The aim of this report is to enable persons having no previous experience of the subject to make reasonably accurate estimates of the service areas of medium- and long-wave broadcasting stations, taking account of the vertical and horizontal directivity of the transmitting installation, its radiation efficiency, and the influence of the ground constants and of interference from other transmitters. It is not intended that the simplified skywave field strength prediction curves in this report be used for international planning; for this the appropriate internationally agreed methods must be used.