In an effort to help preserve the ozone and the availability of diminishing natural fuel sources, alternative energy sources are being investigated. In the case of wind powered energy, efforts have gone past investigation and the full scale implementation of wind turbine farms has become a dramatically growing business all over the world.

Wind turbines convert the kinetic energy from wind into mechanical energy which is used to generate electricity. Although wind turbine technology ultimately has a positive impact on the environment, it has been assessed to possibly impair radio communications systems.

In order to prevent such interference, intensive engineering studies must be performed to assess whether the potential interference on radio communications systems would be significant/intolerable by current radio equipment configurations.

This paper presents how such a wind turbine interference prediction study on an RF communications system can be accomplished using ATDI’s RF planning software packages ICS telecom and HTZ warfare.

ICS telecom/HTZ warfare possesses the ability to model the effect of wind farms on any radio communications technologies such as broadcast, mobile, radar and satellite.

ATDI’s comprehensive radio network planning tool kit offers the following features that allow for the import and configuration of a wind turbine farm on a digital terrain modeling workspace and the ability to model the effect of a wind farm on an RF communications system. A white paper can be downloaded that describes the case of interference from a wind farm on a microwave link.

Practical wind turbine analyses should carefully consider three different criteria that can cause potential worst-case performance degradation of an RF communications system.

These criteria include:

• i) near-field propagation
• ii) diffraction propagation
• iii) reflection/scattering propagation effects that can lead to possible interference scenarios.
• iv). In the near-field zone, the average electromagnetic energy density remains fairly constant at different distances from the antenna. So any wind turbine within the near-field range should cause concern for possible interference effects.

As a function of frequency, wavelength, and the diameter of the antenna, the near-field distance is calculated in ICS Telecom as shown in Figure below.

In the figure below, the near-field regions for both sites are graphically plotted and represented with a blue circle showing no presence of any proposed wind turbines in the area.

Within these ranges, the tool models the radiation as even in all directions until the radiation crosses over the near-field range, at which point the tool assumes the directivity of the antenna radiation pattern.

ii). When a transmitted radio wave is physically obstructed by a wind turbine causing diffraction, a significant negative effect is expected to impact the radio wave. In wind turbine analyses, a complete 2nd Fresnel zone clearance is required in order to provide a more conservative, and realistic, approach toward modeling the varying characteristics of wind turbines.

ICS Telecom offers a working environment that allows the user the ability to visualize the clearance of the 2nd Fresnel zone from wind turbines.

iii). Signal reflection from the physical structure of a turbine propagating into the receiver can potentially result in TD (Threshold Degradation – i.e. rise in noise level) in the receiver system, thus resulting in an critical increase in the C/I ratio requirement for service.

Reflected electromagnetic waves arriving in various directions are analyzed for each turbine to calculate a power sum of the multiple reflected rays arriving at the receiver. Then a C/sum(I) calculation is performed per receiver to determine the effect on system performance.

Multipath Effects Due to Reflection from Wind Turbines.

Simulation of reflection/scattering effects in the function of RCS of structures (blade and tower) performs intensive calculations then a complete report list is created consisting of all interference powers received from any turbines.