Shielding and scattering analysis of lossy cylindrical shells using an extended multifilament current approach

An investigation of the multifilament current method's (MFCM) ability to solve electromagnetic scattering and/or absorption problems involving inhomogeneous cylindrical structures is presented. Dielectric cylinders of arbitrary cross section covered by multiple layers of lossy dielectrics are considered. Both cases of wave incidence, TM and TE, are treated. Like some other moment-method solutions, the MFCM experiences numerical difficulties when dealing with a medium characterized by a high loss tangent or large electrical conductivity. To overcome this problem, a new boundary condition based on an impedance matrix equivalent circuit approach that accounts for the curvature of the surfaces has been developed. This new impedance matrix boundary condition (IMBC) extends the MFCM capability to the analysis of two-dimensional (2-D) structures involving conducting layers with ohmic losses. The usefulness of this extended method is confirmed by the study of metallic shells for which a strong energy coupling with the incident electromagnetic (EM) field is demonstrated at their structural resonance frequencies.