Atmospheric Effects on Short-Wave Radio Propagation

Abstract

IN a recent note¹, we showed that for oversea paths which were low and non-optical, the received radio field-strength on centimetre wave-lengths was much increased by the presence of low-level atmospheric ducts lying directly on the sea. These ducts, which trap the radiation, appear to have heights of up to about 100 ft. over the sea around the coasts of Britain. The purpose of this note is to show that, whereas such ducts have a pronounced effect on the propagation of centimetre-wave radiation for paths lying predominantly within the ducts, they have little effect on the same wave-lengths when either or both transmitting and receiving aerials are well above the top of the duct, or on metre wavelengths even for the same low paths which show pronounced duct effects on centimetre wave-lengths.