I never thought of it that way but actually if I did have to outrun 'em, there'd be a lot more places to lay in and let 'em go screaming by while I carry on.
Duck under the forest canopy, etc.
How to make an EMP or faraday cage.
- Thread starter savageagle
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Duck under the forest canopy, etc.
Gazrok
A True Doomsday Prepper
BTW, how to test if your Faraday cage is working....
http://channel.nationalgeographic.c...eppers/interactives/budget-prep-faraday-cage/
QuietH3art
Active Member
The one thing that I have seen that seems to be missing from all the instructions to build a faraday cage is that the items inside the cage cannot come into contact with the metal lining of the cage. Each item should be wrapped in cloth so metal does not contact metal.
I made one using some left over metal tubes that some scotch comes in (I like my single malt 
)
A broad tube is the outer shell, a smaller, cardboard one is the inner part. The inner tubes do not touch the outer ones anywhere. I cut them down so they are a bit shorter and wrap them in heavy packing paper for insulation.
Right now the two tubes I have are connected by self adhesive velcro. I plan to connect both by soldering a wire to it. That wire will also be able to connect to the ground connection of a power outlet. Right now the lids are just pressed on. I plan to sand them down to get any paint out of the way for a better connection and then solder them shut. Inside I'll store spare batteries, two spare led lights, a spare wind-up radio and a wakawaka solar power charger. So they can stay shut for as long as I don't need the stuff. It's only my first attempt and not perfect but it was fun to make and I learned a lot about how to make a good one I think.
The bits of paracord you see in the pictures are just so I can pull the cardboard lids I put on top of the inner tubes for insulation off more easily.
It's an easy way to make one with most of the materials ready made. I tested it with wires clamped to one of the tubes and to the water pipes in my flat. Put my phone in and called it. When the wires are connected strongly it doesn't ring anymore so it's doing something.
)A broad tube is the outer shell, a smaller, cardboard one is the inner part. The inner tubes do not touch the outer ones anywhere. I cut them down so they are a bit shorter and wrap them in heavy packing paper for insulation.
Right now the two tubes I have are connected by self adhesive velcro. I plan to connect both by soldering a wire to it. That wire will also be able to connect to the ground connection of a power outlet. Right now the lids are just pressed on. I plan to sand them down to get any paint out of the way for a better connection and then solder them shut. Inside I'll store spare batteries, two spare led lights, a spare wind-up radio and a wakawaka solar power charger. So they can stay shut for as long as I don't need the stuff. It's only my first attempt and not perfect but it was fun to make and I learned a lot about how to make a good one I think.
The bits of paracord you see in the pictures are just so I can pull the cardboard lids I put on top of the inner tubes for insulation off more easily.
It's an easy way to make one with most of the materials ready made. I tested it with wires clamped to one of the tubes and to the water pipes in my flat. Put my phone in and called it. When the wires are connected strongly it doesn't ring anymore so it's doing something.
Gazrok
A True Doomsday Prepper
Just using cardboard will do the trick. This is the recommendation for the garbage can cage too. Additionally, if something I'm not going to use except in an emergency, I plan to wrap it up in a rag and foil as well.
savageagle
HamRadio/Office of Emergency Services/Fire-EMT-SAR
Active Region 2371, now classifiead as Beta-Gamma-Delta and located near the center of the disk, erupted with two M-class solar flares - M2.0 and M2.7 - early on June 21, 2015 producing Earth-directed full-halo Coronal Mass Ejection (CME). Arrival is expected midday June 22.
A Type II and IV radio emission (starting at 02:24 UTC, estimated velocity 682 km/s) were associated with the event. Type IV emissions occur in association with major eruptions on the Sun and are typically associated with strong CMEs and solar radiation storms.
Additionally, two 10cm radio bursts were registered. A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.
This series of CME's caused the loss of the local AT&T towers here and I lost internet and cel coverage. the cel service was reduced to emergency calls only and no texts were possible. In this case these were minor bursts and caused minor damage to circuits at the tower. The AT&T tech I talked with said the bursts affected the smaller more sensative circuits which they had to R&R those boards.
