>
> --- In [hidden email], "Charles" <charles@c...> wrote:
> > Hello Beau,
> >
> > I still maintain my meaning about those equations.
> > Let me go further.
> > I think it is a lot of bullshit.
>
> Hi Charles,
>
> I'm glad we can be frank with each other. I agree to disagree with
> you. :-D
>
> Note that another person in our discussion group, David Fancy, found
> measurable reduction in his modem's transverse EM emissions by
> wrapping it in metal window screen mesh. This mesh's aperture spacing
> is much smaller than what is nominal for DSL modem wavelengths.
> Overlapping of layers was probably a factor, too, though.
>
> > No pun intended, but you cannot calculate the shielding effect.
> > You can only MEASURE the shielding effect, and must do that with
> > several different frequencies.
> > As is done by prof. Pauli of the University of the Bundeswehr (Army)
> > in Germany.
> > He is the authority for testing shielding materials.
> > And a lot of materials do react sometimes quite differently as
> > expected!
>
> I don't think we are really saying different things here.
>
> > But a shielding material is not enough.
> >
> > We have to look very hard at the longitudinal waves, which pass
> > right through shieldings.
>
> My post should be taken as limited to non-ionizing, transverse EM
> radiation.
>
> > (Here the other *things*, as mentioned in this group, come into
> > focus. They all have their working related to longitudinal waves)
> >
> > It is an overwhelming new terrain.
> > But the answers to several questions raise much more new questions.
> >
> > I realise, that for many of you, this item sounds like something
> > out of Star Trek, but it is a reality now, and explains a lot of
> > what is happening and why it is happening to many of us.
> >
>
> I value our dialog and the wealth of new information you share.
>
> Thanks,
> Beau
>
> >
> > Greetings,
> > Charles Claessens
> > member Verband Baubiologie
> > www.milieuziektes.nl
> > www.hetbitje.nl
> > checked by Norton Antivirus
> >
> >
> > ----- Original Message -----
> > From: "Beau" <netfarer2@y...>
> > To: <[hidden email]>
> > Sent: Monday, September 27, 2004 20:11
> > Subject: [eSens] Re: shielding Notebook
> >
> >
> > > Hi Charles,
> > >
> > > I respectfully disagree with you concerning the equation. Please
> note
> > > that I conditioned the equation's application by an a priori
> knowledge
> > > of frequencies by saying "*If we can take* the computer's CPU
> clock
> > > speed as its highest frequency component...". Of course, I do
> agree
> > > that we can't know all the frequencies without measuring them
> first.
> > > However, if we assume a maximum for the frequencies a body is
> emitting
> > > we have concurrently placed a minimum on the emitted wavelengths.
> > > Meshes with spacing smaller than this minimum wavelength begin to
> > > appear as continuous surfaces without holes for transverse EM.
> > >
> > > Also, I want to emphasize that I am not saying a mesh provides
> *total*
> > > shielding of the transverse EM from a notebook computer.
> Everyone,
> > > please pardon me if I inadvertently gave that impression by saying
> > > near the end of my previous message "...should readily shield the
> > > transverse emissions in the above example."
> > >
> > > Let me be more complete. Given a mesh with spacing much smaller
> than
> > > the minimum radiated wavelength, the level of shielding is
> dependent
> > > on the characteristics of the mesh material -- its depth, its
> > > permeability, its conductivity -- as well as the geometry and
> > > frequency of the radiated field encountering it.
> > >
> > > If we have an aluminum mesh enclosure fitting our spacing criteria
> > > with wire thickness of 0.25 mm, a 1 GHz transverse EM plane wave
> > > encountering it will be approximately attenuated to around
> > > 1/(2.718)^(100) its original amplitude after penetrating the
> mesh. A
> > > 100 MHz transverse EM plane wave will suffer attenuation to around
> > > 1/(2.718)^(33) its original amplitude. In near-field conditions,
> such
> > > as a mesh around a notebook computer, the level of shielding is
> more
> > > complex to calculate, but it will exist to some extent for these
> > > frequencies for both the electric and magnetic field components.
