A study of the resolvability of vector-sensor array in direction-of-arrival estimation

We first study a theorem on the relationship among linear dependence of steering vectors, correlation among signals, and the number of signals whose DOAs are uniquely determinable, derived by Wax et al. (1989) and Nehorai et al. (see Signal Proc., vol.10, no.3, p.327-342, 1991) for a class of scalar-sensor arrays. We then extend the theorem to include all scalar-sensor arrays, as well as vector-sensor arrays. Subsequently, we show that the DOAs of 2 uncorrelated signals can be uniquely determined with one electromagnetic vector sensor. However, it may be impossible to determine uniquely the DOAs of 2 fully correlated signals. Finally, we establish a relationship between uniqueness in measurements and uniqueness in MUSIC estimates, and conduct DOA estimation experiments using MUSIC to gain a feel of the reliability of our theoretical prediction