[TowerTalk] Slopers from tower

[n4kg@juno.com]

You're missing my point.

The sloper acts as a single 1/4 WL sloping radial
that radiates since there isn't an opposing radial
to c-a-n-c-e-l* it's radiation.   (*forbidden word:-)

The Yagi acts as a Top Load for the vertical
radiator between the feed point and the Top Load.

The Top Load does NOT radiate, but currents in the
vertical portion between the feedpoint and the top load
DO radiate.

Radiation will occur regardless of where the 1/4 WL
sloper is attached.  IF the attachment point results
in the upper portion of the tower plus mast plus
TopLoad representing a (resonant) 1/4 WL, THEN
you will have ZERO reactance at the feedpoint,
resulting in a reasonable match to 50 Ohm Coax
(i.e. Low SWR).

Another way to look at it is that the 1/4 WL sloper
acts as the bottom half of a sloping dipole.  The
(top loaded) vertical section between the feedpoint 
and the top load forms the other half of the (bent)
sloping dipole.

Currents in the tower below the feedpoint may
add or detract from the radiated signal depending
on the geometry, grounding, and other (side) loads.

Tom  N4KG



On Fri, 4 Jan 2002 11:29:09 EST UpTheTower@aol.com writes:
> 
> In a message dated 1/4/02 7:11:26 AM Pacific Standard Time, 
> owner-towertalk@contesting.com writes:
> 
> > Another example:
> >  
> >  K4VX/0 used 1/4 wave slopers for 160 meters fed about 10 feet 
> below his 3
> >  element full sized 40 meter yagi.  The yagi was at 130'.  
> >  
> >  Obviously not 1/4 wave seperation between the feed point and the 
> top load. 
>  
> >  But plenty of tower top load to act as a good counterpoise.  
> Which is the
> >  important thing.  Not the seperation between the top load and the
> >  feedpoint.
> >  
> >  73
> >  
> >  
> 
>
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