Application Of The Reciprocity Theorem To The Composite Scattering Between The Rough Sea Surface And The Target

Firstly, based on the Lorentz theorem of reciprocity, the reciprocity of the two targets in the half space including the rough surface is derived and then is applied to the composite scattering between rough surfaces and targets, so the total composite scattered field can be split into first order scattered field, second order coupling scattered field and third order coupling scattered field. This theorem supplies theoretical foundation for the composite electromagnetic scattering. Using the theorem of reciprocity, the composite electromagnetic scattering from a spherical target above a conductor (dielectric) sea surface is analyzed. The numerical results of the backscattering radar cross sections (RCS) with the different incident angle for the spherical target above the sea surface are presented. The differences between the backscattering composite RCS of the conductor sea surface and that of the dielectric sea surface are given. The dependence of the composite backscattering and secondary coupling RCS of the conductor (dielectric) sea surface on the height of the spherical target above the sea surface are discussed. Meanwhile, using the physical optics method, the moment method and the method of equivalent edge currents (MEC), the RCS of the conductor plate, the cylinder and the cone-cylinder are calculated. Finally, the composite scattering from a cone-cylinder above a time-varying dielectric sea surface is investigated with the theorem of reciprocity. The scattered field from the target and the coupling scattered field are calculated by MEC. The backscattering RCS and the characteristics of the Doppler spectrum are discussed in detail.