Technical Glossary

Attenuation is the reduction in strength of an electromagnetic signal as it passes through a shielding material. Measured in decibels (dB), higher values indicate greater signal reduction. For example, 60 dB attenuation means the signal is reduced by a factor of 1,000,000. Typical SCIF requirements range from 60-80 dB.

Beryllium Copper (BeCu) is a copper alloy known for its exceptional strength, hardness, and electrical conductivity. In shielding applications, it's prized for its excellent RF attenuation properties (90+ dB), fatigue resistance, and compatibility with EMI gaskets. It's commonly used in shielded doors and specialized RF components.

Faraday cage is an enclosure of conductive material that blocks external electric fields. Named after scientist Michael Faraday, who demonstrated the principle in 1836. Architectural shielding systems are essentially large-scale Faraday cages designed to protect entire rooms or buildings from electromagnetic threats.

Gigahertz (GHz) is a unit of frequency equal to one billion hertz. Used to measure high-frequency electromagnetic waves. Common applications: WiFi (2.4/5/6 GHz), cellular 4G LTE (0.7-2.6 GHz), 5G (sub-6 GHz and mmWave 24-100 GHz), and satellite communications (12-40 GHz).

ICD 705 (Intelligence Community Directive 705) establishes the standards for Sensitive Compartmented Information Facilities (SCIFs). It defines construction requirements including RF shielding specifications, acoustic requirements, and security standards. ICD 710 provides technical specifications for SCIF construction.

MIL-STD-461 is a United States Military Standard that establishes electromagnetic interference (EMI) control requirements for electronic equipment. It defines emission and susceptibility limits across multiple frequency ranges and is commonly referenced for defense and aerospace applications.

NSA/CSS (National Security Agency / Central Security Service) is the U.S. government agency responsible for signals intelligence and information security. NSA evaluates and certifies TEMPEST equipment and testing facilities. NSA Type 1 equipment is certified for protecting classified information.

Penetration is any opening in a shielded enclosure that allows utilities to pass through, such as cables, pipes, or ventilation. Each penetration represents a potential RF leak point and must be treated with conductive gaskets, waveguide arrays, or filtered entries to maintain shielding integrity.

Sensitive Compartmented Information Facility (SCIF) is a secure room where classified information is discussed, stored, or processed. SCIFs must meet ICD 705 requirements including RF shielding (typically 60+ dB), acoustic isolation, and strict access controls. Used by government agencies and contractors for intelligence work.

TEMPEST is the U.S. government program for protecting equipment from compromising emanations — unintended electromagnetic signals that can carry classified information. Van Eck phreaking is the non-government term for this threat. TEMPEST-certified equipment is tested to ensure emissions are below safe levels.

Van Eck phreaking is the technique of intercepting electromagnetic emissions from electronic equipment to reconstruct displayed information. Demonstrated by Wim van Eck in 1985, it can capture monitor displays, keyboard input, and encrypted data from considerable distances without physical access.

Waveguide is a conductive tube that allows electromagnetic waves to pass through a shielded enclosure at specific frequencies while maintaining RF isolation. Honeycomb waveguide arrays (HWAs) use multiple small waveguides to provide ventilation while blocking RF signals. Below its cutoff frequency, a waveguide provides excellent attenuation.

Wired Shielded Interface (WSI) is an NSA-certified standard for protecting TEMPEST emanations from signal cables. WSI cables have multiple layers of shielding and filtering to prevent classified information from leaking through connected wiring. Required for connecting classified equipment to external networks.