Sunday, December 18, 2011

The magical gray line

One of the wonderful mysteries of propagation occurse at sunrise and sunset. Those times are when some amazing things happen in terms of propagation. I have written earlier about some events I have observed, and the accomplishments by others are quite remarkable. This is often referred to as grey line propagation.

Tonight at my sunset, I heard JH0INP on 17 meters CW, 599. This was at his sunrise. Hiro had an echo to his signal, which implies multi-path.

Now, was this Short Path and Long Path? Or bent path? Well, on the lower bands (which are attenuated by sunlight), a bent path through darkness would make sense. In this case, it seems unlikely that this would occur on 17 meters. You can see the short path (A, in red), the long path (B, in blue) and the bent path (perpendicular to the gray line, a common path of gray line propagation).

All stations working Hiro were in US along the gray line (MS, ID, IN, and KP4). No EU, no California.

I was using a hex beam pointed short-path. When I switched to the dipole and vertical, I could hear the LP signal much better. It was weaker on the hex beam (as expected).

For more great info on propagation paths, get ON4UN's book.

73 and good DX!

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