High-frequency Method Analysis Of Random Rough Surface And Uncertain Shape Target

The study on the composite electromagnetic scattering characteristics of random rough surface and its upper target has important research value in the fields of microwave remote sensing,target recognition,radar imaging and missile guidance.It also has significant academic value and broad application prospects in the national defense military and civilian fields.In order to meet the real-time requirements,the current engineering applications put forward higher requirements on the speed and accuracy of numerical algorithms.The random rough surface and its composite electromagnetic scattering characteristics with the target is studied in this thesis.The physical optics(PO),PO-PO and PO-IPO which can effectively calculate the rough surface and its composite electromagnetic scattering with the target are introduced and applied.At the same time,the perturbation method and the stochastic collocation method are introduced to analyze the electromagnetic scattering of the uncertain shape target.In this thesis,firstly,the establishment of rough surface model is studied.Some typical statistical parameters of rough surface and several commonly used models of sea spectrum are introduced.In order to suppress the effect of electromagnetic reflection and edge diffraction caused by the sudden cutting off of the rough surface,the tapered wave is introduced instead of the plane wave.The PO method is introduced and applied to solve the scattering from the rough surface.The PO method is one of the classical methods to study the electromagnetic scattering of the rough surface.When the incident wavelength is far less than the radius of curvature of the rough surface,the scattering field at any point on a rough surface can be approximated by the scattering plane tangent to the point.For the composite electromagnetic scattering of a rough surface and a simple target,the PO-PO method is introduced.The surface electromagnetic currents of rough surface and target are calculated by PO respectively.The interaction between the rough surface and target is calculated by the Huygens principle by updating the surface electromagnetic currents until stable.For complex targets with strong electromagnetic coupling structure,the iterative physical optics method is introduced.Therefore,the composite electromagnetic scattering of rough surface and complex target can be studied by PO-IPO method.The PO-IPO method considers the interaction of the target itself and the interaction between the rough surface and the target.The calculation accuracy can meet the engineering requirements.In this thesis,the perturbation method and the physical optics method are combined to study the electromagnetic scattering of the uncertain shape targets.The high frequency methods and stochastic collocation method are combined to study the composite electromagnetic scattering of the rough rsurface and the uncertain shape targets.The target is modeled by NURBS,so the shape of the taget can be changed conveniently by changing the position of the control point.The correctness and efficiency of this method are verified by comparing with the traditional Monte Carlo method.