On Oct 9, 8:28 pm, wrote:
On Oct 9, 12:18 pm, RHF wrote:

On Oct 9, 10:00 am, billy wrote:

What material can be used for shield against potentially dangerous
levels of radio waves. Lets say outside my bedroom is a radio
communication device. What material could stop the waves from
entering. Cement? Lead? How thick?

Aluminium Siding -and- Aluminium Screened Windows

I have a MSEE, but E&M is not my specialty. However, since aluminum is
not a ferous material, I believe the H wave will penetrate it. RF
shielding paint is generally nickle for that reason. I don't recall if
"mu metal" is ferous or not.

Turn your degree in!

Faraday cages, AKA screen rooms, are used to isolated a space from the
outside
world. They use copper mesh, with the junctions welded, and achieve
isolations of
from 80dB up to ~120dB, more dB isolation requiring multiple "walls".
Think nested
Russian dolls.

A RF/EM "wave" consists of both E and H fields. Any conductive case
with completely
conductive seams and walls will stop any RF/EM field.

Take a cookie tin. With unpainted top and bottom join edges.
Put an FM radio inside tuned to the strongest FM local staiton.
As you put the top on the signal will go away.
Works for AM/MW/Cell phones as well.

Over in alt.survival we have several ongoing threads about how to
protect electronics
in a nuclear or solar EMP event.

The better answer would be "why do you think you have dangerous levels
of RF impinging
your home/bedroom?"
And
"What frequencies do you think are present?"

Higher frequencies mean shorter wavelengths, which mean any openings
have to become
smaller and minor joint imperfections become more important.

IE A friend has a home recording studio. He lives within a mile of a
pretty powerful AM/MW
station. He was getting some interference in spite of serious efforts
to filter the RF at the
input to his mixer. At my suggestion he built a screen room of
'chicken wire'. Rat wire
would have been better but the larger wire knocked the signals
intensity down enought
so it was not a problem. His room isn't really RF tight, a good radio
will still pick up the
stronger local MW stations, they are all very weak. A not perfect
screen room but effective
enough for his needs. Cellphones, TVs, FRS HTs and FM radio are fairly
uneffected. Rat
wire with it's 1/4" grid would kill everything below microwave, if you
could build a good enough
door.

Terry