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Re: More ISSTC theory stuff
Original poster: Ed Phillips <evp-at-pacbell-dot-net>
" >Very interesting. I myself have a lot of experience with designing
>microstrip versions of 1/4 wave transformers and similar.
Sorry, I think this needs some more explanation. Here is my theory...
In a ISSTC, the secondary is a 1/4 wave transformer and the primary is
L-match. The fact that they are inductively, rather than directly
complicates things, but not much. (The inductive coupling can be
an ideal step-up transformer, as Antonio showed in his diagram, and
Burnett explains on his site)
Anyhow, a 1/4 wave transformer is equivalent to a L-match, at its
frequency. So if we are modelling the ISSTC at resonance (and since it's
feedback system, it will ALWAYS run at resonance) then we can picture it
two L-matches, OR two 1/4 wave transformers, with the inverter at one
(stepped up by that ideal transformer) and the streamer load at the
If you use PSpice you will end up modelling it as L-matches with lumped
components, since PSpice didn't have a transmission line resonator
last time I looked."
I disagree with a lot of this discussion, at least insofar as it calls
a top-loaded secondary a "quarter-wave transformer". No way! The
typical top-loaded secondary has an almost constant current distribution
and therefore must be considered as an inductor, not a transmission
line. The only transmission line which has a constant current (or
voltage) distribution is one terminated in its characteristic impedance
and is thus equivalent to a transformer with a ratio of 1.