Radio Shielding

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...

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.

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,  
[hidden email] 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...





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