Irregular arraying optimization method for ultra-wideband wide-angle connected conformal array

Abstract

The invention discloses an irregular arraying optimization method for an ultra-wideband wide-angle connected conformal phased array, and the method employs a CMA-ES algorithm as an optimization method, and employs an array sparse technology to optimize the arrangement of array elements of the connected conformal phased array. And array elements in the array are randomly extracted, so that the optimal irregular arrangement of the array is achieved. In order not to destroy the continuity of current between the array elements of the connection type array, the extracted array element positions are filled with metal sheets, and radiation extension walls are loaded at the two ends of the array, so that the edge truncation effect can be effectively inhibited. The irregular sparse array provides greater flexibility in the aspect of array element arrangement, so that the phased array reaches the optimal performance index in a specific application scene. The side lobe level of the array can be reduced, the broadband sweep angle performance of the array is improved, the cost can be effectively reduced by reducing the number of array elements of the array, and the influence of the coupling effect between the array elements can be reduced by optimizing array element arrangement.

Description

Technical Field

[0001] The present invention relates to the fields of connected conformal arrays and irregular array layouts, and particularly to an optimization method for the irregular array layout of an ultra-wideband wide-angle connected conformal array. Background Art

[0002] With the rapid development of electronic communication technologies, phased array antennas have been applied not only in the national defense and military fields, but also in civilian fields such as radar, satellite communication, astronomical meteorology, earth exploration, space exploration, and unmanned driving. Conformal phased array antennas are generally considered to be an antenna form that can break through the carrier limitations of antennas. Compared with traditional planar arrays, conformal arrays have unparalleled advantages such as reducing aerodynamic drag, wide-angle coverage, and increasing the array radiation aperture on high-speed aircraft, missiles, and warships. With the rapid development of modern radar technologies, wideband wide-angle conformal phased arrays, as a high-performance radar antenna system, are playing an increasingly important role in military, civilian, and other fields. Their unique structural design and signal processing capabilities enable the radar system to achieve efficient target detection and tracking within a wider frequency range and a wider viewing angle. However, in order to fully utilize the performance advantages of wideband wide-angle conformal phased arrays, the optimized layout of the array is particularly important.

[0003] The optimized layout of an array refers to making the phased array achieve the best performance indicators in a specific application scenario through reasonable arrangement of array elements and parameter configuration. This involves comprehensive considerations of multiple aspects such as the number, position, spacing, and excitation phase of array elements. An excellent array layout can not only improve the detection range and resolution of the radar system, but also enhance its anti-interference ability and multi-target processing ability. In the design of wideband wide-angle conformal phased arrays, the optimized layout of the array faces many challenges. First, the wideband characteristic requires the array to maintain stable performance at different frequencies, which requires precise control of the frequency response of array elements. Second, the wide-angle characteristic requires the array to have a large scanning angle and coverage range, which requires reasonable design of the arrangement of array elements. In addition, the characteristics of the conformal structure also require the array to be closely attached to the surface of the carrier to achieve good electromagnetic compatibility and stealth performance. Most previous studies have focused on the optimization of array elements in conformal arrays, and the optimization of irregular array layouts in conformal arrays mostly remains at the algorithm theory level. Summary of the Invention

[0004] The purpose of the present invention is to propose an optimization method for the irregular array layout of an ultra-wideband wide-angle connected conformal array, which is used to reduce the sidelobe level of the array, improve the wideband scanning angle performance of the array, effectively reduce costs, optimize the arrangement of array elements, and reduce the influence of coupling between array elements.

[0005] The technical solution for achieving the object of the present invention is as follows: An irregular array layout optimization method for an ultra-wideband wide-angle connected conformal phased array, which is a 64-element connected conformal array composed of uniformly arranged Vivaldi units, and the CMA-ES algorithm is used to optimize its irregular array layout; by extracting some array elements for the irregular layout of the connected conformal array, the positions of the extracted array elements are filled with metal sheets.

[0006] Furthermore, the content of the CMA-ES algorithm is as follows: First, a series of initial points are randomly generated using a normal distribution as the initial population, and the size of the initial population is λ. Then, the fitness value of each individual in the population is calculated, and the top λ / 2 individuals with the best fitness values are selected as the parents of the next generation. New populations are generated using the position information of the high-quality individuals according to the characteristics of the normal distribution to ensure that the algorithm moves towards the optimal point; iterate successively until a satisfactory solution is found or the optimization stops when the stop condition is reached.

[0007] Furthermore, for the calculation of the conformal array pattern, the unit vector pattern needs to be rotated to the unified global coordinate system through Euler rotation and then superimposed according to the far-field superposition principle.

[0008] Furthermore, the array element uses a Vivaldi antenna, and the selected dielectric substrate is RO4350 with a thickness of 0.254 mm and a working bandwidth of 4:1.

