I was very sorry to hear about the severe damage
to N9RVs antennas in the recent ice storms that recently
affected many parts of the U.S. I know Pat worked
very hard to build his excellent station, and now
he faces an even bigger job of redesigning and
rebuilding his antennas so he doesn't face a repeat
I had a similar experience in 1993 that damaged most
of my antennas and damaged and nearly collapsed
three 200 foot towers. As a result, I learned how
to design and install antennas and towers that
survive extreme ice conditions.
Ice is a very serious threat to antennas and towers
in most of of the U.S. For example, at N9RV's
QTH and in much of the midwest, the expected
50 year ice exposure is one inch of radial ice with
a 40 MPH three second wind gust.
If you live in any state other than Florida, and most of
California, Arizona and New Mexico, ice load should
be an important part of the design of towers and
antennas. For example, at my QTH in northern
Maryland, antennas and towers must be designed to
withstand 3/4 inch of ice with 40 MPH of wind.
Ice conditions in parts of New England and on the
western shore of Lake Superior are much more
severe, with 1.25 inch radial ice exposures in much
of the area.
Higher elevations in much of the U.S. experience
far more severe conditions. Its best to consult local
building inspectors and tower construction firms if
you plan to build a tower at high elevations or on the
shore of a large body of water.
Maps of ice and three second wind exposure in the U.S.
are located in the back of this document:
Good luck to Pat and others facing a major redesign and
rebuild this year.
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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