Improving antenna gain estimations in non-ideal test sites with auto-tunable filters

•Antenna calibration in non-ideal OATS is investigated.•Time gating can fail in low SNR conditions and other correction techniques can require many test runs.•We propose an auto-tunable signal processing structure based on adaptive filtering and time gating.•We propose a new fitness function for the PSO-based tuning mechanism.•Results show a reduction of the test duration and good performances in low SNR environments.