[0009] Furthermore, a connected conformal array composed of Vivaldi units with 64 array elements, a curvature radius of 0.3 m, and an element spacing of 3.4 mm is formed, and radiation extension walls are loaded at both ends of the array; the CAM-ES algorithm is used as the optimization method to perform sparse arrangement on the array, and some array elements are extracted from the array, and the sparsity rate is 0.25.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0011] (1) Aiming at the problem of irregular array layout of the ultra-wideband wide-angle connected conformal array, the present invention uses the CMAES algorithm to calculate the irregular sparse arrangement problem of the array.

[0012] (2) Effectively improve the performance of the array during wide-angle scanning. When the array performs wide-angle scanning, problems such as sidelobe elevation and pattern distortion will occur. The irregular array layout of the array can effectively improve the array layout, thereby reducing the sidelobes and optimizing the pattern.

[0013] (3) Significantly reduce the cost and effectively reduce the influence of element coupling. The 64-element uniform array is reduced to a 48-element irregular array with a sparsity rate of 25%. In addition, it also has a significant effect on improving element coupling and can reduce the VSWR of the array during wide-angle scanning. Description of the Drawings

[0014] Figure 1 It is the flow chart of the CMAES algorithm used in the present invention.

[0015] Figure 2 It is the unit model size information of the array in the present invention and its standing wave ratio curve.

[0016] Figure 3 It is the simulation model of the connected conformal Vivaldi phased array of the present invention. Among them, Figure (a) is the uniform conformal array model, and Figure (b) is the irregular conformal array model.

[0017] Figure 4 It is the standing wave ratio performance of the uniform conformal array of the present invention. Among them, Figure (a) is the standing wave ratio results at different scan angles at a high frequency of 32 GHz; Figure (b) is the standing wave ratio during normal phase scanning of the uniform array; Figure (c) is the standing wave ratio during 30° scanning of the uniform array; Figure (d) is the standing wave ratio during 60° scanning of the uniform array.

[0018] Figure 5 It is the standing wave ratio performance of the irregular conformal array of the present invention. Among them, Figure (a) is the standing wave ratio results at different scan angles of the irregular array at 32 GHz; Figure (b) is the standing wave ratio during normal phase scanning of the irregular array; Figure (c) is the standing wave ratio during 30° scanning of the irregular array; Figure (d) is the standing wave ratio during 60° scanning of the irregular array.

[0019] Figure 6 It is the comparison of sidelobe performance and gain loss of the present invention. Among them, Figure (a) is the comparison of sidelobe and gain results before and after irregular layout at a frequency point of 8 GHz; Figure (b) is the comparison of sidelobe and gain results before and after irregular layout at a frequency point of 20 GHz; Figure (c) is the comparison of sidelobe and gain results before and after irregular layout at a frequency point of 32 GHz; Figure (d) is the comparison of sidelobe and gain results before and after irregular layout during normal phase scanning of the array; Figure (e) is the comparison of sidelobe and gain results before and after irregular layout during 30° scanning of the array; Figure (f) is the comparison of sidelobe and gain results before and after irregular layout during 60° scanning of the array. Detailed implementation manners

[0020] The present invention proposes an optimization method for irregular layout of an ultra-wideband wide-angle connected conformal phased array. The CMA-ES algorithm is used to obtain a connected conformal array with an irregular layout. On the premise that the gain loss is less than 3 dB, the irregular array can obtain a lower sidelobe level compared with the uniform conformal array, effectively reducing the number of array elements, so as to achieve the purposes of improving the working performance of the array, reducing the coupling effect between array elements, and reducing costs.

[0021] This method uses the CMA-ES algorithm as the optimization method and employs array sparse technology to optimize the arrangement of the elements of a connected conformal phased array. A uniform 64-element connected conformal array composed of Vivaldi elements is used, with a working frequency of 8 GHz - 32 GHz, a working frequency band of 4:1, and a wide-angle scan up to ±60°. By randomly selecting elements in the array, the optimal irregular arrangement of the array can be achieved. To avoid disrupting the continuity of the current between the elements of the connected array, the positions of the removed elements are filled with metal sheets, and radiation extension walls are loaded at both ends of the array to effectively suppress the edge truncation effect. The irregular sparse array provides greater flexibility in the arrangement of elements, enabling the phased array to achieve the best performance indicators in specific application scenarios. This work has practical significance in the field of wide-angle scanning of ultra-wideband conformal arrays, reducing the sidelobe level of the array, improving the wide-frequency scanning angle performance of the array, reducing the number of array elements can effectively reduce costs, and optimizing the element arrangement can reduce the influence of the coupling effect between elements, which is of great significance for the practical application of ultra-wideband wide-angle connected conformal arrays.

