A Single-Hop F2 Propagation Model for Frequencies Above 30 MHz and Path Distances Greater than 4000 km

Standard textbook explanations of ionosphere propagation suggest that 30 MHz and 4000 km are limiting frequencies and distances for single-hop communications. During the peak of sunspot cycle 22, however, there have been hundreds of reports of F2 communications exceeding great circle distances of 4200 km at 50 MHz. We show that parabolic F2 ionospheric models explain this propagation irregularity. Textbooks and reference books fail to show that such long distances at VHF are possible. As low earth orbit satellite and meteor burst systems proliferate, models which account for sunspot peaks will be needed.