Pattern Synthesis And Subarray Partition Of Antenna Arrays

Pattern synthesis of array antenna is a very complex nonlinear problem. There are many methods that can be selected to solve the problem of array antenna synthesis. Traditional parsing method, such as Taylor synthesis method, Bayliss synthesis method and Chebyshev synthesis method, etc., can solve the array antenna problems when the beam shape and the array elements arrangement are simple. They cannot solve very complex problems. As the development of computer technology, intelligent method and fast iterave method are used into the pattern synthesis of antenna array. Intelligent method can solve the problems that have very strict constrains. They have very strong searching probability and robustness. However, the convergence speed of intelligent algorithms is slow and the computation time of the algorithm is very long. They cannot be used into the synthesis of very large antenna array. Fast iterative methods can solve the problems of large antenna arrays. But the initial condition of these problems is usually strict. Also, they can fall into local optimization values very easily. Non-uniform antenna arrays, dual band shared aperture antenna arrays, antenna arrays based on subarray and subarray partition in monopulse antenna arrays are studied in this paper.Non-uniform antenna arrays have very strict constrains for the minimum spacing of the adjacent elements. Intelligent methods can be used to determined the element positions of the antenna array. However, the algorithm process of the existing synthesis methods for non-uniform antenna arrays is very complex. Also, the synthesis results are poor. In this paper, non-uniform antenna array problems are solved by invasive weed optimization method. The element positions of symmetric linear antenna array, rectangular boundary planar antenna array and concentric circular planar antenna array are optimized. The peak side lobe level(PSLL) of the radiation pattern is selected as the fitness function. Different arrangement strategies of element positions are chosen for different style of arrays. The optimized element positions of the antenna array can fulfill the minimum constrains of the adjacent array elements. Also, the PSLL of the radiation is reduced correspondingly. The approach proposed in this paper can not only reduce the algrithom complexity but also constrain the aperture size and the maximum element number of the antenna arrays.Synthesis of dual band shared aperture antenna array is a more complex nonlinear problem. The elements for different subarrays have more strict constrains. Synthesis of linear an planardual band shared aperture antenna array is studied in this paper. The equations that fulfill the spacing constrains are derived. The PSLL of the two subarray radiation patterns are chosen as the fitness function. The element positions of the two subarrays are optimized by invasive weed optimization method. The optimized elements positions fulfill all the minimum constrains of adjacent array elements. The method proposed in this paper can fulfill the design of shared aperture antenna arrays with large frequency distance.Nonlinear least-square method is a fast iterative algorithm which can solve some synthesis problems of antenna array when the beam shape is complex and the number of the array element is large. Firstly, synthesis of linear muti-subaperture antenna array is fulfilled. The antenna array is divided into several subarrays and each subarray can produce different radiation pattern. Then, synthesis of concentric circular antenna array and hexagon boundary antenna array which are usually used in satellite-based antenna is studied. The whole antenna array is divided into several subarrays and each subarray has one amplitude weight. This will reduce the complexity of the algorithm and the cost of the antenna array.Synthesis of sum and difference radiation patterns for monopulse antenna arrays is an important research area. Synthesis of linear and planar monopulse radar is studied in this paper. The whole array aperture is divided into several subarrays and the elements of the same subarray have the same weight. For linear antenna array, element number and weight of each subarray are selected as the optimization values after the total element number and subarray number are determined. Compared with other methods, this method has the advantages of having less optimization values and fast convergence speed. For planar monopulse radar, in order to obtain good sum and difference radiation pattern, excitation matching strategy and pattern matching strategy are combined.