Closed-form harmonic contrast control with surface impedance coatings for conductive objects

The problem of suppressing the scattering from conductive objects is addressed in terms of harmonic contrast reduction. A unique compact closed-form solution for a surface impedance (,  ) is found in a straightforward manner and without any approximation as a function of the harmonic index (scattering mode to suppress) and of the frequency regime (product of wavenumber and radius of the cloaked system) at any frequency regime. In the quasi-static limit, mantle cloaking is obtained as a particular case for ≪1 and =0. In addition, beyond the quasi-static regime, impedance coatings for a selected dominant harmonic wave can be designed with proper dispersive behavior, resulting in improved reduction levels and harmonic filtering capability.