[TowerTalk] Topband: "T"-Top Vertical Antennas

Joe Subich, W4TV lists at subich.com
Thu Jul 23 21:15:46 PDT 2009

> One of the advantages of the "T" antenna---vs. the inverted 
> "L"---is that horizontally polarized/high angle radiation is 
> supposed to be cancelled by virtue of the opposing tee tops...
> correct?


> So---by lengthening the tee tops, we are---as has been stated 
> here before---moving the current peak up the antenna, away 
> from the base, and toward the tee...still correct?

Also correct. 

> And if THAT'S still so, aren't we then creating an 
> ineffective antenna, by virtue of the facts that:

Absolutely not. 

> (A) It's useless as a DX antenna because the 
> vertically-polarized low-angle current node has moved 
> UP the vertical portion, becoming more high-angled and 
> horizontally-polarized, and,

Your interpretation is incorrect.  The vertically polarized 
radiation is proportional to the integral of the current 
from the feedpoint to the junction of the "T."  It does not 
matter where the maximum (or minimum) is located but placing 
the maximum in the center of the vertical portion, the integral 
of the current is maximized for a given vertical length.  

Raising the height of the current maximum does not raise the 
take off angle any more than elevating a vertical ("ground 
plane") raises the takeoff angle.  Further, as long as the 
"T" arms are balanced, the horizontally polarized radiation 
(radiation from the "flat-top") will be cancelled in the 
far field.  


   ... Joe, W4TV 

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