Radio Preppers

General Category => Tactical Corner => Topic started by: ttabs on January 08, 2013, 09:02:28 AM

Title: Building Your Own EMP Faraday Cage
Post by: ttabs on January 08, 2013, 09:02:28 AM
By now I suspect most of you have read the novel 'One Second After' by William R. Forstchen.  If you haven't, I'd recommend you bump that one up on the priority read.  It's an EMP (Electromagnetic Pulse) story and the author explores just how devastating one would be if used against the US.  In a nutshell, the energy pulse derived by a nuclear detonation above the earth's surface would be magnified many times through what is referred to as the Compton Effect.  As the theory goes, the resulting magnified pulse of energy would destroy anything electronic rendering it useless.  This includes everything from the electrical grid to your car down to your handheld calculator and watch. 

Some simple things could be done to protect key electronic components in such an event. Namely the Faraday Cage which is a grounded structure that houses sensitive electronic items.  The pulse would hit the metal structure and be routed around and out the grounding rod. 

From what I read, Faraday Cages can be constructed of a wire mesh or solid walled metal material.  For all I know, chicken wire might work as well.  I'm no expert on the subject, but I pondered what I could do to somewhat protect my assets in such an event. 

My first "Faraday" idea was to get a metal garbage can and lid and ground it to a grounding rod in my basement.  This project was a rather quick install.  i lined the can with a military foam sleeping pad as an additional insulator and of course grounded the lid to the can.  I think it will work as far as a Faraday Cage is concerned, but it really is awkward storing stuff inside and having to dig through everything to retrieve items.   

Here's a better idea. 

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2112_zps2d8012fc.jpg)

I kept an eye on crags list looking for a metal storage cabinet.  Not many were listed so it was a waiting game.  You could also use a metal file cabinet but I wanted the storage capacity and ease of use of a cabinet.  New - this cabinet runs about $500.  I found this one for $50 as it was a damaged freight item.  It's 4'x2'x7'.   
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on January 08, 2013, 09:06:12 AM
I drilled a 1/2' hole in the concrete floor of my basement here and - using a fence post pounding device - drove in an 8' grounding rod.  Then it was just a simple matter of hooking it to the cabinet. 

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2116_zps1e891c77.jpg)


Now that it's grounded - I then used some military foam sleeping pads cut to length as an insulator on the shelves .....

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2114_zps6cd8080d.jpg)
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on January 08, 2013, 09:12:25 AM
Now it's just a matter of simple organization to get things stored inside.  You can go as far as you'd like to protect yourself from an EMP.  For instance, perhaps getting a spare ECU for your truck/car or other motorize devices would be nice.  I have spare charge controlers and inverters for solar systems.  All my handheld radios and chargers are stored here.  You can see I have a generator stored inside.  Use your imagination here.  I bet I'll have this thing filled when I'm finally done with the project.   

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2113_zpsdeedb3d0.jpg)

So for me - I could use the storage space this cabinet provides.  BUT, by default it also serves as a protective container against an EMP.  Unfortunately, the radios that I use regularly will not be protected as it's not practical to unplug and store for every use.  so I'll have to consider getting spares.  Antennas I believe would not be effected by an EMP so they should survive in good shape. 

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2117_zps1903478d.jpg)
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on January 08, 2013, 09:14:45 AM
And - to maximize efficiency - I added hooks to the exterior for hanging gear and such using pop rivets.  Also, I anchored this cabinet to the concrete wall.  It is rock solid!

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2115_zps4e3ce894.jpg)

So I guess my question is - why risk being vulnerable to an incredibly devastating event when the solution is easy to install and practical for use? I'm interested in your thoughts and discussions. 
Title: Re: Building Your Own EMP Faraday Cage
Post by: gil on January 08, 2013, 11:00:22 AM
Excellent, mine is just a small ammo can.. Make sure the front doors are well connected to the body of the cabinet. Chicken wire would not work, holes are too big. I wouldn't use anything like a mesh anyway. The holes have to be smaller than the wavelength of the "distrubance," or something like that... Anyway, there should be no gaps anywhere...

Gil.
Title: Re: Building Your Own EMP Faraday Cage
Post by: WA4STO on January 08, 2013, 12:56:32 PM
Amazing, Tom, just amazing.  Well done.

I remember when I was working at ARRL HQ we had a small room -- a large closet size maybe -- that was "Faradayed".  As I recall, the lab droids used it for, among other things, doing the spec checks on the various equipment that was to be written up for QST.

