Parametric modelling of the radar signature of helicopters

The problem of helicopter detection and classification requires a simple and fast modelling of rotorcraft signature to aid the design of specific waveforms or to feed deep learning algorithms. To this purpose we here present a parametric model for the baseband radar cross section (RCS) of helicopters in the narrowband approximation. Rotor blades are simulated as one-dimensional objects with a constant reflectivity per unit length and an arbitrary shape in the three-dimensional space, enabling one to take basic flight dynamics into account. The main rotor hub is also modelled as a multiple-scatterer object. The full model is then used to simulate the signature of real rotorcraft, which is compared with experimental data. We show that it is able to accurately predict the most important features of the helicopter radar response, such as blade flash shape and duration.