Two-dimensional probability distribution of attenuation and depolarisation on Earth-space path

Two-dimensional probability distribution of attenuation and crosspolarisation discrimination (XPD) on Earth-space path at 19.5 GHz (circular polarisation) is derived. Moreover, the distribution is approximated by a mathematical function. The distribution is compared with the theoretical relationship between rain-induced attenuation and XPD, which is based on the deformed raindrop model. It is found that the measured attenuation and XPD values are distributed two-dimensionally in an attenuation-XPD plane, and the results cannot be explained by the theoretical relationship. This fact implies that special attention should be paid when the XPD statistics on the Earth-space path are predicted by the theoretical relationship between attenuation and XPD.