Analysis of effect of non-ideal beam-space preprocessors on eigenspace DOA estimators

Analytical expressions for MUSIC DOA estimator variance and bias are used to study the effects of beam-space preprocessor matrix characteristics on beam-space MUSIC. It is shown that simultaneously steering to a desired sector while nulling another via the beamformer matrix in general degrades variance performance with respect to the performance achievable in beam-space. This the degradation is ascribed to the fact that as the null sector approaches the source sector of interest, the beamformer matrix range no longer contains both the span of the array response vectors within the source sector and their derivatives