Calculations of cross-polar discrimination spread for 20 GHz fixed satellite systems using rain microstructure information

摘要

Individual drop images in natural rain from a two-dimensional video disdrometer (2DVD) have been processed to obtain their shapes, sizes, and orientation angles, which, in turn, have been used to derive their complex forward scattering amplitudes at 19.701 GHz. Using these calculations, the specific attenuation for horizontal and vertical polarizations and the specific differential attenuation and the specific differential phase of all drops over 1 min are determined. A point-to-path scaling is used to derive the total rain attenuation for both polarizations as well as the total differential attenuation and the total differential phase. A 19.701 GHz experimental Earth-space link is simulated to determine the variation of cross-polar discrimination versus copolar attenuation (XPD-CPA) and the calculations are compared with 2 years of joint probability XPD-CPA beacon measurements. The comparisons indicate clearly that the variations in drop shape and drop orientation can give rise to significant spread in XPD.