bpnjensen wrote:

(bpnjensen) wrote in message . com...

*The Question*: Am I wrong? Is it possible, or even common, for a
transmitted signal to travel to a receiver via some route other than a
Great Circle route? Is it possible for skip to veer around corners?
People talk about and use Gray Line conditions to their advantage, but
even *that* is a straight line / Great Circle pathway when one
exmaines what is happening - are there others that weave along warped
ways?

Thanks -
Bruce Jensen

As suggested or implied by both of the other posters here -

I looked up issues related to this on the internet, starting with a
Google search for skewed propagation.

After looking over some fascinating information, I think that the
answer to this question is, YES, 'skewing' of signals does occur due
to varying degrees of geomagnetic activity near the poles and,
especially, the locations and degrees of its gradient. At points of
high gradient, and usually well away from the most absorptive regions
where radio signal fear to tread, radio waves can actually take rather
sharp corners from standard great circle (GC) routes, and go from one
GC to another. These are most easily noted by amateur radio
operaters, who can keep careful track of the bearings of their antenna
arrays and the bearings fo their contacts. A careful and
well-informed SWL could do as much, although as most of probably use
nondirectional wires, or wires of unknown direction, it is probably
far less likely.

And, NO, grayline propagation *alone* does not follow warped or skewed
routes, following the clearly-defined GC grayline - but like any other
propagation, can be susceptible to skewing by the geomagnetic
gradient.

Yes, it does, you are very much wrong. It's incredibly easy to see, just by looking at a grey line map.

But heck, believe what you wanna believe!

I remain, and always will be,

dxAce
Michigan
USA

dxAce wrote in message ...
bpnjensen wrote:

(bpnjensen) wrote in message . com...

*The Question*: Am I wrong? Is it possible, or even common, for a
transmitted signal to travel to a receiver via some route other than a
Great Circle route? Is it possible for skip to veer around corners?
People talk about and use Gray Line conditions to their advantage, but
even *that* is a straight line / Great Circle pathway when one
exmaines what is happening - are there others that weave along warped
ways?

Thanks -
Bruce Jensen

As suggested or implied by both of the other posters here -

I looked up issues related to this on the internet, starting with a
Google search for skewed propagation.

After looking over some fascinating information, I think that the
answer to this question is, YES, 'skewing' of signals does occur due
to varying degrees of geomagnetic activity near the poles and,
especially, the locations and degrees of its gradient. At points of
high gradient, and usually well away from the most absorptive regions
where radio signal fear to tread, radio waves can actually take rather
sharp corners from standard great circle (GC) routes, and go from one
GC to another. These are most easily noted by amateur radio
operaters, who can keep careful track of the bearings of their antenna
arrays and the bearings fo their contacts. A careful and
well-informed SWL could do as much, although as most of probably use
nondirectional wires, or wires of unknown direction, it is probably
far less likely.

And, NO, grayline propagation *alone* does not follow warped or skewed
routes, following the clearly-defined GC grayline - but like any other
propagation, can be susceptible to skewing by the geomagnetic
gradient.

Yes, it does, you are very much wrong. It's incredibly easy to see, just by looking at a grey line map.

But heck, believe what you wanna believe!

I remain, and always will be,

dxAce
Michigan
USA

Again, you are relying on a "flat" map that cannot possibly give an
accurate representation of a "spherical" earth. Plotted on a
spherical globe, an accurate model of the planet, the grayline is
unmistakably circular around the globe, and traces a straight line
across the earth's surface through the antipode.

That goofy Mercator's-projection map you've been looking at all these
years has got you flummoxed. You need to read up on maps and what
they do the shape of things plotted on them.

Believing in things that can be proven and demonstrated scientifically
- everything else is theory,

Bruce Jensen,
semi-pro meteorologist,
amateur astronomer,
amateur geographer

bpnjensen wrote:

(bpnjensen) wrote in message . com...

