Angle Estimation of Low-Elevation Signal Source Using LFM Signals with DUCA ST-MUSIC in Maritime EW Environments

In maritime electronic warfare environments, estimating the azimuth and elevation of a noncooperative signal source is challenging in the presence of sea surface multipaths. A single-layer UCA may exhibit elevation ambiguity and biased estimates owing to its planar geometry. This paper proposes a DUCA-ST-MUSIC-based method for stable direct-path angle estimation under multipath interference. The method extracts a time-frequency ridge to estimate linear frequency modulation (LFM) parameters, performs dechirp processing to map delay differences into beat tones for component separation, and applies ST-MUSIC using a space-time covariance matrix formed from DUCA observations to estimate the azimuth and elevation of the direct and multipath components. The simulations demonstrate improved estimation stability compared with conventional single-layer UCA-based processing.