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

[0023] The present invention provides an irregular array layout optimization method for an ultra-wideband wide-angle connected conformal phased array. The method includes the following steps:

[0024] 1) In the entire process of the CMA-ES algorithm, the update of the covariance matrix is the core part, which determines the exploration ability and convergence speed of the algorithm. By continuously adjusting the covariance matrix, the CMA-ES algorithm can maintain the global search ability while gradually focusing on the region with higher fitness, so as to find high-quality solutions. First, according to the actual optimization problem, determine the variables and value ranges, and calculate the mean and covariance of the normal distribution.

[0025] 2) Calculate the covariance matrix C(0), determine the corresponding normal distribution, and generate the initial parent population by sampling the normal distribution λ times. The selection of the number of parent populations is related to the variable dimension M, and its minimum value is λ≥4 + 31nM.

[0026] 3) Calculate the fitness values of each population, and determine whether there is a population that meets the termination condition. If the termination condition is met, the algorithm iteration terminates and the optimal variable value is output; if the termination condition is not met, sort the fitness values of each population in ascending order, and select the first λ / 2 populations with the best fitness values to form the offspring population for updating the mean of the normal distribution.

[0027] 4) Update the M-element normal distribution, that is, update the standard deviation, mean, and covariance matrix.

[0028] 5) After the parameter update is completed, new parents are sampled from the new multivariate normal distribution. Repeat the above steps until the calculation termination condition is met or the maximum number of iterations is completed.

[0029] 6) A connected conformal array consisting of Vivaldi elements with 64 array elements, a curvature radius of 0.3 m, and an element spacing of 3.4 mm. Loading radiation extension walls at both ends of the array can effectively suppress the edge truncation effect. The CAMES algorithm is used as the optimization method to sparsely arrange the 64-element connected conformal array with uniform arrangement, and some elements are extracted from the array with a sparsity rate of 0.25. To avoid disrupting the continuity of the current between the elements of the connected array, the elements are connected by metal sheets.

[0030] The present invention will be described in detail below with reference to embodiments.

[0031] Embodiment

[0032] An irregular layout optimization method for an ultra-wideband wide-angle connected conformal phased array in this embodiment includes:

[0033] The CMAES algorithm first randomly generates a series of initial points as the initial population using the normal distribution N(m, σ 2 C). The size of the initial population is λ. Then, the fitness value of each individual in the population is calculated, and the top λ / 2 individuals with the best fitness values are selected as the parents of the next generation. New populations are generated using the position information of these high-quality individuals according to the characteristics of the normal distribution to ensure that the algorithm moves towards the optimal point. Iterate sequentially until a satisfactory solution is found or the optimization stops when the stop condition is reached.

[0034] The calculation of the conformal array pattern cannot simply use the pattern multiplication theorem in the planar array. The unit vector pattern needs to be rotated by Euler transformation to a unified global coordinate system and then superimposed according to the far-field superposition principle.

[0035] The array element uses a Vivaldi antenna, and the selected dielectric substrate is RO4350 with a thickness of 0.254 mm and a working bandwidth of 4:1.

[0036] A connected conformal array consisting of Vivaldi elements with 64 array elements, a curvature radius of 0.3 m, and an element spacing of 3.4 mm. Loading radiation extension walls at both ends of the array can effectively suppress the edge truncation effect.

[0037] Using the CAMES algorithm as the optimization method, the array described in claim 4 is sparsely arranged, and some elements are extracted from the array with a sparsity rate of 0.25.

[0038] The elements are connected by metal sheets, which can avoid disrupting the continuity of the current between the elements of the connected array.

[0039] As Figure 1 is the flowchart of the CMAES algorithm of the present invention. Figure 2 shows the unit model size information of the array in the present invention and its standing wave ratio curve, and its VSWR < 1.5 in the entire frequency band of 8 GHz - 32 GHz. As Figure 3 is the complete connected conformal array design model of the present invention. Among them Figure 3 (a) is a uniform conformal array model, Figure 3 (b) is an irregular conformal array model. Figure 4 is the standing wave ratio performance of the uniform conformal array of the present invention. Figure 5 is the standing wave ratio performance of the irregular conformal array of the present invention. From Figure 4 (a) and Figure 5 (a), it can be known that as the scanning angle increases, the standing wave ratio also increases. However, after the irregular arrangement, the coupling effect between array elements is reduced. Therefore, the standing wave ratio of the irregular array is basically lower than 2.6, and the standing wave ratio of the uniform array is mostly lower than 3. From Figure 4 (b) and Figure 5 (b), it can be known that the VSWR < 2 when the uniform array and the irregular array are scanned in the normal direction; Figure 4 (c) shows that when scanned at 30°, the standing wave ratio of the uniform array is mostly lower than 2.5 except for individual high-frequency points, Figure 5 (c) shows that the standing wave ratio of the irregular array is lower than 2.2 in the entire frequency band when scanned at 30°, further proving the superiority of the irregular arrangement in the performance during array scanning; Figure 4 (d) clearly shows that the standing wave ratio of many frequency points of the uniform array is higher than 3 when scanned at 60°, but Figure 5 (d) shows the standing wave ratio result of the irregular array when scanned at 60°. In the entire frequency band, the VSWR < 3. From this, it can be known that the irregular array can achieve the purpose of improving the standing wave ratio performance after optimized arrangement.

