Posted on 04/10/2013 6:45:54 AM PDT by Mr. K
Trashcan works because of the “skin-effect” at high frequency, like wave guides on radar systems. The cardboard is to insulate the contents from contact with the metal but since the air in the can (unlike a wave-guide) is moist, it may still allow harmful induced voltage levels.
EMP will produce up to 50,000 V/m, not “100,000 V/cm^2”
1-inch chicken wire, provided it was installed correctly on all 6 sides of a building will provide from 15dB (at high frequencies) to 50dB (at low frequencies) assuming you have no doors, power cables or anything else running into it (not likely) Mil Specs say you have to hit 80dB to protect electronics.
You may not want a hard-wired generator during a solar storm. As the grid fails and transformers blow, you may want to be isolated from the grid and connect the generator to your loads after the grid fails and you isolate yourself.
For a nuclear EMP, you may also want a stand-alone genset, perhaps inside a shielded box, if a brushless type of generator. If you have it connected live, you have to have it inside a shielded box, with protected air intakes, filters on the power, protected fuel pumps, etc. Not a cheap endeavor. Even having it sitting in the garage connected to nothing would be better than having it connected during an EMP event.
A CME will NOT hurt your electronics! It could damage stuff plugged in indirectly through power grid catastrophic failure - blown transformer or something similar.
Lots of useless suggestions here. The issue is far more complex than the treatment given in this article.
Mixing of CME threat with the HEMP threat is a common error, that gets people far more concerned about a solar flare than is otherwise warranted.
Faraday Cages: newest homeland defense measure to control the populace (sarcasm) How long is a Faraday? Is it 24 hours or more?
A few errors and pointers.
Any holes in a Faraday cage must be significantly smaller than the wavelength of the radiation. This means a wire mesh is pretty useless against EMP, as it covers just about every frequency, with a potential of 100,000 Volts per square centimeter, relative to ground.
So for electronic equipment, think “metal box”. Fabbing one with aluminum foil or a space blanket is just silly. Go buy a big steel box. Works great. Even better if you use *conductive* foam inside to pad your electronics from vibration. The most popular military Faraday cage is an empty ammo box.
Do not ground your Faraday box until the lightning, EMP, or solar flare is done. This is because *every* conductive wire, of all kinds, will act as an antenna. See how thick lightening rods are, from top to bottom? In many cases, about an inch thick.
Another important point is where you live, over sandy soil or rocky soil. Sandy soil usually makes a fine ground, but rocky soil usually needs a lot of grounding, even against static.
Useful things to put in Faraday cages include batteries, crank radios, calculators, two way walkie-talkies, hand held and laptop computers, cellphones (even if they may not work for a while), hand cranked flashlights, home medical electronics like blood pressure and diabetes monitors.
Car parts to include batteries, starters, alternators, ignition switch, starter solenoid and voltage regulator, and of course any black boxes the car won’t run without.
Remember you are neither limited in size with metal boxes, nor are you limited in number of boxes.
“If you toss a blanket like this over your appliances the grounding wire can be inserted into the grounding prong in a 3-prong electrical outlet- not as good as a nice copper rod driven into the ground outside but way better than nothing.”
This is useless and will do little to nothing to protect against an EMP. It’s important to note that a nuclear EMP sends energy at you from nearly all directions at once. If you do not have a “6-sided” shield specifically designed for the application at hand, then you have little or nothing of value as far as shielding is concerned.
This sort of mis-information makes people think they are doing something, when they are wasting their time.
From the way I read this, the folks who live in mobile homes are already protected. Maybe we should just move to the trailer park, huh?
“Use a metal garbage can. It can hold a lot of stuff. “
You’ll be much more effective here if you take steel wool shards (raw, not something with soap in it) and drape it around the lip of the garbage can. Then hammer it down tightly with a mallet.
This actually has a chance of doing “something” against a nuclear EMP. It won’t be military grade but is likely to be closer than any other suggestion I’ve seen.
