General Discussion

Why OTH radars are sensitive

Over-the-horizon radars work very differently from conventional radars:
They operate in the high-frequency (HF) band (roughly 3–30 MHz).
They rely on surface-wave propagation along the ocean or ionospheric reflection to see hundreds or thousands of miles beyond line of sight.
They detect very weak Doppler signals from distant aircraft, ships, or missiles.
Because of this, they are unusually sensitive to large conductive objects near the sea surface.

How offshore wind turbines interfere
1. Strong radar clutter
Turbine towers and blades are excellent HF reflectors.
Rotating blades create Doppler shifts that look like moving targets.
Large wind farms can generate persistent “false returns.”

2. Masking of real targets

Clutter from turbines can hide or degrade detection of:
Low-flying aircraft
Cruise missiles
Surface vessels
This is especially serious for early-warning and maritime surveillance radars.

3. Surface-wave disruption

OTH surface-wave radars rely on smooth ocean propagation.
Turbine foundations disturb the electromagnetic boundary conditions along the sea surface.
Dense turbine fields can reduce signal coherence.

4. Multipath and phase distortion

Turbines create unpredictable reflections that:
Distort bearing accuracy
Reduce tracking reliability
Increase false alarms