Antenna loading on monopole design

[bujaman]

I am doing monopole design according to TIA-222-G and was wondering about antennas. If I have an array of 4 antennas around the pole at 0°, 90°, 180°, and 270° and the wind is coming from 0°, then do I have to take into account the antenna at 180°? If so, is the force reduced at all? Thanks in advance.

 

[oldestguy]

Do your antenna providers give wind loadings for different directions and for specific wind velocities? As a ham operator we sometimes get that data for our antennas.

 

[bujaman]

No, most large cellular and microwave antenna manufacturers don't provide that sort of information. I wish they did!

 

[rb1957]

"all" you want is drag ?

Quando Omni Flunkus Moritati

 

[msquared48]

Actually, on some of the antenna spec sheets I have seen, they do provide the wind loading. It varies with the manufacturer though.

I never use them though, relying on the pressures generated by programs such as TnxTower for the specified antenna.

Mike McCann
MMC Engineering

 

[Lesali]

If your antennas are close mount you may not need to consider wind loading on the antenna opposite your wind direction but, if you exceed the distance allowed for shieding then, yes, you need to consider it and a reduced wind force is permitted depending on the amount of shielding provided by the pole (not the opposite antenna). Check TIA 222 for shielding criteria.

 

[racookpe1978]

Well, assume that there is some significant advantage to "not loading" the antenna at 180 degrees with the wind from due north - from 000.

Then, a few minutes later that wind shifts to "slightly not from due north" from 030 or 045. Now, all four antennas are exposed to the wind, and only slightly shielded by the tower itself.

I would check again with all four into account for a wind from 045. It may not be a great increse, but the real world tower will see that off-angle loading as often as a square-on load of 000, 090, 180, or 270.

 

[Ron]

Agree with racookpe1978...check the oblique direction