[spam][crazy] How a Hobbyist Might Start Building Shielded Rooms

[k]

step 1: be able to measure shielding effectiveness

This takes two radios: an emitter and receiver .
It also takes a variety of antenna to handle various frequencies and modes.

There are a number of formal guides (commercial and military specs)
for how to do this, which are a good starting point but leave some
things out.

Basically, you measure signals under identical conditions both with
and without the shielding.  This gives a metric of attenuation for the
exact signals and locations measured.