Better than tinfoil - wire mesh cloth for anti EMF/Spying/EMP pulses

[Anti Federalist]

Let the scoffers scoff and the haters hate. :D

Score your wire cloth supplies at this website:

http://www.lessemf.com/fabric.html

I made a Faraday purse for cel phones from stainless steel mesh cloth that I got through an auto supply house, but these guys have more choices.

[Matt Collins]

My friend keeps flashlights, calculators, radios, and other electronics in a metal ammo box to prevent exactly this.

[GunnyFreedom]

My friend keeps flashlights, calculators, radios, and other electronics in a metal ammo box to prevent exactly this.

A metal ammo box is simply not sufficient to prevent damage from a primary EMP attack within 35 miles. An ungrounded Faraday cage should be sufficient between 20 and 35 miles from a primary EMP burst, and properly grounded Faraday cage is required to protect electronics within 20 miles of a primary EMP burst.

There are also EMP shielding (non Faraday-based) options commercially available for those who do not want to bother with meshes, caging and grounding.

[Anti Federalist]

A metal ammo box is simply not sufficient to prevent damage from a primary EMP attack within 35 miles. An ungrounded Faraday cage should be sufficient between 20 and 35 miles from a primary EMP burst, and properly grounded Faraday cage is required to protect electronics within 20 miles of a primary EMP burst.

There are also EMP shielding (non Faraday-based) options commercially available for those who do not want to bother with meshes, caging and grounding.

A lead lined ammo box might to the trick, but it'll be awful heavy and cumbersome.

[Dr.3D]

I always thought a metal ammo box would work just fine as a Faraday cage. I can't see why it wouldn't work, especially if it were grounded. If there is concern about the material not being conductive enough, then one could of course cover it with aluminum foil just to be sure. My military vehicle uses an aluminum enclosure to keep EMP out and RF from leaking out of it's ignition system.

[Dr.3D]

Seems like that conductive cloth would be great for lining a jacket or shirt for resistance to Tazers.

[GunnyFreedom]

I always thought a metal ammo box would work just fine as a Faraday cage. I can't see why it wouldn't work, especially if it were grounded. If there is concern about the material not being conductive enough, then one could of course cover it with aluminum foil just to be sure. My military vehicle uses an aluminum enclosure to keep EMP out and RF from leaking out of it's ignition system.

A metal box such as an ammo can may be sufficient for basic EM interference, but the Faraday principle of capacitance is required to block intense EMP burst of a actual EM pulse attack.

The problem is one of intensity. Understand that the standard energy density of an RF signal is something likw one-one hundredth of a watt per square meter, while the area directly below an EMP burst will receive something like one million watts per square meter. The reason that such an amazing intensity is even blockable/shieldable with ANYTHING at 15 miles is because this intensity is subject to an inverse-square law diminishing rapidly with distance from ground zero.

AntiFed is correct, lead has shielding properties against EMP, but that is merely a brute force defense. The scientific defense (work smarter, not harder) is the use of a Faraday cage.

Faraday cages rely on capacitance to divert EM energy to ground. Is there enough raw capacitance in the mesh/cage to hold the EM energy long enough for it to discharge to ground? If not, there will be passthrough risking equipment damage.

The aluminum chassis on EMP hardened MilSpec equipment uses yet a third principle that is overly expensive for the civilian market -- aluminum is actually a very agile conductor, and in the event of an EMP event, circuitry is tripped that actually DRAWS the charge away from sensitive equipment. This method is subject to fault due to overload (multiple pulses in short succession) but is used in mobile MilSpec equipment such as vehicles and laptops due to the lack of probable grounding in the event of an actual attack. You can rest assured that sensitive data centers (such as a SCIF) employ a traditional Faraday technique for pulse diversion.

Faraday, the scientist who invented the capacitor, used multiple layers of conductor separated by insulator to create the longest possible conductive surface within a small package for the purpose of holding a charge for later release. A Faraday CAGE operates on a similar principle although it's purpose is not to hold a charge but to release it to ground as quickly as possible.

The conductive surface area of a single-layer metallic box -- even grounded -- is simply not capacitive enough to divert hundreds of thousands of watts of EM energy per square meter.

[ronpaulhawaii]

http://www.lessemf.com/images/a1209-2.jpg


One woman we know wears it on her head as a scarf and swears it reduces EMF noise for her!

a tin foil hat wearer, being used for advertising... lulz...

