Will 4 sides FARADAY CAGE work?

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Discussion Overview

The discussion revolves around the effectiveness of using a four-sided Faraday cage to reduce radio frequency (RF) strength in an apartment. Participants explore the theoretical and practical implications of partially shielding a room with conductive materials, considering various factors such as wave incidence and reflections from nearby structures.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes covering two walls, the floor, and ceiling with conductive material and grounding them to reduce RF strength, questioning if this approach will be effective.
  • Another participant notes that a perfect Faraday cage would block all electric fields, but suggests that without covering all sides, radio waves will still penetrate the room.
  • A different viewpoint expresses concern that covering four sides may not significantly reduce RF strength, indicating uncertainty about the effectiveness of this method.
  • One participant uses an analogy of water flow to argue that the total flux into a box with four walls is not significantly less than one without walls, implying limited effectiveness of partial shielding.
  • Another participant discusses the impact of wave incidence on shielding effectiveness, suggesting that nearby structures could reflect signals back into the room, complicating the shielding effort.
  • A suggestion is made for an empirical test using a metal screen to measure field strength differences, indicating that practical testing may provide insights into the necessity of full shielding.
  • One participant questions the nature of the interfering source and suggests that there may be more practical solutions than attempting to shield the entire apartment.

Areas of Agreement / Disagreement

Participants express a range of views on the effectiveness of the proposed four-sided shielding, with no consensus reached. Some acknowledge that partial shielding may help, while others emphasize the limitations and potential need for full shielding.

Contextual Notes

Participants mention various factors that could affect the effectiveness of the shielding, such as the frequency and modulation of the RF source, the geometry of the shielding, and reflections from nearby structures. These factors remain unresolved in the discussion.

piriya
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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?
 
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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.
 
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?
 
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.
 
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.
 
piriya said:
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.
 

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