EMP protection with multiple layers of mylar bags?

525 Views 21 Replies 11 Participants Last post by Greg5791, 8 d ago

Abraham5

Discussion Starter · 10 d ago

I want to protect an emergency handcrank radio in my bugout bag from a possible electro magnetic pulse. I want to do that by wrapping this radio in a mylar food bag.

Can I improve this EMP protection by using multiple layers of mylar bags? If so, how many layers of mylar would you recommend?

This digital AM/FM-radio has a built-in flashlight, small solar panel, lithium and NiMh batteries and smartphone charger.

I have already tried to cover this radio in three layers of thin aluminum foil, but this kitchen aluminum foil is pretty brittle and vulnerable to wear and tear.

1 - 20 of 22 Posts

Abraham5

Discussion Starter · #2 · 10 d ago

Does it make any difference it I use mylar bags with a ziplock, to protect an emergency radio from EMP? What effect will the ziplock have on this EMP protection?

A ziplock bag might double as a water bag IMO, if used very carefully.

goose3

· #3 · 10 d ago

I have a couple of similar emergency radios. I have one in a faraday cage, double-wrapped with heavy-duty aluminum foil.

If I was bringing such a radio along with me, I'd do it the same way. Your issue is the too-thin aluminum foil. Get heavy duty, wrap with paper, wrap with heavy-duty aluminum foil, paper again, foil again. I use stretch wrap over the second layer of foil to hold it tight and all together.

I have no idea if mylar would work. Let me suggest a couple of tests. Put a cellphone in mylar, seal it or whatever you'd do, and then call it. See if signal gets through. Same with a radio--see if FM gets through, see if AM gets through.

Unfortunately, such tests are failure tests only--they will tell you if signal can get through the bag, and if so, I'd not trust it for EMP protection. If the radio and phone tests work, i.e., you can't get signal, you can't receive AM and FM, then it's certainly better than nothing.

Reactions: 4

Abraham5

Discussion Starter · #4 · 10 d ago

goose3 said:
Your issue is the too-thin aluminum foil. Get heavy duty, wrap with paper, wrap with heavy-duty aluminum foil, paper again, foil again. I use stretch wrap over the second layer of foil to hold it tight and all together.

Thanks but weight reduction is one of the main concerns for my bugout bag. That is why I consider the more sturdy mylar bags.

Why the paper layers?

Canon29

· #5 · 10 d ago

Buy faraday fabric, lighter and more durable for backpacking applications, i actually double layered mine. This also allows you to customize the pouch to exactly fit the shape of what youre trying to cover or if you want to line a compartment in your pack.

Just make a the shape and sew it inside out, leave enough material for a rolled flap closure and sew some velcro to secure it. Rightside out and youll have a pretty professional piece of kit. The poor mans test is to drop your cell into it and see if you can recieve a call.

Reactions: 3

goose3

· #6 · 10 d ago

2

For a while, I was trying to figure out a Faraday cage for both radios and my generator. The problem, as I'm sure you know, is that you want something that works, but can easily be opened and shut so you can use what's inside.

I had a wooden box where the lid nested inside a lip on the bottom part; pics attached. I then wrapped the entire box in aluminum tape. As you can see from the pics, the top nested nicely into the bottom, and the tape completely covered everything.

Didn't work. I can call my cellphone inside and it's as if it's not even an issue. I even went so far as to tape the seam between the two halves; same result.

The two halves are electrically connected; I used a multimeter to check continuity. But it doesn't work as a Faraday Cage, at least it still allows signals. My phone operates off my router, so that may be part of it, but nothing in this experiment leads me to believe this would be effective against EMP.

If you can get a metal box that completely seals and where the top/lid is electrically connected to the bottom, that would likely work. But the devil is in the details. I've diddled with a few other ideas; none have been successful.

See less See more

Reactions: 3

goose3

· #7 · 10 d ago

Abraham5 said:
Thanks but weight reduction is one of the main concerns for my bugout bag. That is why I consider the more sturdy mylar bags.

Why the paper layers?

Heavy-duty aluminum foil will weigh, what, a few grams? It's not enough to make a difference. I doubt it would be heavier than mylar.

What you do with multiple layers is make what's called a nested faraday cage--one inside another. You need paper or other insulator between the layers otherwise you only have one FC.

Reactions: 2

Abraham5

Discussion Starter · #8 · 10 d ago

Canon29 said:
Buy faraday fabric, lighter and more durable for backpacking applications, i actually double layered mine. This also allows you to customize the pouch to exactly fit the shape of what youre trying to cover or if you want to line a compartment in your pack.

Just make a the shape and sew it inside out, leave enough material for a rolled flap closure and sew some velcro to secure it. Rightside out and youll have a pretty professional piece of kit. The poor mans test is to drop your cell into it and see if you can recieve a call.

Thanks. Do you know the effectiveness of double mylar bags in EMP protection? That would save me the sewing.

Abraham5

Discussion Starter · #9 · 10 d ago

Thanks for you interesting replies. I might use a sturdy and tested metal container as a Farady cage in my bugout bag. And if I bug out i could throw this out, to save weight.

