Modal propagation and interaction in the smooth transition from a metal mushroom structure to a bed-of-nails-type wire medium

Abstract

Natural propagation modes of a metamaterial mushroom structure are studied as the patch material transitions from being a perfect conductor to being transparent, in which case the structure becomes a bed-of-nails medium. It is shown that the modes of the perfectly conducting structure smoothly continue to those of the bed-of-nails structure in the complex wavenumber plane, except for some modal interaction regions and degeneracy points associated with complex-frequency branch points migrating across the real frequency axis. © 2012 American Institute of Physics.