As said too, the items placed in a faraday cage must "NOT" touch any portion of the cage and should be wrap with a rag or towel. If you use aluminium foil for any portion of your cage, whatever the size, it must be heavy duty foil with a minimum thickness of 24 microns. Many ammo cans have a rubber seal between the lid and bottom and small openings around the corners and the hinge. to fix this you need to cover the entire ammo can, again with foil or mesh such as window screen material.
You also must or should use desiccant in some form. If you package and wrap your items in a cage on a hot day and bury it, the moisture inside could condense from the temperature change and end up on your items inside. Desiccant, the stuff that is normally in a small package inside a box with an item you ordered to keep it dry and moisture free.
Testing any size of cage is easy with a cel phone or am/fm radio or a handheld CB. place the phone or radio inside the cage, if it's large enough and if your cage is wrapped in screen mesh you can still hear or see the cel phone or radio. Your cel service signal should drop to "NO SERVICE" or if your listening to a radio the signal the radio is receiving should go away, meaning the music your hearing should be nothing but silence. Test this by opening the cage and your radio or cel phone will again operate as normal. close the cage again and if the cage is secure you will lose all signal to your devices, this is because the signals going to your cel phone or radio is being absorbed in the covering you have put on your cage. IE, copper screen mesh.
I will be adding much more to this as for more technical information. these minor bursts we have had has increased my motives to build a much bigger and more secure versions.
A Type II and IV radio emission (starting at 02:24 UTC, estimated velocity 682 km/s) were associated with the event. Type IV emissions occur in association with major eruptions on the Sun and are typically associated with strong CMEs and solar radiation storms.
Additionally, two 10cm radio bursts were registered. A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.
This series of CME's caused the loss of the local AT&T towers here and I lost internet and cel coverage. the cel service was reduced to emergency calls only and no texts were possible. In this case these were minor bursts and caused minor damage to circuits at the tower. The AT&T tech I talked with said the bursts affected the smaller more sensative circuits which they had to R&R those boards.
As said too, the items placed in a faraday cage must "NOT" touch any portion of the cage and should be wrap with a rag or towel. If you use aluminium foil for any portion of your cage, whatever the size, it must be heavy duty foil with a minimum thickness of 24 microns. Many ammo cans have a rubber seal between the lid and bottom and small openings around the corners and the hinge. to fix this you need to cover the entire ammo can, again with foil or mesh such as window screen material.
You also must or should use desiccant in some form. If you package and wrap your items in a cage on a hot day and bury it, the moisture inside could condense from the temperature change and end up on your items inside. Desiccant, the stuff that is normally in a small package inside a box with an item you ordered to keep it dry and moisture free.
Testing any size of cage is easy with a cel phone or am/fm radio or a handheld CB. place the phone or radio inside the cage, if it's large enough and if your cage is wrapped in screen mesh you can still hear or see the cel phone or radio. Your cel service signal should drop to "NO SERVICE" or if your listening to a radio the signal the radio is receiving should go away, meaning the music your hearing should be nothing but silence. Test this by opening the cage and your radio or cel phone will again operate as normal. close the cage again and if the cage is secure you will lose all signal to your devices, this is because the signals going to your cel phone or radio is being absorbed in the covering you have put on your cage. IE, copper screen mesh.
I will be adding much more to this as for more technical information. these minor bursts we have had has increased my motives to build a much bigger and more secure versions.
Last edited:
savageagle
HamRadio/Office of Emergency Services/Fire-EMT-SAR
more on Faraday Cages........
Faraday cages are used in electronic labs where stray EM fields must be kept out. This is important in the testing of sensitive wireless receiving equipment. In addition, a Faraday cage can prevent the escape of the EM fields emitted by a cathode-ray-tube (CRT) computer monitor. Such fields can be intercepted and translated to allow hackers to remotely view on-screen data in real time without the need for wires, cables, or cameras. This practice, known as van Eck phreaking, can also be used by government officials to view the computer activities of known criminals and certain criminal suspects.
