At 09:49 AM 5/7/03 -0700, Ward Silver wrote:
>The bottom line is that trying to make any kind of an A/B comparison over a
>sky-wave path is pretty much an exercise in futility. Signal levels swing
>wildly +/-20 dB in a matter of seconds, so comparisons would have to be made
>on a second-to-second basis.. You would need synchronized antenna switching
>systems and some fairly sophisticated test gear to acquire the data and
>separate it into the individual signals. This is out-of-scope for amateur
>tests and unlikely to provide any real meaningful data. I have no reason at
>this point to question correlation between the range tests and performance
>over a low-angle sky-wave path. Introducing the sky-wave path would also
>introduce so many uncontrolled variables that any conclusions would be of
>questionable validity. These are all code words for, "We are not going to do
>sky-wave tests."
>
>Now, about the horizontal-vs.-vertical question...there are many instances
>in which horizontal antennas have been observed to work better over DX paths
>than vertical and vice versa. The angle at which signals arrive changes
>dramatically over the course of a single band opening, as well as the
>preferred polarization. Having different antennas on the low-bands often
>pays big benefits, no question. This is code for "You can't have enough
>antennas."
Couldn't the signal produced at the VERY low angles between local sites
vary substantially depending on the extent to which a given vertical design
is affected by ground quality and/or radial fields. This is sort of a
cousin of the question I had about the tribander tests, but if anything
would appear to be a more serious issue with verticals.
73, Pete N4ZR
The World HF Contest Station Database was updated 11 April 03.
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