Reactions: 1

Canon29

· #10 · 10 d ago

Abraham5 said:
Thanks. Do you know the effectiveness of double mylar bags in EMP protection? That would save me the sewing.

Everything is questionable at the end of the day. Ive played around with mylar blankets as well as aluminum foil, the faraday fabric kills the cell signal with the least amount of weight/material hands down. I cannot speak for whatever mylar bags you are using as they can vary in thickness/quality. Do the poor mans test yourself and find out.

Im not an expert but i look for the MIL-STD-188-125 rating. Funnily enough im pretty sure that standard is no longer in use, but like i said i just double layered it and called it day.

Reactions: 2

Cigars

· #11 · 10 d ago

Ammo can. Kind of heavy but sturdy. I will test it out tomorrow and post the results.

Reactions: 2

bcvojak

· #12 · 10 d ago

Mylar is not the correct material.

Reactions: 2

gwanghoops

· #13 · 9 d ago

just googling...I found this PDF was pretty good information comparing different methods and some measurements

BUILDING EMP FARADAY CAGES THAT WORK

Reactions: 1

irv818

· #14 · 9 d ago (Edited)

Here's the takeaway from that pdf, which seems to be based on real science and math:

A WARNING OF MIS INFORMATION #1:
Several persons have posted videos on the internet demonstrating their
measurements of metal garbage cans when used as faraday cages. They put their AM or FM radio in their metal garbage can, closed the “tight fitting lid” and the radio stops playing. They then conclude that they have demonstrated their metal garbage can is a good Faraday cage for EMPs.
NOT SO!!! Their garbage can will be worthless in protecting against the higher EMP frequencies in the range of 10 MHz to1 GHz and as result, the contents inside will be fried by any typical EMP.

Reactions: 2

country_boy

· #15 · 9 d ago

irv818 said:
Here's the takeaway from that pdf, which seems to be based on real science and math:

Nope, not really. AM radio is centered at 1 MHz. FM at 100 MHz. The frequency band of greatest interest( highest EMP intensity) is about 1 MHz to 100 MHz. In fact for individuals storing anything other than an AM radio, they would be mostly concerned with 20 MHz-400 MHz- these are the frequencies where the combination of EMP intensity and ability to couple energy into a hand held, or briefcase sized devices represents the greatest threat. 1 GHz might couple well, but there is little intensity at that frequency. 1O MHz is at the peak intensity but with a wavelength of 30m, coupling isn’t that great.

AM radios wouldn’t be a problem, except because AM signals (300m wavelength) don’t couple well, they use a loop antennas inside the radio which is far more effective for its physical size than a wire antenna ( or a wire or printed circuit board trace acting as an antenna). This doesn’t apply to say ham radios which tune close to 1 MHz, but don’t have an internal antenna. One of the first things you learn in electromagnetic compatibility ( or bomb disposal) is never coil wires- they act as loop antennas. Fan folding is acceptable if you have excess wire/cable

Having said all that, no one obsesses about storing handheld electronics not connected to external antennas like survivalists do. They are at extremely low risk. But no one can tell you zero risk, some products are borderline defective when manufactured and EMP may well put them over the edge.

See less See more

Reactions: 4

irv818

· #16 · 9 d ago

This has nothing to do with antennas or what frequencies a radio can tune in.

country_boy

· #17 · 9 d ago

irv818 said:
This has nothing to do with antennas or what frequencies a radio can tune in.

Might want to read you post bud:
They put their AM or FM radio in their metal garbage can, closed the “tight fitting lid” and the radio stops playing. They then conclude that they have demonstrated their metal garbage can is a good Faraday cage for EMPs.
NOT SO!!! Their garbage can will be worthless in protecting against the higher EMP frequencies in the range of 10 MHz to1 GHz and as result, the contents inside will be fried by any typical EMP.

The source you quoted was disparaging the use of radios with built in antennas to test faraday cages. That’s a tally how we test real cages, except with better equipment and more frequencies- like 3-4 per decade: 10 MHz, 17 MHz, 30Mhz, 50 MHz, and 70 MHz.

Reactions: 1

Cigars

· #18 · 9 d ago

4

Follow up... Ammo can and aluminum foil.
So I grabbed a standard 50 cal sized ammo can. This one was for fuzes but same size. I first tried the phone by itself. I dialed it and it rang while locked inside the ammo can. Then I wrapped the phone in about two feet of standard Reynolds Wrap and locked it back inside. No ring and straight to voicemail. Then I took it out and tried calling it again with just the aluminum foil. Same result but this time I got a "not in service" message. So the aluminum foil will block all signal (in this frequency) Not sure about EMP's but I would feel OK about using the tin foil to line my favorite hat. Your mileage may vary.

See less See more

DKR

· #19 · 9 d ago

lets say this does happen.

Someone pops off a nuke or two and actually manages to fry a goodly amount of the US grid, In theory, anyway.

That would be the start of a wide scale nuke exchange - even Xiden couldn't ignore that.

So then who ya gonna call?

My suggestion for your planning today -

See less See more

Illini Warrior

· #20 · 9 d ago

the metal layer for mylar is nothing but metalized material sprayed onto the mylar material - MIL thickness is less than tin foil - it's an air block ......

Reactions: 1

1 - 20 of 22 Posts