>K7LXC@aol.com wrote:
>
>> In Statement #1 you say " The flat projected areas will."
>>
>> In Statement #2 you say "we get to use the larger areas contained
in the
>> oval outlines of the Rohn diagrams".
>>
>> Aren't these contradictory? My question still remains - "WHICH
figure do
>> we use to determine Rohn antenna load capacities vis-a-vis amateur yagis?"
>>
>> Cheers, Steve K7LXC
>>
>
>Hi,Sigh, this can be difficult to explain!Ok , Both of the oval and rectangular
>values in the Rohn drawings are projected
>area.
>The Oval one is larger, because the round members have less drag, hence, less
>load, hence, lower "effective area". The larger oval value generates the same
>applied load on the tower as the rectangular one.
>If the antenna is made with round tubing, use the oval area. If it is made from
>box tubing, use the rectangular area.
>Is that any better?
>
>73, Kurt
Hi Kurt,
I think you are totally correct in what you say, above, assuming you know
that the antenna manufacturer's square foot rating was calculated as HyGain
has just done, that is, Projected Area without regard to element shape.
Some antenna companies REDUCE their area specifications with regard to
element shape so I think there is risk of using this "area reducing" factor
twice in the same installation . . . once for the antenna loads and once
again for the tower ratings . . . this may result in a dangerously
overloaded tower. What do you think?
Stan w7ni@teleport.com
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