Monday, January 13, 2014
A Definitive Video on Building and Testing Faraday Cages
Anyone familiar with EMP (electromagnetic pulse) has no doubt heard about using a Faraday Cage to contain and protect electronic gear. And anyone who has done this sort of research online can attest to all the different opinions on how to do this and how effective each variety is.
For anyone who is not familiar, a faraday cage is simply a conductive metal enclosure in which you place items to be protected from EMP. This enclosure must NOT have large holes or cracks if it is to be effective. The metal simply conducts the energy AROUND the items, rather than allowing the RF energy to go inside and damage or destroy the items you have stored. The more conductive the metal, the more effective the enclosure in keeping out RF energy; thus Faraday shields for laboratory use are often made of copper sheeting or screen.
What an EMP IS: An EMP is an electromagnetic pulse. It has been loosly described as an "RF tsunami"; it is simply a very powerful radio frequency (RF) wave that, like any other radio wave, can be picked up by wiring and other metal objects which act like an antenna and thus conducted into electrical circuitry. These radio waves may be generated by natural events such as a solar Coronal Mass Ejection (CME), or they may be man-made via a high altitude nuclear blast or other weapon specifically designed to produce an EMP.
What an EMP is NOT: An EMP is NOT a "lightening bolt". Why people continue to say it is a lightening bolt, I don't know. That said, a person MIGHT be shocked or electrocuted if he was touching a large enough metal object when the EMP struck. ANY radio wave induces an electrical current in a wire or other conductive objects; this is where the destructive potential comes from. Because of the strength of the electromagnetic field created in the EMP, the currents generated in conductive materials are also large, and that is why electronic equipment is damaged by EMP.
While EMP may well damage or destroy cardiac pacemakers or insulin pumps, most people would NOT be biologically affected by an EMP. People would only figure out there had been an EMP when they discovered that most electronics had simply stopped working.
While looking at some other related youtube videos, I found one that appears to have been created by someone with some actual knowledge of electrical engineering. In this fairly short video, he shows various construction methods for shielding equipment, performs various tests and explains the results that he and others obtain when doing such tests - especially the test using 2-way radios.
Without further adieu, here is the link:
I thought he did an exceptional job of clearing up some of the myths and misunderstandings about this important topic.