Electromagnetic interference from wind turbines

Summary form only given. During the late nineteen seventies and eighties the University of Michigan Radiation Laboratory, under sponsorship from the US Department of Energy, studied theoretically and experimentally the effects of wind turbines (WTs) on the performance of various electromagnetic systems. The article summarizes selected portions of the fundamental work carried out and techniques developed under the program which are now routinely used throughout the world for such interference measurements and analyses. To a receiver of electromagnetic signals in the vicinity of a WT, the rotating blades act as a time varying multipath source. As a result of the scattering from the blades the total signals received are generally amplitude and phase (or frequency) modulated. The former being more dominant for slow moving WTs. These extraneous modulations of the desired signal, if sufficiently strong, can adversely affect the performance of an electromagnetic system. The degree and nature of the interference will depend on the signal transmission and reception methods used by the system, and the electromagnetic scattering characteristics of the WT blades. Wide-ranging theoretical and experimental investigation of the electromagnetic effects of large WTs on the performance of TV and FM broadcast reception, microwave link and variety of navigation systems were carried out. The WT interference effects on TV reception were studied most extensively.