The problem there was that there were a number of 1.5 KW transmitters across the parking lot at W1AW.  Not to mention the fact that the rascal Luck Hurder was often to be found working satellites in the very next room to the lab.  Lots of RF, to be sure.

I admire the way you grounded that cabinet, Tom.

True, antennas themselves wouldn't be a problem, at least until you started putting VHF/UHF preamps up on the tower.  But then there's the matter of absolutely grounding both the shield and the center conductor of all coax runs before the EMP can get to those radios.  Most guys use a 'gap' thingie but here's an interesting one:

(http://static.dxengineering.com/global/images/prod/mediumlarge/alf-lt-arc-plug_ml.jpg)  which can be seen at:

http://www.dxengineering.com/parts/alf-lt-arc-plug (http://www.dxengineering.com/parts/alf-lt-arc-plug)

So?  When ya getting on WINMOR?  I know, pushy, pushy.

73 de Luck, WA4STO
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on January 13, 2013, 02:19:01 PM
I just found a fantastic article regarding the subject of EMP

click here:  http://www.futurescience.com/emp/emp-protection.html (http://www.futurescience.com/emp/emp-protection.html)
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on January 23, 2013, 07:49:17 PM
UPDATE - 

I contacted Jerry Emanuelson, the author of the article listed above regarding my Faraday Cage (I sent him a link to this post).  Turns out that metal cabinets may be more complex than I first thought.  He recommended I spot weld all the joints to create continuity around the cabinet and add a mesh copper seal around all the door contacts for positive connection when the doors are closed.  ALSO, be sure to grind off all the paint around all the components of the cabinet that touch each other so that a positive connection is made.  The pained edges of the panels can act as an insulator.

I'll disassemble this sucker to get it right.  Copper mesh is on order.  I'll post more pics of this project. 

As for grounding - he approved of the job I did but is very careful recommending others to ground their cages.  Most folks will actually create an antenna to better attract a pulse rather than dissipate one.  Going through the concrete in your basement floor is acceptable so long as you know what lies beneath.  In my case - it's fine sand (no sewer pipes or anything).   

An easier faraday cage is a metal garbage can lined with foam.  But then you have to dig through it to get at stuff.  That's the easier way.  Of course I'm going the long way around (yet more functional)!   :P
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on January 24, 2013, 01:19:47 AM
The one weak point in this is the coax, either keep some extra in the faraday cage...and/or use Luck's separator "thingy" on the exposed coax.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on January 24, 2013, 01:21:30 AM
Amazing, Tom, just amazing.  Well done.

I remember when I was working at ARRL HQ we had a small room -- a large closet size maybe -- that was "Faradayed".  As I recall, the lab droids used it for, among other things, doing the spec checks on the various equipment that was to be written up for QST.

The problem there was that there were a number of 1.5 KW transmitters across the parking lot at W1AW.  Not to mention the fact that the rascal Luck Hurder was often to be found working satellites in the very next room to the lab.  Lots of RF, to be sure.

I admire the way you grounded that cabinet, Tom.

True, antennas themselves wouldn't be a problem, at least until you started putting VHF/UHF preamps up on the tower.  But then there's the matter of absolutely grounding both the shield and the center conductor of all coax runs before the EMP can get to those radios.  Most guys use a 'gap' thingie but here's an interesting one:

(http://static.dxengineering.com/global/images/prod/mediumlarge/alf-lt-arc-plug_ml.jpg)  which can be seen at:

http://www.dxengineering.com/parts/alf-lt-arc-plug (http://www.dxengineering.com/parts/alf-lt-arc-plug)

So?  When ya getting on WINMOR?  I know, pushy, pushy.

73 de Luck, WA4STO


Luck, thanks for this (belatedly)...but I'm not sure how I would connect these...?
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 07, 2013, 01:45:47 PM
What do you put in the Faraday cage?  If you have duplicates of everything you use day to day, that would get pretty expensive.  If you pull your equipment out to use it, and put it in the cage when not in use, you've got constant work and if an EMP occurs while you're using the gear, then it is toast anyhow.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 07, 2013, 07:10:35 PM
What do you put in the Faraday cage?  If you have duplicates of everything you use day to day, that would get pretty expensive.  If you pull your equipment out to use it, and put it in the cage when not in use, you've got constant work and if an EMP occurs while you're using the gear, then it is toast anyhow.