> > >
> > > Unfortunately, low-frequency transverse EM won't be hampered by
> this
> > > mesh even though it 'looks' like a smooth surface to it. For a
> 100 Hz
> > > transverse EM plane wave would require the mesh's depth to be 36x
> > > thicker (around 8.5 mm) just to attenuate it down to 1/3 its
> original
> > > amplitude.
> > >
> > > Beau
> > >
> > > --- In [hidden email], "Charles" <charles@c...> wrote:
> > > > Hello,
> > > >
> > > > this equeation does not work.
> > > >
> > > > You can't know what ferquencies are radiating from this thing.
> > > >
> > > > The damaging part are the magnetic fields emanating.
> > > > And we know that they can be heavy.
> > > > Especially above the keyboard, whereunder the hard disk and
> > > motherboard are
> > > > placed.
> > > >
> > > > My CRT monitor radiates hard with 91.1 kHz, but I found many
> other
> > > > frequencies.
> > > >
> > > > You may hold a world receiver in front of your laptop.
> > > >
> > > > Greetings,
> > > > Charles Claessens
> > > > member Verband Baubiologie
> > > > www.milieuziektes.nl
> > > > www.hetbitje.nl
> > > > checked by Norton Antivirus
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: "Beau" <netfarer2@y...>
> > > > To: <[hidden email]>
> > > > Sent: Monday, September 27, 2004 01:48
> > > > Subject: [eSens] Re: shielding Notebook
> > > >
> > > >
> > > > >
> > > > > Hi Glenn & Randolf,
> > > > >
> > > > > If we can take the computer's CPU clock speed as its highest
> > > frequency
> > > > > component then the aperture/mesh size below which shielding
> for
> > > the
> > > > > computer will begin is:
> > > > >
> > > > > (0.3 m)/(CPU speed in GHz) or
> > > > > (300 m)/(CPU speed in MHz)
> > > > >
> > > > > Smaller aperture sizes than this work much better. For
> typical
> > > square
> > > > > mesh, divide by the square root of 2 to account for the
> diagonal
> > > of
> > > > > the mesh being its largest aperture width.
> > > > >
> > > > > For example, if we had a 1 GHz CPU, then square mesh below (30
> > > > > cm)/(sqrt 2) ~ (21 cm) will begin to confine the transverse EM
> > > > > radiation. A 1/4" square mesh has as its largest aperture
> width
> > > > > (0.25") * (1.414) ~ (0.35") ~ (0.89 cm) which should readily
> > > shield the
> > > > > transverse emissions in the above example.
> > > > >
> > > > > Beau
> > > > >
> > > > > --- In [hidden email], "Glenn Coleman"
> <glennhcoleman@h...>
> > > > > wrote:
> > > > > > Hello,
> > > > > >
> > > > > > I have thought of something similar, but to hook an external
> > > > > keyboard, and
> > > > > > use a wire-mesh fence between me and the notebook. I
> figure if
> > > wire
> > > > > mesh
> > > > > > works on microwaves it may work here too. I may even make a
> > > whole
> > > > > box
> > > > > > around my notebook with notebook sitting in cage.
> > > > > >
> > > > > > If it does work, then I can find a finer quality mesh so I
> can
> > > see
> > > > > monitor
> > > > > > better. I was going to start with some wire fencing with
> 1/4"
> > > > > holes to
> > > > > > begin with.
> > > > > >
> > > > > > Glenn
> > > > > >
> > > > > >
> > > > > > ----Original Message Follows----
> > > > > > From: "randolf_everywhere" <Thats@M...>
> > > > > > Reply-To: [hidden email]
> > > > > > To: [hidden email]
> > > > > > Subject: [eSens] shielding Notebook
> > > > > > Date: Sun, 26 Sep 2004 11:09:02 -0000
> > > > > >
> > > > > > Hello,
> > > > > >
> > > > > > I am thinking of shielding my Notebook. Maybe with paint or
> with
> > > > > > wallpaper on its outside. I tested and know shielding it
> will
> > > help.
> > > > > But I do
> > > > > > not know If there can occur problems when I do it.
> > > > > >
> > > > > >
> > > > > > Randolf Weinand
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Yahoo! Groups Links
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>