Simulation and measurement of propeller modulation using FM broadcast band commensal radar

Radar research using transmitters of opportunity (commensal radar (CR)) has experienced a resurgence in popularity, focused mainly on target detection and less so on target classification. This reported work has demonstrated that CR can be used to estimate the rotation rate of an aircraft propeller accurately over a wide range of frontal aspect angles. The propeller induces polarisation modulation, which results in amplitude modulation of the signal received by the passive radar receiver. This effect is derived mathematically and verified with a detailed electromagnetic simulation of the aircraft´s propeller. Lastly, these findings were validated with field measurements of a Cessna 172 aircraft.