Maybe not - I have a 10m/CB radio in one - and in two cars. But it will also hold my 2m rig - along with coax and antenna and instructions for deployment.

If you're a prepper - a base station should either be duplicated in your BOL, or your radio should be able to be disconnected and stowed for transportation quickly.

Here is my 10m/CB/2m HT - Bug Out Radio kit (photo does not show coax - as I was awaiting its arrival - but it fit perfectly):
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 07, 2013, 07:13:49 PM
Some were talking about making there entire current "Bug In Location" EMP proof (ala Gene Hackman's "shack" in the movie "Enemy of the State")...
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 07, 2013, 10:02:58 PM
What is the size of that box?
Title: Re: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 08, 2013, 04:48:35 AM
What is the size of that box?

I'll have to get you the exact dimensions tomorrow - but I think it is roughly 16"-18" square x 6"-8" in depth ( each half of the box is 4" deep and attaches via latches all around the perimeter of the box.

It comes with some very old foam padding - some have told me about a website where new custom pads can be ordered, for now what I have works.

The one thing I do NOT have in the box that will be required is - a power supply/battery.

I'm thinking that my home and BOL will have shielded batteries, but getting from here to there, I don't have an option...other than the car battery...which would have been fried...right? Maybe not though as the metal body of the car should actually act as a Faraday cage, right?
Title: Re: Building Your Own EMP Faraday Cage
Post by: gil on February 08, 2013, 03:52:10 PM
I don't think batteries need protection...

Gil.
Title: Re: Building Your Own EMP Faraday Cage
Post by: WA4STO on February 08, 2013, 05:41:25 PM
..other than the car battery...which would have been fried...right? Maybe not though as the metal body of the car should actually act as a Faraday cage, right?

Gil's right; there's really no 'electronics' (think of itty bitty current paths within a transistor -- those paths get fried easily) in the automotive battery to GET fried.

As for the 'metal body of the car', you might consider the extreme difficulty that mobile hams have had over the decades trying to come up with an effective 'ground' for their antennas. 

The, uh, rubber meets the road as it were, and makes a piss poor conductor of electricity to ground.  Maybe none.

Wanna make a Faraday cage out of your car?  Better find some new-fangled way to come up with about a bajillion ground rods.  :)

73 de WA4STO


Title: Re: Building Your Own EMP Faraday Cage
Post by: raybiker73 on February 08, 2013, 11:36:24 PM

It comes with some very old foam padding - some have told me about a website where new custom pads can be ordered, for now what I have works.


If you find replacement foam for these NVG cases, let me know where! I bought a few of them last weekend at Bob's Army & Navy up in Clearfield, PA, and while the cases are like new, the foam is pretty ratty. I'd like to custom-cut some foam so that the box would hold my FT-817, MP-1 antenna, mic, key, cables, motorcycle battery and folding solar panel.

Also, you may want to consider adding some wingnut-release jumpers between the lid and the case. There is not much continuity between them, as the rubber seal keeps them insulated from one another. The latches provide some continuity, but I'm not sure if it's enough. Not sure about the breather valve, but it may need some EMP mods as well.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 09, 2013, 12:58:30 AM

It comes with some very old foam padding - some have told me about a website where new custom pads can be ordered, for now what I have works.


If you find replacement foam for these NVG cases, let me know where! I bought a few of them last weekend at Bob's Army & Navy up in Clearfield, PA, and while the cases are like new, the foam is pretty ratty. I'd like to custom-cut some foam so that the box would hold my FT-817, MP-1 antenna, mic, key, cables, motorcycle battery and folding solar panel.

I think Luck gave me the link...let me look around a bit...ahhh, here it is:

http://www.thepelicanstore.com/Pick-N-Pluck-Foam-Sets-15.aspx (http://www.thepelicanstore.com/Pick-N-Pluck-Foam-Sets-15.aspx)

By the way...mind sharing what you paid? I bought two on eBay averaged about $35.00 each.

Also, you may want to consider adding some wingnut-release jumpers between the lid and the case. There is not much continuity between them, as the rubber seal keeps them insulated from one another. The latches provide some continuity, but I'm not sure if it's enough. Not sure about the breather valve, but it may need some EMP mods as well.

Theres that continuity issue that keeps slipping by me - would something similar to what Gil designed for his cookie-tin EMP cage, work on this too?

