USING 3-D UNITARY ESPRIT ON A HEXAGONAL SHAPED ESPAR ANTENNA FOR 1-D AND 2-D DOA ESTIMATION

In this work we discuss the problem of direction of arrival qwestimation with a regular-hexagonal shaped 7-element ESPAR (electronically steerable parasitic antenna radiator) array which has been studied in recent publications. In order to exploit symmetries and invariances of the hexagonal shape we define three spatial frequencies instead of one. Estimates for these spatial frequencies can be found using a 3-dimensional version of the Unitary ESPRIT algorithm, which has not been applied to an antenna array on a hexagonal grid before. This algorithm enables us to find estimates for 1-D directions of arrival (i.e., the azimuth angles) or 2-D directions of arrival (i.e., the azimuth and the elevation angles). Automatic pairing of these angles will be ensured by means of the Simultaneous Schur decomposition as a final step in the estimation procedure. After giving details on how to obtain estimates for the spatial frequencies from the observed array output, we discuss various ways how these estimates can be combined efficiently to obtain the direction of arrival angles. Where applicable, results are supported by computer simulations.