Drop shape and size distributions in rain from 2-D video disdrometer and propagation calculations at 20 GHz

Drop shapes derived from the 2-dimensional video disdrometer are presented in terms of probability contours. They show good agreement with the Beard-Chuang model for equivalent diameters up to 6 mm. A fitted equation is used for T-matrix calculations to derive the specific attenuation for horizontal and vertical polarizations at 20 GHz. When compared with the calculations using approximated oblate spheroids, good agreement is obtained for most cases. However, unusual drop size distributions (DSDs) with large median volume diameter can give rise to some differences and for such cases, the fitted equation would need to be used. Also evaluated is the impact on cross-polar discrimination versus co-polar attenuation variation. For the earth-space scenario considered here, no significant difference is observed between the calculations using the contoured shapes and their oblate spheroid approximations. Both show good agreement with 1-year of beacon measurements at 19.7 GHz.