Six meters delivered a mid-afternoon surprise yesterday, with a brief opening between the west coast and Japan. It was one of those openings that would have been missed entirely, a few years ago.
At around 2300Z, JE1BMJ (Han), announced via the ON4KST 50MHz chat page that he would be CQ'ing towards North America on 50.090KHz. I was working at the bench with the receiver running in the background and took a moment to turn my 4el yagi towards Japan and put the receiver on frequency. Nothing was heard for several minutes when, as if a switch had been thrown, the frequency became alive with CW sending "... DX K". About 20 seconds later it started again, a CQ DX from JE1BMJ. It is amazing how often the band or a path will appear to suddenly open, in this case, at just the tail end of Han's CQ ... not a whisper of anything before the very tail end. As I listened, his signal built from the initial 559 to 579 at which point I called and we exchanged signal reports.
I moved down the band and called CQ DX and was immediately called by several loud JA stations. Over the course of the short opening (just 15 minutes from start to finish), I worked the following stations in Japan:
As mentioned earlier, this was an opening that would probably have been missed a few years ago, for several reasons. One factor is the growing use of the Internet to spot activity or stations that are actually on-the-air in real time. Another reason is the very short window of opportunity. Without stations looking, thanks to Han's QRV announcement, it is probable that nobody would have been pointing towards Japan at that time of the day ... but, more likely, the biggest reason is the exploitation of the SSSP path between NA and Asia that has become somewhat of a regular occurrence over the past several summers.
SSSP or Short-path Summer Solstice Propagation is the mechanism uncovered by JE1BMJ in 1999. In that year he discovered that his signals could be heard almost daily in many parts of Europe by transmitting on a regular evening schedule. He then turned his attention to North America, in the morning, and found much the same thing. Han continues to this day on a regular schedule each day and more often than not, works several stations in North America ... from both coasts and everything in between. He has even worked into Central America on SSSP.
SSSP is a summertime-only event in the northern hemisphere and relies on the scattered ice crystals found in the Polar Mesospheric Summer Echo region (PMSE), located about 88km above the ground, very near the same height as the E-layer.
Signals travel through the polar region and never touch the ground until the far end of the path is reached. In all probability, this is the same mechanism that west coast stations are able to work transpolar-Es into Europe during the summer. The season is short-lived (June/July) and openings can have weak rapidly fading signals or, as in yesterday's case, strong steady signals during the course of the opening. Openings can last from just a few minutes to several hours. Thanks to the Internet and real-time chat, most of these openings are no longer being missed.
Stations being worked via SSSP seem to be, for the most part, running high-power and / or large antenna systems. It is rare to work many of the 100 watt stations, although under good conditions, it does happen.
|JR2HCB's 6m Yagi Stack|