Today, 24th July 2018 at solar cycle 24 minimum the 50 MHz band defied long established propagation theories and observations when the station of Gary Ashdown VK8AW near Darwin, Northern Australia in locator square PH57 worked several stations in Europe and was heard by many more between 0700-0800 UTC. The furthest station received being G3TXF in England, locator square IO71VE at a distance of 14,118 km and -09dB signal strength!
The weak signal FT8 data mode was being used.
This is absolutely remarkable as in all previously published theory and observations 50 MHz Sporadic-E signals usually never exceed 7,000 km by multi hop, and there should be no F2 or TEP propagation, unless at solar cycle maximum, which we most definitely are not.
However it appears these remarkable distances were, after all, likely achieved by a combination of TEP and Sporadic-E.
It seems the very weak signal mode FT8 is now allowing us to transmit and receive signals and achieve distances that only solar cycle maximum previously supported and we were able to detect. The FT8 use of standardised frequencies and automatic decode with internet reporting is greatly assisting detection. This is extremely exciting for pushing the VHF boundaries of this radio hobby and our understanding of propagation.