Antenna Support Line
Synthetic Rope Characteristics
Man made fiber ropes are stronger and more durable than those made of natural fibers. Synthetic rope is not affected by most chemicals, rot, or mildew. Most synthetic rope may be stored wet or dry.
Nylon is highly elastic and can absorb sudden shock loads that would break ropes of other fibers. It has very good resistance to abrasion, rot, oils, gasoline, grease, marine growth and most chemicals. Nylon deteriorates more rapidly than Polyester when subjected to direct sunlight. Due to the characteristic stretch of nylon, wire antenna installations will require occasional re-tensioning the support ropes.
POLYESTER (i.e. Dacron®)
Dacron® Polyester is not quite as strong as nylon, but has far better resistance to ultra-violet degradation from sunlight. It is not as elastic as nylon and therefore does not stretch as much as nylon. These characteristics are a plus in an antenna support rope. Other than these two distinctions, the nylon and polyester characteristics are practically the same.
This is a strong, lightweight rope. It is waterproof and resistant to rot, oils, gasoline and most chemicals. Polypropylene is subject to rapid deterioration when exposed to direct sunlight, so its life is very short when used as an antenna support rope.
Polyethylene is similar to Polypropylene, but is slightly heavier. It is not as strong. It, too, deteriorates quickly in direct sunlight.
By weight, Kevlar® is stronger than steel. This is the material used in 'bullet-proof vests.' The molecular structure is such that it does not stretch and this characteristic makes it perfect for many antenna applications (boom and element support in beams, and general antenna use). Without a protective jacket, it deteriorates rapidly in sunlight. To counter this problem, a Dacron® jacket is used to protect the Kevlar core of Kevlar® line. This combination results in an incredibly strong, stretchless, long life support or guy rope.
Kevlar® and pulleys -
When Kevlar® line is used with pulleys designed for synthetic ropes should be used with caution. Kevlar® is small and very strong and it is possible that Kevlar® line could cut through the roller in the pulley.