A heavy-duty Faraday cage can protect against direct lightning strikes. When properly connected to an earth ground, the cage conducts the high current harmlessly to ground, and keeps the EM pulse from affecting personnel or hardware inside.
This ideal cannot be achieved in practice, but can be approached by using fine-mesh copper screening. For best performance, the cage should be directly connected to an earth ground.
Introduction to Faraday Cages
There is a great deal of confusion about Faraday cages. Not only about how to build them, but also what they actually protect against. In this article, Dr. Arthur Bradley, author of Disaster Preparedness for EMP Attacks and Solar Storms, answers a few basic questions and perhaps debunks a few myths.
What is a Faraday Cage?
A Faraday cage (a.k.a. Faraday shield) is a sealed enclosure that has an electrically conductive outer layer. It can be in the shape of a box, cylinder, sphere, or any other closed shape. The enclosure itself can be conductive, or it can be made of a non-conductive material (such as cardboard or wood) and then wrapped in a conductive material (such as aluminum foil).
What does it do?
A Faraday cage works by three mechanisms: (1) the conductive layer reflects incoming fields, (2) the conductor absorbs incoming energy, and (3) the cage acts to create opposing fields. All of these work to safeguard the contents from excessive field levels. A Faraday cage is particularly useful for protecting against an electromagnetic pulse that may be the result of a high-altitude nuclear detonation in the atmosphere (a.k.a. EMP attacks).
Despite rumors to the contrary, a Faraday cage is not necessary to protect against solar coronal mass ejections because the frequency content of such disturbances is at much lower frequencies—they don’t couple energy efficiently into small-scale electronics, except through conducted paths (e.g., wires coming into the system). A better precaution against solar events is to unplug electronics and use quality surge suppressors.
How does field cancelation work?
Field cancelation occurs when the free carriers in the conductive material rapidly realign to oppose the incident electric field. If the cage is made from something non-conductive, the free carriers are not mobile enough to realign and cancel the incident field.
How thick should the conducting layer be?
The conductive layer can be very thin because of something known as the skin effect. That term describes the tendency of current to flow primarily on the skin of a conductor. As long as the conducting layer is greater than the skin depth, it will provide excellent shielding because the absorption loss will be large. The skin depth is a function of the frequency of the wave and the conductor material. As an example, consider that for a frequency of 200 MHz, the skin depth of aluminum is only about 21 microns. EMP pulses can have frequency content that ranges up to 1,000 MHz. Therefore, wrapping a box in a couple of layers of heavy duty aluminum foil (typically about 24 microns thick) provides the necessary conductor thickness to protect against high-frequency radiated fields.
Does it matter what type of conductor is used?
Not much. The conductivity of nearly any metal is good enough to allow the carriers to easily realign to cancel external fields. For example, if silver (the best conductor) is used in place of aluminum, the skin depth at 200 MHz is reduced to about 4.5 microns. Of course, the high cost of silver would prevent using it for such a purpose.
Can a Faraday cage have holes?
Yes, as long as the holes are small with respect to the wavelength of the incident electromagnetic wave. For example, a 1 GHz wave has a wavelength of 0.3 meters in free space. As long as the holes are significantly smaller than that dimension (i.e., a few millimeters), they won’t let in much of the incident wave. This is why fine conductive mesh can be used when constructing a Faraday cage. In practice, the cage’s lid or door usually causes the most leakage. Taping the seam with conductive tape helps to reduce this leakage.
Can you use existing conductive enclosures?
Yes, there are many conductive enclosures that can be used, including ammo cans, metal garbage cans, anti-static bags, and even old microwave ovens. Each has its own level of effectiveness as covered in my book, Disaster Preparedness for EMP Attacks and Solar Storms. The key criterion is that the gaps and seams remain very small.
Must the cage be grounded?
There is a great deal of confusion regarding grounding of a Faraday cage. Grounding of the cage (i.e., connecting it to some Earth-referenced source of charge) has little effect on the field levels seen inside the box. Grounding primarily helps to keep the cage from becoming charged and perhaps re-radiating. The bottom line is that an ungrounded cage protects the contents from harmful electromagnetic fields as well as a grounded one.
