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www.mast-victims.org forum / General discussion / Will Coax Cable Affect Someone with Electromagnetic Sensitivity?
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coax-question
# Posted: 23 Jul 2011 02:42
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Hello, I have a question regarding coax cable that carries an internet or cable signal. I found the following statement regarding the magnetic radiation leakage:

"Real cables do have some level of leakage through the shields, but it is generally very small. Shielding effectiveness values S_dB of 100 to 120 dB are typical of coax. To convert to a power ratio, take 10^(-S_dB/10). S_dB = 100 means that 10^-10, or only 0.1 billionths of the power incident on the cable, will leak through the shield."

I don't really understand the context of the levels that are leaked.

Would this type of leakage affect someone who is electromagnetically sensitive?

Thank you for your answers.

charles
# Posted: 23 Jul 2011 14:23
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Yes it can.
The radiation coming from such cables are what I call *dirty air*.
These are frequencies form 1 Hz up to 30 MHz.

Will
Member
# Posted: 24 Jul 2011 13:07
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Coax is the best possible solution for signal transmission. It has the least leakage of any medium. You have much more to worry about from the national grid and mobile phone network.

coax-question
# Posted: 26 Jul 2011 18:36
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So, are you saying that compared to what's already present in the house, the emfs from the coax would be negligibly?

Would adding a coax line carrying internet make a difference if there were already coax lines carrying cable?

Thank you all very much for your information!

Henrik
Admin
# Posted: 26 Jul 2011 19:44
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charles,

I thought that coax cables were well shielded, some even with double layers of shielding.
Have you measured leakage from coax?
120dB sounds like pretty good shielding effectiveness to me, given that every 3 dB brings the signal down by half ...if my memory serves me right.

coax-question,
can you give an idea of how sensitive you are? do you react to fx. wifi routers? and at what distance? Just to get an idea of sensitivity.

coax-question
# Posted: 30 Jul 2011 19:22
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Well, my neighbors (on the other side of the wall) have wifi and I'm sensitive to that. Also, I'm bothered if I go into stores like malls or Best-buy. I'm also sensitive in areas that have power lines running under the floor (like hostpitals, etc.)

evalon
Member
# Posted: 30 Jul 2011 21:01
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Hi,

Just a bit of hopefully correct math on this:

Let's say that the voltage levels of the coax cable is 0 - 5 volts and the damping is 120 dB. Then it means that the level of radiation outside of the coax would be 5/INV LOG (120/20) which is 5/1000000 = 5 uV. That is just outside the cable and it drops linearly from there.

My guess is that the power outside the coax is very small since that would be INV LOG (120/10) which is "power inside"/1 * 10+12 (a 1 + 12 zeroes).

Hope that helps (and also is correct :-))

Greetings Jesper

evalon
Member
# Posted: 30 Jul 2011 21:02
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Oups - can see that I forgot to erase "and it drops linearly from there". I'm not sure about that...

Jesper

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