Topband: Effect of DC on Ferrite Toroids?

[Robert Kavanagh]

>
>Some ferrite materials are design to change permeability with DC bias,
>sometimes by as much as a factor of ten.  I'm not sure if all mixes will do
>this or only those specifically designed to do so.
>
>I've been trying to come up with a useful application of this property for
>Beverage matching, etc., but so far I can't think of how it could be used
>to advantage.
>
>73,
>
>Charles - K5ZK

Charles:

I'm not sure that this has an application for Beverage matching, but 
I have made use of the variable permeabilty property in remotely 
tuning a loop antenna. This is done by controlling dc in a coil wound 
on a ferrite toroid. In case you might find this idea useful, take a 
look at my article: "Remote tuning of a low-frequency loop antenna" 
in QEX for May/June 2003.

Bob
VE3OSZ