| The modern battlefield environment is increasingly complex,and various active or passive interference in the complex environment has caused a great impact on the phased array radar,so anti-jamming measures must be taken to improve the detection ability of radar in the complex environment.The most commonly used sidelobe interference suppression method in applications is Adaptive Sidelobe Cancellation.This method is one way of spatial adaptive processing.The selection of the auxiliary channel directly affects the interference suppression performance.Therefore,it has important theoretical and practical meaning to study the influence of factors such as the number or layout of large phased-array auxiliary antennas on the interference suppression performance.In addition,since the traditional sidelobe cancellation method cannot suppress the main-lobe interference,it is of great significance to study the anti-main-lobe interference method to improve the working performance of the radar in the complex electromagnetic interference environment.The work of this thesis is mainly developed from the following two aspects:1.Research on the selection scheme of large-scale phased array adaptive sidelobe cancellation auxiliary antenna.In large phased array adaptive sidelobe cancellation,the auxiliary antenna has a great influence on the cancellation performance.In this thesis,a rectangular planar array is used as an example to introduce the received signal of a planar phased array.The research results show that the number of auxiliary array elements should not be less than the number of interference.When the positions of auxiliary array elements are scattered and the selected positions are not uniform,the interference cancellation effect is good.Combined with the simulation analysis and the existing conclusions,in view of the complexity of the selection of large-scale phased array auxiliary elements and the problem of the grating lobe of the synthetic antenna pattern,this thesis proposes a sub-array partitioning and randomly selected auxiliary array element selection method.This method uses The randomness of the position of the auxiliary elements is used to avoid the grating lobes of the composite antenna pattern.The simulation results show that compared with the traditional auxiliary array element selection method,this method can effectively reduce the probability of the occurrence of the synthetic antenna pattern grating lobes,thereby improving the interference suppression performance in the antenna side lobe region.2.Research on main lobe interference suppression method based on sum-difference beam.Both the adaptive sidelobe cancellation algorithm based on the auxiliary array element method or the auxiliary beam method will cause distortion of the composite pattern when canceling the main lobe interference,which not only seriously affects the interference cancellation performance but also affects the subsequent target detection.The root cause of the failure of the adaptive sidelobe cancellation algorithm to cancel the mainlobe interference is that a large amount of noise from the auxiliary channel or auxiliary beam will be introduced during the cancellation,thereby reducing the output signal-to-interferencenoise ratio.The sum-difference beam method uses the difference beam as an auxiliary beam to suppress the main lobe and near-main lobe interference,and has good adaptive beam conformability.However,in the sum-difference beam method,a difference beam as an auxiliary channel can only cancel one main lobe interference.To solve this problem,this thesis proposes a sliding-window-based sum-difference beam interference suppression method.This method uses the array element domain sliding window to provide multiple different beams,so as to obtain multiple adaptive degrees of freedom to cancel multiple main lobe interference.The simulation results show that the method proposed in this thesis can effectively solve the problem of suppressing multi-main lobe interference. |
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