  A rigorous full-wave modal analysis based on the method of moments in the
spectral domain is presented for line waveguides constituted by two-part
impedance planes with arbitrary anisotropic surface impedances. An integral
equation is formulated by introducing an auxiliary current sheet on one of the
two half planes and extending the impedance boundary condition of the
complementary half plane to hold on the entire plane. The equation is then
discretized with the method of moments in the spectral domain, by employing
exponentially weighted Laguerre polynomials as entire-domain basis functions
and performing a Galerkin testing. Numerical results for both bound and leaky
line waves are presented and validated against independent results, obtained
for isotropic surface impedances with the analytical Sommerfeld-Maliuzhinets
method and for the general anisotropic case with a commercial electromagnetic
simulator. The proposed approach is computationally efficient, can accommodate
the presence of spatial dispersion, and offers physical insight into the modal
propagation regimes.
