Main view: In-situ measurements of a small wind turbine.
Insert: Post-processed FEKO simulation results. [From the entry "Dynamic Signatures of Wind Turbines" by Chenchen Li from the University of Texas at Austin, Austin, Texas, USA.]
To create such an ISAR image from computed FEKO back-scattered field results, an angular (or time) swath is processed through the 2D FFT to form a (down range)-(cross range) image. Snapshots in time are created by processing multiple swaths.
"It can clearly be seen that as the blade becomes perpendicular to the line-of-sight (horizontal in the movie), the straight portion of the turbine blade 'flashes' and as the blade continues to rotate, the specular point travels along the curved portion of the blade. As one blade fades, another blade begins to 'flash'. The constant spot in the centre is the hub return." - Chenchen Li, winner of the 2013 FEKO Student Competition.
Results of the FEKO Student Competition 2013: https://www.feko.info/about-us/News/feko-student-competition-results-for-2013