Reducing cellular interference in the Karoo Radio-Astronomy Reserve

This paper describes some of the developments and activities that have been undertaken to significantly reduce the extent of cellular interference in South-Africa´s Karoo Radio-Astronomy Reserve. The main contribution is a new omnidirectional base-station antenna with a single deep null in its radiation pattern. Such an antenna can significantly suppress the interference from a cellular base station along a specified direction, while still retaining much of the coverage in other directions around the base station. The use of femtocells over VSAT links has also been investigated as an alternative way to provide cellular services where coverage will be lost to solve interference issues.