Acoustic leaky-wave antennas (ALWAs) have demonstrated the capacity to steering directive sound waves in frequency-dependent directions, due to the inherent dispersive radiation characteristic of leaky modes. Compared to more conventional uniform linear array (ULA) acoustic traducers for electronic beam steering (which rely on multiple sensors), the ALWA allows for single microphone operation. Thus ALWAs offer a direct mechanism to scan a directive acoustic beam in the angular space by simply sweeping the operating frequency of the acoustic signal, which envisions cost-efficient single-transducer direction finders for SONAR applications.

In this paper we study for the first time, some important features of an ALWA for acoustic underwater Direction-of-Arrival (DoA) estimation applications. First, we study the DoA estimation resolution of a practical ALWA for the first time, following similar direction-finding techniques recently applied for low-cost frequency-scanned LWA radars. Also, we analyze the capacity to reduce the Side Lobe Level (SLL) for enhanced performance, demonstrating aperture tapering techniques to the ALWA for the first time. Besides, also the effect of non-stationary and broadband signals (sine-sweep) in the generation of the directive beams is analyzed, since rapid angular frequency-beam-scanning techniques request for switching among different frequency channels with short duration pulse, or alternatively fast FMCW (Frequency-Modulated Continuous Wave) chirp slopes. Finally, we study the possible non-linear effects (parametric effect) that may arise in the propagation of different frequencies beams with some deviation thereof, which can lead to the long-range propagation of narrow directive low-frequency beams.

All these aspects are of much interest for real applications of ALWA in innovative SONAR systems for underwater scenarios.