Unambiguous Target Localization and Tracking for Distributed Coherent Aperture Radar via Cognitive Beamforming

In this paper, a cognitive transmit frequency allocation approach is proposed for unambiguous target tracking in distributed coherent aperture radar (DCAR). A crucial issue for DCAR is that the ultra-long spacing among each unit radar will generate severe grating lobes (GLs), which will deteriorate the detection performance considerably. It is shown that the locations of GLs are determined by the transmit signal frequency. In the proposed approach, the transmit signal frequency and beam steering are sequentially decided through history observations to overcome the ambiguity. Cost function is adopted as the optimization metric. Simulation results illustrates that the proposed method is able to automatically focus the beampattern toward the target direction unambiguously.