Summer 2008 Issue
Observing the Double-Hop Sporadic-E
Phenomenon on 6 Meters
During the sunspot cycle low, North American 6-meter operators find it
difficult to work many countries. WB2AMU suggests a possible solution to this dilemma.
By Ken Neubeck, WB2AMU
In Europe and other parts of the world,
countries are located close enough to one another such that they can be
worked on 6 meters via single-hop sporadic-E (Es). This is also true for
6-meter stations located in the southern U.S., where they are within
single-hop range of many Caribbean and Central American countries.
However, for many 6-meter stations that are located in the northern
portion of the U.S. and much of Canada, there are not a heck of lot of
DXCC countries that can be worked via single-hop sporadic-E skip. This
would normally be a bleak situation for these operators in their pursuit
of DX on 6 meters when F2 is not a factor. On the other hand, the
occasional presence of simultaneous multiple sporadic-E formations can
help in working long-range DX on 6 meters.
One thing that I have observed over the years with regard to double-hop sporadic-E events (see figure 1) is the fact that they are very rare during the months not in the summer sporadic-E season (May through August for the Northern Hemisphere). Indeed, even though there is a minor winter window for sporadic-E activity, and there have been rare events over the years during the equinox period, I can only recall a very small number of double-hop sporadic-E events that I have observed during the non-summer months over the past 15 years. I recall a special occasion when I observed a double-hop event one evening in the middle of March 1996, when stations in Arizona were being heard on Long Island, along with single-hop skip stations from the Midwest. Otherwise, I have not recorded any multiple-hop sporadic-E events during any of the winter months (October through February) in over 15 years of personal observations.
The significant reduction of double-hop sporadic-E events during the non-summer months is a general, not statistically based indicator of the overall reduction of sporadic-E activity when comparing the two time periods. If we use the observed summer season data that I have collected on 6 meters over the years (see Table 1) and compare it with no days of Es during the other months, this could almost be summed up as roughly a ratio of 100 to 1 for my particular location. While this clearly is not meant to be a scientifically accurate calculation, it gives a rough order of magnitude as to how intense the summertime sporadic-E season is compared with the winter season.
Perhaps the thing that is most important to note is that observations of double-hop sporadic-E events is location dependent, as some locations such as the New England area can experience many more such openings into Europe during the summer months. My location on Long Island is not in that “magic spot” for observing Europe as is, say, K1TOL in Maine, who is geographically favored as well as geometrically favored in terms of the distance for the two hops.
The earliest that I have ever observed double-hop sporadic-E during any year was on May 9th, and the latest that I have observed it is August 17th, roughly a 90- to 100-day window of opportunity for my location. It is most likely that this window of opportunity is somewhat larger for areas such as New England into Europe, and the southeast U.S. into the Caribbean. It could loosely be argued that the peak months for double-hop sporadic-E are June and July. This would not be based on just my observations, but also on the observations of stations in New England. It is also noted that in most cases, the double-hop sporadic-E activity begins almost as soon as the sporadic-E season begins in May and lasts into August.
Also under consideration in this analysis is the fact that there are situations in which the observing station is hearing signals from two opposite directions. This scenario, while not technically called a double-hop sporadic-E event for the observing station, is truly a dual-formation sporadic-E event. These events are also reflected in Table 1 as recorded in the notes that I have collected over the years. I have not recorded any such events in all of my years on 6 meters during the wintertime sporadic-E season. They are a challenge to record, as they are not always obvious, particularly if the beam is pointed in the direction of one of the sporadic-E formations, reducing the strength of the signals from the direction where the other formation is. It is important to note that this case is distinct and not to be confused with strong sporadic-E events that create backscatter conditions in the opposite direction (the backscatter signals typically are not as strong).
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