What Is IEMI?

IEMI, or intentional electromagnetic interference, is the deliberate generation and directed use of electromagnetic energy to disrupt, degrade, or damage electronic equipment, information systems, and electrically controlled processes. The term was formally defined at the 1999 Zurich EMC Symposium as the intentional malicious generation of electromagnetic energy introducing noise or signals into electric and electronic systems for terrorist or criminal purposes. Unlike natural or incidental electromagnetic interference, IEMI involves an adversary selecting a target and engineering an electromagnetic source to produce a specific disruptive effect at a chosen frequency, field strength, and pulse shape.

IEMI belongs to the broader category of high-power electromagnetics (HPEM), which includes both natural threats such as lightning and geomagnetic storms and man-made threats such as electromagnetic pulse (EMP) from nuclear detonations. Within that taxonomy, IEMI is specifically characterized by intentionality and close-in targeting: an attacker brings a portable or vehicle-mounted HPEM source to within meters or tens of meters of a target and activates it to cause a specific operational failure.

High-Power Sources and Attack Mechanisms

IEMI sources exploit the fact that modern electronics operate at low voltages and are sensitive to externally coupled electromagnetic energy. Common HPEM source types include high-voltage impulse generators, microwave oscillators, and ultra-wideband radiators. These devices can produce peak electric field strengths exceeding several kilovolts per meter at close range. The IEC standard IEC 61000-2-13 defines representative HPEM environments for civil facilities and provides canonical waveforms used in analysis and testing.

When electromagnetic energy couples into a target system, effects range from temporary upset, such as a system reboot or data corruption, to permanent damage of semiconductor junctions. Coupling paths include apertures in shielding enclosures, power and signal cable entry points, and antenna structures. The distinction between reversible upset and permanent damage depends on the peak induced voltage relative to device breakdown thresholds.

The threat is not limited to nation-state actors. Research cited in the IEEE Standard 1642-2015 recommended practice notes that off-the-shelf components can be assembled into low-cost IEMI sources, raising concern about use by non-state actors for economic disruption and what some researchers call electromagnetic terrorism.

Detection and System-Level Testing

IEMI detection systems monitor electromagnetic signals for anomalous pulses characteristic of HPEM sources. Detection hardware must cover a wide dynamic range, typically from a few hundred volts per meter up to several kilovolts per meter, across frequencies from tens of megahertz to several gigahertz. This range requires logarithmic amplifiers and fast analog-to-digital converters to capture transient events without saturation.

System-level testing to evaluate IEMI hardness uses HPEM simulators, which are laboratory or field-deployable sources that replicate the waveforms defined in IEC and IEEE standards. IEEE Standard 1642-2015 establishes electromagnetic threat levels, protection methods, and test techniques for publicly accessible computer systems within a 100-meter exposure range. Tested equipment categories include automated teller machines, point-of-sale terminals, traffic control systems, and hospital equipment.

IEMI hardening strategies address the coupling paths identified during testing. Shielding enclosures with reduced apertures, transient voltage suppressors on cable entry points, fiber-optic data links that eliminate conducted coupling, and physical standoff barriers all reduce susceptibility. Testing against FERC-documented IEMI threat scenarios has informed protection requirements for electric grid control equipment.

Applications

IEMI research and protection measures have applications in a range of fields, including:

• Critical infrastructure protection for power grids and water systems
• Defense and military facility hardening against directed electromagnetic attack
• Airport and transportation security system resilience
• Financial services infrastructure, including ATM and payment terminal protection
• Hospital and medical device continuity during electromagnetic disturbance events