[Elecraft] What Vertical Antenna Do I Need?

[FISCHER,GREG]

If I remember correctly, the manual for the Sigma V says 
to run the coax away from the antenna at ~90degrees as 
much as possible to prevent coupling.

I had one of these in the past and was always amazed at 
how well it performed for such a small antenna.


Greg-AB7R


On Tue, 13 Jun 2006 11:14:40 -0700
  Vic K2VCO <vic at rakefet.com> wrote:
> Stuart Rohre wrote:
>> They are coax 
>> fed,with bead chokes on the coax so that bringing off 
>>the coax from the 
>> center is not a problem.
> 
> This isn't true.  The bead balun solves the problem of 
>current flow on the outside of the coax which occurs when 
>the feedline length is such that the outside of the coax 
>has a low impedance compared to the impedance of the line 
>(that is, the common mode impedance is not much higher 
>than the differential mode impedance).  It does *not* 
>prevent imbalance caused by capacitive coupling between 
>the outside of the line and one of the legs of the 
>vertical dipole.
> 
> It's still a good idea to try to reduce such coupling. 
> Having said that, it probably doesn't matter much in 
>practice unless you run the coax parallel to the antenna 
>for some distance.
> -- 
> 73,
> Vic, K2VCO
>Fresno CA
> http://www.qsl.net/k2vco
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