Hi Colin.  It is a centre fed di pole with open wire feed line 
instead of coax.  So you have the centre insulator witht the 2 wires 
which you can have as a flat top or inverted v.  The length depends 
on what you want and how much space you have to fit it in.

Mine is an inverted v configuration cut for 3.58 Megahertz
65.4 feet long, or 19.92 meters.

The feed line which is the tricky part of the aerial is 30.4 meters 
or 102 feet long hanging down as close as possible to 90 degrees from 
the wires.

This comes down to a 4:1 balun, into about 1 meter of RG-213 coax 
into the LDG KT-100 tuner.

There is a lot of interesting and helpful information on the internet 
if you type into your search engine, "Doublet antenna" including a 
very helpful chart with recommended feed line lengths for 80 and 40 
meters.  It also shows how some lengths of feed line are to be 
avoided.  The recommended feed line lengths are in green and the ones 
to be avoided are in red.

Hope that helps.  Stay in touch and hopefully we will have a QSO one 
day.  I hear some good signals from Canada regularly at night.


73


Ian, VK3vin



At 12:49 PM 3/05/2013, you wrote:
>can you describe the basic design and construction of the antenna?
>IE element length and feedline length?
>I've never experimented with a doubllet style and wouldn't mind trying it.
>
>73
>Colin, V A6BKX
>----- Original Message -----
>From: "Ian Westerland" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Thursday, May 02, 2013 8:28 PM
>Subject: Doublet Antenna
>
>
> > Hello to all on the list.  Someone posted a question about doublet
> > antennas a couple of days ago and i have just made one for multi band
> > operation between 80 and 10 meters.  It has been a challenge but the
> > results so far are really better than I thought they would be.
> >
> > The antenna is cut for a low frequency of 3.58 megahertz in our 80
> > meter band, fed with 300 Ohm feed line, through a 4:1 balun into an
> > LDG TK-100 tuner.  The results on 80 meters are the best I have had
> > from any antenna used so far including the standard coaxial fed
> > dipole although there seems no real reason why this should be the
> > case. Maybe it is the lower loss feed line doing the job.
> >
> > I have encountered problems on 40 meters that seem to be related to
> > the length of the feed line but results are improving with a little
> > fine tuning and experimentation with feed line length.  The doublet
> > is 9 meteres off the ground at present, but during next week it will
> > be raised by another 3 meters so it will be 12 meters or 40 feet at its
> > apex.
> >
> > I will post to the list again on the doublet when I complete the
> > project but at present, even though it is not at its optimum, I am
> > more than happy with its performance on both transmit and receive.
> >
> > Ian Westerland, VK3vin