Submarine Detection Technology Based On Synthetic Aperture Radar

As a new weapon in modern warfare,submarine plays an increasingly important role,so the research of submarine detection and anti-reconnaissance has got more and more attention.Under the background of synthetic aperture radar(SAR)and the theory of wakes generation causing by submarine movement,this thesis has deeply studied the calculation model of radar backscatter coefficient and the simulation of radar image.We also give the computer simulation of geometric shapes and results of SAR image of submarine wakes in different submarine working modes,such as submarine dive depth and sailing speed.Based on the above discussion,we propose a new submarine detection and identification methods.In this paper,we first study the flow field and surface wave morphology near submarines,According to the theory of hydrodynamics,the velocity potential flow method and the viscous-flow method are discussed.Then we use linear theory and Navier-Stokes equations to solve the problem of flow field near the surface of submarine.We have compute the internal and surface wave shapes when submarine is moving in single-layer flow,as well as multi-layer flow,then the model of submarine wakes will be got,these results can be used as input for calculating the backscattering coefficient of submarine wakes.After that,According to the small amplitude scattering theory proposed by Wright,we study the method of backscattering coefficient calculation of rough sea surface,basing on the fact that the amplitude which caused by submarine moving is much bigger than the gravity wave(long wave),the calculation model of backscattering coefficient of submarine wakes is proposed,and the shapes of results are similar to the shapes of wakes.We also study the simulation method of SAR images about the scene of sea surface according to the feature relations among the pixels in the radar image.Finally,we design the appropriate parameters of SAR system,and finish the simulation of SAR images of Los Angeles class submarine wakes under different speeds and depths,except that,we also analyze how to use these results to complete submarine detection.