# Proof that farady cages do really work



## Startingout-Blair (Aug 28, 2012)




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## Sentry18 (Aug 5, 2012)

That was cool. Plus now you can expect all drones to be wrapped in cages.


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## gabbyj310 (Oct 22, 2012)

I've heard pro's and cons on old micro waves.I've bought several at thrift shops and yard sales for as little a 5 bucks a piece..My way of thinking was to stack them on top of each other(the OLD big ones on bottom) that way I put anything that I may question in them.Like two way radios/walkie talkies, old computer,batteries,anything(small) electrical that I may want to run on my solar generator at a later date(that hasn't been melted)...I hope also that my "container" helps too!!!!


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## smaj100 (Oct 17, 2012)

I don't wanna throw the first stone but, I will. It has always been my understanding (which may be wrong) that and radio wave carries energy. So if that quadcopter in a cage was being remotely controlled and it was, then certain frequencies of the EMP/CME waves will penetrate the cage and can fry the device. If my logic or understanding is flawed someone please correct me.


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## NaeKid (Oct 17, 2008)

Nice looking Jeep in the background! :laugh:


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## cowboyhermit (Nov 10, 2012)

smaj100 is correct, in fact one of the ways people test diy faraday cages is to see if a radio will function inside. That doesn't mean faraday cages don't work for emp, just that this cage lets in some wavelengths.


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## Magus (Dec 1, 2008)

Frikkin awesome no matter what it proved! the TEST is putting a radio in one and having it near my antique arc welder when it fires up,if its still playing, it works,


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## Marcus (May 13, 2012)

Both smaj100 and cowboyhermit are correct.
As I pointed out in another EMP thread, the wavelength of gamma rays and therefore the wavelength of the Compton Effect electrons pretty much require an EMP enclosure that is solid and not a mesh.


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## Startingout-Blair (Aug 28, 2012)

That all of you for clarifying for me. I am definitely no scientist! I just thought the video was cool!


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## Norse (Jan 30, 2010)

smaj100 said:


> I don't wanna throw the first stone but, I will. It has always been my understanding (which may be wrong) that and radio wave carries energy. So if that quadcopter in a cage was being remotely controlled and it was, then certain frequencies of the EMP/CME waves will penetrate the cage and can fry the device. If my logic or understanding is flawed someone please correct me.


That is because EMP is a MAGNETIC pulse, a metal cage deflects the damaging effects of its energy.

*Electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. Shielding is typically applied to enclosures to isolate electrical devices from the 'outside world', and to cables to isolate wires from the environment through which the cable runs. Electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as RF shielding.
The shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. A conductive enclosure used to block electrostatic fields is also known as a Faraday cage. The amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic field.
*


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## labotomi (Feb 14, 2010)

Norse said:


> That is because EMP is a MAGNETIC pulse, a metal cage deflects the damaging effects of its energy.


It's an ELECTROmagnetic pulse.

Both the electro and magnetic portions of the pulse are potentially damaging. A faraday cage will affect both but by different mechanisms.

The electro portion is counteracted by the rearrangement of the electrons of the cage to produce a field that is equal but opposite of that created by the EMP.

The magnetic portion of the pulse will induce a voltage into the surface of the cage (Faraday's Law of Induction). That voltage causes eddy currents to form which create their own magnetic (Ampère's Circuital Law). The magnetic field formed by the eddy currents will have a polarity that will oppose the magnetic field from the EMP (Lenz's Law)


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## labotomi (Feb 14, 2010)

smaj100 said:


> I don't wanna throw the first stone but, I will. It has always been my understanding (which may be wrong) that and radio wave carries energy. So if that quadcopter in a cage was being remotely controlled and it was, then certain frequencies of the EMP/CME waves will penetrate the cage and can fry the device. If my logic or understanding is flawed someone please correct me.


Radio waves are a form of electromagnetic radiation so you're right. They have a large wavelengths when compared to the other designated radiation "types" of the electromagnetic spectrum.

