UAV Backup Communication via Mechanical Antennas and NLFM Pulse Compression

Establishing a robust backup communication link for unmanned aerial vehicles (UAVs) in GNSS-denied and signal-blocked environments remains a pressing need for the low-altitude economy. This work proposes and validates a penetrative link based on mechanical antennas, enhanced by nonlinear frequency modulation (NLFM) and pulse compression processing. The system encodes backup commands into NLFM waveforms transmitted via a rotating magnet, and employs pulse compression at the receiver to achieve substantial processing gain. Ground measurements corroborate the theoretical gain, showing a 17 dB improvement in signal-to-noise ratio. Crucially, flight tests under realistic occlusion conditions demonstrate that the link remains operational where conventional remote control fails, enabling basic command and control at extended ranges. This method offers a feasible and hardware-agnostic pathway to augment UAV operational safety and reliability in complex electromagnetic environments.