On Thursday 04 April 2002 12:09, Ian White, G3SEK wrote:
> Steve Thompson wrote:
> >On Thursday 04 April 2002 09:56, Ian White, G3SEK wrote:
> >mega snip
> >
> >> Case 1. Directional coupler terminated by a transmission line and
> >> mismatched load; theory based on forward and reflected waves.
> >>
> >> Case 2. Directional coupler terminated by a lumped-component load;
> >> theory based on the relationship between voltage and current at a single
> >> point - NO transmission-line concepts to be used in this theory!
> >
> >The directional coupler is the section of transmission line, and
> > reflections occur at its output end.
>
> That's only one particular type of directional coupler. Something like a
> Bruene bridge doesn't have any internal transmission line, and can be
> considered as making true single-point samples of current and voltage.
Doesn't the 'usual' construction use a coax throught the current transformer,
with one end of the outer disconnected so you get the continuity of
transmission line impedance while also getting the current transformer
effect. Even if you have a plain conductor going through the transformer, it
will have a Zo and some transmission line characteristics unless it has zero
length - can't get my head round whether that would account for things.
Steve
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