"John Passaneau" wrote in message
...
Hi Mike:

I have those books if you can't find them. Many shield rooms also have a
shield of soft iron as well as the copper. The soft iron shields against
magnetic fields.


The traditional modular shielded enclosure has become standardized to a
design of 4' x 8' x 3/4" panels, held with a "hat & flat" clamping rail
system. Each panel is a sandwich of a sheet of galvanized steel, plywood and
another layer of galvanized steel. The steel is often about 24 gauge. This
is a trade-off between weight, manufacturing ease, and durability. The
galvanizing ensures good conductivity at the joints. The steel does give you
a bit of LF H-field SE, but the real reason for the steel is that it's just
a whole lot cheaper that copper screen, and lasts better, since the SE
doesn't degrade and it isn't nearly so vulnerable to puncture.

If you want serious H-field shielding, you need to go to thick steel
(welded) chambers, or employ exotic alloys (expensive, and physically &
magnetically vulnerable).


Ed
wb6wsn