On 3/2/12 11:15 AM, David Gilbert wrote:
>
> That says more about what some people read into computer programs than
> it does about about "what some computer says is optimum". VOACAP is
> based upon empirical data and statistical analysis, and as such it
> displays predicted (not absolute) results for a representative (not
> absolute) time period within certain accuracy limits . HFTA used VOACAP
> to determine the predicted best takeoff angles for various paths **as an
> average over an entire eleven year sunspot cycle**.
>
which is an interesting point.. I think most hams have a "cycle time"
for antennas which is shorter than a sunspot cycle. one might want to
look at predictions for 5 years into the future (yes, speculating wildly
about SSN, etc.) if that's your antenna building planning horizon.
Rather than trying to build something that works for all SSNs, optimize
for the next few years, and then plan to change.
> As a planning tool HFTA is the best we have to work with. It is based
> upon sound science and was written by a competent software engineer.
> It does pretty much exactly what it was intended to do ... give you the
> best chance of optimizing your results over a long period of time.
> Anybody who thinks that it will hold true in every instance, or that
> actual results won't often be even better than predicted, doesn't
> understand the tool that they are using or the physics behind it.
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