Study On The Micro-doppler Effects Of Moving Target Based On Electromagnetic Scattering Model

Radar Automatic Target Recognition(RATR)systems have ability to recognize the target attributes from the radar echo in all-time and all-weather conditions,and therefore widely applied in the military and civilian.Illuminated by radar systems,the moving target or its components always exists some type of complex micro motion forms,such as rotation and vibration.This type of micro motion generates the different Doppler modulations at different times,and results to typically non-stationary characteristics in radar echoes of the moving target,which is named micro-Doppler effects.With the development of RATR systems,there is an urgent demand for improving the ability to accurately describe the target states,which could seriously decrease the performance of RATR system.Therefore,the micro-Doppler characteristics analysis can be considered as an effective method to characterize the local features of the target with micro motion.This paper revolves the problems in micro-Doppler characteristics extraction and analysis and is major in the following aspects.The fundamental concepts of micro-motion and micro-Doppler effect of the target are discussed.Herein,the electromagnetic scattering characteristics of micro-moving targets are considered as the starting point,and then the radar echoes model of moving target is established.Furthermore,the theoretical model of the Doppler modulations of the moving target is obtained.According to the geometrical relationship between the micro-moving target and the radar platform,the theoretical expressions of micro-Doppler frequency induced by the basic micro-motions,such as rotation and vibration,derive by mathematical modeling.Finally,the influence of the micro-motion parameters on the micro-Doppler frequency is analyzed in detail,and the relationship between micro-Doppler features and the movement states of targets is concluded.A series of efficient features are extracted from micro-Doppler signal by using time-frequency analysis techniques.This paper reviews a sample of representative time-frequency analysis algorithms.Their performance is studied from a qualitative and quantitative point of view.For simplicity,we considered the root mean-squared error(RMSE)as measures of performance in the quantitative trade-off studies.Finally,the time-frequency features extraction from micro-Doppler signal of the rotational radar antenna is discussed.The micro-Doppler characteristics of the buoy on the sea-surface,the unmanned aerial vehicle rotor blades,and the parabolic reflector antenna are systematically analyzed by using the time-frequency analysis techniques.According to the modeling of the non-linear dynamics,the spatial electromagnetic scattering distribution of the three classical types of micro-moving targets can be calculated by method of equivalent edge currents(MEC).With adoption of the time-frequency analysis techniques,favorable micro-Doppler characteristics of them are obtained.