TSSP: List Archives

From: Paul
Date: Wed, 20 Dec 2000 19:27:48 +0000
Subject: Re: [TSSP] Coils at high elevation

boris petkovic wrote:

> Despite that 5-10% energy storage part,overall Cint
> influences to 1/4 fo of usual way built close wound
> coils (cylindrical shape of winding not a conical)
> less than might be orginally supposed by upper percent
> presented.

My understanding differs with you there Boris, but then my
understanding is in line with the simulator predictions,
and the simulator predictions appear wrong at high
elevations, so I'm out on a limb. Need more high elevation
measurements to resolve this. 

> As fn resonant frequency increases situations change
> -the effect of  Cint influence  to higher harmonic
> frequency cannot be neglected anymore.

Again we differ. I argue in pn2511, section 5, last para-
graph, that Cint has less effect above the 4th resonance due to
physical range of Cint spanning a wider phase, therefore
on average cancelling effect on phase constant. I admit this
is a weak handwaved argument and I don't know how to work out
the phase constant. But the intervals between resonances are
uniform above the 4th, according to simulator. More measurements
will confirm/refute the uniform interval between odd numbered
resonances about the 4th.

> This year I sent  Malcolm an outline of my papers
> where I explained how and why that appears.

I'd like to see those.

I wrote:

> > At high elevations,
> > external capacitance is reduced and the internal is
> > much more
> > significant. For Malcolm's h/d=1 coil, the internal
> > capacitance
> > accounts for over 50% of the total E-field energy
> > storage [+].

Boris wrote:

> Very much indeed.
> But it is my opinion anyway that  factor of influence
> to 1/4 wave freq. is smaller than
> g=sqrt(Cexternal)/sqrt(Cinternal+Cexternal)
> 
> where fo=g*foe
> 
> foe means calculted res. freq. taking into account
> just external capacity of coil.

You may be right there. Some more arithmetic will demonstrate
if fo/foe < g is an identity.

> -----
> > Therefore if either the determination of, or the
> > implementation of, [Cint]
> ----
> I think it could be implemetation but I'm not sure.
> ----

Yep, I'll try to interpolate past those flat tops of Cint.
 
> > internal capacitance is faulty in any way, the
> > effect will be up
> > to 10 times worse at high elevations. The effect of
> > internal
> > capacitance on the amplitude profiles is
> > particularly interesting,
> > so I'm keen to use high elevation measurements as a
> > means of
> > validating the internal capacitance modeling.
> -----
> Fine.Msm will decide

Yes. f1,f3 and f5 on suspended coils of around h/d = 4 and
h/d = 1 would do nicely.
 
> > [+] Mark's coil, which exhibits a higher discrepancy
> > in f1, has
> > a Cint contribution of only 17%, since it has h/d=6
> > which gives a
> > smaller Cint to begin with. This leads me to believe
> > that Cint is
> > not to blame.

> Becouse of high h/d ratio that is my thinking too.

I hope so - Cint is the hardest to fix! Has anyone heard
from Mark lately?

Regards,
--
Paul Nicholson,
Manchester, UK.
--


Maintainer Paul Nicholson, paul@abelian.demon.co.uk.