Study On The Composite Electromagnetic Scattering From A Dielectric Target Above Oceanic Surface

The characteristics of high-frequency composite electromagnetic scattering from atarget above complex environment of soil and sea surfaces are of great theoreticalsignificance and its extensive applications in the fields of target detection, remotesensing of the environment, oceanic surveillance, interception technology, radarimaging, early warning. The main work and results are as follows:1. The composite electromagnetic scattering from three-dimensional (3-D) conductingtarget above dielectric sea surface is investigated. The radar cross section (RCS) ofconducting cube and combinative object are evaluated by the method of equivalentedge currents (MEC); the scattering characteristics of1-D and2-D sea surface arediscussed using the Kirchhoff Approximation (KA), the reciprocity theorem andMEC are combined to calculate the coupling scattered filed. The numerical resultsof composite backscattering RCS with different azimuth angle from the conductingcube above2-D dielectric sea surface are presented. The effects of the target size,incident angle, the wind speed of ocean are analyzed. In addition, a series ofexperiments are done for the composite backscattering of a combinative objectabove1-D sea surface. The numerical results are in good agreement with theexperimental data.2. The numerical results of the two special functions: Maliuzhinets function andFresnel function are given. The characteristics of impedance wedge are analyzed indetail under the condition of exact impedance boundary condition. Meanwhile. Theelectromagnetic scattering by a half-plane wedge and a π/2-wedge with differentimpedances on both faces excited by an obliquely incident plane wave of arbitraryare numerically calculated.3. The method of physical optics is used to analyze the electromagnetic scatteringcharacteristics of dihedral corner reflectors. The11scattering component in thecalculation of dihedral corner reflector is described in detail. Using two differentmethods, the backscattering of dihedral corner reflector with different includedangles is numerically analyzed. With the introduction of reflection coefficient, thebackscattering RCS of coated dihedral corner reflector is obtained.4. The method iterative physical optics (IPO) is used to deal with the corner reflectorstructure formed by the target and the sea surface. Translate the basic formulas of IPO into terms of linear equations. For considering multiple scattering between thetarget and the sea surface, higher order electric currents should be considered too.The Z-Buffer technology is utilized for the shadowing effect between sea surfaceand target, which can eliminate the sightless elements. The problem of multiplescattering between the target and sea surface is solved primely.