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Both constructions use the same type of material, basically a thermoset FRP (fiberglass reinforced plastic), which includes specially formulated resins, flame retardants and UV stabilizers to produce the unique benefits which characterize fiberglass reflectors. Because some antenna installations must exist in environments containing many corrosive agents, the materials in the construction of the antenna must be carefully selected to alleviate corrosion problems. Obviously, in the case of an aluminum structure, dissimilar metal contact is always a risk factor. A fiberglass dish, on the other hand, all but eliminates this problem - for obvious reasons. The resins used in antennas have been subjected to both field and laboratory tests involving over 130 highly corrosive chemicals at temperatures up to at least 120° F (50° C), with results that indicated little or no detectable degradation of the test samples. Cure of thermosetting resin is initiated by heat in the die and catalyst in the resin mix. The rate of reaction is controlled by heating and cooling zones in the die. The resulting high strength profile is cut to length, ready to use as it leaves the pultrusion machine. The controversy over metal versus fiberglass antennas continues, despite the over whelming evidence in favor of fiberglass. This article summarizes the contents of a number of other separate articles which have appeared in the industry media from time to time and is intended, from an objective point of view, to add credence to our claim that fiberglass is better. The ipso facto use of fiberglass, of course, does not guarantee a good antenna and there are a few antenna manufacturers who have "missed the boat" on techniques, which means there are poor quality fiberglass antennas, just as there are poor quality metal antennas, out there. Fiberglass-reinforced thermosetting resin pipe (RTRP) is available in diameters from 1 in. to 84 in., using epoxy and vinyl ester resin systems. Centrifugally cast pipe is available in sizes from 1 in. through 14 in., and it is used, along with F-Chem filament wound pipe, where extreme corrosion resistance, strength, and durability are required. The installation cost is less expensive than steel pipes. Literature describes advanced performance, epoxy, vinyl ester, high pressure, and specialty piping systems. A chart lists the size range, pressure rating, maximum temperature, types of joints, and typical applications for each type of pipe. The brochure describes 10 different joining systems, tools and accessories, and various fittings.
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