Electromagnetic Pulse

by Bobby Akart

  To construct a simple Faraday Cage using a galvanized trash can, you can follow the step-by-step instructions found on our website: FreedomPreppers.com. Here are the basics.

  The primary requirements for protection when designing a Faraday Cage are:

  · The electrical equipment inside the box cannot touch the metal container. Insulating with foam, cardboard, rubber, plastic or even wads of paper are acceptable methods.

  · The metal shielding must be continuous. There can be no large holes or gaps in the shielding material.

  Now that you understand the basic principles let’s apply them to a simple Faraday Cage for home use.

  There are a few decisions you have to make before starting your homemade Faraday Cage:

  · The shape. The cage can have any shape you like: spherical, triangular, oddly shaped, and so on. If you decide to go with the classic rectangular shape, that’s acceptable, as long as you know that the shape doesn’t affect the cage’s effectiveness. As always, keep it simple.

  · The conductor material. You must choose the material you want to put on the outside of the cage. This should be a simple decision, as the material doesn’t influence the cage’s activity (as long as it is capable to conduct electricity as discussed above). A heavy-duty, galvanized trash can be the most cost-effective material for an efficient DIY Faraday Cage.

  · Holes or no holes. A Faraday Cage can have holes in its walls as long as they are not too big to let the electromagnetic wave in. That’s why you can use an aluminum mesh as the outer layer of the cage. However, don’t risk a design flaw. After an EMP attack, you don’t get a do-over. Use a galvanized trash can and seal the lid with aluminum tape. Make sure the lid is secured firmly to the garbage can.

  · Cushioning material. Use a variety of cushioning material to protect the electronics from the inside walls of the Faraday Cage. We suggest upholstery foam that can be purchased in rolls and cut to fit.

  · Grounding the Faraday Cage. The debate will rage on regarding this requirement. It’s not necessary, in our opinion.

  · Protection against moisture. This is an often overlooked necessity. Moisture will ruin electronics. Your Faraday Cage must be moisture absorbent to create a safe and dry environment for the devices inside. They won’t do you any good if they survive an EMP but they cease to function from moisture damage because of the excessive humidity. Add 50-gram desiccant packs to the inside before sealing.

  Now that you’ve got everything you need, it’s time to start building:

  Begin by wrapping everything you want to put in the cage in a heavy duty aluminum foil. You can add a piece of cloth before putting on the foil if the object you’re wrapping has sharp corners. Make sure you put at least two layers of aluminum foil on each item. It’s important to cover tears or holes in the foil.

  Take the container you are using as the walls of the Faraday Cage and add a protection layer on the inside. Here, you can use a foam cushion or simply a cut up cardboard box. The cushion will be a better protective layer, especially if you need to grab the trash can handle in an expedited bug-out situation. If you’re not going to bang the cage against the walls, you should be fine with the cardboard box material. Make sure that you add this interior layer on the entire interior. The items inside cannot touch the walls of the container, especially if you’re using a galvanized trash can.

  Place the moisture absorbent desiccant packs, and the items you want to protect, inside the container.

  Secure the lid and add an extra layer of aluminum tape around the seal. The layer of tape is just to make sure that the seal is made, and there are no intrusions between the metal contacts. For the cage to work, this seal must be perfect.

  A final test is recommended. Unless you are prepared to construct your own radio frequency weapon, you can’t produce an actual electromagnetic pulse to test the Faraday Cage you just built, but there are other ways to see if it is properly constructed. Place a portable AM/FM radio and turn up the volume so that it is loud. Before securing the lid in place you will still be able to hear the radio’s signal from inside the container. After everything is sealed up, the radio should lose signal. If this happens, it means your Faraday Cage will protect your electronics. You can try the test with a cell phone as well. If your phone rings while inside the sealed cage, look for holes in the container or in the aluminum foil used to wrap the items.

  Now that we know how to protect our electronics, it’s time to learn a few alternative tips and techniques on how to create a Faraday Cage with materials at your disposal.

  · Use nylon stockings filled with crystal cat litter to absorb the moisture inside. It’s an inexpensive and effective alternative to make sure your Faraday Cage is moisture free.

  · Pack your items and put them in the can in the order that you are going to need them. If there are items you need to check on regularly, put them at the top.

  · You could embed a solar panel in a large Faraday cage to keep your electronics running even if the power lines are down. Some argue that a disconnected solar panel is not at risk. There is no definitive answer. Out of precaution, we shield ours.

  · Keep your devices charged, and store charged batteries.

