Topband: Propagation Between MN and Germany

[Clive GM3POI]

Ford Peterson Said:
"I have speculated that the transition point from oval to non-oval is
critical--experiencing substantial attenuation.  Perhaps it is an acute
refraction as the signal passes from one media to another, rather than
"attenuation."  Signals passing 'under the umbrella' experience a different
mode of propagation.  What is this "mode?"  What is the physical mechanism?
BTW.  After thousands of topband Qs during many contests over the recent
years, I have yet to work Alaska and only one JA.  Why doesn't this magic
"under the oval" mode work for these areas?"

One of my more interesting Qs over the years was working AL7BL on a day that
registered an A
index of 41. AL7BL was at Prudhoe Bay on the North coast, and since then I
have concluded that the method was via a form of MF Auroral Es. Having
worked a few OH8/9 on 144mhz with T9 Auroral E signals I don't see why it
can't happen at 1.8mhz. 73 Clive GM3POI (58.9 Deg N)