Resistive and conductive tube boundary condition models for material wire-shaped scatterers

An equivalent boundary condition model is introduced for computing the scattering by material wire-shaped scatterers which are either dielectric or magnetic, but not both simultaneously. While the methodology for numerically computing the scattering by perfectly conducting thin-wire scatterers has been developed for decades, no simple model for material scatterers with large length-to-radius ratios (wire shapes) has been available. This new model can be easily integrated into existing thin-wire computer codes while adding virtually no computational burden. Validating results are shown using comparisons of the full-wave scattering from a number of thin wire-shaped dielectric and magnetic structures with this new equivalent boundary condition model. It is demonstrated that this model is, in essence, an extension of the internal impedance expression for a conducting wire (developed over 50 years ago) to simple-material wire-shaped scatterers possessing a very wide range of material parameters.