In this work, we present a comprehensive experimental investigation into the dynamic disruption of a micro-small fixed-wing drone using a narrowband high-power microwave (HPM) system. The primary objective is to understand the real-time effects of high-power electromagnetic pulses on the flight control system of the fixed-wing drone and to identify the root cause of its subsequent loss of control and crash. Our experiments were conducted in an open, unpopulated area to ensure safety, and we utilized a dedicated HPM experimental system based on relativistic electro-vacuum technology. The target under test was a specific model of micro-small fixed-wing drone, which flew along a pre-planned route at a distance of approximately 15 km from the HPM system. The entire process was monitored via radar and optoelectronic tracking devices, and onboard flight data were recovered after the drone crashed.
1. Experimental System Description
Our narrowband HPM experimental system comprises two major subsystems: target guidance and HPM transmission. The target guidance subsystem includes radar equipment, optoelectronic devices, and system control. Radar detects the fixed-wing drone and guides the optoelectronic tracker for precise following. The HPM transmission subsystem, based on relativistic electro-vacuum technology, consists of a charging power supply, a high-voltage pulsed power source, an HPM source, a radiating antenna, control and monitoring equipment, and a vacuum molecular pump unit. The charging power supply delivers up to 50 kV via constant current to charge high-voltage storage capacitors in the pulsed power source. The pulsed power source, designed using a Marx generator topology, outputs high-voltage pulses of 300–600 kV to drive the HPM source, which then produces gigawatt-level electromagnetic pulses radiated by the antenna. Key characteristics are summarized in Table 1.
| Parameter | Value |
|---|---|
| Charging Power Supply Output Voltage | 50 kV (maximum) |
| Pulsed Power Source Output Voltage Range | 300–600 kV |
| Typical Output Voltage (Measured) | 520 kV |
| Pulse Repetition Frequency | Stable at low repetition rate |
| Radiated Power Level | Gigawatt class |
| Antenna Type | High-power radiating antenna with vacuum protection |
| Output Pulse Width | ~Tens of nanoseconds (typical for narrowband HPM) |
The Marx generator circuit used in the pulsed power source is shown conceptually in Figure 2 of the original text. Its operation involves charging capacitors C1–Cn via inductors L1–Ln, then triggering spark gaps S1–Sn simultaneously to discharge into the load RL. To protect the charging power supply from reverse high-voltage spikes, a protection circuit using high-voltage diodes (V1–V4) and resistors (R1–R2) was implemented, which significantly improved system reliability.
2. Experimental Procedure and Data Collection
The micro-small fixed-wing drone was launched from a point approximately 15 km from the HPM system. It ascended to a cruising altitude following a pre-programmed flight path. Once the drone entered the designated test area, the target guidance subsystem (radar and optoelectronics) acquired and tracked it, then commanded the HPM transmission subsystem to emit a high-power electromagnetic pulse toward the fixed-wing drone. The drone’s onboard flight data recorder logged various parameters including altitude, roll angle, pitch angle, magnetic heading, and control surface deflections (elevator and rudder). After the drone crashed, we recovered the wreckage and downloaded the flight data for analysis.
The flight data revealed a sudden and severe disruption immediately after the HPM irradiation. Table 2 summarizes the pre- and post-irradiation values of critical flight parameters.
| Parameter | Pre-Irradiation Value | Post-Irradiation Value (Immediate) | Final State |
|---|---|---|---|
| Altitude (m) | Cruising altitude (stable) | Rapid descent at ~20 m/s | Ground impact after ~10 s |
| Roll Angle (degrees) | 13.6 | 3.9 (sudden drop) | -66.3 (end) |
| Pitch Angle (degrees) | -3.8 | 21.5 (sudden rise) | 43.6 (then slight recovery) |
| Elevator Deflection (degrees) | -5.9 | -25 (sudden jump, then locked) | Stayed at -25 (locked) |
| Rudder Deflection (degrees) | 0.1 | 9.7 (sudden jump) | Irregular oscillations up to 21.5 |
The altitude profile showed that the fixed-wing drone lost altitude at a descent rate of 20 m/s—far exceeding its normal landing descent rate—indicating an uncontrolled fall. The magnetic heading exhibited quasi-periodic variations during the 10-second descent, with eight cyclic changes, which is inconsistent with normal landing behavior and suggests uncontrolled spiraling.
3. Analysis of the Disruption Mechanism
The observed behavior—sudden large elevator deflection (from -5.9° to -25° and then locked) and erratic rudder deflection—directly led to the rapid changes in pitch and roll angles, causing the fixed-wing drone to enter an uncontrolled spiral descent. We interpret this as a result of the HPM pulse coupling into the flight control system via “back-door” pathways (e.g., cables, slots, and apertures in the drone’s fuselage) rather than through the “front door” (antenna ports).
