[TowerTalk] 15 meter yagi height for 6000 miles
frankkamp at att.net
Fri Mar 2 15:50:55 PST 2012
Pete Smith N4ZR wrote:
>Frank, all that any good current book on antenna design will do is refer
>you back to the same propagation realities that are used by HFTA and
>other modeling software. HFTA produces nomograms that show what the
>best takeoff angle will be for a particular target area, as share of 100
>percent. Those are then matched with the antenna patterns generated
>over real ground profiles, and a figure of merit is produced that tells
>you, on *average*, how well a given antenna system at your QTH will
>perform relative to the target area. Of course, conditions will vary
>from day to day, or year to year, that is exactly what you want to
>know. It doesn't absolve you from the need to design and build a good
>antenna, but even the best antenna will be (on average) inferior if
>placed at the wrong height.
>73, Pete N4ZR
Thanks for the explanation, Pete.
I guess I did not fully understand what HFTA was all about.
Now that I do, I am not convinced it is entirely useful, at least not to
me since I don't have the resources to raise or lower my antennas at
will. I just raise them up to 1/4 wavelength at the lowest frequency
of interest and hope for the best.
So far that has worked for me.
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