UK communications regulator Ofcom has released a study it commissioned on the potential of turbines from wind farms to affect microwave transmissions and radar signals. At present, there are approximately 40,000 microwave connections in the UK serving various needs such as mobile phone backhaul and Internet connectivity. The 3- to 20-GHz band generally used for microwave signals includes the Fresnel Zone. Unfortunately, anything within that zone that causes reflections and refractions will interfere with the intended signal. Calculating the potential for interference is particularly difficult since a wind turbine is by definition dynamic and ever-changing. Its blades change pitch depending on conditions, a feature that promotes efficiency but makes calculating the radar cross section problematic. Nonetheless, experts from Aegis Spectrum Engineering and ERA Technology have authored an 87-page report based on a study of several turbine installations in Cambridgeshire. The report concluded that any likely interference reflected from an individual turbine is a function of frequency, of incidence and scatter angles, the relative yaw of the turbine, and the pitch of its blades. The authors call for more extensive studies since more extensive data will be needed to devise a reliable method for calculating radar cross sections more effectively.The entire report is available online.
Wind Farms and Interference
