Faraday Cages
- Thread starter Gray_R
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Farady Cage
Hey I don,t know much but According to the farady cage If a person is in the ball which is made up of electric conductor , the current will harm if the current is set on.The electric city instead of passing through the body of that person will keep on passing through that conductor and will not cause any harm to that person.
Hey I don,t know much but According to the farady cage If a person is in the ball which is made up of electric conductor , the current will harm if the current is set on.The electric city instead of passing through the body of that person will keep on passing through that conductor and will not cause any harm to that person.
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No, EMP is a wave of energy. Since it moves through the air, it is not effected by counter-conductive measures like insulating it with rubber. From my understanding, Faraday cages are supposed to scatter that wave, protecting sensitive electronics. I am wondering what success the cages have, and if anyone here has any experience with their technology.Big-E said:
erich hartman
New Member
your perfectly safe within these faraday cages because the voltage within an electrical field is zero.Gray_R said:
they also have faraday suits for workers who need to go near high voltage equiptment.
it looks like a suit of chain mail covering all the body except the face and it has a cap peak.
its made of copper and silver woven into threads.
erich hartman
New Member
anyone know how to use your own avatar on this site??
There should be an option for you in the UserCP:erich hartman said:
http://www.defencetalk.com/forums/usercp.php
Kind of had some peripheral involvement. I've seen how a tempest rated room is constructed, and my last job in Fed Govt involved working in what was called "the monkey cage". basically it was an underground security room that was walled with copper grid and mesh,Gray_R said:
the tempest rated room was approx 4 strories underground and was only accessible through a zig zagging corridor that had small waterfalls on each wall. all the lines going in were lead encased (even the fibre optics). access was by biometrics. a palm scanner and an eye scanner coupled with a chipped access card. The site was also Class 100 rated.
actually the biometrics was pretty ordinary. there was always a problem with the readers. it was removed after about 12 months as everyone bypassed it via the security console - a complete breach of security, but it was the only way to do your work.AMTP10E said:
in real terms it was an unmitigated disaster. I went through a hardware security review process approx 2 years later and the technology had demonstrably improved. but it was a pain in the arse at the time.
iris scanners have a higher pass rate than palm scanners etc... but they have their own quirky faults.
In what sense?Gray_R said:
I can give you an idea of how secure some levels of the AustGov (incl ADF) think that a commsd up computer is:
- hi level traffic if it was to be sent over a comms-link had to be sent from a designated clean room
- on the mainland, any correspondence or data at a specific level must be hand delivered by a pre-nominated "dept" internal courier
- pre-nominated "dept" internal couriers must travel in a designated "white" or "green" car "owned" by the sender or known by the sender
- passwords in highly sensitive areas are sometimes rotated as high as every 15 mins
- critical data is only to be delivered in raw copy form, its (except under very rare circumstances) not to be transferred on stored portable medium.
- faxes can only be sent from a predesignated machine in a clean room to another in a similar environment
- clean room to be Class 100 rated
- large volumes of data "must" be sent via satellite if going offshore.
- clean rooms must not have any data landlines installed
- voice lines in clean rooms are connected to what we affectionately called "golliwog boxes" (a play on the german manufacturers name). That way data traffic was monitored in real time so that we could see whether data being sent was a document, text or voice. each package has a header which enables identification. the data is "slowed" for viewing in an interrogation loop before being released.
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Hi, I'm a new member here but this I know about. There are two types of screens being talked about - Tempest screen (designed to keep emmanations in) and an EMP screen (designed to keep emmanations out).
A Temest screen is usually applied to only a small percentage of a building (1 or 2 rooms) and the room is built using sheets of copper that cover the floor, all the walls and the ceiling. The sheets are bonded together and this shield is then bonded to an earth that is not the building earth. All copper cables passing through the shield are filtered including power cables so that if any emmanations are coupled onto the lines accidently that should not be on that line, they are filtered out by the filters and hence don't leave the room. If the room is an on-line room, the entrance will be an air-lock in which only one of the two doors can be opened at any one time. With an off-line romm, there may be only one door. Either way, the doors are RFI doors and are part of the screen. You normally can't see the screen as it is usually hidden by the walls etc.
An EMP screen is quite different. 1st - what is EMP? It is an ElectroMagnetic Pulse (as Gary said). There are only two causes of EMP AFAIK. The first is the Sun. You may recall hearing warnings about increased sunspot activity that may cause interference to communication systems. The interference in these instances is caused by the EMP wave from the sun reaching the earth with enough strength under high sunspot activity circumstances to cause interference but does not do physical damage to equipment. The second cause (and the one that EMP screening is all about) is a high altitude nuclear explosion. This releases a massive amount of energy in the form of EMP (among other things) and it can cause physical damage to communication and computer systems.
