Hermite and Laguerre beamspaces for ultra wide band antenna array

In this paper the use of 2-D Hermite-Gauss (HG) and Laguerre-Gauss (LG) expansions of the space-time signal delivered by an Ultra Wide Band (UWB) linear antenna array is outlined. Signatures of UWB incoming signals are confined within a finite rank signal subspace, parametrized by their direction of arrival (DOA), just as the steering vectors of narrowband array signals. Fast calculation of UWB DOA is allowed by polynomial rooting. To show the potential of this approach, the statistical performance of a Conditional Maximum Likelihood (CML) DOA estimator for a single UWB source in presence of spatially and temporally colored Gaussian noise is estimated with simulation trials. It results that, with a proper choice of the expansion parameters, accuracy approaches the Cramer-Rao bound.