Research On Frequency Diverse Array Dot-shape Transmitting And Receiving Beamforming And Its Application

As one of the core technologies of array signal processing,beamforming has been widely studied and applied in phased array.However,compared with phased arrays,frequency-controlled arrays have more application scenarios in distance dimension because of a small frequency offset between array elements,which can form its unique angle-distance two-dimensional dependent characteristic beam and space beam automatic scanning characteristic.However,the space beam of frequency diverse array has the problem of angle-distance coupling,and the coupling beam distribution does not always meet the practical application requirements,such as the need to only form the main beam lobe in a specific area,and the need to accurately transmit the signal to a specified target point.Therefore,it is of great significance to study the dot-shape beamforming technology of frequency diverse array.The research content of this paper is as shown:Firstly,the theoretical basis and mathematical model of beamforming are briefly described.On this basis,the array structure and signal model of frequency diverse array are studied.Then,the radiation characteristics of the directional pattern of the frequency diverse array are discussed,and the periodic formulas of the Angle,distance and time dimension of the directional pattern are given.Furthermore,the influence of the key parameters of the array on the shape and performance of the pattern of the frequency diverse array is verified through simulation analysis.Secondly,the dot-shape emission beamforming method of frequency diverse array is studied for the angle-distance coupling problem of frequency diverse array.In conventional S-emission beamforming,on the basis of study of the frequency offset schemes to achieve the purpose of a dot beam,respectively to study the logarithmic growth deviation and square deviation,increase frequency deviation and sine with cubic frequency partial solutions,and carries on the comparison and analysis,the simulation results show that although these four frequency offset growth schemes eliminate the periodicity of the S-beam and form an approximate dot-shape beam,the trailing phenomenon of the beam is serious.Then,the paper discusses the idea of sparse frequency offset,and optimizes the frequency offset of each array element in a certain frequency range,and obtains a new set of frequency offset schemes.The simulation results show that this method can improve the beam convergence performance to some extent,but the sidelobe level is still high,and the beam trailing phenomenon still exists.To solve this problem,the multi-carrier array model is studied,and a square root frequency offset scheme is proposed based on this.The simulation results show that this method can obtain a dot-shape beam with concentrated energy and high resolution.On this basis,The LCMV algorithm based on exponential correction is adopted to carry out adaptive beamforming,so that the dot-shape beam with better performance can be achieved under the condition of low or limited fast beats.Finally,two frequency diverse array receiving models,unified receiving and separated receiving,are studied and compared.The simulation results show that the beam pattern under the unified receiving model is not ambulate,and there is a deviation between the beam main lobe pointing and the target position,while the separated receiving model will form a spectral peak at the specified position.On this basis,aiming at the development demand of anti-jamming technology and the main lobe interference problem,the space-time anti-jamming method is studied by using the characteristics of frequency diverse array,and the angle-distance two-dimensional space-time signal model of frequency diverse array is deduced.Compared with the conventional linear constrained minimum variance algorithm,a method of blocking matrix processing based on frequency diverse array is proposed,and the specific structure of blocking matrix is given and the simulation analysis is carried out.The results show that the algorithm can successfully suppress the main lobe interference in the received signal,and has good beam conformal property.