The Radar Cross Section of small propellers on Unmanned Aerial Vehicles

The radar cross section of small-sized unmanned aerial vehicles can be extremely low, making the perception of such objects impossible by standard radar techniques. However, the typical propeller size of these vehicles gives rise to a resonant behavior at some commonly used radar frequency bands. Around the resonant frequency, the radar cross section of the propeller highly depends on the incident wave polarization. Consequently, the rotation of the propeller causes a significant periodic fluctuation of the radar echo, moreover, the propeller length can also be estimated. This phenomenon is studied by means of anechoic chamber measurements and numerical simulations.