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.