Re: Signal Piggybacking
Dr. Slack, Thu Jan 05 2017, 03:26PM

I suspect you're talking about Intermodulation Distortion.

Any incident magnetic field will cause a field in the material. High frequency fields will be attenuated by currents induced in the top layer of the material, the skin depth effect. As the frequency drops, the field penetrates further.

For low values of the field, the permeability will be constant, the B field in the material will vary linearly with the incident H field. For incident signals with two frequencies, the fields will vary with both, and for small signals, the response will be linear, and the effective permeability still constant. Even with two signals, neither will be 'affecting' the permeability.

With stronger signals, the magnetic response can become non-linear, and then you can regard the permeability as being altered, and effectively by whichever signal is stronger.

Look up 'passive intermodulation', a big problem in multi-band cellular antennae working at high power. The main problem is usually electrical, for instance partial contact between metals due to loose bolts or contaminated connectors, but ferrous components can also contribute. They tend not to be used intentionally, but a nearby steel fence can often be irradiated by the cell antenna and cause problems.

Re: Signal Piggybacking
Sulaiman, Thu Jan 05 2017, 05:27PM

Magnetic Amplifier
I imagine the elf signal driving the core, modulating the 600 Hz signal.