[TenTec] OT Kind of. ?? about wide band antennas

[Steve Hunt]

Paul,

When you say "bandwidth" I presume you mean "VSWR bandwidth".

The Resistive component of the feedpoint impedance of a dipole varies 
relatively slowly with frequency either side of resonance, but the 
Reactive component varies much more quickly; so it's the rate of change 
of the Reactive component which largely determines the VSWR bandwidth. 
The rate of change of the Reactive component is closely linked to the 
size of the conductor - the "fatter" the conductor, the slower the rate 
of change of Reactance, and the wider the bandwidth.

Hope that helps.

Steve G3TXQ



On 03/02/2011 21:10, Paul wrote:
> I have been asked a question about why the diameter of the conductor of
> antenna effects the band width.
>
> This question came up while in a discussion with a guy that had built a
> 80 meter dipole out of a semi ridged copper tubing 1/2 diameter.  One of
> the newer hams in the discussion was very curious and interested in the
> subject.
>
> I remember learning about this many years ago, but was totally unable to
> enplane the subject.  I know this group is the best repository of
> knowledge.  So your feed back is greatly appreciated.  I will forward
> your replies onto the interested ham.
>
> Thanks,
>
> Paul K.
> WA0BAG
>
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