A doublet is just a dipole that uses twin lead for its feeder or twin lead or ladder line with the element lengths that are suitable for multi-band use.
Clever hams have hacked their ideas into workable antennas.
Dave NF0R had an idea for the St. Louis Doublet antenna that used ribbon cable as the twin-lead and magnet wire for the dipole arms.
Doug KI6DS took the idea further and made it all from a length length of computer ribbon cable.
At one point someone used the speaker cable idea for this antenna but did not call it the SWD.
The SLD was too fragile in my mind with the use of magnet wire for the radiating elements. I also found the magnet wire to get tangled too easily. But it is very lightweight.
Well finally after 8 years of trying to find the ribbon cable I got a 80 foot roll at the York Region Club Hamfest this year. (Eventually attending the biggest Hamfest in Canada one would find these things often?).
I put a proof of concept together and threw it up in the trees and voila it worked very well with the radio’s built in tuner. I think it should have a balun on it but the initial test in the bitter cold proved that the design was sound and not fragile.
I had made the NORCAL version as well using speaker twin lead (described in a previous post) and it was a great antenna for when I was in Australia. In order to be a gram weenie I used a lighter weight speaker cable and used buttons for the insulators. I think I shaved a few ounces this way which didnt do much on the airport luggage scale but it became more about using the buttons for ham radio.
I made a more rugged version with a beefy center insulator and speaker cable to handle 50 watts of power.
They all worked good but a 4:1 balun will be a useful addition as we are taking a balanced antenna and matching it to a unbalanced coax feed line.
So we have 3 versions for this doublet and they all work just as good.
- St Louis Style – probably more fragile but more robust insulators would be useful and I still think the magnet wire is too fragile.
- NORCAL style using computer ribbon cable
- Speaker Wire style
Choose your for factor and “Go Get on The Air”
http://www.norcalqrp.org/norcaldoublet.htm
I made an NORCAL style as seen below
ve3ips 
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