Reduction of scattering cross section of dielectric cylinder by metallic core loading

The criteria for minimization of the total scattering cross section of a metal-core-loaded dielectric circular cylinder for parallel polarization are discussed. The rigorous expression for the scattered field in terms of cylindrical harmonics is expressed in forms suitable for computer or hand calculation. The phenomena by which a reduction in cross section is obtained are interpreted as resonances for which exact conditions are given. It is shown that when the diameter is less than half the wavelength in the dielectric, the condition that minimizes the cross section is the cancellation of the monopole term in the harmonic series expansion. For larger diameters, the optimum condition corresponds to a compromise between cancellation of the first term and higher-order terms. Design curves are provided over the pertinent range of parameters.