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[TowerTalk] Where did 0.6 come from?

To: towertalk@contesting.com
Subject: [TowerTalk] Where did 0.6 come from?
From: kr2q@optimum.net
Date: Sat, 09 Feb 2013 17:13:00 +0000 (GMT)
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
1.  I am not an engineer2.  Here is where I thought "0.6" came fromBack in the 
late 60's, when I was still in HS, the "square footage" of antennas was a hot 
topic.There were long discussions (in person) about "how did they get that."A 
common practice among my peers at that time was to "do the math" to extent we 
could.Calculating surface area was easy enough, but on a round surface, there 
is only one point(at 90 degrees) that "sees" the full impact of the wind.  As 
one approaches the 0 and 180 points, well, that "point" is barely visible to 
the wind.Somewhere (I can't recall from where now), a simple approach was to 
use the projection of around surface (cylinder).  If you do the math, it comes 
out to somewhere between .6 and .66of the surface area (using round numbers).  
I always used 2/3.I hope the table below comes out OK.But either way, if you 
round off to the nearest whole number, both work the same.And THAT is what I 
did, way back when.  Maybe completely unfounded.  LOLNow, I just go by the 
manufacturer specs.  Probably worth checking.de Doug KR2Q


 
  
  diameter
  
  
  1/2 surface
  
  
  use 0.6
  
  
  use 0.66
  
 
 
  
  1
  
  
  1.571
  
  
  0.9
  
  
  1.0
  
 
 
  
  2
  
  
  3.142
  
  
  1.9
  
  
  2.1
  
 
 
  
  3
  
  
  4.712
  
  
  2.8
  
  
  3.1
  
 
 
  
  4
  
  
  6.283
  
  
  3.8
  
  
  4.1
  
 
 
  
  5
  
  
  7.854
  
  
  4.7
  
  
  5.2
  
 



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