Anti-static Bags
Anti-static bags are readily available to protect electronic components against electrostatic discharge. They can be purchased in many different sizes, including some large enough to hold radio equipment. While they do offer shielding from EMP, not all products are created equal. Testing confirmed that products certified to MIL-PRF-8170 and/or MIL-PRF-131 offer the greatest protection from an EMP. The results from testing three different types of bags are provided in Disaster Preparedness for EMP Attacks and Solar Storms. When selecting an ESD bag, consider not only the shielding effectiveness but also the physical ruggedness of the bag. A tear or large hole can compromise the bag by allowing EMP energy to enter.
Faraday cages are used in electronic labs where stray EM fields must be kept out. This is important in the testing of sensitive wireless receiving equipment. In addition, a Faraday cage can prevent the escape of the EM fields emitted by a cathode-ray-tube (CRT) computer monitor. Such fields can be intercepted and translated to allow hackers to remotely view on-screen data in real time without the need for wires, cables, or cameras. This practice, known as van Eck phreaking, can also be used by government officials to view the computer activities of known criminals and certain criminal suspects.
A heavy-duty Faraday cage can protect against direct lightning strikes. When properly connected to an earth ground, the cage conducts the high current harmlessly to ground, and keeps the EM pulse from affecting personnel or hardware inside.
This ideal cannot be achieved in practice, but can be approached by using fine-mesh copper screening. For best performance, the cage should be directly connected to an earth ground.
Introduction to Faraday Cages
There is a great deal of confusion about Faraday cages. Not only about how to build them, but also what they actually protect against. In this article, Dr. Arthur Bradley, author of Disaster Preparedness for EMP Attacks and Solar Storms, answers a few basic questions and perhaps debunks a few myths.
What is a Faraday Cage?
A Faraday cage (a.k.a. Faraday shield) is a sealed enclosure that has an electrically conductive outer layer. It can be in the shape of a box, cylinder, sphere, or any other closed shape. The enclosure itself can be conductive, or it can be made of a non-conductive material (such as cardboard or wood) and then wrapped in a conductive material (such as aluminum foil).
What does it do?
A Faraday cage works by three mechanisms: (1) the conductive layer reflects incoming fields, (2) the conductor absorbs incoming energy, and (3) the cage acts to create opposing fields. All of these work to safeguard the contents from excessive field levels. A Faraday cage is particularly useful for protecting against an electromagnetic pulse that may be the result of a high-altitude nuclear detonation in the atmosphere (a.k.a. EMP attacks).
Despite rumors to the contrary, a Faraday cage is not necessary to protect against solar coronal mass ejections because the frequency content of such disturbances is at much lower frequencies—they don’t couple energy efficiently into small-scale electronics, except through conducted paths (e.g., wires coming into the system). A better precaution against solar events is to unplug electronics and use quality surge suppressors.
How does field cancelation work?
Field cancelation occurs when the free carriers in the conductive material rapidly realign to oppose the incident electric field. If the cage is made from something non-conductive, the free carriers are not mobile enough to realign and cancel the incident field.
How thick should the conducting layer be?
The conductive layer can be very thin because of something known as the skin effect. That term describes the tendency of current to flow primarily on the skin of a conductor. As long as the conducting layer is greater than the skin depth, it will provide excellent shielding because the absorption loss will be large. The skin depth is a function of the frequency of the wave and the conductor material. As an example, consider that for a frequency of 200 MHz, the skin depth of aluminum is only about 21 microns. EMP pulses can have frequency content that ranges up to 1,000 MHz. Therefore, wrapping a box in a couple of layers of heavy duty aluminum foil (typically about 24 microns thick) provides the necessary conductor thickness to protect against high-frequency radiated fields.
Does it matter what type of conductor is used?
Not much. The conductivity of nearly any metal is good enough to allow the carriers to easily realign to cancel external fields. For example, if silver (the best conductor) is used in place of aluminum, the skin depth at 200 MHz is reduced to about 4.5 microns. Of course, the high cost of silver would prevent using it for such a purpose.
