You'll find in this case that since your antenna height is close to, but
under a top guy, and the turning radius is rather large, that the guy
anchors must be very far away (relative to "standard designs") from the
tower to achieve your goal.
The math (no, you don't need any a^2 + b^2!)
You can calculate the "similar" triangles: they have the same angles, so the
sides scale. Sketch it to see.
The first (larger) triangle 1 is the full tower height (75') for one side,
tower-to-guy distance (length along the ground) as the other side, and the
guy wire itself as the hypotenuse. The other (much smaller) triangle 2 is
the beam-to-tower height (15') as one side, the beam-to-guy wire distance
(IOW, your turning radius = 25') as the other side, and the guy wire as the
hypotenuse. For clearance calcs, we don't even care about the hypotenuse
lengths.
The ratio of one side of triangle 1 to the other side of the same triangle
is the same as the ratio of one side of triangle 2 to the other side of
triangle 2.
75' : x = 15' : 25'
This makes guy anchor distance x = 125' for zero clearance. To get 1 foot
of clearance we change the 25' turning radius to 26' and get: 130' Then
there's ground irregularities and guy wire sag so you may opt for more
minimum clearance. Lower the antenna 5 feet and the 1-foot clearance anchor
spacing is only 98 feet Big difference. Of course, if you have the room
and the EHS...
Note that typical towers are guyed at ~80% of tower height which is about 67
feet in your case. Your original spec nearly doubled it.
Mike N2MG
> I am looking for a formula to determine in advance how far my guy anchors
> need to be for a side mounted antenna at any given height to clear the
> guys. Example, a 75' rotating tower with guy wires attached at 75' and an
> antenna with a turning radius of 25' at say 60'. I'm sure I could graph
it
> out, but I would prefer to know exactly before sinking anchors (I want to
> do things once).
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