A general bianaisotropic metasurface represented by a generalized sheet transition condition is modeled by the finite-difference time-domain (FDTD) method. The dispersive susceptibilities of the metasurface are approximated by FDTD-compatible rational functions which are incorporated in the update equations by the piecewise linear recursive convolution technique. Compared to the existing methods, the proposed technique requires less arithmetic operations. The method is verified by comparing the results with those of the finite-difference frequency-domain method through simulation of wave propagation in five test cases: generalized refraction metasurface, polarization rotator, Bessel beam generator, orbital angular momentum multiplexer, and reflectionless omega-type metasurface.
