Re: tlug: shielding from high EM interference

[kudielka@example.com]

Scott Stone <sstone@example.com> wrote:
> 
> one of the support pillars in our office here (structural support) has the
> main power conduit for the building running through it.  Not usually a
> problem, but any monitor placed anywhere near it will flicker and 'waver'
> very badly from the EM interference, or so it seems.  Is there any kind of
> material we can buy to shield against this?

It's the _magnetic_ field. And low-frequency. Very tough. You need either
_lots_ of the best conductor you can get[1] or some ferromagnetic material.
For the latter, probably the best bet is the sheet metal used in
transformators (plain cast iron?)[2].

[1] Sorry, I don't have the conductivity of copper at hand. But if you use
    something non-ferromagnetic with the conductivity of iron, you get
    a skin depth of 3cm. Obviously a purely academic solution ;)
[2] 2mm of iron. Skin depth should be about 1mm.

I hope I did the math correctly. No guarantee.

-Klaus

PS: A few years ago I visited CERN. As you may know, they have extraordinary
strong _stationary_ magnetic fields. Nothing to do about that.
You had to read the text on the monitors from the lower left corner to the
upper right corner.
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