Calculation of Wave Attenuation in Sand and Dust Storms by the FDTD and Turning Bands Methods at 10–100 GHz

The finite-difference time-domain method and the turning bands method are used to calculate the wave attenuation in sand and dust storms at the frequencies of 10-100 GHz. The digitized models, with a random process using the turning bands method, are simulated for sand and dust particles. The proposed formula shows that wave attenuation in sand and dust storms depends on the visibility, frequency, sand and dust particle radius, and on complex relative permittivity. Obtained results of the wave attenuation are also compared with those obtained by four other methods: the effective material property technique, the Rayleigh scattering approximation, the measured probability density function and Mie scattering theory, and the volumetric integration of Mie scattering results by individual particles. It is found that our formula produces a mean value of wave attenuation among these five formulas. It is confirmed that the wave attenuation is negligible except for frequencies above 30 GHz and for very severe storms with visibility less than 0.02 km. It is also found that the particle size distribution function and equivalent particle radius are two major factors which will affect the wave attenuation in sand and dust storms.