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The August 1994 issue of Six News
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observations on skew-path DX from FM18
Dave Craig, N3DB

 

 

During the fall and winter F2 season I participated in at least three extreme skew path openings to Europe where my beam heading was between 100 & 140 degrees (direct for me is generally 30-65 degrees).  This happened on November 24th, December 30th & 31st 2001, the latter being the furthest, strongest & longest lasting with 29 EU QSOs skewed at 140 degrees.  Surprisingly, almost all of the QSOs on 31st were on SSB with OH, ES, LY & YL.  That day the path later opened direct to Eastern Europe & the Mediterranean.  The last such event thus far occurred on March 2nd 2002 when I was able to work EH8BPX on a skewed path of about 140 degrees (direct to EH8 for me is 83 degrees). 

The presence of extremely skewed paths on 50MHz F2 has been well documented and was not unexpected.  What I did find somewhat unusual, however, was that during many other F2 openings this season I could often hear and work stations with a lesser-skewed beam heading between 80 and 90 degrees.  Though the beam heading was sometimes variable even QSO to QSO, many of the stations so worked were unreadable on a direct path while at other times they were simply stronger skewed.  The path often appeared here in conjunction with direct signals from the CU3URA beacon, even when those signals were weak.

To this end, I looked for reports of this beacon from Europe, and particularly from OH, for if heard in the north country almost invariably I could log at least one or two Finnish stations via the skew path as soon as the beacon appeared here.  Based on this, and plots I made of propagation occurring at the same time to other areas in the states, I suspect that the scatter point for me is somewhere south of or in proximity to the Azores.  On this heading I often did not notice any appreciable flutter, though at other times it was pronounced.   

This skewed heading was also useful in zeroing out or at least drastically reducing high QRN that plagued me at times on the direct path.  At least one other ham I know in an adjacent grid has noticed and made use of the same quiet zone.  At these times it was relatively easy, based on signal reports, to determine when the path was a compromise heading rather than a true stand-alone scatter path.  On at least two occasions strong signals from European stations peaked for me in that direction, yet they could not hear my signals well enough to complete a QSO (even at 1.2 kW) until I turned my beam at least 15 degrees closer to direct, forcing me to see-saw between the two headings.

The 80 - 90 degree path was also useful this past summer on Es.  Unlike on F2, I think the Es scatter point is much closer to me.  After comparing reported propagation to other areas of the Eastern US from specific areas of Europe, a pattern emerged indicating to me that the Es scatter zone lies approximately 800 - 900 miles (around one Es hop) to my east.  For example, I noted that if propagation exists to central or south Florida from Italy and a path is not available to me direct, I can usually still tap into it via this scatter point, which itself is located directly along the great circle path between those areas.  Conversely, I have never been able to hear EH stations along this path when Spain to NA propagation is confined to south Florida, which makes sense because the direct EH to south W4 path crosses my beam heading some 1300-1400 miles distant, slightly beyond a normal single Es hop.  EH scatter signals may still be present, but they are too weak for me to hear them, and the distance is too great for enough energy from my signals to glance off the hotspot and make it to Spain.  In both instances I can usually hear scatter from the North American side of the opening via this path, though in the case of south Florida to EH propagation I have sometimes had to beam 10 to 20 degrees further south to do so.  Though there have been a few exceptions, I find most DX signals via Es on this path to be weak, and the DX stations I most often hear are, as one might expect, operating QRO CW.  Of note too is that the VE1SMU beacon appeared on scatter regularly over the summer along this path, and was present -either direct or scatter- during virtually every Es opening I had to Europe.            

To the south I was able to utilize another well-known F2 scatter point in the Eastern Caribbean that allows North American stations to work Central Americans situated too close to them for a single clean F2 hop.  Quite a few stations appeared on this path this fall and winter, the latest being ZF1DC and two TI stations even as I write this in mid-March 2002.  For me the azimuth usually falls somewhere between 150 and 170 degrees.  Though I have a virtually unobstructed salt-water path in this direction, I have yet to hear any workable scatter from the Central Americans on Es.  I attribute this to the fact that to reach Central America in this manner signals are required to reflect at an acute angle off a common scatter point - highly difficult on Es but relatively easy on F2.  By comparison, the Es scatter path to Europe discussed earlier is very obtuse, requiring only that the signals be refracted slightly at the scatter point.

The northern path also produced some skewed propagation on F2 this season.  Though generally worked direct, I had QSOs with two otherwise unworkable KL7s, one beaming due north and one WNW.   

Finally, I have even noted some skew path propagation on TEP.  Though I was unable to break the pileup, last April I listed to CE3SAD and another Chilean station sharing a QRG working the west coast (which I could not hear) at a sharply defined beam heading of 185 degrees - the true 175 degree azimuth to FF46 produced no signals at all.  Another such event occurred later that month when I listened to an LU work Texas stations beaming at least 10 degrees west of direct.  During an opening in February of this year I worked ZP6CW on a heading 15 degrees east of true, a path I also used during a number of openings to Brazil in 2001.  During the PY events signals sometimes peaked for me at 135 degrees, then almost abruptly shifted to the direct heading of 150 degrees or even slightly further south.

These and other experiences have taught me that significant opportunities are available on six metres via indirect paths, regardless of propagation mode or whether one classifies the path as scatter, skew or backscatter.  Success with such paths will undoubtedly vary based on your location and station particulars, but be willing to experiment with unconventional paths and see what works for you.  Swing that beam, and spend time listening during openings, particularly in directions off the beaten path.  You may be surprised what you can hear and work.

2002 David H. Craig

 

UKSMG Six News issue 73, May 2002

 

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D-layer ionisation on 6m
monitoring 30-50MHz across the pond

a primer on sporadic-E
E-layer and sporadic-E prop.
the solar myth
the doughnut effect

winter transatlantic E's
troposcatter at 50MHz
50MHz sporadic-E in 1996
cometary origin of sporadic-E
rattling old bones about sporadic-E
doppler analysis of 6m signals
tropospheric prop. at 50MHz
50MHz prop. between Africa and Europe 1998
analysis of 50MHz contacts between VK and EU
hidden mode of sporadic-E?
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6m scatter DX
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50MHz F2 prop. mechanisms
more on 50MHz F2 prop.