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Re: Coherence Terminology and Theory
Hi Will,
> Original Poster: "Payne, Will E" <will.e.payne-at-lmco-dot-com>
>
> Some of the discussion about 'coherence', 'beating' and 'decrement' in
> Malcom and Richard's threads still eludes me. If they are defined in the
> archives, I have missed it somehow. Would someone please give a brief
> description or URL defining these terms and their related theory ?
The coherence theory (which I did my best to elaborate on in my
previous post) is solely related to resonator behaviour. The two modes
in question are lumped and transmission line (with one end
unterminated and the other tied to a low impedance). A coil with no
topload is a slow wave structure. Proof of that is that it is
physically much shorter than an equivalent 1/4 wave whip at the same
resonant frequency.
> Also, a question, perhaps related. A pair of resonators exhibit a double
> tuned response when overcoupled. It seems to me that the 'beat' frequency
> between the response peaks would equal the rate at which an applied energy
> pulse 'sloshes' back and forth between the resonators. If so, optimum
> coupling would be strongly related to quenching. Am I on the right track,
> and is this related to the previous question ?
Absolutely correct. In fact, the spectral response of the (over)
coupled system does not give an accurate picture of time domain
goings-on which is exactly what you suggest and which gives rise to
the split spectrum when viewed in the frequency domain. I am certain
that this has been misinterpreted in some quarters. For example, it
is true that if one looks at the spectral response one can rightly
conclude that Fr is not present in the normal unloaded overcoupled
condition with which our coils *must* operate if they are to effect
complete energy transfers. However, looking at it in the time domain,
one sees the primary amplitude decreasing at Fr while the secondary
amplitude increases at Fr.
The overcoupled concept is a pure product of the fact that the
coil operates on a limited energy store contained in the primary
capacitor. Remove that element, shunt the primary cap with a signal
generator etc. and the resultant waveform no longer exists as one
enters CW operation by virtue of an energy source being continuously
on tap. It is the process of emptying the primary store that gives
rise to the response in the first place whatever the spectrum might
show. This part then is about beating and decrement.
This is solely my opinion.
Malcolm
<snip>