Topband: 160m daylight path?

[Dan Robbins]

VE7VV wrote:

"Actually, these topside E layer reflections are just what is needed for
E to F layer ducting propagation with very low loss (since there is no
passing thru the
absorptive D layer)."

While I agree such a proposed path would not suffer D layer absorption,
it would still suffer E layer absorption.  The strong daytime E layer is
a great absorber of 160 m signals.  It makes no difference if the ray
impinges from the top or bottom, the net result is absorption.  If E-F
ducting were present in daylight, it would be possible for a midwest
station at his sunrise to work stations in Eastern Europe at their
sunset right over the top of the East Coast.

The most likely explanation for LARGE angle skew paths is sidescatter or
backscatter off of the surface of the earth.  I have heard 90 degree
skew paths simultaneously on 160,80 and 40. Typically we only hear this
when the regular path is shut down from auroral activity or daylight and
the band is at low noise levels such as those around dawn/dusk.

Here is one example of a skew path where we were able to follow the path
part way:

KL7U and I were hearing a TR8 on 75 meters one evening.  He was loudest
on my SE sloper and KL7U's 2 el beam showed ESE right over California.
This is 90 off of the true path.  W6RJ heard us yelling at the TR8 but
even with his large beam he could not hear him when beaming Africa.  But
when he swung his beam to the ESE, he was able to hear and work the
TR8.  Since both W6 and KL7 were beaming the same direction, we both saw
a common reflection point.  Whether it was over Central America, South
America or the Atlantic, no one knows for sure, but we were at least
able to show a straight leg propagation path part of the way.  Since we
were also hearing South America on a true heading at this time, it was
likely that the skew bender was past that in the South Atlantic.
Furthermore, the reflection point was far removed from the auroral
zones.

Backscatter and sidescatter from the earth's surface happen constantly.
While proposing exotic ionospheric solutions to skew paths is more fun,
bouncing off Mother Earth is well-grounded.

                                                    Dan KL7Y



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