ABSTRACT
Wind turbines (WT) cause electromagnetic interference (EMI) via three principal mechanisms, namely near field effects, diffraction and reflection/ scattering [1-4]. Near field effects refer to the potential of a wind turbine to cause interference to radio signals due to electromagnetic fields emitted by the generator and switching components in the turbine nacelle or hub. Diffraction occurs when an object modifies an advancing wavefront by obstructing the wave’s path of travel. Diffraction effects can occur when the object not only reflects part of the signal, but also absorbs the signal. Reflection/scattering interference occurs when turbines either reflect or obstruct signals between a transmitter and a receiver. This occurs when the rotating blades of a turbine receive a primary transmitted signal and they act to produce and transmit a scattered signal. In this situation the receiver may pick up two signals simultaneously, with the scattered signal causing EMI because it is delayed in time (out of phase) or distorted compared to the primary signal.
