In-Situ ISAR Imaging of Wind Turbines

Measurement and processing methodologies are developed to capture the in-situ inverse synthetic aperture radar (ISAR) image of an operating wind turbine. In-situ measurement data of a small three-blade wind turbine are collected using an ultrawideband radar, and the measured signatures are compared with simulation results based on physical optics. The backscattering phenomenology is examined in the sinogram, spectrogram, and ISAR image domains. It is shown that the resulting ISAR images provide revealing geometrical insight into the blade scattering phenomenology which is not as apparent in either the range profile or Doppler spectrogram alone. Subsequently, the same methodologies are applied to generate the in-situ ISAR imagery of an 18-blade windmill and a 1.7-MW utility-class wind turbine.