[TowerTalk] More on Half Wave (and HFTA)

[David Gilbert]

"Certainly the topography of adjacent radials affects the true 
performance on one radial that won't show up in the HFTA model. No?"

I'm pretty certain that N6BV himself has pointed that out as a 
limitation of HFTA.  It's a complicated world.

73,
Dave   AB7E


On 1/19/2019 8:33 PM, Paul Christensen wrote:
>> "There are folks who claim that a few thousand meters or so is all the further anyone should have to collected data points, but that's a garbage generalization.  I have
> another mountain range about 15 miles east of me and by editing the terrain file to either include it or not I can see definite differences."
>
> And that brings me to this point:  consider a case where a radial is analyzed in HFTA and extends to 14,000 ft.  At that distance, each 1 deg radial is approx. 244 ft apart.
>
>  From what I can determine, HFTA is calculating the radiation profile from data on only one radial.  But since terrain often changes on adjacent radials, sometimes dramatically,  then doesn’t the model really need data that's spliced and factored from adjacent radials to get a true picture of the profile?  If the antenna beamwidth is say...40 degrees, then don’t we really need a more comprehensive analysis of radials within the swath just to determine the profile of one radial?
>
> Performance as actually measured on one radial could be undermined (or enhanced) by adverse terrain characteristics from adjacent radials.  Certainly the topography of adjacent radials affects the true performance on one radial that won't show up in the HFTA model.  No?
>
> Paul, W9AC
>
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