In-Flight UAVs Polarimetric Radar Cross-Section Measurement and Statistical Analysis at X- and L-Bands

The paper introduces a carefully designed experiment based on professional radar hardware setup to collect X- and quad-pol L-bands radar data in a rural area during the simultaneous flight of a commercial and a professional-grade drone. After the definition of a procedure to retrieve the Unmanned Aerial Vehicles (UAVs) Radar Cross-Section (RCS) from the gathered measurements, the research has been focused on how the statistical behavior of the RCS depends on radar frequency, polarization configuration, and drone type. The analysis is based on the evaluation of the Empirical Cumulative Distribution Function (ECDF) of the normalized RCS and its comparison with different theoretical models whose goodness of fit is assessed using the Cramér-von Mises (CVM) distance. In addition, dispersion metrics such as standard deviation, interquartile range, full range, and box-and-whisker plots are employed to provide a quantitative measure of the variability of the RCS under different operating conditions. The results show that, regardless of the frequency band, each UAV conforms to a distinct RCS fluctuation model. Moreover, for a given UAV, the best-fitting pattern changes depending on frequency and polarization. These variations reflect both the different structural characteristics of the UAVs and the frequency/polarization dependence of the RCS, as the scatterers that compose the drone may respond differently depending on the frequency/polarization.