<< True grey line radio wave propagation rarely occurs on 160 meters and true long path propagation even less. When it does the opening is usually only a few minutes long. Instead it's usually a skewed path that includes RF signal ducting in the E Valley/F layer propagation region. >>>>
I'm afraid I disagree 100% long path or SSE/SSW is very common on 160m and almost daily on 80m. Some years long path are more intense, like 2010 I heard and worked XU7ACY on 160 50 days between October and March, 2014 I worked DU7ET every month from October to June! When long path is open it stays open for one or two weeks every day, both station should be inside gray zone and the peak is normally 30 minutes before sunrise and after sunset , when there is more darkness the peak in the middle of the darkness period, like W4ZV mentioned several times on his papers. 80m and 40m the long path SSE SSW is almost every day near SS or SR during DX season. I had a web page on the interweb for 20 years concerning MF radio wave propagation (300-3000 kHz). >>> Antenna polarization plays a large role in the success of a long haul DX contact. As a medium frequency RF signal traverses our planets magnetic lines of force in a perpendicular manner on high and mid latitude paths say between W3 land and SM, higher angle horizontally polarized signals are more readily absorbed then lower angle vertically polarized signals. On other paths on the globe opposite results can be found, i.e. horizontally polarized signals suffer less absorption on a propagation path between VK6 and W4. << again absolutely disagree, Long path on 160. 80 and 40m are mainly horizontal polarized, I see that every day here in Florida using my horizontal WF and comparing with my Vertical WF. It is observed and documented in a daily base since 2009 when I started to use horizontal polarization on 160m. A/B test is a fact not a proposed explanation of ionosphere behavior. 73's N4IS JC _________________ Topband Reflector Archives - http://www.contesting.com/_topband