Antenna Deflection Requirement

[rd78]

Hello-

I wonder if some of you RISA Tower users or other experts can help me understand a requirement. The requirement states "maximum sway of 0.4 degrees from the top or 2% of the height, whichever is less". I can certainly calculate the deflection due to wind and compare to 2% of height. I am asking about the meaning of sway in degrees from the top. Is that the calculated slope of the deflected shape? I see that RISA calculates a "tilt", but I don't know physically what that means (not a user). Perhaps it's the same thing?

Thanks

rd78

 

[csd72]

Just take the deflection of the two top most nodes and calculate the deflection angle from that.

 

[MikeDB]

TIA-222-G defines sway as the angular rotation of an antenna beam path in the local vertical plane of the antenna from the no load position. It is normally measured at service load condition rather than an extreme load condition. So it has to do with slope rather than deflection.

The 0.4 degrees would be a sway limit, but the 2% would be a deflection limit.

According to the RISA TOWER manual, they call sway "tilt".