenna array distortion;
FIG. 4 is a comparison of an ideal pattern, a distorted pattern, and a compensated pattern obtained by compensating phase optimization using the present invention in a horizontal plane when the beam pointing direction of the active phased array antenna is 0 °;
fig. 5 is a comparison graph of an ideal directional diagram and a deformed directional diagram of the active phased array antenna when the beam is directed to 0 degrees, and a compensation directional diagram obtained by performing compensation phase optimization by adopting the method of the invention in a vertical plane.
Detailed Description
The invention is described in further detail below with reference to the figures and examples.
Referring to fig. 1, the present invention is a method for jointly optimizing and compensating a deformed array antenna directional pattern and a quantization error, and the specific process of the embodiment can be described as follows:
step 1, calculating an ideal radiation directional diagram of an active phased array antenna
Calculating an ideal radiation pattern according to the ideal position coordinates and the initial excitation value of the active phased array antenna, wherein the ideal active phased array antenna radiation pattern is as follows:
wherein, InExciting amplitude for the nth radiating element;
for which the phase is excited; f. ofn(θ, φ) is its directional pattern function in an isolated environment;
is its bit vector;
is a spatial unit vector; k is an electromagnetic wave propagation constant; j is an imaginary unit.
Step 2, determining the node coordinates of the corresponding radiation unit after the array surface structure is deformed
And establishing a finite element model according to the geometric parameters, constraint conditions and load information of the antenna, determining the node coordinate information of the radiation unit after the array surface structure is deformed, and only considering the displacement change in the direction vertical to the antenna array surface when the antenna deformation is researched.
Step 3, calculating the radiation directional diagram and the ideal compensation phase of the deformed active phased array antenna
And according to the obtained position information of the array elements of the active phased array antenna after the array surface structure is deformed, only considering the displacement in the direction vertical to the array plane, and calculating a radiation directional diagram and an ideal compensation phase of the deformed active phased array antenna. The calculation is carried out according to the following steps:
(3a) the radiation pattern of the active phased array antenna after the array surface structure is deformed is as follows:
wherein, IncApplying an excitation amplitude value after compensation for the nth radiation unit;
the excitation phase for which it should be applied;
the displacement of the nth array element in the direction vertical to the array plane.
(3b) The amplitude and phase under ideal compensation can be obtained:
step 4, rounding the ideal compensation phase downwards
And uniformly rounding down the ideal compensation phase, and performing the following steps:
(3a) and determining the minimum phase-shifting phase according to the number of the phase shifter bits:
△＝2π/2p
wherein Δ is a minimum phase shift phase; p is the number of phase shifter bits.
(3b) According to the tail cutting method, the tail cutting is carried out on the ideal compensation phase:
wherein,
the tail-cutting compensation phase is obtained by rounding the ideal compensation phase of the nth array element downwards; [ M ] A]Rounded down, i.e., taking integer values not exceeding M.
Step 5, carrying out optimization calculation on the downward rounded compensation phase
And (2) combining the main lobe gain and side lobe level data of the horizontal plane and the vertical plane of the ideal radiation directional diagram obtained in the step (1) to be used as an optimization reference of a genetic algorithm, optimizing the downward rounded compensation phase, and performing the following steps:
(5a) under the condition that the number of array elements is N, chromosomes with the length of N are set, the number of the chromosomes is 10-20, all the chromosomes are randomly composed of 0 and 1, and a population is formed;
(5b) designing corresponding inheritance, variation and cross functions to carry out iterative optimization on the population;
(5c) designing a reasonable optimization cut-off condition according to the known main lobe gain and side lobe level of the ideal radiation directional diagram, so that the genetic algorithm can stop an optimization program when an optimization target is reached;
(5d) and selecting the chromosome with the best compensation effect from the obtained optimal population to obtain the final optimal compensation phase considering the quantization error of the phase shifter, wherein the formula is as follows:
wherein phi isnThe final compensation phase of the nth array element is obtained;
the nth value of the ith chromosome in the optimal population.
The advantages of the present invention can be further illustrated by the following simulation case
1. Determining parameters of an active phased array antenna
The active phased array antenna with the frequency point of 10GHz of the X waveband is used as an analysis case for analyzing the deformation compensation effect of the antenna, the array elements of the active phased array antenna are patch antennas, the spacing between the array elements is half wavelength, the number of the array elements is 256, the arrangement mode of the array elements is shown in figure 2, the excitation distribution adopts transverse Taylor distribution, the longitudinal uniform distribution mode is adopted, and the initial excitation phase is 0 degree.
2. Emulation content and structure analysis
Fig. 3 shows a wavefront distortion diagram, and fig. 4 and 5 show the ideal radiation pattern of the horizontal plane and the vertical plane, respectively, the distortion array radiation pattern, and the compensation pattern obtained by optimizing the compensation phase under the condition of considering the quantization error of the phase shifter. As can be seen from the comparison graph, the deformation has symmetry, so the obtained deformation directional diagram also has symmetry. As for the compensation result, good compensation effect is achieved in the main lobe and nearby lobe areas of the two cross sections. From the data in table 1, the compensation achieves a better effect under the condition of considering the quantization error of the phase shifter, and the maximum error of the compensation value and the ideal value is not more than 0.1 dB. Therefore, the method provided by the invention can play an important role in practical engineering.
