What is a Faraday Cage? How do you build a Faraday Cage?
What is a Faraday Cage?
By definition, a faraday cage is an enclosure created with conductive materials (most commonly metal screens) that blocks both static and non-static external electric fields. Invention and naming is credited to Michael Faraday, who constructed a room lined with metal foil in 1836 and used an electrostatic generator to create high-voltage discharges on the outside of the room. He then used an electroscope to prove that there was no resulting electric charge on the inside walls.
The true Faraday Cage was actually first invented by Benjamin Franklin in 1755, in an experiment with a cork ball suspended inside a metal can. His experiment found that the cork was not attracted to the inside of the can, and though it did touch the bottom, it was not electrified when it was removed. When the cork was touched to the outside of the can, however, it was indeed electrified.
What both of these scientists discovered is that, in these metallic enclosed environments, electric fields (applied externally) create forces on electrons in the conductor (the metal walls), which creates a current that results in rearrangement of the charges. The current stops when the charges rearrange, and the electric field that was applied externally is cancelled on the inside.
Believe it or not, you actually use and interact with Faraday cages every day! For example, when a car or airplane is struck by lightning, the passengers inside are not also affected by the lightning strike – the metal walls of the vehicles are electrified from the outside but the current does not pass through to the inside and the passengers. Another great example is a Microwave Oven – the metal exterior of the microwave traps the microwaves inside to cook the food, while the exterior of the oven is safe to touch and offers very minimal microwave radiation (in new, properly-used microwaves). MRI Rooms are also typically thoroughly shielded, to prevent interference from external electrical sources with the data being transmitted by the MRI machine.
Why do I need a Faraday Cage?
While there are countless reasons why one might need a room, box, container, or “cage” that is entirely shielded from electric fields, the most common reason is shielding from RF and EMF radiation. In some applications, that might mean an RF or EMF “sterile” environment for equipment testing or laboratory applications. Other applications may relate to healthcare, as some people have demonstrated being electro-sensitive or having a negative health impact due to rampant RF and electromagnetic radiation in our highly-wireless society.
Additionally, you will frequently hear people discuss the use of a faraday cage for the protection of their electronic devices in the event of an EMP (Electro Magnetic Pulse). An EMP is a short burst of electromagnetic energy that can be both naturally occurring and man-made. EMP interference even on a minor scale can cause destruction to electronic devices, and a major EMP disaster event (nationwide, worldwide), could theoretically revert modern society back to the stone ages, with no electricity or running water. While an event like this is unlikely, many people see the benefit of owning a Faraday Cage, and storing critical devices (such as an emergency radio) in them just in case. Given just how easy it is to build a faraday cage, large or small, it just makes sense to have one!
How to convert a room in your home into a Faraday Cage
The most important factor in building a faraday cage is ensuring that the cage itself is completely enclosed and grounded. Professional-grade products are available for this, but materials are also easy to source at grocery stores, home improvement stores, and in your own home, making this an easy project for someone of any skill level. Remember that the room must be completely covered with no gaps for the cage to be effective, which means there should be shields both on the ceiling and floor of the room, with overlapping seams. If the room has windows, doors, and air vents, those should be covered as well.
For wall coverings, any lightweight shield will suffice. A smaller surface area (such as a small cage to protect a HAM radio) would be well covered by tin-foil sheets, but a large room would benefit much more from fabric that can be sewn, glued, or stapled in place to ensure minimal gaps or cracks where radiation could penetrate the cage. Overlapped panels of RF shielding fabrics with a self-adhesive backing, such as the AaroniaUSA X-Dream Plus, would be ideal for this purpose as it can be applied in the same manner as a peel-and-stick wallpaper.
For window coverings, a mesh screen could be fitted in lieu of a traditional window screen, but for the most complete shielding, it would be ideal to have something covering the windows from the inside. A lightweight, breathable fabric that allows light to pass through, such as the AaroniaUSA Shield, would be ideal in this application.
Air vents are notoriously difficult, and there are a few ways to convert them into RF-Safe vents. The first is to simply cover them tightly with a lightweight and breathable fabric, such as the AaroniaUSA Shield, and understand that the airflow may be restricted slightly as a result. The second method would be to construct a custom air filter out of a stiff shielding fabric, such as the AaroniaUSA X-Steel, that would fit directly into or over the vent, ensuring complete shielding and performance. We recommend creating several custom air filters at a time, as they will get dirty and dusty over the course of use like any traditional air filter.
The most critical step in the creation of a faraday cage room or shielded home is ensuring complete, grounded shielding with no gaps or cracks. Seams between pieces of fabric shield should overlap, and be secured to the walls and each other to minimize EMF penetration. Be sure to pay special attention to gaps under doorways (place metal door sweeps here – found at local DIY hardware stores), windows, and air vents, to ensure maximized protection.
Home Health and Safety Alternatives
If you are experiencing electro-sensitivity and are in need of a quick fix in your home, health and safety alternatives (such as RF shielded bed canopies) are available and much more affordable than purchasing bulk quantities of shielding fabric and lining an entire room. These canopies are used with a grounding mat for maximized protection, and 100% of electro-sensitive canopy users polled report improved quality of sleep and health benefits after installing and using their Aaronia USA bed canopies. Other customers have successfully used small quantities of RF shielding fabrics to create clothing and personal protective items.
For more information about Aaronia USA RF Shielding Fabrics and Bed Canopies, or to request a custom quote or place an order, please call 214-935-9800 or email sales at aaroniausa.com.
To learn more about Faraday Cages, EMPs, and Electro-Sensitivity, view sources for this article here: