In searching for suitable materials for a wire antenna, I found a few mentions of using string trimmer line to hold up each end of the antenna. This would be a nice option as it is readily available locally. For a long-term installation, I've seen the use of UV-resistant Dacron rope. How does string trimmer line compare in terms of strength and UV resistance? Is string trimmer line an acceptable option for short or long-term antenna installation?
String trimmer line is engineered for high tensile strength, resisting breakage, but it isn't meant for 1) long term outdoor exposure and 2) long, stable lengths.
Number 2 means it will stretch over time. Not a lot, but at the lengths needed to support antennas will needed to be tightened repeatedly over the first day or two, whenever the temperature warms up, and monthly in general. Number 1 means that the plastic will break down over time due mostly to UV exposure, but also because it is hydrophilic (absorbs water) and will be damaged by cold weather, and normal mechanical stress. It should easily last a year, though, for moderate loads.
It isn't rated for tensile strength in long lengths, so you'd have to do some experimentation to find a safe tension and load range, but for most HAM antennas it should be more than enough. Don't try to use it as a guy wire for a mast, though.
I never use any single strand or monofilament line. The weed whacker string is an example of the latter. Evaluate strings, chords and narrow gauge ropes.
Go to a hardware store (e.g., Lowe's, Home Depot), go to the rope and string section and read the notes on the different packages that provide info on load strength, shock strength, moisture performance, UV performance, cold weather performance and other characteristics.
I have had my two dipoles up now for 3 years with .105 trimmer line. I just inspected them and there is no sign of wear; still strong with no sign of deterioration. I think I should get at least 8-10 years from the .105 gauge.
Just make sure it is secured to the insulator. I wrap it twice through the hole, then tie one knot, then wrap. Finally use tie wraps and high quality electrical tape.