The coupling process can be modeled in three stages: free-space propagation, cable coupling, and electronic circuit response. The overall effect on the drone’s control signals can be represented by a cascaded transfer function:
$$
V_{\text{circuit}}(t) = \mathcal{F}^{-1}\left\{ H_3(f,p,\theta) \cdot H_2(f,\tau,p,\theta) \cdot H_1(D,\theta) \cdot \mathcal{F}\{E_{\text{inc}}(t)\} \right\}
$$
where:
- $E_{\text{inc}}(t)$ is the incident electric field at the antenna aperture (before propagation).
- $H_1(D,\theta) = \frac{1}{4\pi D} e^{-j k D}$ (free-space spherical wave factor).
- $H_2(f,\tau,p,\theta)$ represents the cable coupling transfer function dependent on frequency $f$, pulse width $\tau$, polarization $p$, and incidence angle $\theta$.
- $H_3(f,p,\theta)$ represents the electronic circuit response, also dependent on $f$, $p$, and $\theta$.
- $\mathcal{F}$ and $\mathcal{F}^{-1}$ denote Fourier transform and inverse Fourier transform.
The nonlinear nature of the circuit response makes analytical prediction extremely difficult, which is why experimental testing remains essential.
Based on the data, we observed that the onboard sensors (gyroscope, accelerometer, barometer, etc.) and power system remained functional, as the flight data logging continued normally. Therefore, we conclude that the HPM pulse primarily disrupted the central processing unit (CPU) of the flight control system, causing it to output erroneous commands to the servo actuators (elevator and rudder). This led to the observed large, uncontrolled deflections and the subsequent loss of control of the fixed-wing drone.
4. Quantitative Summary of Key Findings
Table 3 lists the time-dependent evolution of the elevator and rudder deflections during the critical first 2 seconds after HPM irradiation, which illustrates the rapid and sustained disruption.
| Time (s) | Elevator Deflection (deg) | Rudder Deflection (deg) |
|---|---|---|
| -0.5 | -5.9 | 0.1 |
| 0 (irradiation) | -25.0 | 9.7 |
| 0.2 | -25.0 (locked) | 11.2 |
| 0.5 | -25.0 | 16.9 |
| 1.0 | -25.0 | 9.9 |
| 1.5 | -25.0 | 21.5 |
| 2.0 | -25.0 | 20.1 |
The magnitude of the elevator deflection (19.1° change from -5.9° to -25°) and the subsequent lock-up indicate a sustained erroneous command. The rudder deflection exhibited non-monotonic, irregular behavior, suggesting that the CPU was producing chaotic control signals rather than a simple step change.
From the dynamic data, we can also calculate the approximate angular rates and accelerations. For example, the roll rate immediately after irradiation can be estimated from the roll angle change of 9.7° (from 13.6° to 3.9°) over one telemetry sample interval (assumed 0.1 s), giving:
$$
\dot{\phi} \approx \frac{-9.7^\circ}{0.1\,\text{s}} = -97^\circ/\text{s}
$$
This is an extremely high roll rate for a fixed-wing drone, far beyond normal maneuvering limits.
Similarly, the pitch rate after irradiation was approximately:
$$
\dot{\theta} \approx \frac{25.3^\circ}{0.1\,\text{s}} = 253^\circ/\text{s}
$$
These values corroborate the violent loss of control.
5. Conclusions and Implications
Our dynamic disruption experiment on a micro-small fixed-wing drone using a narrowband HPM system demonstrated that a single high-power electromagnetic pulse can cause immediate and catastrophic loss of control. The elevator deflection was locked at a large negative value, and the rudder deflected irregularly, leading to a rapid spiral descent and crash. The root cause is attributed to back-door coupling into the flight control CPU, disrupting its normal operation and causing erroneous servo commands.
We emphasize the importance of experimental effect studies for understanding HPM-drone interactions, especially for fixed-wing drones, since static tests cannot fully capture the dynamic flight behavior. The key lessons for improving drone resilience include strengthening the electromagnetic shielding and hardening of the flight control CPU and its interconnections.
Future work should focus on real-time monitoring of the CPU output signals during HPM irradiation, which was not possible in our current setup due to experimental limitations. Such data would help refine theoretical models and improve protective measures for critical drone electronics.
This study provides valuable empirical evidence for the vulnerability of micro-small fixed-wing drones to HPM weapons and offers guidance for both offensive and defensive electromagnetic warfare strategies.