[Anti Federalist]

Seems like that conductive cloth would be great for lining a jacket or shirt for resistance to Tazers.

;)

[osan]

A metal ammo box is simply not sufficient to prevent damage from a primary EMP attack within 35 miles. An ungrounded Faraday cage should be sufficient between 20 and 35 miles from a primary EMP burst, and properly grounded Faraday cage is required to protect electronics within 20 miles of a primary EMP burst.

There are also EMP shielding (non Faraday-based) options commercially available for those who do not want to bother with meshes, caging and grounding.

I might point out that anyone within 20 miles of a likely EMP source strong enough to cook their electronics is likely to have other, larger problems on their menu in fairly short order. Watching the cloud rise, I suspect my first questions will not revolve around whether I'll be able to make use of the minutes remaining on my cell phone for the month. :eek:

[GunnyFreedom]

I might point out that anyone within 20 miles of a likely EMP source strong enough to cook their electronics is likely to have other, larger problems on their menu in fairly short order. Watching the cloud rise, I suspect my first questions will not revolve around whether I'll be able to make use of the minutes remaining on my cell phone for the month. :eek:

EMP attacks generally burst in the troposphere/stratosphere region to minimize physical damage and loss of life, while maximizing the area burned with EM radiation. For a ground strike, if you are close enough to worry about EMP, then EMP will truly be the last thing on your mind. Agree.

[osan]

The conductive surface area of a single-layer metallic box -- even grounded -- is simply not capacitive enough to divert hundreds of thousands of watts of EM energy per square meter.

If you are in an area being popped with hundreds of thousands of watts/m^2, you won't much care what happens to your equipment. YOU will be toast. Literally. 200KW ~= 268hp. If a human's silhouette covers 1/10 m^2, that's getting hit with 26hp worth of EM. Bye bye.

[libertarian4321]

You youngsters might want one of those fancy new hats, but I'm sticking with the tried and true (and very stylish) tin foil hat!

[GunnyFreedom]

If you are in an area being popped with hundreds of thousands of watts/m^2, you won't much care what happens to your equipment. YOU will be toast. Literally. 200KW ~= 268hp. If a human's silhouette covers 1/10 m^2, that's getting hit with 26hp worth of EM. Bye bye.

I don't think so. Remember, radiation exposure is measured in rads per second per second, a t^2 function. Not watts per area. The difference is watt-density (rads) raised by TIME equals exposure. One second in a microwave will do one order of magnitude less damage to you than 2 seconds, which itself does one magnitude less damage than 4 seconds, and so on. So I think you are missing a power here: energy density to the power of time.

An EMP burst is on the order of milliseconds. Sure, there will be some exposure damage, but it's not a sustained radiation, so the damage/exposure will be somewhat more intense than one order of magnitude less than your conclusion.

I believe your assumption is visible: "If you are in an area being popped with hundreds of thousands of watts/m^2..." Being assumes a duration of longer than a few split milliseconds, no?

the proper figure would be (I think):

{watts/m^2}^time = exposure

{e/m^2}^t = e

so your calc doesn't account for 'to the power of time"

Note that microwave energy bursts electronics almost instantly, but a human could stand that field for some time longer than a piece of electronics can, with some but little damage. Electronics are more sensitive, and damage can more easily measured by energy density alone.

[Dr.3D]

If you are in an area being popped with hundreds of thousands of watts/m^2, you won't much care what happens to your equipment. YOU will be toast. Literally. 200KW ~= 268hp. If a human's silhouette covers 1/10 m^2, that's getting hit with 26hp worth of EM. Bye bye.

Seems people tend to forget the voltage involved.

If we are talking about 1 million watts at perhaps 1 million volts, then there is only going to be a current of 1 amp. If the duration of the pulse is in microseconds, I doubt 1 amp is going to be much of a problem.

P=I*E or in other words, Power = Current * Voltage

I'm still having problems understanding why aluminum foil wouldn't be able to conduct 1 amp for a few microseconds or for even a millisecond. A grounded aluminum foil covered box should work very well as a Faraday cage.

[KCIndy]

I'm still having problems understanding why aluminum foil wouldn't be able to conduct 1 amp for a few microseconds or for even a millisecond. A grounded aluminum foil covered box should work very well as a Faraday cage.


Send it in to Mythbusters:

http://dsc.discovery.com/tv/mythbusters/

and let them test it!! :D

[parocks]

Good link. How about links to other technical fabrics? Bulletproof, etc.


