# Re: [TCML] LMD Frequency

```It is well understood that the normal oscillation of a TC
secondary is a longitudinal mode - meaning that the E-field and
H-field both point along the axis of the coil.   By contrast,
the transverse mode is what you'd find in a helical antenna
coil where E and H field vectors point across the diameter.

In a longitudinal oscillation, there is a small amount of
far field radiated perpendicular to the coil, whereas the
transverse mode can radiate quite well out along the axis.

In the transverse mode, voltage differences are max between
opposite sides of a turn whereas in a longitudinal mode the
voltage differences occur along the length of the coil.

There are multiple longitudinal modes - we are very familiar
with them and we sometimes label them 1/4 wave, 3/4 wave and
```
so on. Also there would be a spectrum of transverse modes if the Tesla secondary coil was not too lossy to support them.
```
In a typical sized secondary coil the longitudinal modes occur
at low frequencies, say 30-3000kHz whereas transverse modes
would occur at much higher frequencies - tens or hundreds of
MHz and a TC is probably too lossy for them to be detected
as a resonance because energy propagating in a transverse
mode would probably decay to nothing before it got a chance
to travel the coil length and be reflected.

The longitudinal resonances are easy to model because the
free-space wavelength is much larger than the dimensions of the
coil. This means that to a very good approximation, a change to
the voltage or current in one part of the coil can be considered
to instantly affect the field throughout the coil, so only
Faraday and Coulomb laws need to be used.   A consequence is the
coil can be modeled accurately using a network of small inductors,
capacitors and resistors to represent the distributed reactances
and losses of the system.

'Longitudinal Magneto Dielectric' is not a term used in
science, it's  a nonsense term made up by cranks.   There are
a few mentions of it on the web - they are all crank sites
containing a variety of nonsense of the not-even-wrong kind.
It is rather sad to see such ignorance and superstition and
it's tragic to see enthusiasts being drawn into it.

--
Paul Nicholson
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```