Measured impact of electromagnetic scattering off wind turbines on broadcast signal propagation

The electromagnetic scattering pattern of a wind turbine at DVB-T and DAB frequencies was studied by measurement on a scaled laboratory model, taking into account different yaw and pitch angles, and blade positions. The scattered energy peaks along backward directions, where it is stronger for vertical than for horizontal polarization, and is dominated by the mast. The variation of the yaw angle has greater effect compared to blade and pitch variations. Illuminating the wind turbine from the back results in stronger scattering compared to the front side due to the aerodynamic cross-sectional shape of the blades. The scattering becomes stronger for increasing electrical size of the wind turbine. The experimental approach proves reliable and helpful for the development of propagation models.