W4ZV wrote:
My guess is that signals propagate normally
>toward the perpetual greyline area, are refracted along the boundary of
>south polar sunlight, and then follow a normal path back to the other
>end. There is no way we can really tell but to me this could explain the
>consistency of the signal directions when their Great Circle directions
>are so different.
I also have a "gut feeling" this explanation is correct much of the time.
I have observed only relatively few 160 m LP openings, so it's hard to
generalize there, but I have many hundreds of QSO's on 80 m LP from my QTH
in MA. During our fall and winter season, around sunrise the path is SW
and at sunset it's SE, independent of where the long haul DX signals
originate. I can't determine really precise headings as I am using
Beverages oriented every 45 degrees.
The one notable exception is the path to VK6 at sunset which is, by far,
the most common LP opening here. On 160 I have observed perhaps a dozen LP
openings there and it has always been NE to E--never SE. The same trend
holds on 80 except around the equinoxes when it sometimes becomes SE.
During our summertime the 80 m LP is less common but when it occurs, it is
skewed and the direction is NE. The path to VK6 at those times peaks at
VK6 sunrise which is an hour or more BEFORE my sunset and it's always NE.
One mid-summer opening to YB was also NE. I've mentioned previously the
Singapore BC beacon on 3915 kHz--it comes in throughout the summer before
sunset from the NE. What is consistent here is the fact that the
summertime terminator around those times runs in a northeasterly direction
over northern Europe and the signals seem to roughly follow the grey-line.
I've never seen 160 m LP in the summer since these openings seem to peak
well before darkness here.
Bottom line--be prepared to work them from whatever the direction is!
73, John W1FV
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