Antenna Mast Wind Load Calculator
Peak velocity pressure by terrain and height to EN 1991-1-4, then the force and overturning moment your antennas put on the mast — and whether the mast is rated to take it.
What is mounted on the mast
| Item | Height (m) | Area (m²) | Shape | Cf |
|---|
Area is the projected area facing the wind. For a Yagi that is the boom plus the elements seen edge-on, not the turning radius. Manufacturers often publish it directly as “wind surface” or “wind load area”; use that figure when you have it.
How this is calculated
Wind pressure is not a single number for a site. It depends on how rough the ground upwind is and how far above it you are, and EN 1991-1-4 builds it up in steps.
The basic velocity pressure is what the wind would do in clean air:
The roughness factor scales the mean wind for terrain and height. Below a terrain's minimum height the profile is frozen rather than extrapolated down, because the formula stops meaning anything near the ground:
Then turbulence is added, because gusts are what break things, not the mean:
And finally force on each item, and its moment about the mast base:
A check the standard runs on itself
The basic wind velocity is defined as the 10-minute mean at 10 m over terrain category II. So the roughness factor at exactly that point has to come out as 1, and it does: 0.19 · ln(10/0.05) = 1.007. That only works if the terrain table and the terrain factor expression are both right, which makes it a useful thing to verify an implementation against — including this one.
Height costs you twice
Raising an antenna does two things at once: it reaches faster wind, and it lengthens the lever arm. Doubling the height of a given antenna typically more than triples its contribution to the base moment. This is the single most common way a mast that “worked fine last year” stops working after somebody adds half a metre of pole.
EN 1991-1-4 terrain categories
| Category | z0 (m) | zmin (m) | kr | qp at 10 m, vb = 26 m/s |
|---|
Where the numbers come from
Terrain parameters and the terrain factor are from the published EN 1991-1-4:2005+A1:2010 text (Table 4.1 and expression 4.5), including zmax = 200 m and the recommended air density of 1.25 kg/m³.
The force coefficients are not from any standard, and that is deliberate. TIA-222’s appurtenance coefficient tables sit behind a paid standard and the secondary copies in circulation are incomplete, so reproducing them here would mean publishing numbers that could not be checked. The values offered are typical published figures for simple shapes, every one is editable, and a manufacturer’s coefficient or wind-load area beats all of them.
Your basic wind velocity vb is a local climate figure from your National Annex wind map, not something to guess. It varies enormously: inland Spain sits near 26 m/s while exposed Atlantic coast reaches 29 m/s and parts of northern Europe go higher. Look yours up.
Limitations
This is a static force calculation for a cantilevered mast. It does not cover dynamic or resonant response, vortex shedding, ice loading (which both adds area and adds weight), guy wire tensions and the compression they put into the mast, the fixing or foundation that the mast is bolted to, or any partial safety factors your national code applies. It computes the characteristic load; applying load factors and checking the structure is structural engineering, and for anything carrying real consequence that is a job for someone qualified to sign it.