Underwater Backscatter Array with Phase Compensation for AUV Localization

To address the challenge of low-power underwater communication, this paper proposes an underwater backscatter array with phase compensation for Autonomous Underwater Vehicle (AUV) positioning. The array is designed to be deployed on the seafloor, forming a passive, energy-efficient localization network similar to a Long Baseline (LBL) system. This network supports AUV navigation, path optimization, and mission decision. Since backscatter communication requires the transducers of the array elements to operate near the resonant frequency, it is difficult to set the array element spacing to less than half a wavelength. Based on the theory of Differential Backscatter Wave (DBW), changes in the electrical load impedance of the transducer alter both the amplitude and phase of the DBW. It is proposed to compensate for the phase difference caused by the array element spacing by adjusting the electrical load impedance of the array elements. Finite element and numerical simulations demonstrate that the proposed phase-compensated array can increase the amplitude of Total Differential Backscatter Wave (TDBW) by up to 198%. Furthermore, it is also proved that when the vehicle is navigating at a fixed depth, the designed array has a significant amplitude improvement compared with single transducer solution.