In a message dated 11/4/2008 1:08:00 P.M. Pacific Standard Time,
> 10 Feet - 55 Sq Feet
> 20 Feet - 25 Sq Feet
> 30 Feet - 9 Sq Feet
> 35 Feet - 4.7 sq Feet
> This is based on the 70 MPH Winds.
> To find this chart, go to
> Click on On Line Catalog (Bottom Left of the Menu Bar)
> GT Series (Top Right)
> 25 G (Again, Top Right)
> Then Allowable Antenna Areas
I followed the above instructions and couldn't find the Allowable
Antenna Areas anywhere. :-(
OTOH I do have a Rohn brochure entitled "Manufacturer's Technical
Information for Bracketed or Self Supporting Towers". I don't know the date of
it so I don't know what rev of the TIA-222 it's based on. This is what it
says for 70 MPH:
10 feet - 42.5 sq.ft.
20 feet - 22.0 sq.ft.
30 feet - 12.0 sq.ft.
35 feet - 8.7 sq.ft.
40 feet - 5.1 sq.ft.
45 feet - 2.3 sq.ft.
I'm not sure how to reconcile the different specs but if you're
going to err, err on the side of being conservative engineering-wise.
For the record there is another base spec for a self-supporter that
is kind of hard to find too.
For the guy who wanted to go 45 or so feet above a housebracket with
45G @ 70 MPH, the same pamphlet says
14 feet above the housebracket is 31.0 sq.ft.
24 feet above the housebracket is 13.8 sq.ft.
34 feet above the housebracket is 5.5 sq.ft.
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