Let the scoffers scoff and the haters hate. :D

Score your wire cloth supplies at this website:

http://www.lessemf.com/fabric.html

I made a Faraday purse for cel phones from stainless steel mesh cloth that I got through an auto supply house, but these guys have more choices.

[Pericles]

Seems people tend to forget the voltage involved.

If we are talking about 1 million watts at perhaps 1 million volts, then there is only going to be a current of 1 amp. If the duration of the pulse is in microseconds, I doubt 1 amp is going to be much of a problem.

P=I*E or in other words, Power = Current * Voltage

I'm still having problems understanding why aluminum foil wouldn't be able to conduct 1 amp for a few microseconds or for even a millisecond. A grounded aluminum foil covered box should work very well as a Faraday cage.

I really don't get the whole EMP scare. The idea of 1MT to 10 MT air bursts went the way of the Cols War - weapons of that size are a bit hard to build in the garage. Non - nuke EMP blasts are pretty limited in range, so i tend to agree that the tin foil hat will probably do the trick. Usually an attack that takes considerable resource to achieve has some purpose in mind, so I'm trying to figure out who benefits .........

[Dr.3D]

Send it in to Mythbusters:

http://dsc.discovery.com/tv/mythbusters/

and let them test it!! :D

Well, others have already been testing the aluminum foil boxes.

This web site has a lot of links to other information about Faraday cages.

http://unitedstatesaction.com/emp_and_faraday_cages.htm#faraday

[TNforPaul45]

Didn't you guys hear? The EPA just banned tin foil as being linked to global warming. Yeah the tin foil also goes out and eats baby seals then comes home and rolls itself back up into your cabinet...waiting...plotting...

[GunnyFreedom]

I really don't get the whole EMP scare. The idea of 1MT to 10 MT air bursts went the way of the Cols War - weapons of that size are a bit hard to build in the garage. Non - nuke EMP blasts are pretty limited in range, so i tend to agree that the tin foil hat will probably do the trick. Usually an attack that takes considerable resource to achieve has some purpose in mind, so I'm trying to figure out who benefits .........

My thinking is 1) it takes a lot less EMP damage to disable complex technology like computers and cellphones than it does to disable a car, and 2) Faraday works two ways, it also masks outbound signals, making you effectively silent, and 3) If there were ever a 'war on the constitution movement' I assume EMP weapons would be in the arsenal and on the front lines. Gotta bag him before he gets a signal out and all. I figure directed EMP is both cheaper and more 'stealthy' than is signal jamming. It seems a natural evolution.

[Dr.3D]

My thinking is 1) it takes a lot less EMP damage to disable complex technology like computers and cellphones than it does to disable a car, and 2) Faraday works two ways, it also masks outbound signals, making you effectively silent, and 3) If there were ever a 'war on the constitution movement' I assume EMP weapons would be in the arsenal and on the front lines. Gotta bag him before he gets a signal out and all. I figure directed EMP is both cheaper and more 'stealthy' than is signal jamming. It seems a natural evolution.

I tend to agree with you on that one. There are conventional (pinch type) emp bombs that would do the trick from around 400 miles up and would cover most of the U.S. Being the military would have hardened communications and transportation equipment, the rest of the population would mostly be unable to communicate or travel after one of those had been used. Meanwhile those with the hardened equipment would still be able to do those things and be at a great advantage.

[Pericles]

My thinking is 1) it takes a lot less EMP damage to disable complex technology like computers and cellphones than it does to disable a car, and 2) Faraday works two ways, it also masks outbound signals, making you effectively silent, and 3) If there were ever a 'war on the constitution movement' I assume EMP weapons would be in the arsenal and on the front lines. Gotta bag him before he gets a signal out and all. I figure directed EMP is both cheaper and more 'stealthy' than is signal jamming. It seems a natural evolution.
You've got the Intel experience. Let's talk capabilities and intentions.

(A) Who is capable of making such a device that can deliver a burst 400 miles up (seems like a short list to me)?

(B) Intentions is a bit broader in that the capability does have military utility.

Say for instance, given the number of command detonated IEDs in Iraq, and the crappy state of its infrastructure, why not do an EMP device back in 2005 to fry the insurgents electronics?

[idirtify]

gunny,

How about a 4-square-foot stainless steel tank, with about 1/8 inch thick steel? 1) will it work? 2) if so, will it need to be grounded better than laying flat on the bare ground?

