Improving The Estimation of Earth-Space Link in ITU Rain Attenuation Model

Rain attenuation is the dominant cause of signal degradation especially those operate at high frequencies. Achieving an accurate prediction for rain attenuation to certain location is quite difficult due to the inhomogeneity of the rain along the propagation path. Vertical and horizontal reduction factors are playing primary role to estimate the effective path length by reducing the mathematical path length which not penetrated in the rain. In order to predict precisely the rain attenuation for a certain location, accurate environment characteristics estimation is required because it is geographically dependent. This paper presents a new model that is able to predict the earth-space rain attenuation when the signal path is either completely or partially affected by the rain. It is based on the empirical international telecommunication union model (ITU-R). The frequency of the predicted signal has been carried out in this study is 31 GHz and the specific attenuation was evaluated using power law approximations, where the earth station assumed to be located in Kuantan, Malaysia (3.80°N, 103.32°E). The relationship between the signal path length and the attenuation is compared for different elevation angle, and it is concluded that the rain attenuation has a direct relationship with the elevation angle where it is increases as the elevation angle increase.