Also, maybe it's a dumb question...but why wouldn't the metal latches provide enough continuity? Is there a formula for size of the object and how much continuity is needed? As you stated, these are old night vision goggle cases, wasn't loose/spare 'lectricity one reason the boxes were designed in aluminum?

Remember - I literally know next to nothing regarding electricity, or it's preferences/proclivities...!
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 09, 2013, 06:39:51 AM
You might try something like this over the seams.

http://www.amazon.com/Lilly-Miller-715-15-Foot-Corrys/dp/B000QD3BPW/ref=sr_1_1?ie=UTF8&qid=1360409864&sr=8-1&keywords=copper+tape
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 09, 2013, 09:39:57 AM
You might try something like this over the seams.

http://www.amazon.com/Lilly-Miller-715-15-Foot-Corrys/dp/B000QD3BPW/ref=sr_1_1?ie=UTF8&qid=1360409864&sr=8-1&keywords=copper+tape
that might work..I wonder of the adhesive would interfere with the continuity?
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 09, 2013, 11:33:12 AM
Part of the problem is how to test it.  You won't know if it works until it is too late.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 09, 2013, 06:05:30 PM
Part of the problem is how to test it.  You won't know if it works until it is too late.

Actually - conceptually - I should be able to use my multi-meter to test for continuity...just not sure how
Title: Re: Building Your Own EMP Faraday Cage
Post by: raybiker73 on February 09, 2013, 06:10:44 PM
Yes, you can check continuity with your multimeter (mine has an audible continuity tester which makes it even simpler). As far as the cage function, you can test it to some degree with a cell phone. Turn on your phone, drop it in the Faraday cage, and then call it. If it doesn't ring, the cage is blocking it. If it does ring, back to the drawing board.  :)  You could also drop in an HT and then see if it receives from an HT outside the cage.
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 09, 2013, 06:37:48 PM
Yes, you can check continuity with your multimeter (mine has an audible continuity tester which makes it even simpler). As far as the cage function, you can test it to some degree with a cell phone. Turn on your phone, drop it in the Faraday cage, and then call it. If it doesn't ring, the cage is blocking it. If it does ring, back to the drawing board.  :)  You could also drop in an HT and then see if it receives from an HT outside the cage.

Thanks!  I think I am going to try one with an ammo can and the copper tape.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 10, 2013, 12:26:15 AM
Yes, you can check continuity with your multimeter (mine has an audible continuity tester which makes it even simpler). As far as the cage function, you can test it to some degree with a cell phone. Turn on your phone, drop it in the Faraday cage, and then call it. If it doesn't ring, the cage is blocking it. If it does ring, back to the drawing board.  :)  You could also drop in an HT and then see if it receives from an HT outside the cage.

Hah! Ray! That is exactly my style! I'm more of a mutt than a thoroughbred - so simple and elegant suits me (I do like the walkthru on the multi-meter, keep trying to find reasons to use it anyway)!
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 12, 2013, 09:35:44 PM
I had some ammo cans aon order and the vendor just canceled my order because they were out of stock!  Add that to the list of stuff that is hard to get these days.  Looks like it may take awhile to get my Faraday cage test to happen.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 13, 2013, 01:01:03 AM
Look at the bright side Geek - all that money you were going to spend on guns & ammo (and ammo cans) can now be devoted to radio, antenna, and feedline (RG213U coax)!

By the time they have all that other "stuff" back on the shelves (and more reasonably priced), you will have refilled the coffers (and maybe a FCC license to boot)!
Title: Re: Building Your Own EMP Faraday Cage
Post by: raybiker73 on February 13, 2013, 01:08:54 AM
Plus, there are a lot of things other than ammo cans that can be used effectively. My main "Faraday cages" are a metal filing cabinet that I up-armored and attached to my station ground, and an old surplus rocket case that I welded the vent holes shut on.

The Great Northern Prepper Podcast did a pretty decent show about EMP preparation last week:
http://www.greatnorthernprepper.com/ (http://www.greatnorthernprepper.com/)

EMP is pretty low on my STMAH list, but it's easy enough to prepare for, and having a lot of stuff locked away in metal cases is good security against theft and damage as well.
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 13, 2013, 09:54:39 AM
Look at the bright side Geek - all that money you were going to spend on guns & ammo (and ammo cans) can now be devoted to radio, antenna, and feedline (RG213U coax)!

By the time they have all that other "stuff" back on the shelves (and more reasonably priced), you will have refilled the coffers (and maybe a FCC license to boot)!

