Will 4 sides FARADAY CAGE work?

[piriya]

Hello all,

I plans to reduce RF strength in my apartment by cover the room with conductive material.
- Cover 2 walls which facing the boardcasting tower.
- Cover the floor and ceiling.
Total 4 sides (since the material is quite expensive)

Then I'll grounded them to the apartment electric ground socket.

As I understand, when radio wave hits grounded conductive material, it will change to electric charge and neutralized through the ground. If this is correct, I should get quite good result from this 4 sides covering.

I don't means to perfectly shield the room. Just to reduce field strength.

Theoretically, Will this work?

 

[Retsam]

Well if you had a perfect faraday cage then no electric fields would be able to penetrate it, that is the reason mobile phones don't work in lifts. But if you don't cover two sides then there is going to be radio waves still entering your room. The metal shielding will absorb some of the waves but i still think a large amount will penetrate the room, i don't know for sure though.

 

[piriya]

It's ok to let some EM through. I just needs to reduce some field strenght inside the room.

Think is, I'm afraid that covering 4 sides will not reduce anything at all...

Can anyone help?

 

[Loren Booda]

The way I see it is through the analogy of water flow. The total flux into a "box" with four walls is not greatly less than into one with no walls at all.

 

[wysard]

It depends on the incidence of the waves to the structure. Ie: if you take a pyramid cage with an open base and point the tip directly at the EM source, the signal inside the pyrimid at the tip is vastly diminished, but near or at the plane of the base is much less diminished.

Also, if there are nearby structures opposite the transmitter say a block away from your room that reflect the signal back into the open side of your box then you have a real problem.

I would suggest an empirical test would be your best bet before you invest a lot of money. Buy a 2m square piece of metal screening and put in a frame. Ground frame. Then use a meter to check the field strength in the centre of the side facing the transmitter vs. the strength on the shielded, or actually shadowed side. If the difference is minimal then you know that reflected energy is a significant factor and you need a full shield. If the difference is very high, then perhaps a partial shield will do. Just remember the shield you discuss will at best, only really help the half of the room closest to the center of the shield.

 

[berkeman]

I don't means to perfectly shield the room. Just to reduce field strength.

What is the interfering source? What is the frequency and modulation (like, is it an AM broadcast tower around 1MHz?)? What equipment do you have that you need to cut the interference with? There are much more practical solutions than shielding your whole apartment.