Research On Bistatic Composite Electromagnetic Scattering From Sea Surface And Targets

With the rapid development of computational electromagnetics,the research of composite electromagnetic scattering from rough sea surface with a target located above it has become a popular topic.In this paper,the composite scattering characteristics of a target(such as sphere,cube,Tomahawk missile,etc)located above a sea surface are studied.In performing a composite electromagnetic scattering analysis,the interaction between the target and the complex background must be considered.In order to better analyze the scattering mechanism,electromagnetic scattering characteristics of a target located above a rough sea surface for different calculating coditions(such as different radar parameters,sea surface parameters,the altitude of the target,etc)has been simulated and compared to each other.When calculating the combined electromagnetic scattering between the sea surface and the target,not only did this paper discuss the RCS of the upper half of the target,but also discussed the situation of the receiver in the lower half of the target.In this paper,a hybrid algorithm that combinning the method of moments and physical optics is utilized to simulate the composite electromagnetic bistatic scattering propoties of a target located above a rough surface at both microwave band and the short wave band.In modern warfare,short wave bistatic radar has a longer detection range than that of monostatic radar.Also,the receiver of the bistatic radar has a better stealth than that of monostatic radar.All of these made the bistatic radar widely used in practice.The infulence of the radar parameters(incident wave frequency,incident angle,etc.),sea surface parameters(wind speed,wind direction,etc.)and target parameters(Height,type,etc.)on the scattering characteristics are stuied.The main works in this paper are as follows:1.The basic principle of the method of moments is briefly described.In method of moments,the induced currents is firstly expanded with a suitable basis function.And then a weight function has been introduced to convert the wave equation into a generalized voltage equation and a current equation by performing inner production.Finally,the unknown induced currents can be obtained by solving the equation.2.The Monte Carlo Method is introduced in modeling one-dimensional and two-dimensional random rough surface.And the influence of related parameters(correlation length,rms height,wind speed,etc)on the rough surface is discussed.The tapered incident wave is introduced in performing electromagnetic scattering analysis to avoid the artificial reflection from the edge of the rough surface.And finally the MOM is applied to calculating the RCS of a sphere located above a sea surface.3.The theory of the hybrid MOM-PO algorithm is briefly introduced.The two main way to combine MOM and PO,modify impedance matrix method and the iterative method,are presented.The advantages and disadvantages of the two methods are analyzed and summarized.The composite electromagnetic scattering properties of a target located avove a two-dimensional rough sea surface are studied.The influence of incident angles,frequency,altitude of the target on the far-field and near-field RCS are discussed in detail.4.The principle of bistatic radar is briefly described.The composite scattering RCS of one or two target located above a rough sea surface under short wave band are calculed by appling the hybrid MOM-PO.The effects of radar parameters(incident wave frequency,incident angle)and sea surface parameters(wind speed,wind direction),target type on the composite bistatic far-field RCS and near-field field electric strength distribution in the lower half space are discussed in detail.