Jim,
Quite so! In the measurements and modelling I've done on folded dipoles,
nearly all the VSWR bandwidth enhancement (around 97% of it) can be
attributed to the "fatter" conductor; the contribution caused by the
changing parallel impedance of the "inherent" series-connected,
quarter-wave stubs was minimal (3%).
73,
Steve G3TXQ
Jim Brown wrote:
> If I wanted the SWR bandwidth improvement of a folded dipole (nice
> for 80/75M and 10M), I would simply build an ordinary dipole, but
> making the conductors fatter by building a 2-wire or 3-wire dipole
> with spacers. That would allow me to feed it with coax, which in
> turn allows me to put a good coaxial ferrite choke up at the
> feedpoint to kill noise pickup on the line. If it was a low dipole
> for NVIS, I would use 50 ohm coax. If it was a high dipole, I would
> use 75 ohm coax.
>
> There are lots of easy ways to build spreaders. I buy 1/2-inch UV-
> resistant PVC conduit, cut it into suitable lengths, and drill holes
> through the pieces for the wires to pass through. Some folks use
> wood dowels that they seal against moisture.
>
> 73,
>
> Jim K9YC
>
>
>
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