Topband: Tophat? Does it have to be at the top?

[Donald Chester]

>There are very few hats that 100% stop all current beyond
>the hat, since it is really an impedance ratio problem and
>the hat is almost never near zero impedance and the area
>above the hat almost never near infinite impedance. Adding a
>hat can do about anything from the range of positive to
>negative effects depending on many separate issues.
>

I recall reading that a sphere makes more effective top loading than a 
simple disc shaped top hat.  Although I have never tried it, I have often 
wondered if you would get any improvement over a top  hat at the very top of 
the vertical by fabricating something in the form of a geodesic sphere, 
using wires and horizontal arms attached to the vertical element.  
Naturally, an 8' diameter sphere would take up the top 8' of vertical 
element.

-k4kyv

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