Realistic modeling of electromagnetic wave propagation in the radar
frequency band requires a full solution of Maxwell's equations as
well as a complete description of the material properties. We present
a two-dimensional (2-D) flnite-difference time-domain solution of
Maxwell's equations that allows to account for the frequency dependence
of the dielectric permittivity and electrical conductivity typical
of many near-surface materials. In close analogy with the viscoacoustic
case, the governing equations are obtained by assuming dielectric
and conducting relaxation functions. The finite-difference solution
is second-order accurate in time and fourth-order accurate in space,
conditionally stable, and computationally only marginally more expensive
than its standard equivalent without frequency-dependent material
properties. The algorithm is applied to a realistic problem illustrating
the respective damping effects of conductivity and frequency-dependent
dielectricity.