[TowerTalk] guy wire clearance

[Barry Kutner]

Hi Bruce,
Definitely an important calculation! I'm not aware of a formula, but it 
is a simple geometirc calculation using similar triangles. I really 
can't do formulas or draw diagrams on e-mail, so let me explain. 
Here's what you want to do:
You are setting up two ratios,
Height of guy wire above ground = y
Distance from tower base to guy wire or anchor entering ground = x
Distance from tower to guy wire at height of antenna = a
Distance from antenna to guy wire attachment on tower (which is 
the height of guy wire above ground minus the hieght of the 
antenna on tower) = b
Now, x over y = a over b. Solve for 'a' which = x times b divided by 
a.
'a' is the key number. You want the turning radius to be less than 
this. Don't forget to account for any horiz offset from tower by 
sidearms, width of tower section, etc. 
Do the calculation at least 3 times to make sure it's correct.

Personally, I made sure there was at least 3 feet of clearance, to 
acount for any mis-measuring, guy wire droop, and general fudge 
factors.
Hope this helps. 
73,
Barry

On 29 Sep 00, at 8:06, Bruce Makas wrote:

> 
> I recall that there is a simple formula that lets you know when an
> antenna will clear guy wires but I can't find it. Variables include
> antenna turning radius, height of antenna, height of guy wire
> connection and distance from base to ground guy point. Does any one
> have this formula handy?
> 
> 73, Bruce
> 
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--
Barry Kutner, W2UP              Internet: w2up@mindspring.com
Newtown, PA         FRC         alternate: barry@w2up.wells.com

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