Sensitivity analysis of the Capon beamformer

A first-order analysis of the sensitivity of the Capon beamformer to look-direction errors which causes differences between the look-direction vector used by the Capon beamformer and the true look-direction vector is presented in this paper. Expressions for the sensitivity function of the beam pattern with respect to the said error are obtained and analysed by varying (i) number of sensors, (ii) source powers and (iii) location of the desired source. With the aid of these sensitivity functions, the effect of look-direction errors on the beam pattern and on SINR performance was studied and tested by simulation. This analysis assumes that the exact covariance matrix of array element outputs is known (the infinite data case).