Off-broadside mainbeam jammer suppression using soft constraint methods

A penalty function method (PFM) has been developed which maintains low-sidelobe levels and prevents jitter in linearly constrained minimum variance (LCMV) adapted beampatterns. A perceived drawback of this method was that for effective mainbeam jammer suppression a unique weighting matrix 'Z' has to be computed for every beam steering direction. We describe an alternative formulation of the original method (APFM). The performance of the two methods is assessed by considering their use in a mainbeam jammer scenario. It is shown how both methods can be extended to beams steered off-broadside with a concomitant, small increase in compuational load. Furthermore, we investigate alternative 'approximations' to the Z matrix. One of these approaches is shown to perform acceptably whilst reducing the computational load to that of the unsteered case.