[0040] As Figure 6 (a) shows, at 8 GHz, when scanned to ±60°, the sidelobe of the irregular arrangement is reduced by 2.7 dB to 5.7 dB, and the gain loss is less than 0.8 dB; at Figure 6 (b), it can be seen that in the range of the scanning angle of ±60° at the 20 GHz frequency point, the sidelobe of the irregular array is reduced by 1.6 dB to 6.3 dB compared with the uniform array, and the gain loss is less than 1.1 dB; as Figure 6 (c) shows, at the high frequency of 32 GHz, in the range of the scanning angle of ±60°, the sidelobe of the array after the irregular arrangement is reduced by 1.6 dB to 5.4 dB, and the maximum gain loss is only 1.7 dB; the sidelobe and gain results of the array when scanned in the normal direction are shown in Figure 6(d) shows that within the entire broadband, the sidelobes of the irregular array are 3.7 dB to 5.2 dB lower than those of the uniform array, and the gain loss is less than 1.3 dB; when the array is scanned at 30°, the sidelobes after the irregular arrangement are reduced by 2.5 dB to 4.4 dB, as shown by Figure 6 (e) shows that the gain loss is less than 1.4 dB within the entire frequency band; Figure 6 (f) shows the comparison of sidelobe and gain results when the array is scanned to 60°. The sidelobes of the irregular array are 1 dB to 4 dB lower than those of the uniform array, and the gain loss is less than 0.5 dB within the entire broadband.

[0041] As can be seen from the above, the present invention proposes an optimized design method for the irregular arrangement of an ultra-wideband wide-angle connected conformal array. A uniform connected conformal array is composed of Vivaldi elements operating at 8 - 32 GHz. By optimizing the element position layout of the array through an algorithm, the number of elements is reduced, and the elements of the irregular array are connected by metal patches. After the irregular arrangement, the sidelobes of the array can be reduced by 1 dB to 6.3 dB within the wideband and wide-angle range, and the overall gain loss is less than 1.7 dB; at the same time, the influence of element coupling between arrays can be improved, and the standing wave ratio performance of the array during wide-angle scanning can be optimized; reducing the number of elements can effectively reduce the processing and application costs, which is of great significance in the field of communication radar.

[0042] The above description is only a preferred example of the present invention and is not intended to limit the present invention. Any modifications, substitutions, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0043] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered that the scope described in this specification.

Claims

1. A non-regular array optimization method for ultra-wideband wide-angle connected conformal phased array, characterized in that: The CMA-ES algorithm is used to optimize the irregular arrangement of a 64-element connected conformal array composed of uniformly arranged Vivaldi units. The irregular arrangement of the connected conformal array is optimized by extracting some array elements, and the positions of the extracted array elements are filled with metal sheets.

2. The irregular array optimization method for ultra-wideband wide-angle connected conformal phased array according to claim 1, characterized in that: The specific content of the CMA-ES algorithm is as follows: first, a series of initial points are randomly generated as the initial population using normal distribution, and the size of the initial population is λ. Then, the fitness value of each individual in the population is calculated, and the first λ / 2 individuals with the best fitness value are selected as the parents of the next generation. The position information of high-quality individuals is used to generate a new population according to the normal distribution characteristics to ensure that the algorithm moves towards the optimal point. Iterate in sequence until a satisfactory solution is found or the optimization stops when the stopping condition is reached.

3. The irregular array optimization method for ultra-wideband wide-angle connected conformal phased array according to claim 1, characterized in that: To calculate the conformal array pattern, the unit vector pattern needs to be transformed into a unified global coordinate system through Euler rotation, and then superimposed according to the far-field superposition principle.

4. The irregular array optimization method for ultra-wideband wide-angle connected conformal phased array according to claim 3, characterized in that: The array unit uses Vivaldi antenna, and the dielectric substrate is RO4350, which is 0.254mm thick and has a working bandwidth of 4:

1.

5. The irregular array optimization method for ultra-wideband wide-angle connected conformal phased array according to claim 3, characterized in that: A connected conformal array with 64 elements, a curvature radius of 0.3m, and an element spacing of 3.4mm is formed by Vivaldi units, and radiating extension walls are loaded at both ends of the array; The CAM-ES algorithm is used as the optimization method to sparsely arrange the array and extract some array elements from the array with a sparse rate of 0.25.

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