  Chapter Twenty-One

  Sophisticated Shielded Rooms

  Faraday Cages cannot block static or slowly varying magnetic fields, such as the Earthʹs magnetic field. To a large degree, though, they shield the interior from external electromagnetic radiation, if the conductor is thick enough and any holes are significantly smaller than the wavelength of the radiation. For example, certain computer forensic test procedures of electronic systems that require an environment free of electromagnetic interference can be carried out within a screened room. These rooms are spaces that are completely enclosed by one or more layers of a fine metal mesh or perforated sheet metal. The metal layers are grounded to dissipate any electric currents generated from external or internal electromagnetic fields, and thus, they block a large amount of the electromagnetic interference.

  Shielded room

  An ideal Faraday Cage or a shielded room is a sort of a metal box without any openings. Naturally, we need some openings for entering the shielded room, allowing for cable duct, and openings for vent and cooled air, etc. These aspects of a Faraday Cage relate to the cage’s attenuation—which refers to the reduction in strength of an EMP wave as it attempts to enter the cage.

  Shielded rooms are constructed in two optional methods in order to function as a Faraday Cage:

  · A modular room with prefabricated 1‐2mm steel plates which are collected and assembled on site with EMP‐gaskets between all elements. This type gives very high attenuation and shielding effectiveness. It is also the most expensive option.

  · ʺThin plateʺ construction; on-site built shield with 26-gauge steel plates covering all room surfaces. This can be constructed on a DIY basis and gives a fairly high shielding effectiveness.

  Both types of construction comply with most common regulatory attenuation requirements for civilian purposes. The shield itself must be constructed of an electric conductive material. Typically, thin galvanized steel plates are used, but in some cases, other metals like copper or brass foil are suitable. You can purchase 26-gauge steel sheets from your local steel fabricator or metal roof supplier.

  Doors and Entryways

  Doors in this type of shielded room are specially designed with high EMP attenuation performance. The door frame and leaf have a special EMP gasket for sufficient coupling and good sealing effect. An EMP proof door is expensive. There are DIY alternatives, but the cost of the door will be one of the biggest expenses of your shielded room.

  There are two different types of such doors;

  · High performance, EMP shielding door with knife frame and copper finger gasket. They cost thousands of dollars.

  · A slightly less robust door designed like the lid of a Faraday Cage.

  Option one is a professionally designed shielding door filled with spe
cial shielding materials to protect devices and human beings from invisible radioactive rays, electromagnetic waves, and microwaves. Depending on the purpose or use, the shielding door is categorized into radiation shielding doors which are installed in X-ray rooms, nuclear medicine rooms, Radioactive Isotope laboratories, or the radioactivity control rooms of industrial facilities, and electromagnetic wave shielding doors which are installed at magnetic wave shielding compartments, protecting medical instruments in hospitals or MRI rooms.

  The electromagnetic wave shielded door protects a particular space against Radio Frequency or Conducted Noise which occurs due to unnecessary electromagnetic waves and hinders strong electromagnetic waves generated from an EMP. The conventional purpose of an electromagnetic wave shielded door is to protect devices at hospitals or laboratories from electromagnetic waves. They also are designed to withstand a high-altitude EMP attack.

  Option two is to use a solid, pre-hung and fire-rated steel door with a steel welded frame. These can be purchased at any home improvement store for less than a thousand dollars. Cracks or openings should be filled with an EMP gasket and for added protection, the door frame and door handles should be sealed with aluminum foil tape when not in use.

  We suggest a metal knit EMP shielding gasket which consists of a layer of knitted electrically conductive metal wires over a low-closure-force rubber or elastomer core. For heavy duty applications like an EMP, or for high temperature fire-proofing, the gasket is sometimes combined with an environmental seal.

  These knitted wire mesh gaskets, available online, provide a cost-effective solution to high-shielding performance from an EMP. If you choose the all-metal knitted mesh or knitted metal mesh over an elastomer core, the door can be opened and closed frequently, as the gasket will allow recovery after compression. When combined with the pre-hung all steel entry door, you have a single entry system for roughly $1,200.

  Single Entry Cabling and Ductwork

  All cabling and ductwork for a cooling system is usually fed through the walls of the shielded room in one cable duct called the Single Entry. By reducing the number of cable entries to one, you can minimize the potential for low-frequency or high-frequency intrusion.

  There are two types of Single Entry Cabling and Ductwork:

  · A honeycomb shielding vent panel can be directly welded to your shielded steel walls. These are available online for under $200.

  · Cable glands with mesh tube sealing; mounted directly on the shield wall. There are two types with different performances: a military grade that is outside of most budgets, and an industrial electromagnetic compatibility, or EMC glands. A single entry EMC gland plate is available online for around $200.

  The EMP shielding vent panels consist of either a rectangular or a circular frame with a honeycomb structure inside. The honeycomb vent is series of hexagonal ʺtubesʺ that acts as a waveguide, guiding electromagnetic waves in/out of the shielded room and blocking the airflow. The airflow is led nearly unobstructed through the honeycomb while the electromagnetic pulses are stopped effectively.