[Aratus]

EMPs can vary in size and effect... good question!

[GunnyFreedom]

You've got the Intel experience. Let's talk capabilities and intentions.

(A) Who is capable of making such a device that can deliver a burst 400 miles up (seems like a short list to me)?

(B) Intentions is a bit broader in that the capability does have military utility.

Say for instance, given the number of command detonated IEDs in Iraq, and the crappy state of its infrastructure, why not do an EMP device back in 2005 to fry the insurgents electronics?

I cannot imagine in this day and age detonating a device on that scale except perhaps for China, and I do not really anticipate a Chinese attempt to overrun and conquer America.

My EMP concern primarily focuses on much smaller, more portable devices. As for IED's, 1) the US either did not anticipate this problem, or 2) chose not to destroy all the electronics in Iraq, or 3) decided that the political price for detonating a nuclear device would be too high to pay.

To the point of smaller EMP devices, an EMP could just as soon detonate an IED as pacify it.

[GunnyFreedom]

gunny,

How about a 4-square-foot stainless steel tank, with about 1/8 inch thick steel? 1) will it work? 2) if so, will it need to be grounded better than laying flat on the bare ground?

I think the reflective area is as important as volume. That's why multiple layers of foil or Faraday wiring. As an EM signal passes through metal, hitting the interior surface, EM energy is reflected back into the metal which then carries the charge away. The better your grounding, the more effective your "carrying away" will be, and the more layers/surface/reflective area your sink has, the more EM it will absorb.

[Pericles]

Where I'm coming from is this:

Of course you can find additional resources on the web by searching for
electromagnetic pulse or similar search terms. A couple of things to keep
in mind:
1. The EMP produced by non-nuclear weapons can be effective over a range
of a couple hundred yards. A nuclear EMP may be effective over hundreds of
square miles. The only way that non-nuclear EMP weapons offer an advantage
over nuclear EMP is by taking advantage of the microwave frequencies
produced by some devices.
2. EMP generators may be considered weapons, depending upon their power
and their use. Sometimes a science experiment can have legal
ramifications, especially in this era of hightened tensions. So...Be
careful and good luck.

from- http://www.madsci.org/posts/archives/2005-07/1121806696.Ph.r.html

How much effort should I put into defense from something that has less effective range than a machinegun?

[GunnyFreedom]

Where I'm coming from is this:

Of course you can find additional resources on the web by searching for
electromagnetic pulse or similar search terms. A couple of things to keep
in mind:
1. The EMP produced by non-nuclear weapons can be effective over a range
of a couple hundred yards. A nuclear EMP may be effective over hundreds of
square miles. The only way that non-nuclear EMP weapons offer an advantage
over nuclear EMP is by taking advantage of the microwave frequencies
produced by some devices.
2. EMP generators may be considered weapons, depending upon their power
and their use. Sometimes a science experiment can have legal
ramifications, especially in this era of hightened tensions. So...Be
careful and good luck.

from- http://www.madsci.org/posts/archives/2005-07/1121806696.Ph.r.html (http://www.madsci.org/posts/archives/2005-07/1121806696.Ph.r.html)

How much effort should I put into defense from something that has less effective range than a machinegun?

I would assume that if you have reason to believe that you will never be targeted by the information-cops, that you will have almost nothing to worry about in this area.

[Anti Federalist]

Where I'm coming from is this:

Of course you can find additional resources on the web by searching for
electromagnetic pulse or similar search terms. A couple of things to keep
in mind:
1. The EMP produced by non-nuclear weapons can be effective over a range
of a couple hundred yards. A nuclear EMP may be effective over hundreds of
square miles. The only way that non-nuclear EMP weapons offer an advantage
over nuclear EMP is by taking advantage of the microwave frequencies
produced by some devices.
2. EMP generators may be considered weapons, depending upon their power
and their use. Sometimes a science experiment can have legal
ramifications, especially in this era of hightened tensions. So...Be
careful and good luck.

from- http://www.madsci.org/posts/archives/2005-07/1121806696.Ph.r.html

How much effort should I put into defense from something that has less effective range than a machinegun?

Lots of good information came out of this thread.

I think the point was missed somewhat though.

I'm not that concerned about EMP damage to my electronics, I've already taken steps to prevent total dependency in key areas (vaccum tubes and breaker points FTW ;) ).

The point in posting the source for wire mesh is to prevent unwanted RF emissions from getting out.

