[TowerTalk] HFTA Accuracy / Usefulness

[Pete Smith]

At 03:37 PM 3/18/2009, Steve Hunt wrote:
>I developed an analysis techniques which correlates an antenna's
>vertical response with the Angle-of-Arrival statistics published by
>ARRL. Basically it gives you a "figure of merit"  for an antenna at a
>particular height on a specific path and frequency. It's a useful tool
>for analysing the trade-offs at various heights. It shows very clearly
>that an antenna CAN be too high.
>
>QST will be publishing it next month or the one after. If you want a
>"sneak preview" the same material in a different form is presented on my
>web-site:
>http://www.karinya.net/g3txq/hexbeam/height_2/
>
>73,
>Steve G3TXQ


Steve, I published substantially the same method in the US National Contest 
Journal in January 2001, with a correction in the September/October issue 
to incorporate the point about applying the weighting to linear rather than 
logarithmic relationships.  N6BV incorporated a Figure of Merit using the 
same method in the first version of HFTA, which has been out since around 
2003 or 2004.

A rather more interesting question to me, at this point, is what antennas 
should be specified for the two ends of the path to generate the arrival 
angle statistics.  There is a discussion of this on the ARRL TIS web page, 
but as far as I'm concerned the jury is still out on that subject; in the 
past, I had argued for isotropic antennas on each end of the path, so that 
the statistics would reflect the actual behavior of the ionosphere rather 
than the selection of antennas.  I'm now coming around to a somewhat 
different view, if what you're interested in is trying to open up the most 
"layers" of stations to work in a contest, for example.  At some point, the 
lowest layers are guys with low dipoles or lossy ground-planes.

With luck maybe we can smoke Dean out and restart the discussion.

73, Pete N4ZR