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Shielding from microwaves

Discussion in 'Electronic Components' started by eric, May 23, 2007.

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  1. eric

    eric Guest

    Hi, I am having a little microwave experiment, and I want to shield some
    cracks from leaking microwaves. A pal said to me that a paper-type
    called "mica" is used for such reasons in microwave ovens. Actually what
    he told me is that it allows microwaves to pass through, but it blurs
    them so as they are not focused as before.

    Is it true, or does anyone know any better way to make leaking
    microwaves less harmful (apart from Faraday cage, this is too hard for
    me to make, I suppose).
  2. Mica's a mineral, often associated with granite, it forms thin sheets.

    Metal will reflect micowaves. If the leaks are small, patching with metal
    will work, if the enclosure is made to contain them as an oven is (that is
    a Faraday cage, btw). Whether you're using an existing system or a new one,
    take care with high power sources, as usually you need to make sure the
    energy is safely absorbed or dissipated somewhere.
  3. Chris Jones

    Chris Jones Guest

    Mica is only used to cover the waveguide hole in the ovens because it does
    not allow FOOD to pass through it. The microwaves pass through practically
    as though it weren't there. Compared to plastic, mica has the advantage
    that it doesn't melt or burn when it gets hot.

    Metal foil will stop microwaves, but the microwaves can go around the edges
    of the foil, unless the foil is continuously connected along the seams,
    which is very hard to achieve. In some cases a wide overlap at the seams
    will help but without knowing what you are trying to do, it would be hard
    to give advice.

    You need to get yourself a leakage detector, then you can tell whether you
    have solved your problem or not. Get a meter that can show the amount of
    leakage, not just one that has a light that indicates "too much" leakage.
    If you get a meter that shows a reading that indicates the relative amount
    of leakage then you can see if the meter is still working because you can
    see the leakage of a normal oven. Any meter that only has a light
    indicating "too much" leakage is inferior because a very high amount of
    leakage could destroy the meter completely and you would then not know that
    the meter was not working.

    One of the best ways to reduce your exposure is distance. To a reasonable
    approximation, the leakage power density will decrease with the square of
    the distance. This means if you go ten times as far away from the oven,
    the leakage will be 100 times less.

  4. eric

    eric Guest

    It is a classic experiment that proves that there is no ether. For
    various reasons we do not want to have microwaves leaking behind the
    surface they hit. I think the ideal for it would be some kind of
    material that "absorbs" the microwaves, as lead does for radiation. If
    you know such materials or have better ideas, it would be great to let
    me know.
  5. eric

    eric Guest

    On the web I came across references to Velostat. Does anyone know if it
    absorbs microwaves and where may one get it from?
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