LCMV and GSC Algorithms with Low-Sidelobe Pattern Control

In this paper, the Linearly Constrained Minimum Variance (LCMV) method is considered as a way for combining deterministic nulling and adaptive nulling. Two methods are considered for including tapering for sidelohe control. One method modifies the constraint matrix with the tapered-steering vector and the other adds the tapered-steering vector in the constraint matrix. The designed algorithms have the salient features of achieving both deterministic nulling and adaptive nulling with low sidelobes in both the quiescent antenna pattern as well as in the adaptive antenna pattern, while also maintaining unity gain in the beam-look direction. In addition, two beamspace implementation schemes are discussed: one scheme involves performing adaptive nulling on the main-beam and clutter beams followed by optimal beam-combination. The second scheme consists of a generalized sidelobe canceller (GSC) in beam space, where the main-beam as well as the jammer beams include the deterministic clutter nulls.