TSSP: Tests and Measurements

A model or simulation is meaningless unless there is firm experimental evidence that its predictions agree with reality. This page provides a summary of the comparison tests which have been applied to this model.

Updated: 19 Jul 2008


Results are presented for
Resonant frequencies, the lowest few overtones are compared.
Voltage profiles, detailed voltage profile measurements by Terry Fritz.
Current profiles, detailed current profile measurements by Terry Fritz.
Transimpedance, and effective series inductance, requiring measurements of top voltage and base current.
Energy storage inductance, requiring measurements of input impedance and Q factor.

Coils are identified by a 'system name', the first two letters of which indicate who provided the measurements, according to the following table:
mdMarco Denicolai
mmMarc Metlicka
mwMalcolm Watts
mzMark Rzeszotarski
pnPaul Nicholson
skKurt Schraner
tfTerry Fritz

We use the abbreviations f1, f3, f5, etc to indicate the resonant mode in terms of the number of electrical quarter-waves involved in the whole resonator, ie topload included.

  Resonant Frequencies

Unless otherwise stated, these resonant frequency results apply to the base fed model configuration. Results shown are all computed with version 0.9d of the model - a version which is set up for a fairly quick calculation, at the expense of accuracy. Coils are listed in order of reducing h/d ratio.

Unloaded (Bare) Coils

      measured   modeled error

 mm2: bare d=0.108m h/d=9.97 sr=0.81 b/h=0.31 turns=1700
 f1    276.9kHz  272.7kHz -1.5%
 f3    711.8kHz  696.9kHz -2.1%

 mm1: bare d=0.091m h/d=8.92 sr=0.76 b/h=0.41 turns=1221
 f1    455.5kHz  464.1kHz +1.9%

 sk16b55: bare d=0.161m h/d=8.71 sr=0.90 b/h=0.39 turns=1976
 f1    161.4kHz  155.5kHz -3.7%
 f3    386.4kHz  385.5kHz -0.2%
 f5    562.0kHz  566.7kHz +0.8%
 f7    710.3kHz  725.2kHz +2.1%

 mm4: bare d=0.114m h/d=6.78 sr=0.83 b/h=0.39 turns=1600
 f1    237.0kHz  241.9kHz +2.1%

 tfsm1: bare d=0.108m h/d=6.14 sr=0.91 b/h=0.03 turns=1176
 f1    358.8kHz  357.2kHz -0.5%
 f3    883.1kHz  882.3kHz -0.1%
 f5   1265.5kHz 1295.0kHz +2.3%
 f7   1602.5kHz 1628.9kHz +1.6%
 sk12b49: bare d=0.121m h/d=4.83 sr=0.92 b/h=0.84 turns=894
 f1    405.1kHz  405.9kHz +0.2%

 mm3: bare d=0.221m h/d=4.66 sr=0.93 b/h=0.35 turns=2989
 f1     61.9kHz   63.4kHz +2.5%
 f3    157.9kHz  157.4kHz -0.3%
 f5    229.7kHz  229.3kHz -0.2%
 f7    294.4kHz  295.0kHz +0.2%
 f9    355.6kHz  358.7kHz +0.9%

 mwa1-4hd0: bare d=0.168m h/d=4.00 sr=0.92 b/h=0.74 turns=1106
 f1    224.0kHz  224.1kHz +0.1%

 mwa2-4hd0: bare d=0.168m h/d=4.00 sr=0.49 b/h=0.74 turns=1106
 f1    220.0kHz  224.0kHz +1.8%

 sk20b49: bare d=0.205m h/d=3.26 sr=0.90 b/h=0.73 turns=943
 f1    217.2kHz  206.4kHz -5.0%
 f3    497.8kHz  488.8kHz -1.8%
 f5    709.9kHz  716.8kHz +1.0%

 tfltr: bare d=0.261m h/d=2.92 sr=0.67 b/h=0.03 turns=1000
 f1    148.4kHz  146.5kHz -1.3%
 f3    353.4kHz  353.4kHz +0.0%
 f5    513.8kHz  522.7kHz +1.7%
 f7    666.4kHz  674.0kHz +1.1%
 f9    819.8kHz  850.0kHz +3.7%
 f11   977.4kHz 1015.1kHz +3.9%
 f13  1133.1kHz 1188.5kHz +4.9%
 pn2: bare d=0.580m h/d=2.84 sr=0.88 b/h=0.08 turns=725
 f1     92.0kHz   91.2kHz -0.9%
 f3    213.0kHz  217.9kHz +2.3%
 f5    320.0kHz  322.7kHz +0.8%

 pn1: bare d=0.590m h/d=1.36 sr=0.91 b/h=0.05 turns=356
 f1    150.7kHz  152.2kHz +1.0%
 f3    360.0kHz  367.1kHz +2.0%
 f5    543.0kHz  573.8kHz +5.7%

