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LF: Sea Paths

To: "LF-Group" <[email protected]>
Subject: LF: Sea Paths
From: "Alan Melia" <[email protected]>
Date: Mon, 22 Mar 2004 12:23:42 -0000
Reply-to: [email protected]
Sender: [email protected]
Hi Rik, and David. There is not doubt that "mainly sea" paths do have an
advantage. We have the KLIX / Quartz Hill results from last year, and I find
that Joe VO1NA is visible most nights despite a relatively low ERP. CFH
(Halifax) is received in the UK much better than in mainland Europe. However
trans-polar paths should not be totally ruled out. There was little
difference between the signals received by Laurence from G3LDO and DF6NM
despite ERP differences. These distances are very similar and almost
northerly. I have discussed this previously with Brian CT1DRP who is
probably one of the best placed in Europe to get a long sea path to ZL. We
concluded that a path over the Cape Horn area in winter might be the most
promising. Even there the "window" of total darkness is quite short.

I doubt that there is a "reflecton" loss effect at a sea surface, the
incoming wave direction at extreme distance is almost tangential. I would
suspect that any difference with land paths might be one of "surface
roughness" and scattering/diffraction. I suspect the "successful ray" will
merely skim over the surface and head straight up to the ionosphere again
( see the geometry on my web page), suffering little more than a little
"bending". I suppose the "surface roughness" might be a little worse in the
Cape Horn area :-))

Some ideas of the approximate strengths of the signals on the ZL<>UA0 path
would be of interest. I think the 10,000 kms path would approximate to 5
"hops". On a sea path the major loss would seem to be from the ionospheric
return. By comparison VO1NA to UK is a 2 "hop" path.

Propagation conditions have been "generally favourable" but not
spectacularly good. There should be many such occurrances in the next few
"quiet sun" years, probably many that will be much better.

Great work, congratulations to all concerned (who said we wouldn't get out
of our back gardens on this band !!)
Cheers de Alan G3NYK
[email protected]

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