What Is A Faraday Cage?
Finding reliable information on how to build a faraday cage on the internet is extremely difficult. There are tons of varying opinions and very few “experts” on the subject. Most of the research that has been done into this subject has been accomplished by various military forces and most of them have not been forthright in sharing the information with the public. With that in mind I set out to do the best I could to filter through as much information on faraday cages as I could find and bring together the best information I could on how to build a faraday cage.
Wikipedia defines a Faraday Cage as follows:
A Faraday cage or Faraday shield is an enclosure used to block electromagnetic fields. A Faraday shield may be formed by a continuous covering of conductive material or in the case of a Faraday cage, by a mesh of such materials. Faraday cages are named after the English scientist Michael Faraday, who invented them in 1836.[1]
A Faraday cage operates because an external electrical field causes the electric charges within the cage’s conducting material to be distributed such that they cancel the field’s effect in the cage’s interior. This phenomenon is used to protect sensitive electronic equipment from external radio frequency interference (RFI). Faraday cages are also used to enclose devices that produce RFI, such as radio transmitters, to prevent their radio waves from interfering with other nearby equipment. They are also used to protect people and equipment against actual electric currents such as lightning strikes and electrostatic discharges, since the enclosing cage conducts current around the outside of the enclosed space and none passes through the interior.
Faraday cages cannot block static or slowly varying magnetic fields, such as the Earth’s magnetic field (a compass will still work inside). To a large degree, though, they shield the interior from external electromagnetic radiation if the conductor is thick enough and any holes are significantly smaller than the wavelength of the radiation. For example, certain computer forensic test procedures of electronic systems that require an environment free of electromagnetic interference can be carried out within a screened room. These rooms are spaces that are completely enclosed by one or more layers of a fine metal mesh or perforated sheet metal. The metal layers are grounded to dissipate any electric currents generated from external or internal electromagnetic fields, and thus they block a large amount of the electromagnetic interference. See also electromagnetic shielding. They provide less attenuation from outgoing transmissions versus incoming: they can shield EMP waves from natural phenomena very effectively, but a tracking device, especially in upper frequencies, may be able to penetrate from within the cage (e.g., some cell phones operate at various radio frequencies so while one cell phone may not work, another one will).
A common misconception is that a Faraday cage provides full blockage or attenuation; this is not true. The reception or transmission of radio waves, a form of electromagnetic radiation, to or from an antenna within a Faraday cage is heavily attenuated or blocked by the cage, however, a Faraday cage has varied attenuation depending on wave form, frequency or distance from receiver/transmitter, and receiver/transmitter power. Near-field high-powered frequency transmissions like HF RFID are more likely to penetrate. Solid cages generally provide better attenuation than mesh cages.
Many preppers build faraday cages to house some of their electronics just in case there is an Electromagnetic Pulse attack on the USA. There are a couple of different types of EMP’s. To learn more about EMPs and to understanding some of the misconceptions about EMPs check out this video I did on the subject not long ago.
Click here to watch on Youtube: https://www.youtube.com/watch?v=GARhAT0zLV0
This is obviously a personal choice but I will go ahead and make a few recommendations based on what I plan to put into my own faraday cage.
Having these items after an EMP attack would make life much easier and would give you an edge over many other people in the preparedness realm. What other items would you put in a faraday cage? Let us know in the comments below.
The question of whether or not to ground a faraday cage is probably the most debated aspect of this topic. From the research I conducted it appears that the community is divided on the matter. Personally I fall into the category of NOT grounding small faraday cages that are less than 2 foot x 2 foot. Anything larger should probably be grounded. Room size or building sized faraday cages should definitely be grounded. The best reason I found for not grounding smaller faraday cages is that during an EMP a long ground wire will act as an antennae and will actually attract more electromagnetic energy and funnel it towards the cage, instead of helping to direct the energy toward ground. Independent of a ground the smaller faraday cages will only attract a relatively small amount of electromagnetic energy and the skin effect of a properly nested faraday cage will reduce and cancel out the EM energy effectively enough to protect your small electronics. Adding a long ground just attracts additional energy and may serve to overwhelm the capability of the “skin effect” to dissipate the EM energy.
In a normal environment it makes sense that you would ground a faraday cage in order to help quickly route the energy to the ground and not into the electronic device. But the pulse produced by an EMP does not produce a “normal” electrical environment. The pulse will be all consuming and all surrounding, the electromagnetic energy will be all around the device and even absorbing several feet into the earth depending on your distance from the epicenter of the EMP. And sense electricity follows the quickest path to ground, the energy from an EMP will disguise where exactly “ground” is. Meaning that the electromagnetic energy will not “flow” as normal Alternating Current electricity does during the EMP event.
When building my faraday cage I used the parts listed below. Support this site by purchasing your gear through my Amazon link! It won’t cost you anything and helps me out a lot! Amazon Affiliate Link: http://amzn.to/2tm7Pa8
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Behrens 10 Gallon Galvanized Steel Can: http://amzn.to/2sSpwdI
Glad Press N Seal Wrap: http://amzn.to/2ug1ugm
Quart Size Zip Lock Bags: http://amzn.to/2tgfqTk
Click here to watch on Youtube: https://www.youtube.com/watch?v=jGJYvOPP9O0
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What Is A Faraday Cage?
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