Estimation of source separation with an array of arbitrary shape

Analytical expressions are obtained for the Cramer-Rao bound on average bearing and angular separation of two independent far-field sources radiating narrowband Gaussian noise. It is shown that all relevant features of array geometry are summarized by the conventional beam pattern function. For sources separated by less than the main lobe width of the beam pattern, the significant properties of the beam pattern are summarized by two simple geometrical factors. For small source separations lack of prior knowledge of source power levels seriously degrades performance