Direction finding for wideband signals using an interpolated array

The authors derive a novel direction finding algorithm for multiple wideband signals received by an arbitrary array, and analyze its performance. Using an interpolation technique, a set of virtual arrays is generated, each for a different frequency band, having the same array manifold. The covariance matrices of these arrays are added to produce a composite covariance matrix. Direction of arrival (DOA) estimates are obtained by eigendecomposition of this composite covariance matrix using the narrowband MUSIC algorithm or its variants. By choosing the virtual arrays to be linear and equally spaced the root-MUSIC algorithm can be applied to this problem. Closed form expressions for the asymptotic covariance matrix of the DOA estimation errors are derived using perturbation analysis.