I am only presenting the possibility that if the ionosphere (where 160
propagation happens) isn't uniformly smooth and instead consists of "warps,
wrinkles and tilts" that in a *dynamic ionosphere*, this could be at least
one reason we are experiencing slow fades.
Elliptical polarization, assuming that it is ever changing, could provide
yet another degree of selective fading.
I'm don't think I *totally* understand why KL7AJ says that "at HF the
ionosphere forbids the propagation of linearly polarized signals". If at
the magnetic equator, and signals were East to West to equal the earth
magnetic tilt of the signals, it seems that at an instance in time that a
linear polarized signal could happen. But that may be nit picking.
Jim - KR9U
From: JC N4IS [mailto:firstname.lastname@example.org]
Sent: Wednesday, February 05, 2014 10:45 PM
To: email@example.com; 'Tom W8JI'; firstname.lastname@example.org;
Subject: RE: Topband: circular polarization on 160m
You brought a good article about HF propagation, however the behavor on 160m
is different from HF. If you check on the KL7A arcticle figure 1 what is
happening between 1 and 2 MHz you can see that the green and red does not
behaivor the same way as above 2 MHz.
This subject is more complex because there us no shirt answer, actualy
between 1 and 2 MHz. the ionosphere does not support linear polariration
wave. The wave are actualy eliptical and not circular for most directions.
You can check the long answer on the "must read book" from NM7M . R Brown
'The Big Gun's Guied to Low Band Propagation" . Magneto-iomic Theory pag 47
to 56 ; and Power coupling pag 57.
Thanks to Karl. K9LA, the book is available on his also must read site on
the 160m link
Topband Reflector Archives - http://www.contesting.com/_topband