I'm a newly-licenced ham and currently starting out with HF. My home doesn't allow for a permanent setup. I can therefore only operate portable from parks and such, with limited TX power (my rig goes up to 20W), so an efficient antenna seems important to ensure the best rate of success.
Of all portable antenna configurations I've tried, I've had the most success with a monoband 20m vertical consisting of a 5-meter fiberglass fishing rod with a wire spirally wound(*) around it top to bottom and 4 radials laying on the ground.
I would now like to try working the bands that lie lower down (for now 30, maybe 40 meters), but for that I'd have to get myself a longer mast, and all the 7+ meter fishing rods that I could find have at least some carbon fiber content.
CF is conductive, so logically it must interfere with the antenna's operation, possibly throwing off the tuning and/or causing resistive losses in the carbon. I'm also considering hoisting a speaker wire dipole on such a mast. In that case, again, it seems that a conductive mast must interfere with the twinlead section of the feedline.
How significant is this effect in practice, and how exactly does a poorly conductive mast affect antenna performance for the configurations mentioned?
clarifications: (*) the spiral is a very spread-out/slow one, pitched just enough so that the wire would sit tightly against the mast without flapping around in the wind. It is nowhere near tight enough to count as a loading coil, so the antenna should be considered equivalent to one where the wire runs up in a straight line.