OK, so what is an EMP screen. It depends on how much protection you want. The ones I have seen are made of steel mesh and again the whole room (but more likely the whole building) is enclosed in it. The smaller the mesh, the greater the attenuation of the wave; the larger the mesh, the less attenuation. The screens is also bonded to an earth and in this case, it can be bonded to the building earth. All metal passing through the screen enters through a waveguide. A waveguide is a hole in the wall with a metal tube (usually rectangular in shape) running through it and bonded to the wall. Its dimesions are calculated using the lowest frequency expected and it acts as a barrier to the wave. Copper cables need to be filtered so that any energy induced onto the copper does not get past the waveguide. Fibre is a much easier way to go. Similarly, metal pipes passing through the waveguide need to be broken using some non-conducting material such as PVC pipe. The biggest waveguide I've seen was big enough to park two 5 ton trucks in it side by side and the smallest allowed one fibre cable through.
Both as you can imagine are very expensive especially if they are being retroffited to a building. As there is no danger from sunspot activity damaging equipment, it only leaves a high altitude nuclear explosion to worry about. Ground or subterranean expolsions won't do it unless you are close to ground zero and if you are that close, you'll have other things to worry about.
What's the chance of a high altitude explosion occuring in the southern hemisphere? Not much I would suggest. There is more chance of it happening in the northern hemisphere and then we would get some protection from the curvature of the earth. For my money, EMP screens in Australia are a waste of money especially now that the Cold War is over.
A Temest screen is usually applied to only a small percentage of a building (1 or 2 rooms) and the room is built using sheets of copper that cover the floor, all the walls and the ceiling. The sheets are bonded together and this shield is then bonded to an earth that is not the building earth. All copper cables passing through the shield are filtered including power cables so that if any emmanations are coupled onto the lines accidently that should not be on that line, they are filtered out by the filters and hence don't leave the room. If the room is an on-line room, the entrance will be an air-lock in which only one of the two doors can be opened at any one time. With an off-line romm, there may be only one door. Either way, the doors are RFI doors and are part of the screen. You normally can't see the screen as it is usually hidden by the walls etc.
An EMP screen is quite different. 1st - what is EMP? It is an ElectroMagnetic Pulse (as Gary said). There are only two causes of EMP AFAIK. The first is the Sun. You may recall hearing warnings about increased sunspot activity that may cause interference to communication systems. The interference in these instances is caused by the EMP wave from the sun reaching the earth with enough strength under high sunspot activity circumstances to cause interference but does not do physical damage to equipment. The second cause (and the one that EMP screening is all about) is a high altitude nuclear explosion. This releases a massive amount of energy in the form of EMP (among other things) and it can cause physical damage to communication and computer systems.
OK, so what is an EMP screen. It depends on how much protection you want. The ones I have seen are made of steel mesh and again the whole room (but more likely the whole building) is enclosed in it. The smaller the mesh, the greater the attenuation of the wave; the larger the mesh, the less attenuation. The screens is also bonded to an earth and in this case, it can be bonded to the building earth. All metal passing through the screen enters through a waveguide. A waveguide is a hole in the wall with a metal tube (usually rectangular in shape) running through it and bonded to the wall. Its dimesions are calculated using the lowest frequency expected and it acts as a barrier to the wave. Copper cables need to be filtered so that any energy induced onto the copper does not get past the waveguide. Fibre is a much easier way to go. Similarly, metal pipes passing through the waveguide need to be broken using some non-conducting material such as PVC pipe. The biggest waveguide I've seen was big enough to park two 5 ton trucks in it side by side and the smallest allowed one fibre cable through.
Both as you can imagine are very expensive especially if they are being retroffited to a building. As there is no danger from sunspot activity damaging equipment, it only leaves a high altitude nuclear explosion to worry about. Ground or subterranean expolsions won't do it unless you are close to ground zero and if you are that close, you'll have other things to worry about.
What's the chance of a high altitude explosion occuring in the southern hemisphere? Not much I would suggest. There is more chance of it happening in the northern hemisphere and then we would get some protection from the curvature of the earth. For my money, EMP screens in Australia are a waste of money especially now that the Cold War is over.
erich hartman
New Member
i must be blind, i can only see predefined avatars and no option to upload your own.WebMaster said:
erich hartman
New Member
thanks buddy
DoC_FouALieR
New Member
Theorically, Faraday cages are enclosed conductive cages that are traversed by electrical currents.
Let see some physical considerations:
-There is no EM field created by the cage inside it (direct application of Gauss' theorem). So no danger for a person nor malfunction for computers.
-According to the Maxwell's equations concerning the propagation of EM waves when passing through charged/current traversed surfaces, wavesstill exist inside the cages but they are severly altered by the cage
So if you want to protect a room in order not to allow radio communications, install a Faraday cage. To avoid the effects from an EMP, it is, in my view, useless.
Let see some physical considerations:
-There is no EM field created by the cage inside it (direct application of Gauss' theorem). So no danger for a person nor malfunction for computers.
-According to the Maxwell's equations concerning the propagation of EM waves when passing through charged/current traversed surfaces, waves
So if you want to protect a room in order not to allow radio communications, install a Faraday cage. To avoid the effects from an EMP, it is, in my view, useless.