PROPAGATION - by AD5Q HOUSTON, TEXAS -- MAY 1997


20 Meters continues to improve. The evening openings are great, especially if you like running CW Russians. This path follows the post-sunrise area across Siberia and Russia to Eastern Europe and Scandinavia. Around midnight the polar path closes, but signals continue to come through from the west.

On 20 CW, westerly signals from the Pacific, Australia and New Zealand are hardly numerous enough to keep the band jumping with DX activity. Most amateurs in these areas are primarily SSB ops, just as most in Russia and Eastern Europe prefer CW. When paths are open both over the pole and to VK/ZL, an SSB operator on 20 will find most DX activity to the west, while the CW op will more likely notice a band that is wall-to-wall with that sound we all know and love: polar warble. In the late evening, the westerly opening expands as signals cross the darkness back into daylight where it is late afternoon. If the band were to stay open well past midnight (assisted by an extra 10 or 20 points of solar flux), the late afternoon region would approach Asia and a path to Japan would open up nicely. Some excellent runs in past WPX contests come to mind.

In the morning we find good openings over high latitude paths into Asia. Here we routinely work JT, BV, VS6, HS, 9V, V85, etc. while tuning and wishing for signals even more exotic (9N, A5, VU4, XW). This morning pipeline does not last long, but is changing as summer approaches.

At the high end of the solar cycle, we notice a deterioration in 10 Meter conditions during May due to a heating and thinning of the ionosphere that lowers the MUF; effecting 15 Meters in mid-summer and forcing most DX activity down to 20. We call this phenomenon "summer absorbtion." At the low end of the cycle we have already written off 10 and 15 anyway, and should notice that the effect of this summer heating on 20 Meters is beneficial. It keeps the MUF hovering above 14 MHz for most of the morning, lengthening the duration of our opening into the Asian evening darkness. During our own evening, we work into this same broad area of morning as it spans Russia and Siberia. Instead of a narrow pipeline into a sunrise area, a large region of a remote continent is workable - improving QSO rates in the CW WPX beyond what would be expected at the low end of a sunspot cycle.

Thus, 20 Meters will continue its transition to this summer configuration. The main opening to Europe will be in the late afternoon; working into their late evening window to the west before the band closes for them.

Other bands? 40 is still in excellent shape with rising QRN levels (and low band contacts count double in the WPX). I would expect that conditions on 30 are even better, but I have yet to find room for a serious antenna on any WARC band and claim no expertise.

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