The attenuation of millimeter-wave signals in a sand and dust storm (SDS) can be used to retrieve SDS parameters. A parabolic wave equation method is proposed to simulate millimeter-wave propagation in an SDS, including the effects of absorption and Rayleigh scattering by dust particles with given height profiles of particle-size distribution and total number density. Three different aperture fields of the transmitting antenna are also chosen to simulate wave attenuation under different sets of SDS parameters.