Background Unmanned aerial vehicle (UAV) swarms rely heavily on integrated sensors and communication links, making them vulnerable to intense electromagnetic interference. Ultra-wideband electromagnetic pulse (UWB-EMP) can penetrate electronic systems through multiple coupling paths, yet the mechanisms of back-door cable coupling in swarm UAVs remain insufficiently understood.

Purpose To systematically investigate the interference effects and coupling mechanisms of UWB-EMP on a quadrotor UAV swarm, and identify the most sensitive back-door coupling paths.

Methods Irradiation experiments were conducted on a three-UAV swarm under field strengths of 38.2–93.6 kV/m and pulse repetition frequencies of 1–100 Hz. A refined full-wave electromagnetic model incorporating the airframe, antennas, and internal cable systems was established in CST. The coupling voltages at cable terminals and antenna ports were simulated, and the influences of pulse width, incident angle, and polarization were analyzed through parametric scanning.

Results Three primary effect phenomena were observed: transient link disturbance, obstacle avoidance sensor data anomaly, and magnetic compass anomaly. The gimbal ribbon cable was identified as the most sensitive back-door path, exhibiting omnidirectional high-coupling and broadband high-pass characteristics, with its coupling voltage increasing significantly as pulse width decreased. In contrast, the datalink coaxial cable dominated below 600 MHz but was insensitive to pulse width variation. The ultimate interference effect was determined by the inherent vulnerability of terminal circuits and the fail-safe logic of the flight control system.

Conclusions UWB-EMP interferes with UAV swarms primarily through back-door cable coupling. The gimbal ribbon cable constitutes the most sensitive path, with the threat persisting across multiple incident directions, polarizations, and pulse parameters. Countermeasures can focus on attacking sensor back-door links using narrower pulses, while protection should prioritize shielding and filtering of critical back-door interfaces.