[AMPS] Re: The Worldwide, No Holds Barred, SWR Quiz.

[Gilmer, Mike]

On Monday, October 04, 1999 1:40 PM, Vic Rosenthal
[SMTP:rakefet@rakefet.com] wrote:
> 
> measures wrote:
> > 
> > >What is the SWR as measured at the generator with a 50-ohm
> > >characteristic-Z  SWR meter?
> > 
> > ? At the end of an any characteristic.-Z halfwave transmission line,
the
> > termination Z repeats itself --  with a reactance reversal.  .
Since
> > there is no reactance in this termination, the Z at the end of the
93-ohm
> > halfwave line is 50 +/- j0 ohms, the SWR is 1:1.
> 
> No.  It is correct that the impedance seen by the generator is 50 ohms
but the
> SWR is unchanged, regardless of the line length.   The SWR is entirely
> determined by the impedances of the line and the load.
>

Yes. From what everyone's told me, this is 1.86:1 (93/50) regardless of
the line length.
The Z looking into the cable is 50 ohms, but there's standing waves on
it from the load/cable mismatch.
Those SWs don't change (or go away) because the Z changes.
 
> > Question 3:
> > 
> > In Question 1, if the SWR meter were moved from the 1/2 wave point
to the
> > 1/4 wave point, what would the SWR reading be?.
> 
> The same, for the above reason.  The impedance seen by the generator
would
> change, though (see Smith chart).
>

Is it? I mean, the real SWR is 1.86:1, but in this case the impedance
looking into the cable is not 50 ohms (it was in Question 1).  Now it's
25 ohms.  So what does a 50-ohm swr meter actually display?
Depends on its construction I suppose?


> 73,
> Vic, K2VCO
> Fresno CA
> 


Mike N2MG

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