Reflectivity of foil/wire mesh on rf signals

[bononos]

How much of outside rf signals would be lost from bouncing off the aluminium foil that normally lines walls as part of the insulation layer?

What if fine thin wire mesh was substituted for the aluminium layer?

Does the foil/mesh have to be grounded to be an effective barrier (like a faraday's cage)?

 

[PsiStar]

Depends on the thickness of the foil & frequency with frequencies 500 MHz (or so) getting attenuated more than lower. The interaction is skin effect. Lower frequencies may be able to penetrate the foil where the higher frequencies not so much.

Depends on the mesh size & frequency with higher frequencies more likely to pass than lower with caveat. As the frequency approaches the quarter wave length size of the mesh opening it will be far less attenuated than other frequencies.

No.

 

[bononos]

Thanks for the info. How much of an attenuation would it be for the frequencies >500Mhz which you stated? - assuming standard kitchen aluminium foil thickness - wiki says its 0.022 mm (0.9 mils) thick.

Now would the mesh opening size (for a netting) have to be a minimum of 1/10 the wavelength or is it 1/100 to block a certain rf frequency? Eg. 1.25cm or 1.25mm for 2.4Ghz signal.

Can 1 layer of standard kitchen aluminium foil block rfid chips, smartcards, credit cards w/embedded chips?

 

[PsiStar]

These will make me or someone else think a little more for anything specific.

 

[AD5MB]

look at a wifi grid antenna. slots big enough to put your fingers through, and the grid behaves like a solid dish reflector at 2.4 ghz

 

[jackcon]

I believe that any wire mesh size used in this instance would have to be 1/10 the wavelength.

How about material when it comes to the fine wire mesh, something like copper is probably the best bet yes? Can be found pretty easily through google, but heres an option for users: http://www.bwire.com/