“I don’t think this guy knows what he is talking about. The bomb releases a magnetic pulse that is NOT electrical.”
It’s electric and it’s magnetic.
50,000V/m factoring in the impedance of free space is also 133A/m in magnetic field
“I realized after I posted that copper mesh is an effective Faraday cage, so the magnetic field alone must not be an issue. Thanks for information. “
A nuclear EMP has a broad frequency content. At low frequencies (say between 10kHz and 10MHz) the magnetic field predominates - best way to shield against it is to use a ferromagnetic material (like steel) - but if it’s thick enough it will also shield against magnetic fields (like 1/3”) so a copper mesh will work for the energy above 10MHz, but will not be so effective against energy at lower frequencies.
The Faraday cage was "invented" by Michael Faraday in 1836, hence the name "Faraday Cage".
Those who are ignorant of history will look ignorant.
My car doesn’t have enough real metal to be a cage.
And you don’t have to ground it, in fact you might not want to ground it. Grounding helps draw electrical current.
You should wrap it in insulation first, because if it is touching the metal, it might get fried anyway.
Hey, some people who are IN the field don’t know much about actual RF engineering.
And it USED to be my “field”, in the sense that I learned it, but since I got a job it’s been all about programming, and nothing fun.
Electrodynamics was my favorite college class though. And one of my summer jobs was working in a faraday cage, doing performance tests on microwave equipment (cool stuff, small circuits on boards with blocks of aluminum bolted around them for shielding, and how tight you made the bolts changed the circuit characteristics).
I was discussing this with my wife. It is a sad thing that so many people need drugs to survive, and yet the government won’t let you buy a long-term supply.
Personally, if I was dependent on a drug, I would have enough stock for my lifetime, or at least up to the expiration date of the drug (in which case each month my new supply would go to the back of the line).
I’m fortunate not to be dependent on anything.
If you can get your doctor on board, you can sometimes get a double-dose of the medication. Do that for a couple of years, and you have a long-term supply stored up.
Works well for drugs where you take “half a pill”, if you get them to prescribe the full pill.
So the electrical factor degrades quite quickly form an air burst and is hardly a factor out of the burst radius in a ground burst. If an air burst were over Omaha my main concern would be the voltage induced in wiring. I understand the the impedance of air is 377 ohms. I always wondered why transmitters were based on 50 ohms and not 377? Any way the thing I would miss the most is the internet. I have about a dozen sets of plans for crystal and simple radios but that would not pick up much either. I suppose short wave away form the blast would be the best source of news and such.
“You should wrap it in insulation first, because if it is touching the metal, it might get fried anyway.”
Yes
“So the electrical factor degrades quite quickly form an air burst and is hardly a factor out of the burst radius in a ground burst.”
No, that’s not how it works. It’s the change in impedance that would reflect/refract energy - in a homogenous medium then the energy continues little degraded (for a hemp pulse)
For a hemp pulse, the energy comes from a large area above you - you are effectively in the “near field” which means that standard decay does not apply.
How far might the “near field” extend before the energy starts dissipating?
My 78 YO memory ain’t nearly as good as a 32 GB jump drive. I have almost 10 GB of preparedness information (backed up on multiple devices) I’ve collected from many sources and will be able to access it with a ZOOM tablet, a pocket eDGe, or a laptop. These are all stored in a legal size filing cabinet which has been completely enclosed with metal and lined with insulation inside.
Internet and cell phones will be useless, but I will be able to read the many ebooks stored on the tablets, laptop, and Kindles which are also stored in the filing cabinet.
I have solar chargers to charge their batteries along with the rechargeable AAA, AA, and 9V for LED flashlights and portable two way radios, CB radio, and an am/fm weather radio w/hand crank feature.
The solar panels, chargers and inverters are stored in a large metal garbage can. I understand that LED bulbs will not survive an EMP because they are essentially a diode.
I don’t think I’ve under prepared for surviving a complete financial collapse or an EMP. At least till the ammo runs out somewhere around 2045, but then, I won’t be around to use it, dammit!
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