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Hi Mudge,
OK, now I see your reasoning a bit better... Is the 3F4 study on the 'partnered coils' list somewhere?
The guy who did extensive study of the dielectric constant of various ferrites was J. L Snoek, but his book came out in 1947. There is also a paper in my files somewhere on 'anomalous dispersion in ferrites'. I'll do some looking and see if there is more hard data on 'ferridielectric dispersion'. I found a paper on e in NiZn right away-- around 40 and starts dropping off at a maximum of 40 Khz or so. Fig. 4 on pg. 5 shows the inverse relation of resistivity to e for these ferrites.
On the other hand the Brockman patent attached shows that Snoek measured e of MnZn in the 10-4 to 10-5 range, resulting in high core losses:
"In view of the large permeability and the large dielectric constant the wave length of the electromagnetic wave generated in the core becomes of the same order of magnitude as the dimensions of the core in its usual form and thereby standing waves are established in the core".
I'm not sure exactly what was seen in the toroid, but this standing wave could certainly cause an interesting situation. Although he is representing this as a loss, the standing wave is actually adiabatic and transmits energy quite well, although of course energy is extracted from the source so not OU in itself.
If indeed the effect you are seeing is due to a magnetoelectric wave through the ferrite, then the geometry, the size, and the bulk mu and permittivity would factor into the resonances, so only experiment will show what they are in any particular case, without some wave mechanical simming inside a ferrite-- ouch.
The domain wall movement could also also be very fast with short pulses with a high rise time, so there is the possibility of the combination of domain wall and magnetoelectric effects.
There is a wealth of literature about this subject, so maybe I should send to your email rather than to the group at large.. does everyone want to get the full ream of papers and patents I can potentially send ? :-)
orthofield
The reason I treat ferrite like a magnetic dielectric with the velocity related to permeability and permittivity is (a) work done on 3F4 material that indicates this could be so and (b) claims of delays in the tens of nanoseconds that also fit that assumption. There may be much slower effects for domain wall movement that could on the one hand improve matters but on the other hand since energy is involved it could make matters worse. Hence the need for experiments.
It may be that the previous measured effects are not due to mu or even domain wall movement at all, maybe the dielectric constant of ferrite is much greater than the figure of about 7 that I use. My trusty Reference Data for Radio Engineers says that dielectric constants as high as 100,000 have been measured on several ferrites having a small amount if divalent iron in their composition. So maybe the EM propagation previously seen is due to that, and it represents a weak transmission running ahead of the slow domain wall one. All I can say at the moment is a large 3F4 toroidal core in a magnetic delay transformer exhibited anomalous effects at 14MHz, and the use of bucking coils would considerably amplify that effect and make it appear at a lower frequency.
Smudge
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Topic: A closer look at a simulated Negative resistance coil. (Read 79941 times)