  Chapter Twenty-Two

  Shielded Cables, Cabinets and Accessories

  Electrical cables

  As discussed in the prior chapter, all electric cables must be shielded when installed through a shielded room. This is an absolute requirement. Cables and wires act as an antenna during a geomagnetic storm event. Unshielded cables penetrating the shield will act as unwanted antennas and destroy the shield’s effectiveness. Poorly shielded cables will cause serious leakages and damages of the internal installed equipment in the shielded room in the event of a HEMP.

  Be aware that some high quality, but less recommended cables are available . Some manufacturers advertise and promote their shielded cables as EMC, without disclosing that some of these are not recommended for EMP protection. Quad-dense, braid/mesh shield or a mesh/foil shield is highly recommended, such as this cabling:

  Shielded telephone wire is also suggested:

  Finally, here is an example of shielded electrical wire:

  Shielded Racks/Cabinets

  Shielded racks and cabinets can be constructed as Faraday Cages. There are two different types:

  · Rugged, high-performance steel shelves with knife/copper EMP‐gaskets in the door. Primarily used in industrial settings, this type is supplied with cable filters (power and telecom), in addition to the standard equipment like a small Single Entry, honeycombs and fans for vented air.

  · Semi-rugged, high-performance steel racks with a simpler (less dense) mesh EMP‐gasket in the door leaf. Like the above type, this is also typically equipped with honeycomb vents or a mesh door. However, this type is less costly.

  Manufactured EMP‐racks are expensive, but affordable compared with a professionally-installed shielded room. Assembly of cabinets is of course much easier and less expensive than the design/build of shielded rooms. An affordable alternative is to follow the instructions for creating a shielded room, but on a smaller scale—closet size.

  Steel Shipping Container

  An EMP‐proof shipping container or shelter is a bigger Faraday Cage; steel box; built with approx. 3‐5mm thick steel plates. Such containers are normally equipped with a shielded door, air vents with honeycomb, a Single Entry, cable filters, etc. The shielding effectiveness is very high; often equal to shielded rooms. This solution is fairly expensive, but effective, when there is lack of in‐house space. The key is creating a seal around the entry door.

  Grounding of Shielded Cabinets and Containers

  Grounding of electric systems and equipment has several meanings, definitions and purposes:

  · Protective grounding | protecting people to prevent user contact with dangerous voltage if electrical insulation fails.

  · Functional grounding | usually the neutral in an electrical power supply system. For EMP shielded rooms and cabinets, the grounding “network” is essential for obtaining good shielding effectiveness. The shielding cabinets main purposes; EMP absorption and reflection, are dependent on a correctly grounded shield.

  Since the shielding systems of a cabinet or shipping container may involve human contact, it is recommended to conduct and drain possible unwanted currents to a grounding source. Normally, the shield is connected with a massive grounding cable connected to the main earthing bar in the building and to the grounding rod outside. Correct grounding shall provide equal protection on the outside and inside of the shielded cabinet. It further avoids risk of electrocution by human contact.

  Operation and Preventive Maintenance

  The shielded enclosures and cabinets have to be regularly maintained to ensure specified shielding effectiveness. Typical maintenance activities are:

  · General inspection and eventual repair of holes, slots, and other irregular openings in the enclosure

  · Cleaning, lubrication, and greasing of EMP‐gaskets

  · Checking for possible EMP‐gasket damages

  · Door lock gear inspection and adjusting

  · Air vents (honeycombs) dusting and vacuum cleaning

  · Single Entry frame and modules inspection

  · Filter inspection and bolt tightening

  · Grounding and bonding cables inspection and tightening bolts, cable lugs, etc.

  Mountain Plants/Underground Bunkers

  Vulnerable electronic equipment could be adequately protected even without extra shielding in a Faraday Cage, if it is placed deep enough inside in a mountain plant or underground bunker. The shielding effectiveness is dependent on some important preconditions related to:

  · Rock and soil environment depth and thickness

  · Rock and soil type; i.e. the ground conductivity

  · Cables from outside into the mountain or underground bunker; types, length, etc.

  A note about construction, knowledge and competence

  Construction and completion of shielded rooms is typically a process involving several parties like consultants, suppliers, installer companies,
and dedicated consultants for a final test and control measurements. Common for all of these parties is a demand of sufficient competence, knowledge, and experience to secure high-quality performance and shielding effectiveness. If you are undertaking the construction of a shielded room, cost may or may not be a factor. These projects can be undertaken by anyone with a basic knowledge of construction, but testing is important after completion. At the very least, hire a competent professional to conduct the requisite testing.

  Verification, test and measurements