[TheForge] somewhat off topic: antenna tower

[Gabriel Cain]

I have some experience with microwave networking.  For what you're talking, you 
probably want to go the guyed tower route - it will be the cheapest, and the 
ligthtest.   Monopoles have to be guyed, too (3 guy wires from two locations up 
the tower 40% up and 90% up) (to avoid oscilations that even spacing would 
premit).

There are many guyed towers available.  And in my experience they are cheap to 
do.  (And really fucking scary to climb!!!)  Big self-supporting towers are far 
less scary than little guyed towers.

That said, good luck with the microwave internet.  It's very cool. :)

Andrews makes good antennas, btw. :)


terrylr@blauedonau.com wrote:
> hello;
> 
> i have searched the amatuer radio pages and have found alot about
> antenna but nearly nothing about building a tower. the little information
> i did find was assuming a large antenna with high wind loading.
> 
> basically what i want to do is build a 100 ft tall monopole tower.
> the only antenna on this tower is a 24 db gain parabolic dish microwave
> antenna. the wind loading is slight since it is a wired grid design.
> (
> if you are interested the antenna may be seen at:
> http://www.hyperlinktech.com/web/hg2424g.html
> )
> 
> one person suggested i get an aluminum flag pole. hey right they cost about
> the same as a self supporting tower not including the foundation work.
> 
> rohn self-supporting towers cost $10K+. that is way out of my price range.
> 
> i thought of using schedule 80 pipe and start out with 8 in pipe.
> use an 8 inch to 6 inch reducer. go with 6 inch for 40 ft and then reduce
> down to 4 inch for 20 ft then end in 2 inch. 
> 
>          |  |    <---- 20 ft of 2 inch
>          |  | 
>          |  |
>          |  |
>         /    \ <---- 4 inch to 2 inch reducer
>         |    |   <---- 20 ft of 4 inch
>         |    |
>         |    |
>         |    |
>        /      \ <---- 6 inch to 4 inch reducer
>        |      |  <---- 20 ft of 6 inch
>        |      |
>        |      |
>        |      |
>       /        \ <---- 8 inch to 6 inch reducer
>       |        | <---- 20 ft of 8 inch
>       |        |
>       |        |
>       |        |
> 
> i am unable to find my copy of the machnist handbook to look up the weight
> of each section, so i have no good feel for what it would weigh nor what kind
> of foundation should it have. it does seem to be over kill for such a small
> antenna. the only experience i have to go by is when i worked on putting in
> cellular towers. some of those had 50 ft deep 4 feet diameter concrete piers.
> with 20 ft long 4 inch bolts embedded in the concrete.
> 
> aluminum schedule 80 pipe cost more than steel schedule 80 pipe.
> there are benefits to using aluminum such as weighs less, will not rust.
> 
> the reason for building a new tower is the current tower is a rohn 25gt.
> it is next to the house. ( i know bad place to put it. ) at 40 ft it does not
> need guy wires at 100 ft it need three guy wires per leg. the family has voiced
> rather loudly that they do not want guy wired. i do not like guy wires either
> for safety reasons. people get 'clotheslined' by them.
> 
>