Due to the oblong spheroidal shape of the earth, there exists a curvature between two points, in this case between Delhi and Patna. As electromagnetic radiation propagates rectilinearly, it will be hindered by the Earth due to its curvature while travelling directly between stations. To counter this, we use a satellite positioned such that the transmission occurs in straight lines through it. In this way there is no obstruction present in the path of the signal and it is easily transported between two places.