Rearch On Digital Beamforming Technology Based On Hemispherical Array

As drones joined the modern war,the bee colony drone combat system developed rapidly.What followed was the development of the “anti-bee colony drone system”.In the implementation of anti-UAV operations,the UAV must first be detected and tracked and early warning.Since the bee colony drones may come from all directions,the radar system antenna design needs to have multiple beams and meet the capability of simultaneous full airspace coverage.The hemispherical array is perfect for the above functions.Therefore,this thesis has carried out a series of work based on hemispherical array beamforming: 1.The basic principle of hemispherical array beamforming is studied.The models of the hemispherical array steering vector,array distribution and antenna element pattern are derived.The two distributions of the hemispherical array,the equiangular distribution and the spiral distribution,are described.The array elements are assumed to be directional antenna elements and ideal antenna elements.By beamforming and analyzing its pattern performance,it can be found that the spiral pattern array pattern performance is better than the equiangular distribution.2.A sparse optimization method for hemispherical arrays is proposed.Aiming at the complexity and high cost of large phased array systems,an improved genetic algorithm is proposed,and a fixed-point random method is proposed to ensure that the sparsity rate is unchanged during the genetic algorithm process,and the hemispherical arrays of the above two distributions are sparsely optimized.Through simulation experiments,it can be proved that when the sparse rate is between 0.25 and 0.4,the sparse array of the algorithm can optimize one of the 3dB beamwidth and the highest sidelobe level of the array pattern,and ensure that the other one does not deteriorate.At this time,the sparsely optimized array is the most cost-effective.3.A hemispherical array the sum and difference decoupling angle measurement method are proposed.For the problem of large amount of data to be pre-stored for the difference angle measurement,when the array is an area array,the coordinate system is generally decoupled.In this thesis,the above idea is applied to the hemispherical array,under ideal conditions,The mathematical model of the hemispherical array the sum and difference decoupling angle measurement method is derived.Then,assuming that the array element is a directional antenna unit and the array distribution is a spiral distribution,a hemispherical array the sum and difference decoupling angle measurement method are proposed by using the engineering approximation idea.By analyzing the simulation results,it can be concluded that the algorithm can reduce the amount of data pre-stored by the hemispherical array the sum and difference decoupling measurement angle algorithm by about two orders of magnitude,and the angular error is within the range of 0.1°~ 0.2°.