Rebar Faraday Cage???

[JJNiles]

Hay guys would it be posabol to use the rebar in a concreat wall as a faraday cage if it continued through the cealing, and floor? Or would the holes in the rebar matrix be too big for it to work? Any ideas would be helpfull, I'm not building one, I just had the thought wile looking at some blueprints.

 

[MikeMl]

AFIK, the rules for RF screening a room require the aperture between the conductors(left to right AND up to down) to be a small fraction of a wavelength at the cutoff frequency. Since most rebar I have seen is about a foot apart, it might work at frequencies below about 100Mhz (3m wavelength) , but not well at 1GHz (0.1m wavelength). Another problem is that rebar is usually rusty, and probably does not make good electrical contact to the crossing piece of rebar.

 

[RadioRon]

The Faraday cage needs to completely wrap around the interior. Rebar in the walls only cover four walls, but not the ceiling or the floor. If the rebar is electrically tied to the ceiling and floor, which may be made of metal, then there is a chance.

 

[Torben]

AFIK, the rules for RF screening a room require the aperture between the conductors(left to right AND up to down) to be a small fraction of a wavelength at the cutoff frequency. Since most rebar I have seen is about a foot apart, it might work at frequencies below about 100Mhz (3m wavelength) , but not well at 1GHz (0.1m wavelength). Another problem is that rebar is usually rusty, and probably does not make good electrical contact to the crossing piece of rebar.

The last point is easily solved with a weld at each joint. But I suspect that making the welds would become a significant fraction of the total build time--although I bet you'd be pretty quick at it toward the end of the welding. I'm also not sure you want that much rigidity in the structure, though. I am certainly no structural engineer. I would think that with the concrete you'd want as much rigidity as you can get.


Torben