Research Of Electromagnetic Characteristics Of Complex Coated Targets Using High Frequency Methods

Stealth is one of the most important indices for the measurement of the operational efficiency ofmilitary weapon, in which painting radar absorbing material (RAM) is an important way to reduce theradar cross section (RCS) of military targets. Efficient and accurate computation of RCS ofelectrically large coating targets has important theoretical significance and engineering value forstealth performance evaluation of coating targets. In this paper, the electromagnetic scatteringcharacteristics of complex coating targets by using the high frequency approximate method arestudied, which mainly include,(1) Based on Maxwell’s differential equations and the constitutive equations of bi-anisotropic media,the propagation characteristics of electromagnetic waves in common media is studied. Also thepropagation equation of electromagnetic waves in stratified bi-anisotropic media is derived, whichalso can be degenerated into anisotropic and isotropic media cases.(2) Imposing the boundary condition at the interfaces between two different dielectrics and betweendielectric and conductor, the reflection coefficients matrix on the surface of multi-layer bi-anisotropicmedia coated on an infinite PEC plate is deduced. And based on this reflection coefficients matrix, thetotal electric field and magnetic field is calculated. According to the approximate theory at highfrequency, the equivalent electromagnetic currents on the dielectric surface are derived, which can beapplied in stratified anisotropic and isotropic media cases. Then the RCS of PEC targets coated withstratified common media is calculated.(3) A heuristic corrected truncated-wedge incremental length diffraction coefficients (TW-ILDCs)method is proposed and the diffracted fields of wedges coated with stratified media are computed,which improve the precision of the physical optics to a certain extent.(4) The effects of the count number of the coating media, the coating depth, the frequency of incidentwaves and the angle of the incidence to the RCS are discussed.