title: Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays.
abstract: For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed). In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.
authors.affiliation: Department of Electrical, Electronic, Telecommunications Engineering, and Naval Architecture (DITEN), University of Genoa, 5-16126 Genova, Italy. andrea.trucco@unige.it.|Pattern Analysis & Computer Vision (PAVIS), Istituto Italiano di Tecnologia (IIT), 30.16163 Genova, Italy. andrea.trucco@unige.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Trucco
authors.affiliation: Department of Electrical, Electronic, Telecommunications Engineering, and Naval Architecture (DITEN), University of Genoa, 5-16126 Genova, Italy. federico.traverso@ginevra.dibe.unige.it.
authors.forename: Federico
authors.initials: F
authors.lastname: Traverso
authors.affiliation: Pattern Analysis & Computer Vision (PAVIS), Istituto Italiano di Tecnologia (IIT), 30.16163 Genova, Italy. marco.crocco@iit.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Crocco
keywords: beamforming; end-fire arrays; maximum directivity; microphone and hydrophone arrays; oversteering; white noise gain