TABLE 1 comparison of compensated data for ideal, deformed and quantized errors of phase shifters
The invention is not limited to the above-mentioned case, and based on the technical scheme disclosed by the invention, some technical processes in the invention can be changed without creative labor according to the technical content disclosed, and the changes are all within the protection scope of the invention.
Claims (6)
1. A deformation array antenna directional pattern and quantization error combined optimization compensation method is characterized in that:
(1) calculating an ideal radiation directional diagram according to the position coordinates and the excitation distribution of the active phased array antenna under the undeformed condition, and extracting and retaining main lobe gain and side lobe level data of a horizontal plane and a vertical plane;
(2) establishing a finite element model according to the geometric parameters, constraint conditions and load information of the antenna, and determining the node coordinates of the corresponding radiation unit after the array surface structure is deformed;
(3) calculating the far field of the deformed array surface, converting the influence of the deformation of the array surface on the directional diagram into phase change, and obtaining an ideal compensation phase for compensating the deformed array radiation directional diagram to an ideal radiation directional diagram;
(4) uniformly rounding down the ideal compensation phase according to the minimum phase shift stepping of the phase shifter;
(5) and (3) taking the main lobe gain and side lobe level indexes of an ideal directional diagram as compensation targets, optimizing the phase compensation quantity after downward rounding by utilizing a genetic algorithm, wherein the phase adjustment value in the optimization process is an integral multiple of the minimum phase shift step, so that the optimal phase compensation quantity considering the quantization error of the phase shifter is obtained.
2. The method for jointly optimizing and compensating for a deformed array antenna pattern and a quantization error according to claim 1, wherein the step (1) comprises:
(1a) calculating the radiation pattern of the ideal active phased array antenna, wherein the radiation pattern is as follows:
wherein, InExciting amplitude for the nth radiating element;
for which the phase is excited; f. ofn(θ, φ) is its directional pattern function in an isolated environment;
is its bit vector;
is a spatial unit vector; k is an electromagnetic wave propagation constant; j is an imaginary unit;
(1b) and extracting and retaining main lobe gain and side lobe level data of the horizontal plane and the vertical plane of the ideal directional diagram.
3. The deformed array antenna pattern and quantization error joint optimization compensation method of claim 1 or claim 2, wherein: the step (2) comprises the following steps: when determining the coordinates of the nodes after the deformation of the array surface structure, only the displacement in the direction vertical to the array plane is considered, and the displacement of the array elements along the array direction is ignored.
4. The method of claim 3, wherein the step (3) comprises:
(3a) the radiation pattern of the active phased array antenna after the array surface deformation is as follows:
wherein, IncApplying an excitation amplitude value after compensation for the nth radiation unit;
the excitation phase for which it should be applied;
displacement of the nth array element in the direction vertical to the array plane;
(3b) the amplitude and phase under ideal compensation can be obtained:
5. the method of claim 4, wherein the step (4) of uniformly rounding down the ideal compensation phase comprises:
(4a) and determining the minimum phase-shifting phase according to the number of the phase shifter bits:
△＝2π/2p；
wherein Δ is a minimum phase shift phase; p is the number of phase shifter bits;
(4b) according to the tail cutting method, the tail cutting is carried out on the ideal compensation phase:
wherein,
after tailing for ideal compensation phase of nth array elementTail-cutting compensation phase; [ M ] A]Rounded down, i.e., taking the largest integer value that does not exceed M.
6. The method of claim 5, wherein the step (5) of optimizing the rounded-down phase compensation by using a genetic algorithm comprises:
(5a) under the condition that the number of array elements is N, chromosomes with the length of N are set, the number of the chromosomes is 10-20, all the chromosomes are randomly composed of 0 and 1, and a population is formed;
(5b) designing corresponding inheritance, variation and cross functions to carry out iterative optimization on the population;
(5c) designing a reasonable optimization cut-off condition according to the known main lobe gain and side lobe level of the ideal radiation directional diagram, so that the genetic algorithm can stop an optimization program when an optimization target is reached;
(5d) and selecting the chromosome with the best compensation effect from the obtained optimal population to obtain the final optimal compensation phase considering the quantization error of the phase shifter, wherein the formula is as follows:
wherein phi isnThe final compensation phase of the nth array element is obtained;
the nth value of the ith chromosome in the optimal population.
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| CN117572369A (en) * | 2024-01-19 | 2024-02-20 | 中国科学院空天信息创新研究院 | Method for calculating distance-to-orbit deformation error of satellite-borne SAR active phased array antenna |
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| CN117572369A (en) * | 2024-01-19 | 2024-02-20 | 中国科学院空天信息创新研究院 | Method for calculating distance-to-orbit deformation error of satellite-borne SAR active phased array antenna |
| CN117572369B (en) * | 2024-01-19 | 2024-04-09 | 中国科学院空天信息创新研究院 | Method for calculating distance-to-orbit deformation error of satellite-borne SAR active phased array antenna |
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