Can a Faraday cage have holes?
Yes, as long as the holes are small with respect to the wavelength of the incident electromagnetic wave. For example, a 1 GHz wave has a wavelength of 0.3 meters in free space. As long as the holes are significantly smaller than that dimension (i.e., a few millimeters), they won’t let in much of the incident wave. This is why fine conductive mesh can be used when constructing a Faraday cage. In practice, the cage’s lid or door usually causes the most leakage. Taping the seam with conductive tape helps to reduce this leakage.
Can you use existing conductive enclosures?
Yes, there are many conductive enclosures that can be used, including ammo cans, metal garbage cans, anti-static bags, and even old microwave ovens. Each has its own level of effectiveness as covered in my book, Disaster Preparedness for EMP Attacks and Solar Storms. The key criterion is that the gaps and seams remain very small.
Must the cage be grounded?
There is a great deal of confusion regarding grounding of a Faraday cage. Grounding of the cage (i.e., connecting it to some Earth-referenced source of charge) has little effect on the field levels seen inside the box. Grounding primarily helps to keep the cage from becoming charged and perhaps re-radiating. The bottom line is that an ungrounded cage protects the contents from harmful electromagnetic fields as well as a grounded one.
Anti-static Bags
Anti-static bags are readily available to protect electronic components against electrostatic discharge. They can be purchased in many different sizes, including some large enough to hold radio equipment. While they do offer shielding from EMP, not all products are created equal. Testing confirmed that products certified to MIL-PRF-8170 and/or MIL-PRF-131 offer the greatest protection from an EMP. The results from testing three different types of bags are provided in Disaster Preparedness for EMP Attacks and Solar Storms. When selecting an ESD bag, consider not only the shielding effectiveness but also the physical ruggedness of the bag. A tear or large hole can compromise the bag by allowing EMP energy to enter.
savageagle
HamRadio/Office of Emergency Services/Fire-EMT-SAR
I guess some very important things can be taken from the above information.
The cage does not need to be earth grounded but the cage covering can be charged and therefore re-radiate so grounding it to earth will allow any charge to be relieved to ground.
In the shielding, COPPER screen mesh is best and at any opening of a cage the shielding of the cage and the shielding on the door opening should come in contact when closed.
Also mentioned is the minimum thickness of foil is 24 microns as in heavy duty foil.
It also talks about the "wave length", small items such as cel phones, small FRS radio's and the like should not suffer from solar attacks.
I hope this helps to clarify the wrongs and rights of a faraday cage.
Myself, I have a 12' x 14' shed and i'm thinking of shielding it for various items. Although I would not put anything in it that I will need when TSHF or I want the "G" to find, it could save things I may need until someone comes searching for those items they will never find.
I think it was Gazrok who said, giving up duplicates your not needing to seem cooperative while your good stash is well hidden might be a good thing. They are not going to spend too much time searching and not with GPR to find anything when they have already found things that will satisfy them.
The cage does not need to be earth grounded but the cage covering can be charged and therefore re-radiate so grounding it to earth will allow any charge to be relieved to ground.
In the shielding, COPPER screen mesh is best and at any opening of a cage the shielding of the cage and the shielding on the door opening should come in contact when closed.
Also mentioned is the minimum thickness of foil is 24 microns as in heavy duty foil.
It also talks about the "wave length", small items such as cel phones, small FRS radio's and the like should not suffer from solar attacks.
I hope this helps to clarify the wrongs and rights of a faraday cage.
Myself, I have a 12' x 14' shed and i'm thinking of shielding it for various items. Although I would not put anything in it that I will need when TSHF or I want the "G" to find, it could save things I may need until someone comes searching for those items they will never find.
I think it was Gazrok who said, giving up duplicates your not needing to seem cooperative while your good stash is well hidden might be a good thing. They are not going to spend too much time searching and not with GPR to find anything when they have already found things that will satisfy them.
