EMF shielding protection
http://www.cecer.army.mil/facts/sheets/FL16.html
LOW COST EMP/EMI TEMPEST SHIELDING TECHNOLOGY
The Problem
Dependence on electronic systems for military and other national security command, communications, control, computing, data processing, and intelligence continues to increase. The state-of-the-art electronics components used in most systems are susceptible to upset or damage from Electromagnetic Interference (EMI), including the Electromagnetic Pulse (EMP) from nuclear weapons. Further, to ensure communications security (TEMPEST), it is often necessary to prevent compromising emanations. Many defense-related facilities require EMI, EMP, or TEMPEST protection. Historically, a metallic liner or shield has provided protection by completely enclosing the electronics systems. The conservative designs typically provide more shielding than required and are very expensive to design, construct, test, and maintain.
The Technology
The U.S. Army Construction Engineering Research Laboratories (CERL) has been experimenting with low-cost electromagnetic shielding designs for several years. These studies can be categorized as follows:
1. New Materials Development: Materials included are conductive polymers and advanced coatings for use on shield components. Materials being considered include amorphous metals and intercalated graphites. Consideration is also being given to making concrete electrically conductive.
2. Use of Inherent Shielding of Standard Construction Materials: Examples include aluminum-foil-backed gypsum board, aluminum-foil-backed insulating sheathing, metallic-clad siding, copper foils (normally used for vapor barriers), wire meshes, and sheet metal roofing.
3. Adaptation of Application Techniques: These techniques include the use of thermal spraying (primarily arc-spraying) of metals in which molten metal is sprayed in much the same manner as paint is sprayed. This metal bonds to most construction surfaces. Another technique is the use of laser welding to allow efficient welding of thinner sheet metals than conventional methods.
4. New Construction Assembly Techniques: This effort includes an investigation of seam-joining techniques for thin sheet metals, such as galvanized steel, metal meshes, aluminum panels, and copper sheets.