Radiation Attenuation Fabrics
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Dear all,
There's a lady (can't remember her name) who so affected by radiation that she goes around looking like a beekeeper, except that the netting is a see-thru EMR protective fabric. Anyone knows what she's using? I'm trying to get the same. Have been looking at what's available at www.lessemf.com/fabric.html. While checking out RadioScreen, I found this: http://www.metacafe.com/watch/7713398/review_of_swiss_shield_and_radioscreen_rf_radiation_attenuation/ I'm not knowledgeable about this stuff. What does 8 dBm mean? I see dBm on my Cornet ED7, but don't know how to link it with "dB" used in www.lessemf.com/fabric.html. No mention of dBm there. There's a page explaining about dB: http://www.lessemf.com/decibel.html I suspect the answer I want is somewhere there, but don't understand enough about this stuff to decifer to gobbledygook. Can anyone help? All I want is know how much of attenuation is 8 dBm? kb |
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sarah dacre ?
In a message dated 25/09/2012 09:43:58 GMT Daylight Time, [hidden email] writes: Dear all, There's a lady (can't remember her name) who so affected by radiation that she goes around looking like a beekeeper, except that the netting is a see-thru EMR protective fabric. Anyone knows what she's using? I'm trying to get the same. Have been looking at what's available at www.lessemf.com/fabric.html. While checking out RadioScreen, I found this: _http://www.metacafe.com/watch/7713398/review_of_swiss_shield_and_radioscree n_rf_radiation_attenuation/_ (http://www.metacafe.com/watch/7713398/review_of_swiss_shield_and_radioscreen_rf_radiation_attenuation/) I'm not knowledgeable about this stuff. What does 8 dBm mean? I see dBm on my Cornet ED7, but don't know how to link it with "dB" used in www.lessemf.com/fabric.html. No mention of dBm there. There's a page explaining about dB: _http://www.lessemf.com/decibel.html_ (http://www.lessemf.com/decibel.html) I suspect the answer I want is somewhere there, but don't understand enough about this stuff to decifer to gobbledygook. Can anyone help? All I want is know how much of attenuation is 8 dBm? kb [Non-text portions of this message have been removed] |
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In reply to this post by Kumara
>I'm not knowledgeable about this stuff. What does 8 dBm mean? I see
>dBm on my Cornet ED7, but don't know how to link it with "dB" used in >www.lessemf.com/fabric.html. No mention of dBm there. The m in dBm means that the signal strength is being measured in milliwatts (mW) where 0 dBm is equal to 1 mW. By itself (without the m), dB is just a way to compare two values to each other, and give an indication of how much larger one is in comparison to the other. It is easier if you think of dB in terms of percentages instead: signal shielding dB (decibels) strength effectiveness 0 100% 0 -10 10% 90% -20 1% 99% -30 0.1% 99.9% -40 0.01% 99.99% -50 0.001% 99.999% A fabric rated at -10dB will block 90% of the signal, and let the other 10% through. -8dB is approximately 16%, so 84% will be blocked. Often, you'll see numbers without the minus sign, 10 dB instead of -10dB for example. But because they are referring to a reduction of 10dB, this is really equivalent to -10dB. So if your meter was displaying -20dBm, and you completely surrounded it with a fabric rated at -8dB, you should see your meter's measurement drop to -28 dBm. But the effectiveness varies depending on the frequencies being used. In general, lower frequencies are easier to block than higher frequencies. The Swiss Shield company has more detailed information about how well their fabrics perform at http://www.swiss-shield.ch/Swiss-Shield-Textiles.46.0.html?&L=1 Click on the fabric type, and on the next page, they have a PDF file with much more detail that can be downloaded. |
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Looks like all the space characters in my chart got stripped out, making it hard to read. Here it is again, with underscores instead of spaces. Hopefully this will be more readable:
________________signal__________shielding dB (decibels)_____strength________effectiveness 0_____________100%_____________0 -10______________10%___________90% -20_______________1%___________99% -30_______________0.1%__________99.9% -40_______________0.01%_________99.99% -50_______________0.001%________99.999% |
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In reply to this post by PUK
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In reply to this post by JamesH
Thanks. That's very helpful.
