Research On Synthesis And Optimization Of Sparse Antenna Arrays Based On Superdirectivity

In the range of high frequency,the causes of external noise are complex and analyzed difficultly,which directly affects the analysis and improvement of signal-to-noise ratio of the system.However,when the system can ensure that the external noise is dominant relative to the internal noise,the SNR of the system is not related to noise,but is proportional to the directivity coefficient of the array antenna.Therefore,improving the directional coefficient can indirectly improve the SNR of the receiving system.In the study of improving the array antenna directivity coefficient,the synthesis of the super-directional array can achieve the optimal directionality coefficient under the condition that the external noise is dominant;and for the super-directional array,fewer array elements can be used to achieve a higher directional coefficient,which is of great significance to study the miniaturization of receiving arrays.he sparse antenna array not only can reduce the antenna elements to reduce the engineering cost of the antenna system,but also has more freedom in the position of the array element on the aperture of the array,and can obtain more superior antenna performance.For sparse arrays and uniform arrays with the same number of array elements,the sparse array can obtain narrower mainlobe and lower peak sidelobe levels,and when the arrays have the same aperture,the sparse array and the uniform array have the same mainlobe width,but because the sparse array has a larger array element spacing,the mutual coupling effect between the array elements is weakened,and the overall performance of the antenna array is improved.Therefore,the sparse array antenna has been widely used in practical engineering.In order to reduce the sidelobe level of the array,it is necessary to optimize the array elements positions and excitations of the array antenna.In this paper,we mainly study the position of array elements with constraints of the aperture of array,the number of array elements,and the minimum spacing between array elements,and then optimize the positons of array elements to obtain the peak sidelobe level as low as possible.In this paper,we apply a super-directional array synthesis method,which can optimize the array's directional coefficient with the constraints of the noise ratio factor which satisfies that the external noise dominates.At the same time,in order to meet the mainlobe-sidelobe ratio requirement of target recognition and antijamming,sidelobes can also be controlled through iterative methods.Based on the basic knowledge of array antennas,a formula of the directional coefficient of arbitrary array is been derived,and the typical array are been optimized above superdirectional array synthesis method.In addition,a mathematical model for the optimization of sparse antenna array was constructed to optimize the peak sidelobe level of the array.The Fourier algorithm,the large-mutation genetic algorithm and the particle swarm algorithm based on simulated annealing algorithm were used to the optimization of sparse linear array.Finally,are choosed.The appropriate parameters are selected to design the endfire array and super-directional circular array,which considered the directional coefficient and the array miniaturization.Then the super-directional endfire array and circular array are used as array elements,and select the appropriate array form which include uniform arrays and sparse arrays for the design of receiving arrays in high frequency.