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Homework Help: Faraday Cage

  1. May 16, 2008 #1
    1. The problem statement, all variables and given/known data
    For my physics project I decided to make a Faraday cage to cancel out cell phone signal.

    2. Relevant equations

    3. The attempt at a solution
    For my first attempts at making a successful project I used chicken wire and wire mesh to make a cylindrical cage. Our goal was to cancel out all cell phone signals within the cage but we only managed to drop a few bars in service. We tried grounding the cage but we didn't notice any difference in signal strength. One cage had about 1cm gaps in between wire and the other had about 1mm. The second cage did produce better results but nothing satisfactory. IF anyone has any experience or has an idea for building a Faraday cage it would be appreciated.
  2. jcsd
  3. May 17, 2008 #2
    The most effective Faraday cage would be a solid metal box (grounded). One other thing that might work well is steel wool.
    Keep us updated on your results.
  4. May 18, 2008 #3
    Yea I knew the solid metal box would work well but never thought of using steel wool. I will try that and keep you guys posted on the results.
  5. May 18, 2008 #4
    Thanks lzkelley, you're a legitimate badass. The steel wool idea worked. We made two working Faraday cages. One is a box lined with steel wool and the other is the solid metal box that is grounded.
    Last edited: May 18, 2008
  6. May 18, 2008 #5
    Does grounding the box actually make a difference? I wouldn't have thought it would matter.
  7. May 18, 2008 #6
    If you think of the metal as perfect conductors then no it doesn't matter -> either will work.

    But if you take into account the dielectric properties of the metal, the grounding reduces it by an order of mag or 2, depending on the situation.
  8. May 19, 2008 #7
    Hi Krankles welcom,

    Did you tried put a radio inside of your first cage(chicken wire)? Does it working there?

    I want to ask that, what is the relation between the wavelength and the gap of cage? As i know cellphone freq. is 900-1800MHz and velocity is 3*10^8 m/s thus, wavelength is max 1/3 meter. How this wave come inside?
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