What Are IEMI Detectors?

IEMI detectors are electronic measurement systems designed to sense, characterize, and record the electromagnetic pulse signals produced by intentional electromagnetic interference (IEMI) sources. Their function is to provide warning that an HPEM (high-power electromagnetic) attack is in progress, to capture signal parameters that allow forensic analysis, and to supply data for assessing exposure levels against device susceptibility thresholds. Because IEMI sources can produce peak electric fields exceeding several kilovolts per meter across a frequency range from a few megahertz to ten gigahertz or more, detector systems must combine broadband antenna coverage with a wide amplitude dynamic range, properties that make their design considerably more demanding than conventional electromagnetic compatibility measurement equipment.

IEMI detectors serve both a protective and an investigative role. In operational deployment near critical infrastructure, they function as alarm systems. In laboratory settings, they characterize the output of HPEM simulators to validate that testing meets the waveform requirements specified in standards such as IEC 61000-2-13.

Sensor Architectures and Antenna Design

A fundamental requirement for IEMI detection is polarization-independent broadband antenna coverage, since an attacker may radiate at any polarization and across a wide frequency band. Practical detector systems use antennas such as planar log-periodic dipole arrays (PLPDAs), conical spiral antennas, or biconical antennas to achieve impedance matching and consistent gain across the operating band. A forensic IEMI detection system described in IEEE Xplore employed a four-channel configuration with four polarization-independent broadband antennas and logarithmic amplifier-detector units, enabling simultaneous direction finding toward the HPEM source.

The antenna signal is connected to a high-dynamic-range receiver chain. Because the field strengths of interest span from ambient levels to many kilovolts per meter, linear amplification would saturate at strong inputs or lose sensitivity at low levels. Logarithmic amplifiers, which produce an output proportional to the logarithm of the input power, are standard in IEMI receiver frontends. After the logarithmic amplifier, an analog-to-digital converter samples the signal at sufficient speed, typically with sub-nanosecond time resolution, to capture the pulse-width and rise-time parameters that characterize the source type.

Signal Classification and Forensics

Raw field-strength measurements are necessary but not sufficient for a functional IEMI detector. Distinguishing an IEMI attack from unintentional interference, nearby radar emissions, or legitimate high-power communications requires classification of the detected pulse train. Key parameters extracted from each detected event include peak field strength, pulse width, pulse repetition frequency, frequency content, and the total number of pulses in a burst.

Research on IEMI applications for safety and security published by IEEE addresses how these parameter sets can be compared against known HPEM source signatures to distinguish attack waveforms from background. Forensic-grade systems also record timestamped signal envelopes with down to 10 ns time resolution, preserving a verifiable record usable in post-incident analysis.

Multi-sensor networks add a spatial dimension. By correlating detection events across geographically separated sensors, a network can estimate the source location, track movement of a mobile IEMI source, and discriminate a single localized source from distributed background interference. The MDPI Sensors review of electromagnetic interference on UAV sensor modules illustrates how these detection principles extend to platform-level protection in mobile systems.

Applications

IEMI detectors have applications in a range of fields, including:

• Critical infrastructure protection for power substations, data centers, and financial networks
• Defense perimeter monitoring at military installations and command facilities
• Airport and transportation hub electromagnetic security screening
• Laboratory HPEM simulator characterization and standards compliance testing
• Forensic evidence collection following suspected electromagnetic attack incidents