Deep-sea acoustic shadow-zone ensonification using a phased array and glider-based passive reception

Continuous wide-area detection and communication are vital for deep-sea applications. However, deep-sea acoustic shadow zones cause significant energy attenuation, severely limiting the effective coverage of underwater acoustic systems. Phased array emission combined with bottom reflection exhibits the potential to achieve acoustic shadow-zone ensonification; however, systematic experimental validation remains limited, and observational capabilities for large-scale acoustic field characterization are constrained. To address these issues, this paper conducts a theoretical analysis and sea trial verification of the phased array emission sound field, proposing a wide-area observation method utilizing an underwater glider as a passive reception platform. In a deep-sea experiment conducted in the South China Sea at a depth of approximately 4310 m, shadow-zone ensonification within a horizontal range of 14.5-32.5 km and a depth interval of 58-889 m was achieved and experimentally verified by steering the phased array emission angle. Experimental results indicate a distinct negative correlation between the optimal phased array emission angle and the acoustic energy focusing distance; simultaneously, an acoustic energy gain of approximately 30 dB was achieved at a near-field range of 14.5 km, and an energy enhancement exceeding 14 dB was maintained in far-field and greater-depth regions.