Faraday cage redux

[Tempstar]

Hi all, after being in a lengthy discussion on another site, and seeing a few older posts here about EMP and Faraday cages, I wanted to chime in on the subject.
Electromagnetic Pulses have distinct attributes that makes defending against them do-able. No one is certain of the specific wavelengths of a nuclear induced one, but be assured that the three pulses that accompany the deployment will be close to the same as those generated in a laboratory. In the early 90's I was able to work in a facility that was researching the hardening of electrical transmission equipment, and they used several methods of producing an EMP. Here is some of what I learned from those guys:

Shielding- A metal container with any holes being smaller than the wavelength of the pulse will protect what is inside. Since the measured wavelengths approaching 100 ghz, and with pulses the strongest around 60 ghz, any hole size larger than 0.006" would allow the pulse inside. Microwave ovens seem to be a popular idea to protect electronics, but the holes in the plate inside the glass are sized to keep 2.4 ghz inside, which would be around 0.202". Best bet for this would be a metal 5 gallon can with a tight fitting metallic lid, ammo can, or any other tight sealing metal can. By not allowing the RF inside, it will flow along the outside and continue on.

Amplitude- The energy will decrease as a square root of the distance, and objects extremely close to the initial activation will allow the particles inside the enclosure to become excited enough to cause damage without penetration of the electromagnetic wave itself.

Currents and heating- Metallic objects offer resistance to the flow of electrons, and this generates heat as the charge seeks equilibrium. This is what caused telegraph wires to catch on fire during the Carrington Event of 1859 as the currents imparted on the wires by the resulting geomagnetic storms sought their path to a point of lesser concentration. No one knows what a Coronal Mass Ejection aimed at Earth would do to our modern electronics.

Protection- Devices in a sealed metal enclosure {should} survive an EMP at several miles distance from the source. Any metallic object that enters the enclosure such as a power line, ethernet cable, charging cord, etc. will act as an antenna and allow entry. Obviously, anything connected to an antenna will suffer such as radios and televisions.

[pkveazey]

Damn Skippy...... Finally, somebody who agrees with me on why a ground wire on a faraday cage is a bad idea. My position has always been, ground it if you want to and you might be alright but that ground wire is just an antenna and I'm not grounding any of my metal enclosures. The holes is also spot on. I have listened to people rant on and on about how you absolutely have to seal the metal trash cans with metal tape because the pulse can get inside if you don't. I've always maintained that it is not necessary because the gap is very tiny and the pulse will have to find the opening and then bounce back and forth between the gap until it becomes so weak that by the time it gets inside most of its energy would be gone. Your point about heat being generated also hit home with me because I don't like metallic MYLAR bags because that microscopic thin layer would heat up and melt the plastic bag. OK, the MYLAR bag might be fine at about 100 miles from the source of the pulse. The bottom line is, we'll all know one way or another when an EMP happens.