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Radio Wrangler · 25th Feb 2018, 8:33 am

Ferrites can be classified into two groups:

"Hard" Ferrites are materials developed to be permanently magnetised, they are found as ferrite magnets at the back of some loudspeakers. Also in core memories found in old computers (one in tfe Apollo spacecraft), and some jukeboxes.

"Soft" Ferrites are materials developed for linear operation with very low hysteresis. These are the ferrites used in inductor/transformer/antenna cores.

Both types are mechanically hard to the point of being brittle.

Hard ferrites are made to be magnetised, which makes them polarised.

Soft ferrites follow whatever field is applied to them and carry no polarisation of their own. Some interesting (and brain-twisting) tricks can be done with soft ferrites polarised by a separate permanent magnet in their vicinity. Look up the microwave 'circulator' for some weirdness...

The standard book is "Soft Ferrites Properties and applications" by E C Snelling usually referred to a Snelling, Soft Ferrites. It's amusing how often people's eyes convert that n to an m and leave the reader surprised.. Smelling soft ferrites... some new perversion? What's it doing in Dewey decimal 621.xxx shelves? People-watching can be fun.

David

25th Feb 2018, 8:33 am	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Active Ferrite Rod Antenna Ferrites can be classified into two groups: "Hard" Ferrites are materials developed to be permanently magnetised, they are found as ferrite magnets at the back of some loudspeakers. Also in core memories found in old computers (one in tfe Apollo spacecraft), and some jukeboxes. "Soft" Ferrites are materials developed for linear operation with very low hysteresis. These are the ferrites used in inductor/transformer/antenna cores. Both types are mechanically hard to the point of being brittle. Hard ferrites are made to be magnetised, which makes them polarised. Soft ferrites follow whatever field is applied to them and carry no polarisation of their own. Some interesting (and brain-twisting) tricks can be done with soft ferrites polarised by a separate permanent magnet in their vicinity. Look up the microwave 'circulator' for some weirdness... The standard book is "Soft Ferrites Properties and applications" by E C Snelling usually referred to a Snelling, Soft Ferrites. It's amusing how often people's eyes convert that n to an m and leave the reader surprised.. Smelling soft ferrites... some new perversion? What's it doing in Dewey decimal 621.xxx shelves? People-watching can be fun. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done Last edited by Radio Wrangler; 25th Feb 2018 at 8:46 am.