Re: Radio Shielding

[Guest guest]

I read that radio reception in a concrete building is poor due to steel rebar

that reinforces the concrete. Has anyone been in a concrete building and

noticed that? Just wondering.

[Guest guest]

all I know is that I have heard that the transmitter in wroughton uk may

have to be switched off as so many people have been falling ill due to the 2m

wave length of the radio 2 transmissions resonating with adults bodies, so

they will switch to digital which is likely to be more offensive to

children !!!

In a message dated 20/02/2011 14:02:07 GMT Standard Time,

emraware@... writes:

Anyone have luck shielding against radio transmissions?

I've always found that radio reception is still sufficient within canopy

fabrics. I'm not sure if it's b/c radio can work with extremely low levels.

Even if I wrap the radio with layers of the fabric, it doesn't seem to

block it either, although a cell phone would certainly lose reception after,

say, 1 layer. I suspect it also has to do with the lower wavelengths, which

are much more difficult to shield.

Herbert Kapitza, Some Remarks on Shielding

suggests steel is better than copper at low frequencies, but copper is

better for higher frequencies > 100 kHz

Has anyone tried different thicknesses of metal? EMI Shielding Theory

suggests, " When skin depth is considered, however, it turns out that thickness

is only critical at low frequencies. At high frequencies, even metal foils

are effective shields. "

I suspect the other problem is that although conductivity is good for

reflecting away microwaves, it's also good for increasing electrical field

exposure if there are nearby energized wires.

Re: living in the cellar, I've found that to be good to lower microwaves,

but often bad in terms of air quality and radon...