Using speaker wire, zip cord, or ribbon cable has higher loss than RG-174 coax, and you may
not get as good of a match because the impedance isn't necessarily 50 ohms. The plastics
used aren't optimized for RF.
Using such feedline at a high SWR with a tuner is even worse. (You did want an efficient
solution, right?)
The 20m dipole fed with a half wavelength of 300 ohm twinlead will be reasonably efficient on
ONE band. Well, maybe 10m as well, where the length is a full wavelength. The SWR will be
much higher on most other bands (though there might be some serendipity, as is the case with
the G5RV and relatives.)
Using 50 ohm coax gives you a good match and reasonably low losses on all bands of
interest with out the bother, weight and expense of a tuner. You can use RG-58 if the weight
isn't an issue, but you probably can't support it as high up the mast as you can the RG-174.
(Use a combination of the two if you need a long run from the base of the mast.)
The rest of the construction, including providing a loop or hook of some sort to attach it to
the mast, can follow the general principles shown in the various articles.
I am wanting opinions since I am by no means any sort of antenna expert if taking the ends and bringing them down into an inverted V would still allow with work achieving resonance at 14Mhz. I think that a little tuning work might be needed on this since my pole wouldn't quite be 30'.
For best performance you want to keep the ends of the wire as high off the ground as possible.
That usually means tying them off with a rope at least as long as the antenna wire itself. You
certainly don't want to bring the wire ends down to the ground. Some knot tying practice
helps if you are gong to tie the ends off to a fence post or bush.
Mason's twine is convenient, or dental floss can be pressed into service if you want the ultimate
in light weight and a convenient dispenser. My favorites are hard-braided line that I found in a
commercial fishing shop in Alaska, but it really doesn't matter that much.
You do need to learn to wind it up so it doesn't tangle, however, if you want to set the antenna
up quickly.
There are many sorts of light wire that will work. I'd typically use something like #22 or #24
stranded, insulated hookup wire. (Whatever I have on hand or can get cheap.) Solid wire
tends to kink badly, but some thin solid aluminum fence wire might work out.
I've never heard the term "linked dipole", but I have built several such devices over the years.
The concept certainly isn't new. The real question is what sort of multi-band capability you
want: the linked / switched / sectional version means you only have a single dipole to put
up, but requires that you lower the ends and move the jumpers to change bands. That's fine
if you stay on one band most of the time. I use multiple dipoles on a common feedpoint
(sometimes mis-termed a "fan dipole" - that's a different antenna). That allows me to use
multiple bands without changing the antenna - quicker if you want to operate multiple bands
without having to go outside. I have a center insulator on the end of my coax and tie on
the dipole wires for whatever band(s) I think I'm going to use each time I set it up. If you
build the sectional dipole using the plastic electric fence insulators that look like small
carabiners it is easy to remove sections that you won't be using.
Either approach works with good efficiency - the choice depends on your constraints of
weight and setup effort vs. operating complexity.