Excellent point, but the ammo cans were about the only thing I was looking for.  I hope they bring a few back from Afghanistan.  :-)

Raybiker:  EMP is low on my list as well.  I am still at the stage of acquiring things that would be useful in a wide variety of scenarios.  Nonetheless, I would like to protect a few electronic items that aren't in daily use anyhow.  For instance, I acquired a generator, which proved to be a stroke of genius when Hurricane Sandy took out the electrical service for more than a week.  I was without power for about 20 seconds.  :-)  This thing has about 5 minor electronic parts.  I didn't want to learn that the generator needed a part right after the power went out, so I have spares, currently stored in mylar anti-static bags.

The parts would easily fit in an ammo can.  If I really start to prep for an EMP, I would need to start acquiring duplicates of a variety of electronics.  I am not intending to do that any time soon, but storing things that are not in daily use anyhow seems like a worthwhile thing to do.
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on February 13, 2013, 09:28:52 PM
I should post a pic of my 'other' faraday cage.  It's a metal garbage can grounded out and lined with a foam military sleeping mat.  It only holds a few items so I went with the cabinet idea.   

I just ordered up 40' of copper weave on ebay.  I'm going to use that stuff around the doors and such.  Been too busy to do more with the cage idea for now but April is coming.  That's the mud season as I call it when the snow starts to melt and all the snowmobiling is over and done. 

If you guys are going to use ammo cans as a cage, be sure to replace the rubber lid gasket with a copper weave material.  Grounding the can is optional. 
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 18, 2013, 05:59:03 PM
As far as the cage function, you can test it to some degree with a cell phone. Turn on your phone, drop it in the Faraday cage, and then call it. If it doesn't ring, the cage is blocking it. If it does ring, back to the drawing board....

Excellent continuity test ray - I did the test 5 times and the cage/case (without alterations) did NOT block the signal 4 out of 5 times.

The only time the signal seemed to be blocked was when the case was placed on the concrete floor of my garage. When I stacked two cases, the phone rang consistently...so, back to the drawing board....

...maybe I will try ttabs idea of copper mesh, next?
Title: Re: Building Your Own EMP Faraday Cage
Post by: gil on February 18, 2013, 06:16:56 PM
The phone test is a good one, but failing the test does not mean that your Faraday case is insufficient..  I remember seeing a test on a video where a guy puts a phone in a microwave oven, protected by a Faraday bag. The phone still rang when called but was not damaged by the microwave. Of course the phone was toasted without the bag...

I am going to test my KX3 Faraday box tonight with my phone... Stay tuned...

Gil.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 18, 2013, 10:39:01 PM
I guess it would get back to the power generation frequencies and those utilized for communications...

Looking forward to your assessment of your KX3 test!
Title: Re: Building Your Own EMP Faraday Cage
Post by: gil on February 18, 2013, 11:30:32 PM
It's not a test of the KX3, but a test of the cookie tin can I use as a Faraday box. I put my phone in it, inside a plastic bag. It does not ring! When I take it out of the can, it takes a few seconds to show a signal. The lid is electrically connected to the can, so there is no leakage.. So, test successful!

Gil.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 19, 2013, 02:32:50 AM
It's not a test of the KX3, but a test of the cookie tin can I use as a Faraday box. I put my phone in it, inside a plastic bag. It does not ring! When I take it out of the can, it takes a few seconds to show a signal. The lid is electrically connected to the can, so there is no leakage.. So, test successful!

Gil.
Gil, very cool! I wonder if your method of electrically connecting the lid to the base would work for my case, or should I use the copper mesh ttabs suggested?
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 19, 2013, 09:29:37 AM
I read an article once about Faraday cages that indicated that any Faraday cage reduces a portion of the energy.  Therefore a Faraday cage inside a Faraday cage is a good idea.  I don't know if this is correct, but placing a cookie tin in a cardboard box, that goes in a galvanized trash can, may work where either the cookie tin or the trash can was insufficient.
Title: Re: Building Your Own EMP Faraday Cage
Post by: Frosty on February 19, 2013, 11:04:21 AM
I read an article once about Faraday cages that indicated that any Faraday cage reduces a portion of the energy.  Therefore a Faraday cage inside a Faraday cage is a good idea. 