I supposed what the video showed wasn't fair, or even clear. Wonder if there are better experiments on video. --- In [hidden email], JamesH <j7077-eagle@...> wrote: > > >I'm not knowledgeable about this stuff. What does 8 dBm mean? I see > >dBm on my Cornet ED7, but don't know how to link it with "dB" used in > >www.lessemf.com/fabric.html. No mention of dBm there. > > The m in dBm means that the signal strength is being measured in milliwatts > (mW) where 0 dBm is equal to 1 mW. > > By itself (without the m), dB is just a way to compare two values to each > other, and give an indication of how much larger one is in comparison to the > other. It is easier if you think of dB in terms of percentages instead: > > signal shielding > dB (decibels) strength effectiveness > 0 100% 0 > -10 10% 90% > -20 1% 99% > -30 0.1% 99.9% > -40 0.01% 99.99% > -50 0.001% 99.999% > > A fabric rated at -10dB will block 90% of the signal, and let the other 10% > through. -8dB is approximately 16%, so 84% will be blocked. > > Often, you'll see numbers without the minus sign, 10 dB instead of -10dB for > example. But because they are referring to a reduction of 10dB, this is > really equivalent to -10dB. > > So if your meter was displaying -20dBm, and you completely surrounded it > with a fabric rated at -8dB, you should see your meter's measurement drop to > -28 dBm. But the effectiveness varies depending on the frequencies being > used. In general, lower frequencies are easier to block than higher > frequencies. > > The Swiss Shield company has more detailed information about how well their > fabrics perform at > http://www.swiss-shield.ch/Swiss-Shield-Textiles.46.0.html?&L=1 > > Click on the fabric type, and on the next page, they have a PDF file with > much more detail that can be downloaded. > > > > > > > -- > View this message in context: http://esens.966376.n3.nabble.com/Radiation-Attenuation-Fabrics-tp4023201p4023214.html > Sent from the eSens mailing list archive at Nabble.com. > |
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In reply to this post by Kumara
Also remember this stuff has a shelf life, it oxidises and wears off
depending on its location/environment and handling .. puk In a message dated 29/09/2012 09:49:37 GMT Daylight Time, [hidden email] writes: Thanks. That's very helpful. I supposed what the video showed wasn't fair, or even clear. Wonder if there are better experiments on video. --- In _eSens@yahoogroups.com_ (mailto:[hidden email]) , JamesH <j7077-eagle@...> wrote: > > >I'm not knowledgeable about this stuff. What does 8 dBm mean? I see > >dBm on my Cornet ED7, but don't know how to link it with "dB" used in > >www.lessemf.com/fabric.html. No mention of dBm there. > > The m in dBm means that the signal strength is being measured in milliwatts > (mW) where 0 dBm is equal to 1 mW. > > By itself (without the m), dB is just a way to compare two values to each > other, and give an indication of how much larger one is in comparison to the > other. It is easier if you think of dB in terms of percentages instead: > > signal shielding > dB (decibels) strength effectiveness > 0 100% 0 > -10 10% 90% > -20 1% 99% > -30 0.1% 99.9% > -40 0.01% 99.99% > -50 0.001% 99.999% > > A fabric rated at -10dB will block 90% of the signal, and let the other > through. -8dB is approximately 16%, so 84% will be blocked. > > Often, you'll see numbers without the minus sign, 10 dB instead of -10dB for > example. But because they are referring to a reduction of 10dB, this is > really equivalent to -10dB. > > So if your meter was displaying -20dBm, and you completely surrounded it > with a fabric rated at -8dB, you should see your meter's measurement drop to > -28 dBm. But the effectiveness varies depending on the frequencies being > used. In general, lower frequencies are easier to block than higher > frequencies. > > The Swiss Shield company has more detailed information about how well their > fabrics perform at > _http://www.swiss-shield.ch/Swiss-Shield-Textiles.46.0.html?&L=1_ (http://www.swiss-shield.ch/Swiss-Shield-Textiles.46.0.html?&L=1) > > Click on the fabric type, and on the next page, they have a PDF file with > much more detail that can be downloaded. > > > > > > > -- > View this message in context: (http://esens.966376.n3.nabble.com/Radiation-Attenuation-Fabrics-tp4023201p4023214.html) > Sent from the eSens mailing list archive at Nabble.com. > [Non-text portions of this message have been removed] |
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