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[TowerTalk] Measuring DX Performance of Verticals

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Subject: [TowerTalk] Measuring DX Performance of Verticals
From: (Ward Silver)
Date: Wed May 7 12:49:48 2003
> Without giving away the farm, is there any reason why the book only tested
> antennas on a ground wave level vs actual DX performance?
> While common sense states that local test range data has a relation to DX
> performance, one could also point out that a vertical antenna is going to
> heard much louder than one laying horizontal, locally, but that perhaps
> DX distances, the horizontal antenna will far out perform the vertical.
> Taking this example further, could the same be said for the DX performance
> the various vertical designs tested if one compared their local
> to that of their DX performance?  That is, antenna A gets a poor report on
> your test range but is heard well in YA while the antenna with a great
> signal is not audible at the same DX location-
> Are you all planning any future studies comparing DX rather than local
> results comparisons?   The studies are awesome but I wonder if they would
> enhanced by this effort-
> 73  Paul  N0AH

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

73, Ward N0AX

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