Study On Electromagnetic Scattering From Targets In Maritime Scene

The study on the electromagnetic scattering characteristics of the target on the scene-level sea surface has been the challenging topic in the realm of research on radar features of target.Especially in the multi-ship scene,ship-ship coupling and ship-sea coupling scattering analysis,including the electromagnetic scattering characteristics of the ship wakes are difficult.The difficulty lies in the complex scattering characteristics of the sea surface and the complex electromagnetic coupling effect between the target and the sea surface.The coupling scattering field between the ship-like target and the sea surface has serious disturbance to the scattering echo of the target,which affects the tracking and guidance of the ship-like target.Now for the research on the electromagnetic scattering characteristics of the ship-like target on the scene-level dynamic sea surface is still in a continuous improvement stage.Thus it is the first task and goal to explore an efficient hybrid method from the geometric modeling of maritime scene to the electromagnetic modeling at high frequency in the realm of target detection and identification at sea.This thesis presents the research of the electromagnetic scattering characteristics of the ship-like target on the sea surface.Based on the OSG technology,the scene-level dynamic sea surface is realistically simulated.The composite electromagnetic scattering model of the ship-like target on the sea surface is established.Therefore,an integrated high frequency hybrid method,from the modeling and the simulation of the maritime scene to the calculation of composite electromagnetic scattering in real time,is established.The main works are as follows:1.Based on the geometric model of the sea surface,the geometric modeling of the ship wakes is completed.The C++ and FORTRAN hybrid programming techniques are used to realize the OSG simulation of real-time dynamic maritime scene.Analyze the principle of "real time" and "dynamic" for the maritime scene in detail,and then the relationship between the runtime fluency of the maritime scene and the discrete points of the sea surface is analyzed.2.In the traditional four-path model,the Fresnel reflection coefficient is replaced by the complex reflection coefficient to establish the modified four-path model.Based on theion and simplification of the actual maritime scene and the validity of the four-path model in the calculation of the composite electromagnetic scattering,the KA and the modified TSM are used to calculate and analyze the composite electromagnetic scattering characteristics of the ship-like target in the real-time maritime scene.The influence of the coupling contribution of each path on the composite field is analyzed,and the relationship between the composite scattering strong point and the ship-like target under different polarizations is explained.Therefore,an integrated high frequency hybrid method,from the modeling and the simulation of the maritime scene to the calculation of composite electromagnetic scattering in real time,is established.3.The distribution of the unit scattering field is analyzed in detail.The fluctuation law of unit scattering field indirectly reflects the random characteristics of height fluctuation of sea surface as a rough surface influenced by wind and the electromagnetic scattering characteristics of the ship-like target.From the perspective of the distribution of the unit scattering field,the influence of the ship-sea coupling and the ship-ship coupling on the ship-like target and the sea surface is analyzed.