Adaptive Beam-Forming Algorithms for Active Array Sensors: an enabling capability for cognitive radars

Cognitive Radar (CR) is a new paradigm to design the next radar generation in accordance to criterions inspired to mental abilities related to knowledge. This approach is thought to dramatically improve the current generation of systems as it leverages the adaptivity of the sensor to the changing environments in which radars operate. The sections that follow illustrate how the Digital Array Radar (DAR) and advanced digital signal processing might be the enabling system architecture and technologies to implement a CR. In this regard, Adaptive Beam Forming (ABF) algorithms, which adaptively suppress possible interferences impinging on the array antenna, are one of the key features CR should possess to minimize the jammers and maximize the performances. Possible implementations of two ABF architectures and three algorithms are analyzed, and their performances evaluated in the case of analogue inter-channel receiver mismatch present among the receivers. In greater detail, two algorithms leveraging the DAR architecture are analyzed and their performances evaluated against the analogue formed beams approach that was used in the previous generation of radar sensors. The performances of the three algorithms are assessed as far as cancellation capability of both main beam jammer and sidelobe jammer is concerned, in presence of inter-channel phase and amplitude mismatches among the analogue receivers.