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Blocking ISM band frequencies

  1. Nov 23, 2014 #1
    The ISM band is a set of frequency bands from about 6 kHz to 246 GHz; see http://en.wikipedia.org/wiki/ISM_band#ISM_bands.

    Is there a design that will block all of these bands? A guess is in the attached file: each box is solid metal or wire mesh, and the boxes nest in a Matryoshka-doll fashion.
     

    Attached Files:

  2. jcsd
  3. Nov 23, 2014 #2

    dlgoff

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    If one of your 2.4 GHz devices is being interfered with, you may want to check out these ways of resolving interference.
     
  4. Nov 24, 2014 #3
    My question's a little bit broader than that. I'd like to block as much of the ISM band as possible and would like to know if the design shown in the drawing (which is like King Tut's tomb; see below) is a reasonable approach. Will nesting, say, 4 Faraday cages each with different mesh sizes block four separate bands of frequencies?
     

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  5. Nov 24, 2014 #4

    davenn

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    Its more likely to block everything
    a gridded/holed Faraday shield, like a waveguide is basically a highpass filter

    Consider the holed grid of a microwave oven, it blocks everything up to and a little beyond ~ 2.5 GHz
    everything higher in freq above that goes through up to light and beyond

    so if there is something inside the box that you want to be able to receive say 450MHz
    that signal will be filtered out

    I think you need to explain in much more depth what you are trying to achieve

    regards
    Dave
     
  6. Nov 24, 2014 #5
    "King Tut's tomb design", Lolo0)
     
  7. Nov 24, 2014 #6

    meBigGuy

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    Building a cage that blocks the high frequencies will block all below it. As davenn said,
    "Its more likely to block everything a gridded/holed Faraday shield, like a waveguide is basically a highpass filter"
     
  8. Nov 24, 2014 #7
    A microwave oven is designed to contain it's working frequency via a 1/4 shunt constructed along the periphery of the door. Thus wide bands below and above the design frequency will leak through the gap around the door. To get wide-band performance, the door would need a conductive seal all around.
    To seal RF in / out, totally constructive chambers are constructed with conductive spring fingers all around the doors. Absorbent materials are usually included along the walls to suppress resonances.
     
  9. Nov 24, 2014 #8
    Sorry, but what is a "constructive chamber"? I couldn't find it on Google.
     
  10. Nov 25, 2014 #9

    davenn

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    You still haven't told us what you are trying to achieve

    doing so will help you get better answers, at the moment we are all just guessing
     
  11. Nov 26, 2014 #10

    Baluncore

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    One faraday cage will solve the problem. You do not need to nest multiple faraday cages.
    Make sure that any holes are smaller than about one tenth of a wavelength at your highest frequency.
     
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