Study On Electromagnetic Scattering From Transverse Dunes And Its Composite Scattering With Targets Using FDTD

The electromagnetic scattering of random rough surface and its compound scattering characteristics with targets have important theoretical significance and practical value in the fields of target detection and recognition,microwave remote sensing,wireless communication,medical imaging,ocean engineering,surface optics and semiconductor physics.In this paper,the electromagnetic scattering from the surface of transverse dunes and its composite scattering with targets are systematically studied by using FDTD numerical calculation method.The main research contents are as follows:(1)Monte Carlo method is used to simulate the surface of transverse dune with exponential distribution.Based on the general formula of soil moisture and dielectric constant proposed by Herkelrath,and combined with the data obtained by domestic scholars through fitting research on many kinds of soil,appropriate parameters are selected to calculate the dielectric constant of sandy soil.The incident wave is TM wave.The electromagnetic scattering characteristics of the surface of transverse dune are studied by FDTD method,and the influence of root mean square of height fluctuation,the correlation length,the height of transverse dune,the horizontal distance of windward slope,the horizontal distance of leeward slope,the distance between sand ridges,the incident angle and the sand humidity on scattering coefficient are analyzed.(2)The composite scattering characteristics between the surface of horizontal dunes with exponential distribution and Gaussian distribution and the rectangular target above are studied.The variation laws of scattering coefficient with the root mean square of height fluctuation of the surface of transverse dune,the correlation length,the angle of incidence,the length,width,inclination and height of rectangular section,the height of transverse dune and the horizontal distance of windward slope are analyzed.(3)The composite scattering characteristics of the surface of an exponentially distributed transverse dune and a partially buried cylindrical target are studied when the incident wave is TM wave and TE wave.The influence of root mean square of height fluctuation of the surface of transverse dune,the correlation length,the angle of incidence,the radius,burial depth and permittivity of cylindrical targets,the height of transverse dunes and the horizontal distance of the leeward slope on the scattering coefficient are analyzed.(4)Using Topp empirical model to calculate the dielectric constant of sandy soil,take incident wave as TM wave.The composite electromagnetic scattering between the surface of transverse sand dune and two targets(cylinder and rectangular cross-section column)is studied,the cylinder and rectangular section column are located above and below the surface of the transverse dune respectively,and there are two layers of media with different water content below the surface of transverse sand dune.The variation laws of scattering coefficient with the root mean square of height fluctuation of the surface of transverse dune,the correlation length,the angle of incidence,the radius and buried depth of cylinder target,the target of rectangular length,the water content and thickness of the first layer of sandy soil medium are analyzed.