Research On Jamming Method For Sidelobe Cancellation Of Phased Array Radar

Because of the rapid development of phased array radar,radar countermeasure is put forward strict requirements.With the updating of adaptive sidelobe cancellation(ASLC)algorithm and the vigorous development of electronic technology,adaptive sidelobe cancellation technology has been widely used in new radar system.It has a strong ability to resist sidelobe jamming.By adjusting the weight of the auxiliary antenna,the radar antenna pattern has a deep depression in the jamming direction and it can eliminate the interference signal in the main antenna,the conventional jamming method has been difficult to achieve the expected jamming effect.Under the background of such military requirements,it is particularly important to develop targeted jamming countermeasures according to the characteristics of phased array radar equipped with ASLC system.By analysing the principle of sidelobe cancellation,aiming at the weakness and limitation of this technology,the precise intermittent sampling interference to ASLC and optimization of multi node interference distribution for ASLC are studied.The research work of this thesis mainly includes the following three parts:Firstly,the basic principle of ASLC technology is introduced.In this thesis,the array antenna model of phased array radar and the echo signal model of target,noise and jamming are established respectively.The common optimal solution principles of adaptive sidelobe cancellation are introduced.The simulation patterns under different principles are compared horizontally,and the classical minimum mean square error(MMSE)is selected as the subsequent optimal solution criterion.Based on the uniform linear array,the adaptive sidelobe cancellation algorithm is simulated.The traditional ASLC effect evaluation index is introduced,and a new index is proposed for the new interference scenario(especially for the forwarding interference scenario)proposed in this thesis.These basic theories of adaptive sidelobe cancellation provide a theoretical basis for the research of ASLC interference technology.Secondly,by solving the optimal weight vector of the adaptive sidelobe cancellation algorithm,it can be proved that the optimal weight is based on the premise that the target signal is not correlated with the interference signal.If the adaptive sidelobe cancellation wants to get a good cancellation effect,it must be based on the premise that the interference signal is not correlated.When the jamming signal of the jammer has strong correlation with the target signal,the adaptive sidelobe cancellation technology of phased array can be affected.The influence of the correlation between jamming signal and target signal on ASLC is analyzed,and the influence of uncertain factors such as time difference and frequency difference between signals on signal correlation and jamming effect is further discussed.The precise interrupted sampling jamming is proposed and simulated,which verifies the effectiveness of the proposed jamming and the necessity of precise interference.Finally,the multi node interference to ASLC is studied,including multi-node interference and multi-node interference location optimization based on particle swarm optimization(PSO).Among them,the multi-node jamming method can consume a lot of system freedom by using multiple noise suppressing jammers to interfere with the sidelobe of ASLC system.When the number of jamming nodes is larger than the number of auxiliary antenna array elements,the adaptive weight of sidelobe cancellation can not be calculated accurately,which affects the cancellation performance of ASLC system.After a large number of experiments,it is found that when there is a specific relationship between the distribution of nodes,even if the number of jamming nodes does not meet the jamming conditions,effective interference can still be achieved.Therefore,the PSO algorithm is introduced to optimize the distribution angle of interference nodes,which makes the multi-node interference signal form dense interference in spatial domain,so that the antenna pattern formed by ASLC is distorted.This jamming method will make the radar antenna pattern distorted.The effectiveness of this jamming method is verified by simulation experiments.