Main-lobe Jamming Suppression Algorithm For Phased Array Radar

With the development of radar technology,phased array radar,characterized by its long detection range,strong ability of anti-jamming,and multi-beam synthesis,has been widely used.As an important branch of phased array radar,adaptive beam forming technology(also known as ADBF)can suppress the sibelobe jamming when the desired signal is received at maximum power.However,its performance tends to deteriorate when jamming enters from the mainlobe of the antenna pattern,greatly affecting the detection performance of radar on targets.Aiming at the difficult and hot issue of radar mainlobe jamming suppression,this paper is designed to study algorithm of mainlobe jamming suppression by theoretical derivation,MATLAB simulation and measured data based on uniform linear array when the echo signal contains both the desired signal and the mainlobe and sidelobe jamming.The details are as follows.First,the author makes reasonable assumptions based on the problem of mainlobe suppression,and study the linear frequency modulation signal and noise frequency modulation signal used for establishing the mathematics signal model.Principles of beam forming and adaptive beam forming technology are also expounded in this paper,where more focus are put on the adaptive algorithm based on linear minimum mean square error criterion.By simulation,this paper explains the effect of mainlobe jamming on adaptive beam forming technology,laying a foundation for subsequent researches in this field.Second,taking adaptive beamforming technology as the starting point,this paper makes a specific analysis of the two preprocessing mainlobe jamming suppression algorithms based on block matrix preprocessing and eigen projection matrix preprocessing,respectively.The author first theoretically analyzes the mainlobe interference suppression mechanism of them by formula derivation and then verifies their mainlobe jamming suppression performance by simulation,with the conclusion that both algorithms can effectively suppress the mainlobe jamming.Based on several current methods of determining the eigen vector corresponding to the mainlobe jamming in the EMP algorithm,the author makes a deep coenenmparison and analysis of the performance of each method by simulation experiment.Since there still exists peak offset both in the two preprocessing algorithms,the author not only introduces the principle of several common maintenance methods using the BMP algorithm as an example but also analyzes the maintenance performance of each algorithm by simulation.And the comparison results of the advantages and disadvantages of each algorithm are given in this paper.Last,guided by the principle of BMP and EMP algorithm as well as the idea of PCA for dimensionality reduction of data matrix,a mainlobe jamming suppression algorithm based on PCA and an improving EMP-CMR algorithm are studied.Specifically,the simulation experiment shows that the proposed algorithms not only outperform the EMP-CMR method in the output signal-to-noise ratio but also have a great mainlobe maintenance performance in nulling deeply at the direction of side lobe jamming.Besides,the author,by adopting multiple sets of measured data,verifies and analyzes the performance of the two preprocessing algorithm and the main lobe maintenance methods respectively,hoping that it can provide some reference value for the application of main lobe jamming suppression algorithm of phased array radar into the engineering practice.