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VOR - Very high frequency omnidirectional
range
DVOR - Doppler-VOR
Medium range classical enroute navaids
Problem:
The powerful wind generators today
can be in total as high as 100m, comprising a metallic tower shaft, a generator
case and the rotor blades (Fig. 1).
The VOR/DVOR have to be installed
often on non-ideal sites.
Increasingly often, new objects shall
be established in some distance to the VOR-site.
Today large farms of huge wind generators
are constructed.
The building restriction areas (BRA)
are merely applicable for this problem.
The wind direction determines the
azimuthal position of the rotor plane.
The scattering pattern of the rotating
blades creates a time variant distorting signal, creating additional frequency
sprectrum lines.
Observations:
The decisive navigational parameters
(azimuth/bearing angle, modulation incdices) may be affected.
Due to the time variant nature of
the distortions of the wind generators the effects are very difficult and
costly to measure.
The analysis of this electromagnetic
problem have to be combined with system analysis
The ground can create a problematic
elevation pattern with distinct minima depending on the height of counterpoise,
in particular if located on top of a mountain.
The distortions by objects for a
VOR/DVOR are known to be a maximum in these elevation minima.
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