Electromagnetic Wave Scattering from Cylindrical Structure with Mixed-Impedance Boundary Conditions

Recently, a new boundary condition is introduced in which surface shows different impedances for TE and TM electromagnetic fields. This new boundary condition is called mixed-impedance (MI) boundary condition and can be expressed in terms of normal components of electromagnetic fields. In this paper, the cylindrical structures with MI boundary condition were investigated and the scattering of such structures was obtained for both normal and oblique incidence and both TEZ and TMZ polarizations. The interesting feature of MI boundary condition was that the boundary conditions of PEC, PMC, DB, D'B', and isotropic impedance boundaries were special cases of the MI boundary. Therefore, by calculating the electromagnetic scattering from a MI boundary, scattering from various boundary conditions could be easily obtained. It was also demonstrated that, by proper choice of boundary conditions the forward or backward RCS (radar cross section) could be significantly increased or decreased.