  This paper investigates the propagation characteristics of circular
waveguides whose interior surface is coated with a thin metamaterial liner
possessing dispersive, negative, and near-zero permittivity. A field analysis
of this system produces the dispersion of complex modes, and reveals in detail
intriguing phenomena such as backward-wave propagation below the unlined
waveguide's fundamental-mode cutoff, resonant tunneling of power, field
collimation, and miniaturization. It is shown how the waveguide geometry and
metamaterial parameters may be selected to engineer the lined waveguide's
spectral response. Theoretical dispersion and transmission results are closely
validated by full-wave simulations.
