Friends in Top Band Land,
In my original posting on 3/20in response to that of Jeff, K1ZM, I made
mention of signal ducting in the electron density valley above the
night-time E-region. And in discussing how signals got out of the duct, I
noted that ionospheric tilts would play a role.
Tilts are well-known but not in the literature readily available to most
amateurs. There is one exception, the book
The Ionosphere: Communications, Surveillance and Direction Finding
by Leo F. McNamara, Krieger Publishing, 1991.
That book was the basis for a later, smaller volume by McNamara
Radio Amaterus Guide to the Ionosphere
The discussion of ionospheric tilts is in the first book, in connection
with direction finding.
Not only did I fail to mention that reference but also one more recent and
relevant:
How the Ionosphere REALLY Works by Eric P. Nichols, KL7AJ.
QEX, March/April. p. 37-40, 1998.
In that article, Nichols not only gives "a catalog of aberrant behaviours"
of the ionosphere but goes on to mention the matter of ionospheric tilts,
the order of 35-40 degrees over certain regions. Additional details are
not given but his e-mail address is there:
enichols@gci.com
so I presume he would be responsive to any inquiries. I might add that
his affiliation was with the HIPAS Observatory in Alaska.
Again, my apologies for the oversight. Maybe this will help you understand
my remarks better.
73,
Bob, NM7M
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