[Radioroslyn]

It's somewhat frequency dependent. I like dipole antennas they are much quieter than single wire antennas. The lower the frequency the longer the ant. Think of it in wavelength. You don't have to have a full wavelength for it to work well a 1/2 wave works well too and is 1/2 as long. For instance the 41m band (abt 6.8mc) works out to abt 140' for a full wavelength but you can use two 35' lengths of wire. The insulators can be a few short pieces of small pvc pipe w/holes drilled near the ends. The wire in the center can be coax but that's not a real good impedance match for your old set. Most are around the several hundred ohms. Coax is 50 or 72 ohms generally.

The wire for the ant it self I like copper plated steel. It's strong and conducts like copper. Ant length becomes critical when you use it to transmit on. If the ant stretches then it's resonant frequency changes too (lowers). Transmitter doesn't like that much at all. So strong is good. Copper is soft. Litz wire is for winding high Q coils.

https://www.researchgate.net/figure/The-..._320751102