Wind turbine radar interference reduces coastal radar coverage

Estimated reading time: 5 minutes · Last updated: 27 September 2026

Interesting Engineering first reported that a Chinese study in Radio Engineering, released last month, found offshore wind farms can degrade shore-based vessel-tracking radars. The paper's authors measured an effective coverage drop of up to 6.9 percent at ranges of around 3 miles (5 km) and an increase in radar blind-spot area of roughly 14.9 percent. They attribute the effect to a combination of shadowing, clutter, multipath reflections, blade Doppler signatures and ghost returns that together make coastal radar pictures harder to interpret.

A wind turbine is itself a huge metal object, so it will inevitably interfere with radar signals.

Unnamed military expert to the South China Morning Post

How turbines alter coastal radar returns

Wind turbine structures and their rotating blades change the way radar energy behaves near the coast. A steel tower and long composite blades are significant radar reflectors: they can block direct paths (shadowing), scatter pulses into clutter, and create multiple return paths from sea surface reflections and adjacent structures.

Those multiple return paths can produce false echoes or 'ghosts' — apparent targets that do not exist at the indicated position — when radar energy bounces between a ship, a turbine and the water before returning to the receiver. Rotating blades also generate Doppler shifts that can resemble the velocity signatures of small craft, making discrimination harder for systems tuned to separate moving from stationary echoes.

Key phrase: shadowing, clutter, multipath reflections and blade Doppler signatures. This combination is why a coastal radar that works well in open water can struggle when a dense offshore array sits between the radar and local traffic.

What the Chinese study measured and where

The study, published in Radio Engineering, modelled and measured radar performance near offshore turbines and reported two headline effects: a fall in effective coverage of up to 6.9 percent at ranges of around 3 miles (5 km), and an increase in blind-spot area of about 14.9 percent. The authors framed the results in a marine-navigation context, emphasising small-craft detection and vessel tracking among dense turbine layouts.

Those numbers describe relative changes in the radar's detection envelope as modelled for the study scenarios; the paper does not, in the text supplied to us, name the study authors or give full field-trial datasets. The finding is notable because it quantifies impacts at a short, operational range where coastal radars are most relied on for port approaches, search-and-rescue and traffic monitoring.

Mitigation options engineers and authorities use

Mitigation is multi-pronged. The Radio Engineering paper's authors recommend responses such as smarter radar siting, use of infill radars to cover shadowed sectors, exclusion zones for shipping, and improved signal processing to filter blade clutter and multipath returns. Physical measures can include careful turbine layout planning to reduce coherent reflections into key radar bearings.

Design changes to turbines or blades and dedicated maritime surveillance radars with processing tuned for wind-farm environments are other options. The piece also quotes an unnamed military expert who observed that countries including the United States and United Kingdom have addressed these problems since around 2004, using a mix of the steps above rather than a single technical fix.

Implications for shipping safety and coastal planning

For civilian navigation the study's numbers matter because coastal radars are a redundancy and often the primary sensor in poor visibility or when AIS (automatic identification system) data are missing. A 6.9 percent reduction in effective coverage at about 3 miles (5 km) can shrink the window in which controllers or vessel crews detect and resolve close-in conflicts, and a 14.9 percent rise in blind spots concentrates that risk in particular bearings.

Planners face a trade-off: larger, denser wind farms deliver greater energy but change the electromagnetic environment. That pushes decisions into spatial planning, mandating radar-impact assessments before consenting developments and encouraging investment in countermeasures where navigation safety or security concerns are material.

Cases for and against wider alarm

The bottom line

The Radio Engineering study gives planners and operators quantifiable reasons to assess radar impacts where offshore wind is proposed or expanding. The headline numbers — a 6.9 percent drop in effective coverage at roughly 3 miles (5 km) and a 14.9 percent rise in blind-spot area — are a useful starting point, but they do not substitute for site-specific modelling and field trials. In practice, the choice is between accepting limited detection degradation and investing in mitigations such as infill radars, processing upgrades and layout changes; regulators and navigation authorities will need those local assessments before consenting large or dense arrays.

What to watch

• watch for an English abstract or full-text release of the Radio Engineering paper and the named authors; no date has been set.
• watch for guidance or formal radar-impact rules from coastal authorities or navies in jurisdictions planning large offshore arrays; no date has been set.
• watch for published field trials or vendor reports showing radar performance inside operating wind farms; no date has been set.