East Coast to Japan Long Path

The potential for Long Path openings to Asia from the Southern reaches of the United States is well known, particularly after the fantastic fall F2 season of 2001 and the Spring season of 2002. Stations in Florida as well as the Gulf Coast region worked Japan and Okinawa on a number of occassions, and some lucky Americans managed QSOs with Hong Kong, Malasia and for the first time ever on 6 meters, Taiwan. Long path QSOs to the Japanese Islands have also been made from Kansas, Oklahoma, Texas, New Mexico, Arizona and Southern California. During peak solar years these events can occur in October & November, as well as the Spring months of March and April. They are early morning events (local time) in the United States, and night-time local in Asia.

Propagation to these areas is not necessarily limited to the Southern United States, however. Attentive stations as far north as Minnesota have worked Japan via the long path, and during the last cycle East Coast stations at least as far North as North Carolina and Virginia did it as well. This cycle I heard JAs in FM18 at least twice beaming over the South Pole, and heard 49.750 Asian video on at least 4 occassions. Aside from 49.750 or other Asian video, signs of a possible opening along this path include audible YV beacons, as well as pronounced backscatter. Look for YV beacon posts from Japan on the loggers. During the first opening which I heard LP JAs, the band was open weakly to central Brazil as well. Though when heard here the LP signals were on the "direct" antipodal path, Florida stations sometimes reported skewed paths of approximately 150 degrees.

The great circle path curves on the map above are slightly out of position over South America and somewhat disproportioned in the polar regions but should serve well enough to illustrate the path. For stations in the Southern United States, the first "hop" of the path is in all likelyhood made on pure TEP, as is the final hop to Japan North of the polar region in the Indian Ocean West of Australia. For stations farther North in the United States, however, bar exceptionally strong & Northerly TEP propagation, some other form is necessary in order to make the initial trip into that zone. During the fall F2 season this is almost certain to be a "conventional" North to South F2 path. An Es link to the Southern United States would likely be even better, but would be rare indeed given the time of year. As suggested by K6MIO in his brilliant essay 50 MHz F2 Propagation Mechanisms, the path over the pole is likely also a form of TEP propagation, with the signals making it through the initial cross-equatorial (TEP) hop then refracting sufficiently to follow the curvature of the earth over the pole & to re-enter the TEP zone on the opposite side. Whatever the mechanism, it works, and during the fall of solar peak years it is a path that bears watching even for stations in the more Northern portions of the United States.

Given the success with this path to other areas of Asia and other discoveries over the last year, it is likely other long paths useable on 50MHz are waiting to be discovered. W7XU operating in CE0Y in the spring of 2001, for example, discovered a long path over the North Pole into India. What other polar paths could exist? For stations in the Northern portion of the hemisphere a route over the North Pole would be difficult to reach due to the relatively high angle of incidence involved, though other paths to the south should offer better possibilities. Stations in the Southern portion of the U.S. (in the TEP zone) have the best chance of finding them, but again, stations within an F2 or Es hop distance of it should pay attention too. If we use other known 50MHz long paths as a guide, it is apparent the typical (unassisted) long paths generally originate and terminate somewhere between 35 and 50 degrees above or below the geomagnetic equator, making two passes across it. A cursory review of the geomagnetic map show a number of countries within reach of the United States meet this criteria, including India, a number of middle eastern nations including Oman, Yemen and Saudia Arabia, and virtually every Southeast and Eastern Asian nation, including China. Could paths exist?

I think it likely that at least at some time or another, propagation could be possible. However, a problem with most of these paths not encountered with the ones to Japan and nearby regions is the time of day at the North American side of the path, though this would likely effect only more Northern US stations. The JA paths were all morning events in the United States and night-time ones in Japan. In order to take advantage of a daylight F2 path as far as possible on the American side, long path QSOs crossing Central America and into the Southern Pacific region would have to be made just before sundown from the East Coast. D layer absorbtion as well as a sharp decrease in ionization could present a problem, and on the other end of the path, ionization in the equatorial region would likely have to have persisted throughout the night in order to complete the path. The other single biggest problem in finding such paths is a lack of activity. Attentive monitoring of various 48 & 49 MHz video and two-way communications frequencies from relevant areas in Asia would be a start. Decently equipped stations would have the best chance. Hopefully these areas will provide some surprises in the near future.

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