Scattering of Microwave and Millimeter-wave Signals in a Sand and Dust Storm

The thesis is composed of three parts. In the first part, a parabolic wave equation (PWE) method is proposed to simulate millimeter-wave propagation in an sand and dust storm (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. In the second part, a 3D SDS model is proposed, in which the total number density is height dependent and is circularly symmetric in the horizontal plane. The effects of Earth curvature and ground reflection on microwave wave traversing an SDS are studied by using the PWE method and a two-ray model. A time record of microwave attenuation is also simulated and compared with the measurement data to verify the efficacy of the proposed method. In the third part, a PWE-based radar equation is proposed to compute the backscattered power of millimeter-wave in an SDS, in which the height profiles of particle-size distribution and total number density are accounted for. The conventional radar equation is also improved by incorporating the effects of Earth curvature and beam divergence. The improvement of accuracy by using these two radar equations, especially when the specific attenuation is a function of height, is verified by simulations.