Estimation of Rain Attenuation of Earth-to-Satellite Link over Nepal for Ku & Ka Bands

Abstract

Due to the extensive use of lower frequency bands & huge demand of large bandwidth in satellite communications, engineers need to use the higher frequency bands such as Ku to Ka bands. However, the rain attenuation is severe in these bands. Before installing an earth station, the estimation of the rain attenuation is a prerequisite task to know the required fade margin to ensure a certain availability of the network. In this paper, we estimate the rain attenuation for different regions of Nepal. The R-H and ITU models are used for rain rate and rain attenuation estimation, respectively. A significant temporal and spatial variation in rain attenuation is observed. Among three different regions of Nepal, namely Terai, Hilly, and Himalaya, while the maximum rain attenuation is found in Terai region, the minimum is in Himalaya. Jhapa of the Terai region experiences the highest attenuation and requires 80 dB and 24 dB fade margin for Ka and Ku bands, respectively. Solukhumbu of Himalaya region, on the other hand, is found to be the least rain attenuation affected site. The required fade margin for an earth station site in Solukhumbu for using Ku and Ka bands are 12 dB and 40 dB, respectively. The minimum attenuation, which is observed in November and December, is several times lower compared to the highest rain attenuation, observed in July. The minimum attenuation caused by the Ka band is higher than the maximum attenuation caused by the Ku band irrespective of the locations of the earth station sites.