  Simple dispersion relations for the guided modes in a grounded DNG/DPS
bilayer slab are given in terms of normalized parameters. Relations
corresponding to the grounded single-layer DNG slab are refound as specific
cases. Numerical examples are given showing dispersion curves of the lower
order modes and the respective total normalized power carried on the
propagation direction. Snapshots obtained by the finite-difference time-domain
method are provided showing the electromagnetic field inside the grounded
DNG/DPS bilayer slabs. Since an important characteristic of the guided modes in
the slab containing a DNG layer is the existence of a turning point (TP) at
which the power carried by each mode of order m>0 equals zero and changes the
sign, we present implicit relations at the TP for the normalized parameters of
the guided modes in the grounded DNG/DPS and DNG slabs. We show that a thin DPS
layer coating on the grounded DNG slab produces a shift of the TP on the
dispersion curve.
