Scattering of electromagnetic waves from arbitrary shaped bodies coated with a chiral material

Abstract

Chiral coatings have been advocated in the past for management and reduction of radar cross section of a variety of scattering objects. The theoretical analysis of the scattering from chirally coated bodies is complicated due to the fact that the left and right circularly polarized waves propagate in the chiral layer with different propagation constants. In this paper, a generalized EBCM or the T-matrix method has been used to analyse the scattering from chirally coated scatterers. The scattering characteristics, viz., absorption, extinction, radar and scattering cross sections have been computed for both RAM-type chiral polymers and realistic chiral materials. The results have been presented for various size parameters, angles of incidence, coating thickness and for various volume concentrations of embedded metal helices. From the results it can be seen the normalized radar cross section of a chirally coated spheroid is 10-15 dB lower than the conducting spheroid over wider ranges of angles of incidence. This performance is also superior in comparison with the conventional RAMs. This reduction in the RCS has been shown to be due to increased absorption and reduced scattering cross section.