*The Question*: Am I wrong? Is it possible, or even common, for a
transmitted signal to travel to a receiver via some route other than a
Great Circle route? Is it possible for skip to veer around corners?
People talk about and use Gray Line conditions to their advantage, but
even *that* is a straight line / Great Circle pathway when one
exmaines what is happening - are there others that weave along warped
ways?

Thanks -
Bruce Jensen

As suggested or implied by both of the other posters here -

I looked up issues related to this on the internet, starting with a
Google search for skewed propagation.

After looking over some fascinating information, I think that the
answer to this question is, YES, 'skewing' of signals does occur due
to varying degrees of geomagnetic activity near the poles and,
especially, the locations and degrees of its gradient. At points of
high gradient, and usually well away from the most absorptive regions
where radio signal fear to tread, radio waves can actually take rather
sharp corners from standard great circle (GC) routes, and go from one
GC to another. These are most easily noted by amateur radio
operaters, who can keep careful track of the bearings of their antenna
arrays and the bearings fo their contacts. A careful and
well-informed SWL could do as much, although as most of probably use
nondirectional wires, or wires of unknown direction, it is probably
far less likely.

Regardless of how some SWL's antennas are aligned, the physics of wave propagation dictate how the signal will
arrive, not the antenna position. But... if one has an antenna, or antennas to position properly, they will be
able to take greater advantage of the direction the signal is coming from, thereby getting better reception.

Now go ponder that grey line map again.

I know you'll get it yet! It's actually very simple.

dxAce
Michigan
USA

dxAce wrote in message ...

Regardless of how some SWL's antennas are aligned, the physics of wave propagation dictate how the signal will
arrive, not the antenna position. But... if one has an antenna, or antennas to position properly, they will be
able to take greater advantage of the direction the signal is coming from, thereby getting better reception.

Now go ponder that grey line map again.

I know you'll get it yet! It's actually very simple.

dxAce
Michigan
USA

Here are some websites that not only describe some things about
grayline propagation, but also clearly show it's true shape and why a
flat map will portray a grayline differently than its true shape
(which is, in actual fact, a great circle with an approximately
85-minute-wide width along the sunrise/sunset terminator).

http://www.iri.tudelft.nl/~geurink/grayline.htm
http://www.kc4cop.bizland.com/propagation_gray_line.htm
http://www.cpcug.org/user/wfeidt/Misc/n4kgprop.html

There are numerous websites also that but discuss how, through
geomagnetic-solar-induced electron gradients, radio propagation may be
diverted from its normal great-circle path onto *another* and
different great circle pathway - and how, if one is lucky, one of
those great circle paths may a grayline terminator that will deliver a
wondrous DX signal to your ears.

Some other websites even go on to say that, unless you are
running/listening to CW or high-powered SSB, these diversions are not
always likely to yield good results, because much is still lost when
the RRF shifts pathways.

Radio waves, like light waves (which they really are), do not just
bounce around as they like depending upon random events and
conditions. They travel in straight lines, and are affected (under
earthbound conditions) only by reflective and refractive factors -
ionospheric skip keeps them near the earth, and geomagnetic electronic
gradients can veer them. Absent the latter, within a very narrow
bound, those signals will assume a great circle pathway -

Which brings us to the tentative conclusion that DxAce's most common
and likely reception pathway for Diego Garcia is a great circle route,
and a trace of that route is going to give you, for practical
purposes, a pathway that closely approaches the north or south
geomagnetic pole. If it sounds watery one day and not so watery the
next, it is because the interaction between the solar flux and the
earth's geomagnetic field varies from day to day - providing, perhaps,
modest skewing or rippling of the signal.

Based on examining a number of pretty well-documented websites, and on
what I know from astronomy and geophysics, I have few doubts about
this description, which is admittedly general as it is.

I would suggest that anyone who is unfamilar with maps and
projections, and the distortions they introduce into plots of
spherically-coordinated surfaces and lines, should look at some
websites on maps. It is fascinating how maps and their various
projections can be used to show specific points, while at the same
time totally distorting others.

Try Google searches for "map projection(s)" and for "skewed" or
"grayline" + "propagation" as well.