have A Question about transportation and Electromagnetic pulses's

Originally posted by Evolutionsend
reply to post by TheRedneck

 

According to other threads and articles I've read about constructing a faraday cage it must be an entirely closed metal box with all sides clearly touching (metal to metal). The rubber weather stripping on a trunk would make it pretty useless as a faraday cage.

I've looked at that, too. The hinges on my GM are metal, and are a conductive bridge across the weather stripping to the trunk lid

One of the notes in the report is that the results were quite variable and unpredictable. Two cars of the same make might be next to each other, with one affected and the other seemingly fine.

Again, if the car is not turned on during the pulse, it is probably small enough to avoid having its circuits burned.

reply to post by Evolutionsend

A Faraday Cage is nothing more than magnetic shielding, hence it must be made of a ferrous material like iron or steel. All it needs to do is to conduct the magnetic field in the EMP around the edge of the cage. A Faraday Cage can then be made of steel wire as long as the wire is closely enough spaced to pull the magnetic field into it and can carry the amount of magnetism it is shielding against.

While it is better if the sides are touching each other, it is not absolutely critical. Small air gaps will only decrease the magnetic susceptibility, not remove it.

In the case of a car trunk, the entire area is surrounded by sheet steel (fiberglass bodied cars notwithstanding) and is therefore an almost perfect Faraday Cage. Any areas which are not surrounded by steel directly are surrounded by the entire body of the automobile itself.

Do some reading on magnetic circuits and flux paths to see how it really works. It's the same principle used in grounding your home's electrical system to prevent electric shock, only with magnetism instead of electricity.

TheRedneck

P.S.: Sorry for the late reply, kinda busy lately.

reply to post by TheRedneck


So that's the answer? Put it in the trunk!

If I ever find an electronic device that I can't do without, I'll put a spare in my trunk. Actually put a spare pcm in there....just in case!

reply to post by Evolutionsend

Yep, that's the answer.

Michael Faraday invented the things back in 1836 (and using wire, not sheet material); they're not rocket science. Like most things, a little understanding backed up by a little study puts a wealth of possibilities at one's fingertips.

TheRedneck

Originally posted by Evolutionsend
reply to post by TheRedneck

 

According to other threads and articles I've read about constructing a faraday cage it must be an entirely closed metal box with all sides clearly touching (metal to metal).

IF there are "holes" or mesh in the walls of the faraday cage, then EM waves with a smaller wavelength can pass through the holes. I have Faraday cages for other purposes, and a 5mm mesh is fairly standard for blocking both 60hz (radiation from normal household circuits) and radio/cellphone signals.

If I remember correctly, the EMP is a single gigantice wave, like a tsunami, with a wavelength of many meters. In that sense, the only wiring cable of acting like an antenna for a wave that big is giant cable networks--things like TV cables (not fiber-optic!), power lines, "long wave" radio dx, pipelines and railroads.

I have a back-up "universal radio" reciever that picks up practically all frequencies worldwide. But to get the longer frequencies, I have to run wire up and between to trees in my back yard, in order to create an antenna long enough.









The rubber weather stripping on a trunk would make it pretty useless as a faraday cage.

If you've ever seen the pcm box under a hood, it is pretty much a simple metal box that could work as a faraday cage. Some of them use plastic ends though, I'm guessing those would not work as well.