Nested cages, that's what I do as recommended by the futurescience site ttabs already mentioned.  Foil, bag, foil, bag, etc.  Then throw the individual packages in a big cardboard box lined with more foil at the end, and put it on the shelf.  Got a 1000w Honda gennie stored that way.   Hard to remove items from it, but they're just spares.  By my reading, there's not really a "protected" versus "vulnerable" distinction, each item's sensitivity varies as will the pulse strength.  All you can do is attenuate the amount the item receives and hope it's below the failure threshold of the individual item.
Title: Re: Building Your Own EMP Faraday Cage
Post by: Tadpoe62 on February 20, 2013, 09:32:00 PM
Here's a question guys, I just purchased a 40' shipping container in which to store some of my "supplies".  Couldn't I ground that and perhaps construct a commo room in there that would protect my equipment?
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 20, 2013, 10:09:55 PM
The problem as I understand it is that any opening defeats the Faraday Cage effect, so you need to seal all openings and seams.  If your idea was to store the entire room and you seal up the openings on your way out, you should get some protection.  If you expect to operate the room, go in and out, or have openings for antennas, etc. you're not going to get a benefit.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 20, 2013, 10:32:05 PM
The problem as I understand it is that any opening defeats the Faraday Cage effect, so you need to seal all openings and seams.  If your idea was to store the entire room and you seal up the openings on your way out, you should get some protection.  If you expect to operate the room, go in and out, or have openings for antennas, etc. you're not going to get a benefit.
ah yes, but if you set up spares inside the "EMP shack"(40' shipping container) and had the antenna EMP blocking connectors that WA4STO posted earlier - i believe this shack would be sealed during and after any event - the coax might compromised - but that is what the spare coax inside the shack is for...
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 21, 2013, 08:55:05 AM
I was actually concerned not just about the antenna, but the fact that there has to be a hole someplace for the antenna to pass in and out of the container.  It seems to me that the hole is a problem for getting proper Faraday cage benefits.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 22, 2013, 09:09:52 PM
I was actually concerned not just about the antenna, but the fact that there has to be a hole someplace for the antenna to pass in and out of the container.  It seems to me that the hole is a problem for getting proper Faraday cage benefits.
since its a field effect - a hole won't necessarily matter, depends on how far away from a right angle it is. The stronger the current/surge the further out you go from the two opposing metal walls. The repelling force comes from the similar charge on the same structure - running into itself at right angles. Cranking up the charge would actually spread the effect further away from the fulcrum point of the angled wall.
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 23, 2013, 05:41:00 AM
I was actually concerned not just about the antenna, but the fact that there has to be a hole someplace for the antenna to pass in and out of the container.  It seems to me that the hole is a problem for getting proper Faraday cage benefits.
since its a field effect - a hole won't necessarily matter, depends on how far away from a right angle it is. The stronger the current/surge the further out you go from the two opposing metal walls. The repelling force comes from the similar charge on the same structure - running into itself at right angles. Cranking up the charge would actually spread the effect further away from the fulcrum point of the angled wall.

Are you saying that a stronger charge would be less likely to make it through the hole in the wall?  What about a weaker charge?  With a CME you might be faced with highly variable EMP effect spread over a period of time.

I don't follow the point about right angles either.  Are you saying that it is better to have any gaps closer to a corner or further away from a corner?
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 24, 2013, 04:04:04 AM
I was actually concerned not just about the antenna, but the fact that there has to be a hole someplace for the antenna to pass in and out of the container.  It seems to me that the hole is a problem for getting proper Faraday cage benefits.
since its a field effect - a hole won't necessarily matter, depends on how far away from a right angle it is. The stronger the current/surge the further out you go from the two opposing metal walls. The repelling force comes from the similar charge on the same structure - running into itself at right angles. Cranking up the charge would actually spread the effect further away from the fulcrum point of the angled wall.

Are you saying that a stronger charge would be less likely to make it through the hole in the wall?  What about a weaker charge?  With a CME you might be faced with highly variable EMP effect spread over a period of time.

I don't follow the point about right angles either.  Are you saying that it is better to have any gaps closer to a corner or further away from a corner?
Im certainly not an expert - but I was speaking to the concern regarding holes.

The Faraday Effect happens when you send a charge thru a metallic object. My familiarity of it comes from manufacturing - and it is best expressed by the way two magnets of similar charge repel one another regardless of the amount of mechanical force applied to overcome it.

In the example used - a shipping container - the thickness of the steel walls would come into play, but the entire cage is effected by the applied charge...the effect repels with the most intensity at the corners...as you move away from the corner/right angles, the effect diminishes...unless you crank up the voltage, which would cause the effect to intensify somewhat further away from the corner/right angle (again, depending on the thickness of the metal wall, the distance away from the corners, and the voltage applied).

