Mid Sweden University

Unequal “directivity orders” between two figure8 directional microphones/hydrophones are proposed and analyzed in this paper for beamforming. Specifically, two figure 8 sensors here, possibly of different “directivity orders”, are (i) orthogonally oriented to facilitate spatial filtering in both the azimuth and the elevation, and (ii) spatially colocated with an isotropic sensor (thereby decoupling the incident source's azimuth-elevation-radial dimensions from the impinging signal's time-frequency dimensions). This versatility (in the sensors’ diverse “directivity orders”) contrasts with all prior open literature on beamforming using a colocated triad of possibly directional sensors. Instead, this paper analytically explores how unequal directivity orders between two perpendicularly colocated figure-8 acoustic sensors would affect the triad array's “spatial matched filter” beam steering. The resulting “actionable” insights show which directivity-order combinations allow the beam of full maneuverability toward any azimuthal direction, and which directivity-order combinations only partial maneuverability.