OOps. Thinking of a 67 foot dipole in the math. Of course the
wavelenth should be about 140'. (the product of approx 3'/M X 40M
much greater than 67' DUH!)
73 de Brian/K3KO
n4kg@juno.com wrote:
>
> A FULL Wavelength on 40M is 140 ft.
> A HALF WAVE Dipole is 66 ft allowing ~5% for end effects.
> A 47 ft boom is .335 WL. The square root is .58 sq rt WL
> (whatever the ***? those units represent). If we accept that
> the units should be WL, that corresponds to 81 ft which is
> close to optimum. Actually, stacked 2L40's exhibit peak
> gain when stacked at 80 and 160 ft.
>
> Tom N4KG
>
> On Sat, 28 Jul 2001 16:18:19 +0000 alsopb <alsopb@gloryroad.net> writes:
> >
> > As stated originally the boom length in the formula is in
> > wavelengths.
> > A 47' boom is about .7 wavelength on 40 meters. The formula
> > predicts
> > a spacing of .84 wavelenth or about 56 feet.
> >
> > 73
> >
> > Tom Rauch wrote:
> > >
> > > Hi Brian,
> > >
> > > I don't understand what the following means. Is something wrong?
> > >
> > > > I queries WX0B about the rule of thumb regarding "optimum"
> > stacking
> > > > height.
> > > >
> > > > Here was his response:
> > > > ***********************************
> > > > For HF antennas over ground, W2PV did the math correctly and the
> > > > formula is SQ rt of boom length is the widest stacking distance
> > you
> > > > should use on a yagi. The results are in boom lengths just as
> > you
> > > > state.
> > >
> > > My 40 meter yagi has a 47 foot boom. Optimum stacking distance
> > > for gain is ~90 feet, depending on array mean height.
> > >
> > > Using that formula, I should stack my 40 meter beams sqrt of 47,
> > > or 7 feet apart MAXIMUM?? A 1 WL boom antenna would stack
> > > at .7WL...which also would be much less than optimum
> > > ....although getting closer.
> > >
> > > Was something stated or conveyed incorrectly above, or is
> > > something missing? It clearly is not correct.
> > > 73, Tom W8JI
> > > W8JI@contesting.com
> >
> >
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