Loaded (Toroided) Coils

      measured   modeled error

 mdthor: toroided d=0.400m h/d=3.94 sr=0.86 b/h=0.05 turns=939
 f1     65.5kHz   66.5kHz +1.5%
 f3    222.8kHz  240.0kHz +7.8%
 f5    346.3kHz  371.2kHz +7.2%

 tfltr45: toroided d=0.261m h/d=2.92 sr=0.67 b/h=0.03 turns=1000
 f1     97.9kHz   95.3kHz -2.6%
 f3    321.4kHz  327.4kHz +1.9%
 f5    490.2kHz  506.3kHz +3.3%

 pn2t: toroided d=0.580m h/d=2.84 sr=0.88 b/h=0.08 turns=725
 f1     66.7kHz   66.2kHz -0.7%
 f3    193.3kHz  206.2kHz +6.6%
 f5    307.0kHz  316.4kHz +3.1%

Small radius/high elevation coils

We are having some difficulties at small radius and high elevation, as can been seen from the following results:

      measured   modeled error

 sk5b185: bare d=0.051m h/d=8.03 sr=0.91 b/h=0.45 turns=934
 f1    919.5kHz  958.5kHz +4.3%

 mz1: bare d=0.051m h/d=6.00 sr=0.92 b/h=2.33 turns=875
 f1    885.0kHz 1041.2kHz +17.7%
 f3   2338.0kHz 2520.5kHz +7.8%
 f5   3436.0kHz 3673.9kHz +6.9%

 mz2: bare d=0.051m h/d=6.00 sr=0.87 b/h=2.33 turns=1310
 f1    645.0kHz  699.9kHz +8.5%
 f3   1627.0kHz 1694.6kHz +4.2%

 mz3012-1: bare d=0.089m h/d=3.18 sr=0.88 b/h=0.07 turns=622
 f1    647.8kHz  695.7kHz +7.4%
 f3   1575.4kHz 1669.6kHz +6.0%
 f5   2264.1kHz 2461.5kHz +8.7%

 mz3012-5: bare d=0.089m h/d=3.18 sr=0.88 b/h=1.97 turns=622
 f1    665.9kHz  714.9kHz +7.4%
 f3   1591.1kHz 1687.2kHz +6.0%
 f5   2277.9kHz 2474.2kHz +8.6%

 mwa1-1hd0: bare d=0.168m h/d=1.00 sr=0.91 b/h=3.94 turns=272
 f1    600.0kHz  633.3kHz +5.5%

In some cases these discrepancies are caused by the model's failure to take into account lead wires and fittings near the top of the coil. Failure to account for the coil former's dielectric properties may also be a contributing factor. At high elevation the coil's capacitance is hard to determine accurately. Work is ongoing to resolve these difficulties, but there is as yet no evidence that these poor results invalidate either the model or the theory.

Estimate of prediction error limits, for coils b < h, h/d > 1.5, and d > 0.1 are

1/4 wave, +/- 4%;     3/4 wave, +/- 3%;     5/4 wave, +/- 3%;

when using the following resolutions:

M: turns x turns,     Cint: 32 x 512,     Cext: 512,     Ctor: 32

Difficulty accounting for the coil's surroundings is the reason behind the poorer estimation at f1.

For h/d < 1.5 the internal capacitance begins to dominate and the model tends to over-estimate the higher mode frequencies, we think because we are not allowing for the permittivity of the coil former dielectric. A first order correction for this is in the pipeline.

  Transfer Impedance

The equivalent series inductance Les is related to the forward transfer impedance by
Zft = j w Les
so that
|Vtop| / |Ibase| = w Les
Therefore by simultaneously measuring the top voltage and base current at f1 to obtain Zft, we can immediately calculate Les. The top voltage measurement requires a probe connection directly to the top of the coil, which introduces some additional capacitance and load resistance. The predicted values are obtained from a model in which the probe capacitance is adjusted to make the predicted f1 match the observed f1, after having first ensured that the resonance of the unprobed coil is modeled correctly.

Terry Fritz measured his small coil to obtain the comparisons

       measured     modeled       error
tfsm1p: probed d=0.108m h/d=6.14 sr=0.91 b/h=0.01 turns=1176
 f1:  310.9 kHz    310.9 kHz      0.0%  Ctop adjusted to match: 3.145 pF
 f3:  847.8 kHz    828.4 kHz     -2.3%
 Zft:   34450 ohms  34874 ohms   +1.2%
 Les:   17.64 mH    17.85 mH     +1.2%
  Equivalent Energy Inductance, Lee

The energy storage inductance is related to Q factor and input resistance at f1 by
Rin = w Lee/Q
By taking simultaneous readings of Rin and Q at f1, we can measure Lee.

Terry Fritz has provided the following comparisons for his small coil.

        measured     modeled       error
 Lee:   13.58 mH     13.66 mH      +0.6%

Maintainer Paul Nicholson,