The (similar/like) charge actually meets itself head on in a corner - creating a "void" in the electrical field....like trying to push those two magnets with same polarization together...nothing electro-magnetic will ever be forced into that corner...

When you paint electrostatically, this effect actually occurs on the inside of a channel at the point of the right angle. The paint is actually repulsed, leaving a void emanating from the angle point, out wards. That void is increased when the charge is turned up...

It's not holes so much as gaps, or a lack of contact surface (i.e., continuity).

I'll attach a picture of how it applies in my field - and how I think about the problem:
Title: Re: Building Your Own EMP Faraday Cage
Post by: tinker on February 24, 2013, 07:38:14 PM
Really great and extensive thoughts and ideas in reference to this subject.
ttabs: Excellent photos of the bonding to ground using clamps and ground rods - - I personally would have an extra heavy copper run to a plumbing clamp on the pipes too.
gil: Batteries are considered to be immune by all the test data that has been released to the public. I personally have high voltage caps in parallel with all my DC battery feeds so that any transcients are ensured to be absorbed in a momentary field surge. I figure, why take a chance, we only get one shot at protection.
cheers,
73 de Ian
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 25, 2013, 12:36:12 AM
Just found something from APN (American Preppers Network) regarding this topic:
From the link:

http://www.americanpreppersnetworkradionet.com/2013/02/a-primer-on-faraday-cages.html?utm_source=APN+Newsletter+for+week+of+Feb+24%2C+2013&utm_campaign=Constant+Contact+11-3-2012&utm_medium=email (http://www.americanpreppersnetworkradionet.com/2013/02/a-primer-on-faraday-cages.html?utm_source=APN+Newsletter+for+week+of+Feb+24%2C+2013&utm_campaign=Constant+Contact+11-3-2012&utm_medium=email)

"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 one 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 also be used for making a Faraday cage. In practice, the lid or door usually causes the most leakage. Taping the seam with conductive tape greatly reduces this leakage....
"
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 25, 2013, 02:15:49 AM
APN is an out of control forum.  I wouldn't trust it.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 25, 2013, 10:58:02 AM
APN is an out of control forum.  I wouldn't trust it.
I did not mean to sell the website - especially to anyone here. I refer to the science behind the article (as far as I understand it), which seems sound. I'll let the experts pass judgement though.
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on February 25, 2013, 07:49:23 PM
APN is an out of control forum.  I wouldn't trust it.
I did not mean to sell the website - especially to anyone here. I refer to the science behind the article (as far as I understand it), which seems sound. I'll let the experts pass judgement though.

I didn't take it that you were promoting the site, but my experience is that it is a place for the "moderators" to pontificate, but they don't always know what they are talking about and don't appreciate someone else providing useful information.  When they are wrong they are adamantly wrong.
Title: Building Your Own EMP Faraday Cage
Post by: White Tiger on February 25, 2013, 11:59:18 PM
Then I resubmit my post #45 ;-)
Title: Re: Building Your Own EMP Faraday Cage
Post by: Ken on May 27, 2013, 11:26:57 PM
The phenomenon is actually sometimes referred to as the Carrington Effect after Richard Carrington who recorded the effects of the 1859 Coronal Mass Ejection.  Our engineering Faraday cages (actually rooms) were built of screen wire panels.  As has been pointed out, the door is the weak point.  The effectiveness of the cage depends upon the skin effect - high frequency (rapidly rising) electromagnetic energy actually travels only on the surface of a conductor.  So as long as your cage is properly constructed as a continuous conductor no energy will travel below the surface.  The need to insulate the contents and ground the cage are over-stated (good ideas, but probably not necessary - I'll let you know after the CME). I use military boxes of various types.  On all I have replaced the rubber seal with the tinned-copper braid commonly used for ground straps.  As has been pointed out, do not forget to remove the paint from both surfaces! EMP/CME knowledge consists of a lot of theory and less practical experience. Jerry Emanuelson seems to have the most up-to-date information on his web site already referenced here (http://www.futurescience.com/emp.html). The limited history does prove that the risk is REAL and that prudent individuals will prepare!
Title: Re: Building Your Own EMP Faraday Cage
Post by: s2man on May 28, 2013, 09:03:38 PM
Thanks for the link, Ken.  That's a good article.  I pulled up my bookmarks and checked my favorite article on EMP protection.  Guess what? It from the same site, linked in your article.  http://www.futurescience.com/emp/emp-protection.html

Note to self: Still need to get ferrite beads to help protect the fridge and freezer from power surges...
Title: Re: Building Your Own EMP Faraday Cage
Post by: White Tiger on June 01, 2013, 01:38:46 PM
I drilled a 1/2' hole in the concrete floor of my basement here and - using a fence post pounding device - drove in an 8' grounding rod.  Then it was just a simple matter of hooking it to the cabinet. 

