Survey of the Gibraltar¿United Kingdom ionospheric scatter measurements

The paper describes the origin of the Gibraltar¿United Kingdom circuit working on forward scatter in the ionosphere. Aerial input powers up to 40kW have been used and observations made on frequencies in the range 37 to 70Mc/s and at distances in excess of 1100 miles. The scope of the work undertaken by various interested organizations is outlined and the main conclusions are given in relation to the claims that have been made for this mode of transmission by the pioneer workers in the United States. Special reference is made to the serious interference problems arising from the reception of signals from other stations and noise sources by reflection from sporadic-E ionization, particularly in lower latitudes. Similar troubles, including the effect of back scatter and round-the-world echoes, have been met owing to normal F-layer reflection as the sunspot cycle has progressed from a minimum to a very high maximum of activity.