Guy wire roof anchors7/24/2023 ![]() There is potentially also a bending moment if the mast is connected rigidly to the ground, through for simplicity I've omitted it here. That force is countered by two others: tension on the guy wire (green), and compression on the mast (red). You propose having the anchor point only 3 feet away from the base, and I think that's only marginally better than no guying at all.Ĭonsider, the wind wants to blow the pole over (blue). Generally you would not want to bring the anchor point closer to the base than this. ![]() If you have a single 20 foot pole you might do without, depending on the rigidity of your pole and maximum wind load. Since this is a push-up mast it's in two sections, so this is unavoidable. ROHN also has a 2nd set of wires at the midpoint. Here you can see the top set of wires is up about 19 feet, and is 18 feet away from the base. The H20 has a maximum height of 19.25 feet, so not unlike your pole. You might look at the ROHN H20 push-up mast guy plan. Instead you may opt to employ "That Looks About Right" (TLAR) engineering principles, where you look at other things that have worked, combine some experience and intuition, and come up with something about right. In the case of an antenna, the most significant force is usually wind, and the objective is to make it strong enough that the structure doesn't blow over. You might calculate a sheer and moment diagram, look up all the material properties, and calculate the failure points of all the components. What you have is a basic civil engineering problem.
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