For many years I've been using Grade LE phenolic plates in outdoor antenna
applications, and many of these materials have been exposed to the weather
continuously for over 25 years! Grade LE phenolic is readily available,
moderately priced (comparable to aluminum of the same size), and has
excellent electrical insulation and mechanical strength properties.
For example, I use Grade LE phenolic plates to mount Yagi elements on
their supporting booms. I fabricated the 12" x 12" x 1" Grade LE plates
that support the full size elements of my three element 40M beams in 1971,
and one such antenna is still functioning well on top of a 200 foot tower.
The last time I looked at these plates, they were somewhat discolored
(still brown, but a lighter brown than 25 years ago), and there is no
evidence of delamination or structural weakening. I recently had an
occasion to drill a hole in one of these 25 year outdoor-exposed
plates, and -- believe me -- it was as tough as ever! The same can be
said of the 1/2 inch thick Grade LE mounting plates I use on my 20, 15 and
10 meter monoband Yagis.
Grade LE phenolic is readily available in sheet, rod and tube shapes from
McMaster-Carr Supply Company, under the trade name "Garolite." McMaster
Carr's phone number is 908-329-3200 (M-F 0700-2100 Eastern Time). For any
of you who have not purchased hardware from McMaster-Carr, its one of the
premier hardware businesses in the USA. You can place an order with a
credit card any time before 9 pm weekdays and expect to have the item on
your doorstep in 12-36 hours!
Approximate prices for just a small sampling of the Grade LE phenolic
shapes available from McMaster-Carr:
12" x 12" x 3/8" sheet $25 Catalog # 8525K616
12" x 12" x 1/2" sheet $30 8525K618
12" x 12" x 1" sheet $55 8525K623
1/2" dia x 72" rod $20 8526K57
3/4" i.d. x .25" wall tube $38 8640K261