# 'quarter wave vs lumped models'

```Subject:  'quarter wave vs lumped models'
Date:   Wed, 7 May 97 09:04:28 EDT
From:   pierson-at-ggone.ENET.dec-dot-com
To:

mail11:;;;;;-at-us4rmc.pko.dec-dot-com-at-us4rmc.pko.dec-dot-com-at-unknown.domain.pupman-dot-com;;;;;;;;
(-at-teslatech)
CC:
pierson-at-ggone.ENET.dec-dot-com

>One of the ways of looking at a Tesla coil is to think of it as a
>quarter wave transmision line.

>A PERFECT quarter wave line can be thought of as a current to voltage
>converter (or vice versa) where the voltage at the top is proportional
>to the current at the bottom.

>There have been some heavy discussion on the list about quarter wave
>line vs. lumped constant models of Tesla coils,

Philosophical rant on.  8)>>

(NB: NO Directed AT anyone...)
There seems to be something in the human approach to solving
problems that leads to this _vs_ that, one _or_ the other.  In
some cases its applicable.  In Some Cases NOT.  In the case of
coiling:

Fact:
Any coil will have a physical self-resonant frequency, based
on wire length and aspect ratio.
Fact:
Any coil will have a 'lumped constant' self-resonant frequency,
based on 'L' and 'C'.

From which it follows that any coil has two resonant freqs [1].

Speculation:
A key ingredient in The best performers is to have the _two_
freqs
closest together, or equal, (other things being equal).  Where
the lumped_constant resonance and the physical_length resonance
are the same.

I'm not speaking of primary/secondary interactions, but of any
coil (or coil plus cap, in the case of a primary) having two
freqs, which (for best performance) need to be the same.

Or i could be talking rot...

===========
[1]
Actually, there will be lots of freqs, notably the physical one will
resonate at f, 2f, 3f, etc, etc.  But confining thoughts to the
'fundamental' (1/4 wave) case is reasonable.

regards
dwp

```