A Faraday Cage (or Faraday Shield) is a sealed enclosure that has an electrically conductive outer layer. It can come in the form of a box, a cylinder, or any other closed shape. The material from which the container is built can have conductive properties or not. This doesn’t really matter that much, since the entire box will be wrapped in a conductive material (such as aluminum foil).
Basically, this is how a Faraday cage works:
- The conductive layer reflects incoming fields.
- The conductor absorbs incoming energy.
- The cage acts to create opposing fields.
All of these principles work together to safeguard the electronics inside from excessive field levels. Although the Faraday cage works better in case of a high-altitude nuclear explosion (aka EMP attack), it’s not bad to have it at your disposal in case of a solar EMP. The solar EMPs do a lot less damage then a nuclear EMP would do, so for that, we are thankful, but as you just read, the CME left a lot of people without electricity so you can never be too careful.
Building Your Own Faraday Cage
Let’s get right to it. You will have a means of protecting your electronics in no time.
This picture actually represents the building steps of a Faraday cage. It’s really THAT easy to build and it’s tested against EMP pulses
How Thick Should The Conducting Layer Be?
The skin effect already determined the thickness of the conductive layer before we ever had a chance to do so. The skin effect describes the tendency of the current to flow primarily on the skin of a conductor. As long as the conducting layer is greater than the depth of the skin, it will provide top notch shielding because the absorption loss will be high. So, wrapping a box in a couple of layers of heavy duty aluminum foil (about 24 microns thick) can be a good idea if you want to protect against high-frequency radiated fields.
You don’t have to worry on what type of conductor you’ll use for your cage. The conductivity of nearly any metal will be good enough to allow the carriers to easily realign to cancel the external fields.
Another question that causes confusion when building the Faraday Cage is whether the cage should be grounded or not? Grounding the cage has little to no effect at all on the field levels present inside the box. Grounding only helps the cage to keep it from becoming charged and perhaps re-radiating. Long story short, an ungrounded cage protects the contents from EMF (electromagnetic fields) as well as a grounded one.
I Have a Lot Of Electronics And I Need A Larger Cage!
It’s true that in this day and age we all have a lot of devices and electronics that make our life easier from day to day. Storing them might require an entire room. The engineers trained in elecromagnetism often use these kinds of rooms to conduct experiments because they filter out interfering signals.
You can make a shield room right at home by using a closet. You’ll need to cover it up with heavy duty aluminum foil on all four walls, the floor, the ceiling and the inside of the door. Make sure that you place a piece of plywood or cardboard on the floor so that you can walk in it without damaging the aluminum foil.
Overlap and tape the seams using cellophane tape as there can be no conductive penetrations into the room. Cover all electrical outlets, light switches, etc with aluminum foil and DO NOT PLUG anything into the electrical outlets.
You should have by now a decent comprehension on what EMP is and what kind of damage it can do to our country. Because we don’t know much about EMP and EMC (research was conducted in other departments which are more likely to cause disasters like atomic bombs and such) it makes the phenomenon the more dangerous.
Let me know how your cage turned out. Are you aware of other means of EMP protection? Share your thoughts in the comments section below.