Topband: Long Path

[Bill Tippett]

W8JI:

>For example, a few weeks ago ZL3REX was skewed NW (normal is 
>definitely SW) and it was two hours before daylight here. 
>Occasionally VK3ZL and the others move from SW to NW, or vice 
>versa. On much rarer occasions, the JA's skew SW to W. The XZ's 
>were readable SE in the evening and SW in the mornings, etc.
>
>When I look at the greyline, it more often than not has nothing to 
>do with the direction of the skew path.

        Skew caused by geomagnetic disturbances (K>3-4) and the SSW/SSE long
path are two completely different phenomena IMHO.  Geomagnetic skew is usually
away from auroral zones (South for Northern Hemisphere stations and North
for Southern Hemisphere stations) and this can occur at any time of the
day.  These are the cases where EU is skewed South, JA is skewed South,
VK/ZL is skewed North, etc.  I've seen skew approach 90 degrees when the
A-index was 103 (equivalent to K 6-7) and cited the following case in my 1991
article...SM6CPY was skewed from a true bearing of 27 degrees (Colorado to
SM) and peaked on my 110 degree Beverage.  Carl also noted my signal was skewed
South and coming from the direction of South America from his side (WSW from
Sweden).

        This is not the same thing as the SSW/SSE long path which only
occurs near sunrise/sunset, most commonly between stations in the Northern
Hemisphere whose reciprocal Great Circle azimuths are 30 to 330 degrees (the
exceptions being VK6 at East Coast sunset and the Indian Ocean at West Coast
sunrise).  

        In my article I noted the following countries worked via 80 meter
sunrise long path from Colorado...note how the bearings generally fall into
the above range (~30 to 330):

True bearings from W0ZV for QSO's made via sunrise long path at 210 degrees
with exceptions noted in parentheses:

040-049:  3B8, 3B9, FR (these 3 only were best at 250 degrees)
030-039:  ER, HA, OZ
020-029:  4K, 4L, A6, A7, A9, EK, ES, EW, HZ, LA, LY, OH, OH0, SM, UA2, UR, YL
010-019:  A4, EP, EZ, UA3
000-009:  8Q, AP, EX, EY, UA9, UK, UN, VQ9, VU7
350-359:  4S, 9N, VU2 
340-349:  JT 
330-339:  BY, HS, UA0, VU4, XW 
320-329:  3W, VR2, XU
150-159:  FT8X (best at 315 degrees)

        I also have data from W4DR for many 80 meter contacts he made via
the SSE sunset long path but I'm not going to wade through all those now.
With the exception of VK6, they range from JA to VU4 (~330 to 15 degrees
true bearing) following the same pattern cited above (330 to 30 degrees).  

        Unfortunately data for 160 long path is lacking due to it being much
more uncommon but it generally follows the same patterns we've seen on 80
since it was first reported there over 30 years ago.  I've seen a picture
of W1BB with a VS1LP (now 9V1) card above his radio and I suspect that QSO
could have been long path although from W1 it could also have been skew
path over Europe.  At my sunset I've worked 9V1XQ via 150 degrees and 9M2AX 
via 40 degrees even though they are essentially the same QTH...a perfect 
example of two completely different mechanisms at work.

                                                73,  Bill  W4ZV


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