Buy essay on Effects of Wind Farms on Military Radar

One of the tasks of defense is to safeguard territorial integrity. The Military Forces must be able to detect violations of airspace and sea territories. Radar is an important instrument for revealing any infringements. There are radar stations around nearly every country coast for this purpose. At the same time, however, radar surveillance is sensitive to interference. Radar requires free line of sight in order to function at 100%.
The wind industry strongly supports responsible, effective actions designed to identify and address any potential conflicts with airspace and radar due to proposed wind farms. Wind turbines, radar, and military and civilian airspace needs can co-exist. Experience shows that technical case-bycase analysis of potential airspace and radar interactions can resolve some concerns, and mitigation measures should be able to resolve others.
The determination of the radar signatures of wind turbines has serious national security implications, especially for offshore installations and wind farms in the vicinity of airports. Radar reflections from turbine blades can affect radar systems used in commercial and military installations, Air Defense Radars (ADRs) of E/F, I, J and K bands military assts, Phase modulated radar transmission with range resolution of 15 meters and 18 centimeters, Air Traffic Control (ATC) and air route radars, marine navigation and even weather monitoring and prediction (Wizelius 2007).
The rotor blades cause a Doppler problem and the nacelle and structural tower contribute to false plots.
The problem of wind farm’s cooperation with military radars is not a concern of the US, but of other countries. Thus, for example the UK`s Ministry in 2005 asserted that four wind farms off the cost of Britain interfere with the radar antennae line of sight, creating radar holes in areas under radar surveillance that prevent the detection of aircraft flying above these wind farms. (Kanter 2009).
Wind turbines have also led to the decrease in the radar sensitivity of civilian aircraft traffic control near airports.
The resulting radar hole is independent of the height of the aircraft, the height of the turbine or the height of the radar station.
Wind turbines also create a shadow beyond the wind farm so that low flying aircraft flying within this shadow go undetected.
The magnified shadow of the turbines blades and the moving rotors are visible on the radar screens of the weather and air traffic control radars.
Radar cross section, blade flash effect.
The rotating turbine blades fool the established radar techniques used to filter out all buildings, trees and other stationary objects. The fact that various blades can be picked out during the radar sweeps, banks of turbines is a confusing, creating mass on screens of military radars that may create difficulties in picking out the targets. Scientists worry that turbines cast a radar shadow behind them, in which planes of an enemy could be invisible, as current research indicates that it would last for only a few hundred meters and would hide only very small objects.
Wind turbines have a large Radar Cross Section (RCS) compared with the target aircraft making it difficult to detect the aircraft. The RS of a flying object is a measure of its detectability by radar. Commercial aircraft possess a large RCS, whilst stealth aircraft are designed to have a very low RCS. The RCS is dependent on the size of the object, the reflectivity of its surface and its shape.
A blade flash effect was also observed caused by intermittent rotation of the wind turbine rotor blades.
The ratio pf the RCS of wind turbines to that aircraft was unchanged outside a 74 km range limit. Therefore it was suggested that this limit be dropped in the siting guidelines of wind projects in line of sight of radar surveillance stations.
The RCS of studied wind turbines was 25 dB. square meters. However, it was found that some offshore wind farms can have RCS values 100 times larger.
The large RCS, in addition to the blade flash effect result in a loss of radar sensitivity. The causes of why the wind turbines have a large RCS are:
1. Material reflectivity:
Most wind turbines rotor blades are made of Glass Reinforced Plastic (GRP) that is 38 percent reflective to microwaves.
Wind turbines reflect radar signals because their carbon fiber or glass reinforced plastic blades are shot through with metal lightning conductors. It shows that they are picked up by the radar which is used for controlling air traffic and current systems cannot distinguish between flying airplanes and whirling turbines, creating serious safety concerns.
Specular reflection of the radar signals occurs off the leading edge of the rotor blade. The trailing edge has vibration absorbing foam that also reflects radar.
When the rotor blades are in their vertical position, leading as well as training edge radar flashes are produced.
2. Yaw and pitch effects:
The RCS value of a wind turbine depends on the yaw or overall orientation of the turbine as will as the blade pitch of the individual rotor blades.
3. Nacelle and tower:
The nacelle and the structural tower of wind turbines have a large RCS. The RCS of a cylindrical shape is quite large and is proportional to the square of its length.
4. Array configuration:
The spacing of the turbines in a wind farm affects the RCS. Even if a single turbine has a small RCS, tightly packed turbines present a large RCS (European Wind Energy Association 2009).