My app uses a 1uH inductor.
Problem:
It's going to be near some other power inductors with strong E and M
fields and I'm concerned about interference by E or M coupling.
Guessing...
Make the inductor with a pot core?
Maybe put foil on the pot core?
Put the inductor in a ferrite box covered with foil?
Perhaps use something like those IF transformers found in AM FM
radios?
Put the inductor in a grounded steel box?
Is there something in production?
Toroids with astatic windings have no external magnetic field and are
insensitive to external magentic fields.
In theory, a pot core is topologically identical to a toroid, but the
slits for the leads mean that the external field rejection isn't as
good.
Shield against
electric fields with a box around the toroid. If you
put a can over a toroid and a saucer underneath it, don't clamp them
together with a metal bolt running through the central hole in the
torod, because that creates a shorted turn - nylon bolts are fine, but
a couple of metal bolts or clips out side the toroid are even better.
If you can get away with a pot core, you can get pretty good electric
field shielding with a ground copper foil screen wrapped around the
outside of the coil - overlap the ends, but keep them separate with a
bit of insulating tap (you really don't want the screen to form a
shorted turn here either). It will push up the stray capacitance of
your coil to ground, but I think it reduces the parallel capacitance
of the coil - I was never in a situation where this was important
enough that I had to measure it, which means that my opinion on the
subject isn't all that reliable.
If you want chapter and verse, Ralph Morrison's "Grounding and
Shielding Techniques" is the book to read. It's up to its fifth
edition now, published in March 2007 ISBN-10: 0470097728, ISBN-13:
978-0470097724.
The earlier editions that I bought for various employers over the
years were largely aimed at 50Hz and 400Hz interference. The fourth
edition - which I bought for myself - does have a chapter on RF which
is useful, if not up the standard of the low frequency advice. Amazon
gives the table of contents for the fifth edition and it does seem to
have a lot more on high frequency techniques.