Range-spreading and Evening Type Trans-equatorial Propagation

Abstract

THE term trans-equatorial propagation (TEP) is used to denote the existence, on trans-equatorial circuits, of unusual communication contacts which are due to abnormal modes of propagation. The phenomenon has received considerable attention since the reports by amateur radio operators in 1947 of 50 MHz contacts over trans-equatorial circuits approximately bisected by the magnetic equator. These contacts were of interest because the frequencies used exceeded the conventional MUFs for the circuits concerned and involved unexpectedly high signal strengths. Reviews of the characteristics, occurrence and suggested propagation mechanisms for these contacts have been given by Nielson1 and by McCue and Fyfe2.