New dispersion characteristics and surface-wave suppression in double-negative metamaterial grounded slabs

In this work, the modal properties of a double-negative (DNG) metamaterial layer on a ground plane are extensively investigated. As is well known, such structure may support both ordinary waves (transversely attenuating only in air) and evanescent waves (transversely attenuating also inside the slab). On the basis of a simple graphical analysis of the dispersion equation for TE and TM ordinary and evanescent modes, fundamental conditions are presented which ensure the suppression of a guided-wave regime for both polarizations. Numerical simulations based on an experimentally-tested dispersion model for the permittivity and permeability of the considered DNG medium are reported, which confirm the existence of frequency ranges of surface-wave suppression as predicted by the theoretical analysis.