NM7M's comment on the D region taking a heavy toll on W5 to Heard Island is
well taken.
If you look at the path for W5 to VK0IR around 0000 UTC (Dallas sunset), the
last several thousand km into VK0 have a solar zenith angle of about 82
degrees. Using the absorption nomographs (Figure 7.5 and 7.6) in Ionospheric
Radio Propagation (Davies) at 4MHz and scaling to 1.8MHz, the estimated
absorption per hop for a 1.8MHz signal in this sunlit part of the path is
greater than 50dB! That's a bunch.
The exact value of that isn't too important - it's sufficient to say that it
is prohibitive for W5s. What's interesting is the W2 path never sees a
solar zenith angle less than 100 degrees in that area - that's essentially
0dB absorption. So as NM7M said, the W5s gotta wait for a DXpedition to go
in a different season.
I can sympathize with the W5s - we lived in the Dallas/Ft Worth area for
nine years. Great place to live, but not good for Heard Is on the low bands
in January.
Carl K9LA
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R. Carl Luetzelschwab Mail Stop: 25-71 Phone: 219-429-4338
Fax: 219-429-8215 E-mail: rcluet@most.fw.hac.com
Hughes Defense Communications, 1010 Production Road, Fort Wayne, IN 46808-4106
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