Topband: T Vertical feed

Paul Christensen w9ac at arrl.net
Fri Jan 27 07:20:16 PST 2012


> This is a terrible error in logic.  Current on the radials will divide
> based on the impedance of each radial.  If the feedline happens to be
> a "pathological" length its (outer) shield can carry *all* of the
> antenna return current.

To Joe's point, I don't think we want the feedline to become a radial.  It 
also seems that placement of the line should occur under the radial field 
and not on top of it, but I have not seen any studies that compare 
measurements.  Anyone have this data?  My initial thought for base-fed 
verticals is to use a CM choke at the base and also at the perimeter of the 
radial field, unless by placing the line under the field significantly helps 
to reduce coupling to the line.

Paul, W9AC 



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