In a long-awaited study that was released last week, the Department of Defense said its tests have shown that large wind farms degrade the effectiveness of military radar if they are located within the line of sight of the installation. However, Air Traffic Control radar systems used by the FAA are much less prone to such interference. According the report, "ATC radars can rely on both primary radar returns and [transponder] returns to ensure safe airspace operations. ... The presence of a wind farm does not appear to significantly affect the performance of [those] systems." However, the report notes that decisions about wind-farm impacts on ATC radar are up to the FAA.
This is a companion discussion topic for the original entry at https://www.avweb.com/briefs/dod-wind-farms-impact-on-atc-radar-minimal