What blocks one wavelength will not necessarily block other wavelengths.

The arcs striking the cage is a form of electrostatic discharge produced by a Tesla Coil and not electromagnetic radiation however the discharge produces an EMP but not anywhere close to that produced by a HEMP.

Even though it's a cool experiment and video, it isn't demonstrating the ability of a faraday cage to withstand an EMP. Since the wavelength of the radio waves is so much larger than that experienced during a HEMP the ability of the helicopter to receive signals would show that the structure of the cage would not protect against the smaller wavelengths from a HEMP. The ability of the copter to withstand the *small* EMP generated by the electrostatic discharge is a testament to the weakness of that EMP and/or to the construction of the copter itself.


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## crabapple (Jan 1, 2012)

Norse,
Thinks for saying it so a mechanic can understand it.
My welder mess with my walkie talkie, so I cut/switch it off, when welding.


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## LincTex (Apr 1, 2011)

smaj100 said:


> So if that quadcopter in a cage was being remotely controlled and it was, then certain frequencies of the EMP/CME waves will penetrate the cage and can fry the device. If my logic or understanding is flawed someone please correct me.


I am going to speculate that the little quadcopter is being controlled by an IR signal, as most toys like that are nowadays. Because the signal path is infrared light and not radio frequency, that could explain the method of control?


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## TheLazyL (Jun 5, 2012)

LincTex said:


> I am going to speculate that the little quadcopter is being controlled by an IR signal, as most toys like that are nowadays. Because the signal path is infrared light and not radio frequency, that could explain the method of control?


Nope. Transmitter has an antenna


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## HamiltonFelix (Oct 11, 2011)

I'm certainly no expert on Faraday cages. I watched a guy on YouTube do some crude tests. He put his cell phone inside different enclosures. We're talking microwave band here, very short wavelengths. 

A sheet steel storage cabinet did not block signal until he sealed up the gaps with metallic tape. 

Wrapping two or three layers of foil around the phone isolated it. 

The trusty old ammo can did not work. If you think about it, ammo cans or those steel first aid kits we see at work, do not really completely surround their contents with unbroken steel. The watertight rubber gasket would be enough of a gap to admit the very short wavelengths. 

A buddy put his phone inside a Mylar bag and it still rang. Even though Mylar was invented to bounce radio waves for the Echo satellite program, it apparently doesn't have enough metal to reflect all of them...


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## SmokeyNJ (Jun 12, 2013)

I store some small handhelds and GPS in metal coffee cans, heavy foil (as wrinkle free as I can get it) then sealed with metal tape, and stored on bare concrete slab floor. So pretty much air/watertight. Think this is good protection?


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## LincTex (Apr 1, 2011)

SmokeyNJ said:


> Think this is good protection?


You didn't say anything about having them wrapped in plastic or cardboard so they are not touching the inside of the metal can. I think the theory states that is essential.


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## HamiltonFelix (Oct 11, 2011)

Now I'm trying to recall the YouTube tests. You're right; I don't think the guy wrapped the phone in insulating material. He did toss it into a microwave, and it still rang. Makes me wonder if I really should stand close to the microwave when it's running.


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## cowboyhermit (Nov 10, 2012)

HamiltonFelix said:


> Now I'm trying to recall the YouTube tests. You're right; I don't think the guy wrapped the phone in insulating material. He did toss it into a microwave, and it still rang. Makes me wonder if I really should stand close to the microwave when it's running.


I always have to hold myself back when people talk about how a properly operating microwave lets out no radiation Anyone with any sort of spectrum analyzer in the vicinity of 2 GHz knows differently. Anywhere in the same house let alone the same room and it will light up like a Christmas tree


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## LincTex (Apr 1, 2011)

HamiltonFelix said:


> He did toss it into a microwave, and it still rang.


I only tried it with one microwave (small, but with turntable); plugged in and unplugged - and it never rang. I even shined a light through the glass, and the phone screen said "no service".


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