[TowerTalk] Antenna Windload Ratings & Tower Windload ratings

[jimlux]

On 6/13/17 4:17 AM, TexasRF--- via TowerTalk wrote:
> Kurt, please correct me if I am wrong. When I read EIA/TIA 222 I see
> reference to EPA which I have assumed means Effective Projected Area, Not simply
> "projected area" or "effective area"  as mentioned in your email. I know
> this is splitting hairs but we might as well call it by the correct name to
> help  reduce the confusion that has been going on so long as you so well
> brought  out.
>

It is a bit challenging, because there's several EPAs and there's some 
coefficients involved in calculating the loads

The old standard basically assumed a constant Cd, independent of windspeed.

The newer standard takes into account the Reynolds number effects, so 
the EPA changes with windspeed, so you can't just use one number to rule 
them all.

That is, the antenna mfr would need to publish a set of numbers for the 
different wind speed zones.

However, I can't see this taking more than a few hours for a typical 
multielement Yagi, especially once you've built a little spreadsheet to 
grind through the calculations.

The rev G standard also considers seismic loads, and does away with 
"normal" soil.

This seems to cover a lot of it:
http://www.towernx.com/downloads/TIA-222-G_Explained.pdf