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Electromagnetic Waves from My PC

  1. Feb 29, 2012 #1

    Much of what I am going to write in this post is based on what I have read and understood (with very, very limited knowledge of the subject) on the Internet. So, if I have been misinformed or I have misunderstood anything, please don't hesitate to correct me. I would appreciate it.

    As the title of the thread suggests, my question is to do with electromagnetic waves being emitted from my PC. I have come to understand that they can do me great harm physically and, as I spend a lot of time next to my Pc, I have been looking to see if I can reduce these effects.

    One of the ways that I've been looking at is to try and construct some sort of Faraday cage around it. I know that this system is said to work when trying to protect a Pc from electromagnetic attacks and so I am wondering if the reverse would be true and so by constructing a Faraday cage around the Pc I would catch the electromagnetic emissions from it.

    Something else I've read is that for a Faraday cage constructed from wire mesh to work the gaps in the mess must be smaller than the height of the waves. I have considered constructing one from sheet metal but that seems a bit extreme and would be very costly.

    So my question is, does anyone know what the height of the electromagnetic waves coming from my Pc is?

    Many thanks in advance for any help.

    Just one more note, if you haven't already realised, my knowledge of physics and so forth is extremely elementary so please, keep it simple! I really would appreciate it.


    Paul Eamonn
  2. jcsd
  3. Feb 29, 2012 #2
    It is the wavelengths and not "height" that effect the size of the mesh required. (Just in case you didn't mean that, when most people think of the height of the wave they are thinking of the amplitude).

    The wavelengths coming from your PC would be dependent on the PC design. Just guessing, but to really knock out the emissions you would probably want to block at least the 3rd harmonic frequency of the CPU clock and below. This puts you are 9GHz for 3GHz processor. This also puts you at a very small mesh, so much so that I imagine obtaining that mesh would be more expensive than making a solid one.

    9GHz = 33mm wavelength. You want the mesh to be about 1/10th of that so you need a 3mm mesh.

    That being said, I think the risks of the EM radiation from your computer harming you are pretty low.
  4. Feb 29, 2012 #3
    Hi Floid - many thanks for taking the time to reply to me.

    Firstly, thanks for clarifying the termonology. To be quite honest, I wasn't entirely sure what it was I was referring to. That's why I called it the 'height'!

    Regarding the mesh - would this do? The spec says that the mesh is 2mm x 1mm.

    It is also interesting that you reckon that I shouldn't get harmed by the Pc - admittedly, I've never heard of anyone else suffering. All I can say is that, when I sit at the Pc, my left knee is then about 6" away from the tower and I feel a low level buzzing or humming in my knee. A bit like it's being sizzled. Occasionally, if I've been there for quite a while, it starts to become quite uncomfortable. Just for clarification, I never feel this sensation anywhere else; only when I'm sitting at the Pc.

    I'm sure it sounds odd but that is what I feel. So, that being the case, I decided I'd try out the Faraday cage idea if there was any chance of it working.

    I'd really appreciate some feed back on that mesh I've linked to and, once again, many thanks for your help.


    Paul Eamonn
    Last edited: Feb 29, 2012
  5. Feb 29, 2012 #4
    Isn't you computer enclosed in a metal case, as the usual models are?
  6. Feb 29, 2012 #5
    Are laptops enclosed in a metal cage too? I never took mine apart to see.
  7. Feb 29, 2012 #6


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    Staff: Mentor

    Welcome to the PF.

    We only deal in mainstream science here. Could you please provide a mainstream scientific article that makes the claim in your post that I've highlighted above?
  8. Feb 29, 2012 #7
    I did not mean laptop but the standard PC.
    An I am not implying that they are in the metal case to shield the EM fields from harming people. I was just curios why would one put a wire mesh around a metallic box.
  9. Feb 29, 2012 #8


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    Staff: Mentor

    The main reason PCs and laptops are shielded internally is to prevent Electromagnetic Interference (EMI) from causing interference and noise for RF broadcast devices.
  10. Feb 29, 2012 #9
    Hi nasu and chill_factor - thanks for taking an interest in this subject.

    In answer to your question - yes, I guess a Pc is, in the main, encased in metal. But I would imagine there are holes in the shell somewhere.

    As a matter of interest, my knee is on a level with the CD-ROM drive and I wouldn't expect that to be all solid metal, would it?

    berkeman - This has been something of a problem to me for sometime (physically) though the idea that electromagnetic waves are harmful is not something new to me. If I had to hazard a guess I would say that this dates back to the questions raised about the harm that can arise from the constant use of mobile phones and a memory that my ear and the side of my head used to buzz when I had been on the phone for too long.

    Therefore, with regard to scientific papers..............hmmmm, to be honest, I'm not too sure if I would recognise one if it came up and kicked my in the shin! I did Google 'Scientific papers on the harmful effects of electromagnetic radiation especially from computers' and came up with this lot. I don't know if this is what you are looking for.

    Alternatively, I found the attached .pdf. More a submission than the 'proof positive' that I suspect you are looking for. But, nevertheless, the fact that the subject is considered to be of sufficient importance to be brought before the European Parliamentary Assembly should, at least, raise some interest in the scientific community. I found section 9.42 quite interesting.

    While I appreciate that you will be keen to protect your members from the 'wild and wacky', surely a matter such as this with the potential if not the proof to harm warrants the attention and some further investigation by the very people that populate your forum.

    Finally, I will leave you will this other link that ought to, at least, question in your mind whether this subject 'should' be in the 'mainstream' - as you call it - even if, in your opinion, it may not be.

    Dr Mercola - Link

    I look forward to reading you reply.

    Meanwhile, once again, many thanks to all those who have taken an interest in this thread and offered their help and advice.


    Paul Eamonn

    Attached Files:

    Last edited: Feb 29, 2012
  11. Feb 29, 2012 #10


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    Staff: Mentor

    No, your links are not to mainstream scientific publications. There is a list of those publications in the Rules link at the top of the page.

    There is a huge difference in the magnitude of the RF radiation from an intentional radiator like a radio transmitter, versus the small unintentional radiation from a PC or laptop that passes radiated EMI standards.

    This thread is done.
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