I personally think you have created a lot of problems on all bands with 3
large towers so close together.
70ft between two is acceptable. But having one in the middle can cause a
number of problems in my mind...
Ray,
N6ve
On Thu, Sep 27, 2018, 2:23 PM Joe Subich, W4TV <lists@subich.com> wrote:
> On 2018-09-27 5:01 PM, Edward via Topband wrote:
> >
> > I have three crank-up towers spaced 35' apart. T
>
> With towers spaced 1/16 wavelength, they will almost certainly
> all be coupled to each other. The coupling will be greatest
> when they are nearest to resonance.
>
> Your "tower #3" is probably very close to resonant on 160 meters
> depending on the top loading. As a first approximation, take
> 1/2 the boom length of the longest boom yagi and add it to the
> height of its attachment to the mast. If, for example, you have
> a 32' boom 6 meter yagi 15' up the mast -> 106 + 15 + 16 = 137'
>
> I would strongly consider gamma (or omega) matching the 160' tower
> and then using skirts to detune the other two towers.
>
> > What kind of separation is needed for 2 ele array?
>
> Typically somewhere between 0.20 and 0.25 wavelength. If they are
> phased it is much easier if they are identical (otherwise one needs
> unequal currents to account for the differences in height and
> impedance).
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2018-09-27 5:01 PM, Edward via Topband wrote:
> > Jon,
> >
> > I have three crank-up towers spaced 35' apart. Tower #1 is 89' plus 20'
> mast, with some antenna top loading. Tower#2 is 70' crank up with 20' mast
> with minimal antenna too loading. Tower #3 is 106' crank with 20' mast plus
> top loading.
> >
> > What kind of separation is needed for 2 ele array?
> >
> > Thanks,
> > Ed NI6S
> >
> >> On Sep 27, 2018, at 11:00 PM, Jon Zaimes <jz73@verizon.net> wrote:
> >>
> >> Either crank up should work fine with adequate radial field.
> >>
> >> Inverted L may suffer from interaction with the towers.
> >>
> >> Depending on tower spacing and orientation, you may be able to feed
> both in a 2-element array.
> >>
> >> 73/Jon AA1K
> >> Www.aa1k.us
> >
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> >
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