Warren,
You might check out my article in the ARRL Antenna Compendium V, and perhaps
get a copy of US Patent 5,489,914. I don't have any reference material on
hand in electronic form.
Then if passive coupled resonators look interesting, I can supply additional
practical information. This design is commonly (and inaccurately) called
'open sleeve.' Basically, it looks like paralleled dipoles, but feedline is
only connected to the lowest frequency element; the higher bands are
'floating' and coupled by their proximity, with impedance set by the
spacing.
The main difference with paralleled or fan dipoles/verticals is that each
band is more easily adjusted for resonance and impedance match. Sometime in
the past, a KL7 and a VE3 wrote up articles on multiband verticals using
this technique, but I've lost track of them.
This type of antenna models well in NEC and MININEC, but you need to be
careful to align pulses on adjacent conductors.
73, Gary
K9AY
-------------
> Greeting folks:
>
> I must default to a simpler antenna system until the loot shows up for
> the
> BIG tower
> and yagis.
>
> I am quite familiar with paralleling a pair of dipoles for two or more
> bands.
>
> This concept leads me to consider paralleling a pair of verticals for 40
> and
> 20 meters.
> Before I invest in the aluminum, does any one know such a system in use?
>
> I suppose trying to get some 15 meter operation out of such a system
> would be
> pushing it. I do not mind a bit of fixed matching network at the base.
>
> Comments appreciated, Warren; W7WY
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