Design And Implementation Of Low Altitude Angle Measurement Algorithm For Phased-array Radar

With the rapid development of modern radar technology,the mission and mission of radar are constantly improving.As early as the initial last century,there are a considerable number of experts and scholars have conducted in-depth research on the radar,but whether it is because the development needs of national defense or civilian radar demands on the development of all walks of life,the radar technology are in continuous innovation.But the low altitude field has been radar detection blind zone,one of the most important reasons is the multipath effect,the multipath effect will lead to a sharp decline in the performance of the radar when the target is captured at low altitude.Because of the multipath effect,the radar received the direct signal and the reflected signal reflected by the reflector,it is difficult to separate the direct wave signal and the reflected signal from space,time domain or frequency domain.In addition,the multipath environment is complex and changeable,and the reflection surface is usually unknown and time-varying.This increases the difficulty of radar detection in low altitude areas.In the research and practical application,it is found that phased array radar has many kinds of excellent performances,its ability to search for low observable targets is stronger,and because of the progress of economic strength and the decline of manufacturing cost,the cost of phased array radar is also low,phased array radar technology is becoming more popular,more widely used.Therefore,phased array radar can be used to detect low altitude targets.In this thesis,the problem of angle measurement of phased array radar in low altitude is studied.First,in order to understand the multipath effect,in this thesis,two kinds of multipath effect models are established,one is the plane model,the other is the spherical model considering the curvature of the earth.The relationship between the derivation of the two models of the direct wave and reflection wave angle,analyzed the composition of the original radar echo signal is received,the main direct wave signal,specular reflection and diffuse reflection signal.Then,aiming at the difficulty of low angle measurement,this thesis introduces several angle measurement algorithms,such as maximum likelihood estimation algorithm,generalized MUSIC algorithm based on real number domain and the elevation measurement method based on matrix beam,these algorithms have their own characteristics,there is also the difference between measurement precision.In this thesis,from the principle of the algorithm to the flow chart and the steps of the algorithm,the accuracy and the amount of calculation of several algorithms are compared,and the advantages and disadvantages of each algorithm are analyzed.Finally,the feasibility of the algorithm is verified by simulation.Finally,according to the characteristics of the algorithm,the low angle measurement system of phased array radar is designed.The original data are saved and the results stored in external storage space,the calculation of the original signal and system using MATLAB simulation results comparison,analysis of the performance of the algorithm,the correctness and accuracy of calculation results verify the system meets the requirements,but also to further verify the correctness of the algorithm,the advantages and disadvantages of several algorithms are summarized from the time consuming and the computational error,different algorithms are selected according to the actual measurement.