EQUATORIAL PROPAGATION AND THE OCCURRENCE OF SPREAD F.

It is found that the appearance of irregularities in the ionosphere near the geomagnetic equator has a direct effect on communication paths that traverse these regions. The irregularities which manifest themselves as spread F on ionograms and as scintillation in satellite signal recordings affect VHF transequatorial propagation, normal ionospheric HF propagation and ground to satellite links. Some studies are reported of the morphology of spread F and its variation with time, season, solar cycle and latitude, made for the Australasian equatorial region. Suggestions are made for using these data for the improvement of communications on equatorial circuits.