Study On Adaptive Beamforming At Subarray Level Of Missile-borne Phased Array Radar

The application of missile-borne phased array radar has become more and more extensive,which raises higher requirements on the performance of radar systems.In order to achieve high-resolution measurements in angle and angle,large phased array is widely used.However,large phased array commonly consisted of many antennas units,and realizing a full digital beamforming can result in a mount of equipments,computation and storage.The system's hardware architecture is too complex to use in the missile-borne phased array radar.In order to reduce the cost and complexity,it is necessary to physically reduce the dimension.By using a feed network,multiple array elements are microwave-combined into subarrays,thus adaptive beamforming can be achieved at the subarray level.Based on the basic theory of digital beamforming and adaptive signal processing,this paper studies adaptive beamforming at the subarray level and the methed of suppressing the mainlobe interference.Finally,the mainlobe interference suppression at the subarray level is completed.The specific researches are as follows: 1.Based on the array signal model,the basic principles of beamforming and adaptive beamforming are introduced.Then,this paper analyzes and compares several criteria and common algorithms for adaptive beamforming.2.This paper studies the adaptive beamforming at the subarray level.First of all,regular configuration subarray,irregular configuration subarray and overlapping subarray are intrudeced.Then the model of irregular configuration subarray and the method of optimizing subarray position are proposed for uniform linear array and rectangular array respectively,which avoids the effect of grating lobes and grating nulls.Finally,the noise normalization method is adopted to improve the adaptive performance of the irregular configuration subarray.3.In this paper,several methods of suppressing the mainlobe interference are studied,including blocking matrix preprocessing,eigen-projection matrix preprocessing and eigenprojection covariance matrix reconstruction.For the problem of traditional BMP algorithm,this paper proposes a method of using different array spacing to destructive.The computer simulation proves that the method of using four array spacing to destructive performs best,which can reduce the notch in the direction of interference and the loss of signal energy.In this way,the subsequent detection probability can be improved.At the same time,the loss of the array aperture is small,and the angle measurement accuracy is guaranteed.4.This paper subdivides the missile-borne phased array,and uses EMP,EP-CMR,and improved BMP algorithm at subarray lavel to eliminate the influence of mainlobe and form a null in sidelobe,which solves the distrotion of mainlobe and the increase of sidelobe.Therefore,this paper completes the mainlobe interference suppression at the subarray level.