Non-contact radar-based monitoring of large mechanical constructions is currently gaining much attention from the RF/microwave community. In particular, Doppler radars can be coherently exploited to extract spectrograms - i.e., time-Doppler maps - of industrial-type wind turbines. This work conducts short-range experiments corresponding to a 50-m-height Vestas wind turbine illuminated by two custom-designed quadrature radar prototypes operating at 5.8 and 24 GHz, respectively. It is observed that the obtained experimental radar signatures - that are shaped by flashes and quasi-sinusoidal halos - exhibit distinct characteristics depending on the acquisition geometry and the operation frequency of the radar sensor. These features might lead in the future to a radar-based non-contact monitoring solution of the structural health of industrial-type wind turbines.