To isolate, RF wise, the hundreds of electronic "dog collars" that are out there, from RFID chips in "smart cards" to unwanted RF emissions from cel phones.

[osan]

I don't think so.

I believe your assumption is visible: "If you are in an area being popped with hundreds of thousands of watts/m^2..." Being assumes a duration of longer than a few split milliseconds, no?[/quuote]

I was assuming, based on what was written, that the exposure was more or less instantaneous. A watt is a scalar quantity. It can be applied over an arbitrary time interval. The usual interval is "seconds". If your body absorbs 26hp of energy in 1 second, there will be precious little left of you to complain about the result.

[QUOTE]{watts/m^2}^time = exposure


This is correct. Perhaps my assumption of quantity/interval is mistaken. But we were speaking of EMP and those last for very short durations, usually - unless we situate ourselves at the center of a quasar or some such. :) When mentioning hundreds of thousands of watts/m^2, per second seemed a reasonable rate of application.


so your calc doesn't account for 'to the power of time"

Maybe, maybe not. I'm willing to concede this if I an incorrect. But even so, several hundreds of thousands of watt/m^2 would have to be distributed over a significant interval not to cause one some serious harm.

[joncro55]

Just stumbled across this forum and I figured I would throw a source out there for all of you guys looking for wire mesh, if any of you out there are.

I just got some here:
http://www.bwire.com/

Good old fashioned company, good service and nice product. Just an FYI.

[acptulsa]

My thinking is 1) it takes a lot less EMP damage to disable complex technology like computers and cellphones than it does to disable a car.

Only to the degree that the car body is, in fact, sort of a Faraday cage. Seems to me that a little cage around the main car computer would be a nice second line of defense. I'd be very surprised--very surprised--if they aren't busy trying to figure out how to kill a speeding car without also killing the cop cars chasing it. If we hear that cops are going back to points and condenser ignitions, we'll know they failed to do it but are installing EMP generators in cop cars anyway.

In the end, you'd probably have to wrap the distributor and coil of even an old points-and-condenser ignition system, and you probably couldn't wrap all of the sensors a computer needs to work a modern engine.

Besides, we're missing the more important point. This new age chain mail is handy against the new microwave 'crowd control and dispersal' weapon they came up with. Nothing like nuking some protestors for all you're worth and having them stand and grin at you...

[Aratus]

some old fashioned screen doors have
a very similar effect to this cloth stuff?

[acptulsa]

some old fashioned screen doors have
a very similar effect to this cloth stuff?

Undoubtedly, though that real steel mesh we remember for its indestructability from long ago is now rarer than hens' teeth. And the weave isn't exactly optimized for scattering microwaves.

[PaulConventionWV]

I have no idea what you guys are talking about, or what EMPs are, but EMFs are very real. Here is something I use to protect myself from the radiation coming from everyday electronic devices.

hXXp://www.energystore.biz/index_files/pendant_new.htm

[Aratus]

you izz a young pup...?
we must sound like auld
hillybilly folk ahhhh talkin'
about thah clyme & tyme
after bill mckinley arrived
socially in d.c and set off
the whole town aplenty...!

[Vessol]

I see how it is Anti-Fed! You WANT me to get rid of my tinfoil, you WANT me to replace it with this!?

I see it now, it's all a part of your plot.

I will NOT give up my tinfoil, thank you very much!

[Dr.3D]

I see how it is Anti-Fed! You WANT me to get rid of my tinfoil, you WANT me to replace it with this!?

I see it now, it's all a part of your plot.

I will NOT give up my tinfoil, thank you very much!
But this cloth is so much more comfortable. That tinfoil makes me itch in hot weather.

[Aratus]

some of the old fashion'd screen doors most enduringly lacking rust
also have an effect physics~wise akin to this new mesh cloth???
admittedly wearing vintage screen doors as nouveau clothing apparel
when going out and about on errands or even shopping for things...

[Anti Federalist]

Just stumbled across this forum and I figured I would throw a source out there for all of you guys looking for wire mesh, if any of you out there are.

I just got some here:
http://www.bwire.com/

Good old fashioned company, good service and nice product. Just an FYI.

Great tip, I had heard of them before as well.

Welcome to the forum.

Thanks for the bump.

[speciallyblend]

You youngsters might want one of those fancy new hats, but I'm sticking with the tried and true (and very stylish) tin foil hat!

can line it in your snowboard cap tin or cloth ,then it looks nicey:) note i haven't tried this:)