Direction of arrival estimation in uniform circular arrays composed of directional elements

We address the problem of estimating the azimuth and elevation angles of multiple far-field signals in uniform circular arrays (UCAs) composed of identical sensor elements. Unlike previous search-free approaches, which strongly rely on the omni-directional element assumption, in this paper the element pattern is modelled as direction dependent. A new computationally efficient eigenstructure-based estimation method, revered to as the UCA-RARE algorithm operating in beamspace is developed. The algorithm allows to estimates the azimuth parameters of the source directions decoupled from the elevation parameters without employing exact knowledge of the element pattern in a search-free procedure. The corresponding elevation angles are estimated in a subsequent step using a closed-form algorithm.