Modal interactions in resonant metamaterial slabs with losses

Modal phenomena in planar metamaterial structures modeled by simple scalar frequency-dependent constitutive parameters are investigated. Modal interactions and modal transformations are found in frequency ranges close to the medium resonances when material losses are introduced and their level is continuously varied through certain critical values. Numerical results for TE and TM modes of a grounded metamaterial slab are reported in the form of dispersion curves and pole loci in the complex wavenumber plane for both surface- and leaky-wave propagation regimes. Useful insights into the reported results are provided through the identification of the branch-point singularities in the complex frequency plane that govern the modal interactions.