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2116_zps1e891c77.jpg)


Now that it's grounded - I then used some military foam sleeping pads cut to length as an insulator on the shelves .....

(http://i106.photobucket.com/albums/m277/ttabs/IMG_2114_zps6cd8080d.jpg)

OK, ttabs (and anyone else using grounding straps on their Faraday Cage), I just read something on the link provided by Ken - and linked to by s2Man - that seemingly discounts the need for grounding to insulate your gear due to a solar storm or EMP:

http://www.futurescience.com/emp/emp-protection.html

"...Large professionally-built faraday cages need to be well-grounded, but for smaller faraday cages, such as you would use to shield a radio or a laptop computer, any wire running to a ground is likely to just function as an antenna, and possibly as a very efficient antenna for gathering EMP...

...For shielding small items like radios and other electronics equipment, use the nested faraday cage system of alternating foil (or screen) and plastic, and don't bother with the ground connection (unless you plan to physically bury your equipment).  EMP grounding gets very tricky, and the ordinary rules for grounding do not apply.  (Most high-power transmitter antennas are actually at a DC ground.)


Now, please keep in mind that I am still the least technical guy any of you will ever know...so help me understand if I've got this wrong...otherwise, Im not grounding a metal cabinet or a metal trash can, to protect items I plan to store inside...
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on June 21, 2013, 07:51:17 AM
Sorry for the late reply - I'm not getting notifications via email from this website anymore to stay on top of my threads.   

I mentioned (and linked) to an article on page 1 that is a good read on EMP.  I went so far as to contact the author to discuss my Faraday set-up.  I too thought I'd get dinged on the grounding rod but he stated in my case, it was a plus.  Grounding is not necessary and in many ways can act as an antenna bringing in more energy onto the cage.  So his recommendation is to not use a grounding rod.   Also he mentioned that all painted surfaces need to be grounded for positive connection and that using doors presents a significant problem.  I have purchased some braided copper to line my doors so they make a positive connection.  To date, I have not done it yet. It's one of those 'rainy day' projects that's been put on the back burner.   

To date, the best, quickest, and easiest faraday cage I've seen is to buy a metal garbage can and line it with a thin foam sleeping pad.  I've done this also.  It's sloppy and awkward just dumping all your stuff in there but it will work well. 

Here's a link again to that article ....

http://www.futurescience.com/emp/emp-protection.html (http://www.futurescience.com/emp/emp-protection.html)
Title: Re: Building Your Own EMP Faraday Cage
Post by: Geek on June 21, 2013, 08:28:20 AM
Since you have used the garbage cans, what did you use to seal the lids?
Title: Re: Building Your Own EMP Faraday Cage
Post by: ttabs on June 21, 2013, 10:23:48 AM
The lids are metal and make contact with the can.  It's sealed for purposes of a Faraday Cage. 
Title: Re: Building Your Own EMP Faraday Cage
Post by: Jim_Duncan on December 13, 2013, 10:40:19 PM
Is it necessary to ground the garbage can in any way?
Title: Re: Building Your Own EMP Faraday Cage
Post by: RichardSinFWTX on December 14, 2013, 11:15:18 AM
If it's sitting directly on something the concrete garage floor I wouldn't think so; but a little extra protection can't hurt.
Title: Re: Building Your Own EMP Faraday Cage
Post by: Bigguy49 on November 29, 2015, 07:06:15 PM
Been reading this post and had a thought on using the ammo cans , and that is what about using aluminum foil to cover the opening of the can then closing the can lid on top, if the paint was removed from the can body and the foil makes full contact with the can edge I think it just might do the job of shielding the contents
Title: Re: Building Your Own EMP Faraday Cage
Post by: RichardSinFWTX on December 01, 2015, 09:21:05 AM
Here's the video I made about making Faraday containers out of popcorn tins.

     https://youtu.be/jk2gs906I8k (https://youtu.be/jk2gs906I8k)