TopBand: Rohn SSV as 160M antenna?

Wed, 20 Aug 1997 12:39:56 +0000

> Subject:       TopBand: Rohn SSV as 160M antenna?
> Date:          Wed, 20 Aug 97 11:58:34 +0000

> I am putting up a rhon SSV 100' freestanding tower with #8 bottom
>section and #4 straight top section. There will be a 6 meter beam on 
>a 34' boom and a 17' mast out the top.  Has anyone else loaded s> 73 
>GEO (K0FF)

Hi George,

When a structure tapers to a narrower point at the outer end, it 
looks electrically shorter and the bandwidth gets narrower. Think of 
it as a backwards fed discone, with opposite results. 

That's because the distributed capacitance decreases right where you 
need it most, at the most concentrated area of E-field. You wind up 
with a long area of antenna with reduced current, and hence reduced 
radiation.

I have no idea how that will affect your tower, the beam on top 
will tend to offset the effect somewhat. It would be worth 
looking at on a modeling program, because you might find (or might 
not find) a uniform cross section wire cage will help.  

73 Tom

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