Gazrok
A True Doomsday Prepper
We actually had lightning hit our garage a few days ago. But, we have some pretty heavy duty lightning rods that did their job, and channeled it into the ground harmlessly. We live in the lightning capital of the US (some say the world), yet I'm surprised how many here DON'T have rods on their structures.... We have a tree that's been hit twice too. I'm STILL in the process of chopping that bad boy up....
Brent S
Top Poster
I recently finished splitting a nice white pine that took a hit. It was still alive, but had a slight lean towards the house, so it's this years heat source now.
savageagle
HamRadio/Office of Emergency Services/Fire-EMT-SAR
Wow, pre-conditioned firewood................LOL. I went hunting back in 92 up in sanoma in september and standing about 80 feet from a large tree. A thunder cloud came through and myself and dad hit the ground and waited. A strike hit that tree and I could not hear for at least 2 minutes or see much from the flash for a minute. I saw the bolt and it seemed to be 10 feet across. After the cloud past we walked for 15 minutes down the meadow and looked back and the tree was still pouring heavy smoke out of it. I've seen a tree in yosemite that was hit and it smoldered for 3 days. As long as the path to earth ground is sufficient I guess thousands of volts can be easily directed without damaging the cage. imagine the damage if a power pole was hit, and you watched the voltage travel from pole to pole down to your house and nothing was protected or unplugged. i've seen that happen, voltage going from pole to pole while blowing all the transformers along the way. It's got to have ground.
I had to study this stuff when I put up a 55 ft free standing antenna tower. It had a concrete base 4'x4'x6'deep and the attaching points for the tower had to be isolated from the rebar supporting the base concrete and a 6 gauge cable from the tower to a rod in the ground 30 inches. If I hadn't done that right lightning would hit the tower and travel down into the concrete base and explode it trying to get to ground.
I had to study this stuff when I put up a 55 ft free standing antenna tower. It had a concrete base 4'x4'x6'deep and the attaching points for the tower had to be isolated from the rebar supporting the base concrete and a 6 gauge cable from the tower to a rod in the ground 30 inches. If I hadn't done that right lightning would hit the tower and travel down into the concrete base and explode it trying to get to ground.
Gazrok
A True Doomsday Prepper
I've actually been indirectly hit 3 times (explains a lot, huh?).
Once, when I was a kid, it arced out of a light socket when it hit the house, and fried my hand a bit.
Again, when a teen, was walking on the beach, when it hit the beach nearby. Got knocked out even...but had a cool fulgarite after.
Later, when in my 20's, went river rafting with friends. Had just gotten to the end of the tubing river, and literally had one foot out of the water already, when it hit the riverbank, and gave me a good jolt. My buddy behind me got knocked out, and we had to do CPR to get him back to normal (luckily, just the chest compressions, not mouth to mouth).... He coughed up water after about 4 compressions, and was really wigged out, lol.
Then again, my area is known for it. There's a reason our teams are called The Lightning, The Storm, etc.
A buddy of mine got hit standing by his sink when it arced out and flew him across the room. He had to go to the hospital, but was fine the next day. Granted, we were all very lucky. Can kill you just as easy.
Yep, and if that close, your body probably felt a bit numb, like when a foot goes asleep, but by a factor of 10 or more.
Once, when I was a kid, it arced out of a light socket when it hit the house, and fried my hand a bit.
Again, when a teen, was walking on the beach, when it hit the beach nearby. Got knocked out even...but had a cool fulgarite after.
Later, when in my 20's, went river rafting with friends. Had just gotten to the end of the tubing river, and literally had one foot out of the water already, when it hit the riverbank, and gave me a good jolt. My buddy behind me got knocked out, and we had to do CPR to get him back to normal (luckily, just the chest compressions, not mouth to mouth).... He coughed up water after about 4 compressions, and was really wigged out, lol.
Then again, my area is known for it. There's a reason our teams are called The Lightning, The Storm, etc.
A buddy of mine got hit standing by his sink when it arced out and flew him across the room. He had to go to the hospital, but was fine the next day. Granted, we were all very lucky. Can kill you just as easy.
Yep, and if that close, your body probably felt a bit numb, like when a foot goes asleep, but by a factor of 10 or more.
