Topband: Top-band Prop along grayline

[Tom Rauch]

> K2TQ:
>  >John's post about long-path to Japan on top-band is very
interesting. It
> would seem, as John mentioned, to be very rare.

First it just depends on what you call "longpath".

"Longpath" strongly implies the path is opposite the
shortest path, or the longest possible straight path. We can
be sure that isn't the case, that it is really just a skewed
or bent path. All we know is the path is a little longer
than the direct great circle path.

Examples of a "true" longpath would be my working VK at my
sunset on an easterly path. An example of a path that is
clearly NOT longpath would be something like my QSO's with
ZL3REX or VK3ZL in the morning while beaming NW path from
here, or JT1CO in the mornings via SSW or W path. Those are
skewed short path QSO's, NOT actually longpath.


I've had many QSO's during mid-summer with JA's via W paths,
and northern Europeans via a due east path. These skewed
shortpath cases are actually much more common than a direct
shortpath, and I'll have to respectfully disagree that they
follow the terminator or greyline. They are just as common,
if not more common, into the middle of the dark area. They
are very repeatable when the path is a long distance path
that isn't due east or west by shortest route.

As Bill points out, we also don't know where that path
actually goes when it leaves the antennas at each end and
there is little likelihood we will ever find out. It might
be 200 miles before the path skews or curves, or it might be
2000 miles. We only know someplace it bends, we don't know
where.

In my opinion skewed longpath QSO's on 160, which shorten
the path considerably from true longpath, are actually
fairly common if the distances are about equal each
direction. For example I could hear XZ here almost every
evening via East path, and while WR4U was visiting he worked
them from here using my call with good signals. There are
about a half dozen other examples of DXpeditions that I hear
both at sunset and sunrise, but unfortunately most are
temporary operations in needed countries in a very noisy
location where they don't hear me well and once they are
worked shortpath or skewed shortpath it makes no sense to
hammer at them just to do it. Some of the VK9's are
examples.

The only thing  we can say for certain is the paths are
through a dark area, and they are not as short as short
direct path and almost certainly
not nearly as long as true longpath. There isn't a single
person on this reflector that actually knows what the path
is. These paths show up on stations as close as 4000 miles
to me, but are more common as the path is longer. They
almost always occur when the direct path goes near the
magnetic poles, or when we are having severe solar
disturbances.

All this gives people something to speculate about. That's a
good thing as long as we remember most longpath claims are
not actually longpath, but some distance from slightly
longer than shortpath to not as long as true longpath. It is
quite common here for me to hear JA's at sunrise via W or SW
path, up to 90 degrees from NW. That isn't longpath, it's
just a bent path.

73 Tom