Scattering-free subwavelength acoustic direction sensing via virtual acoustic resonance

Abstract

Conventional direction sensing relies on digital phase extraction after analog-to-digital conversion, which becomes computationally demanding as subwavelength phase differences shrink. Here, we introduce a virtual resonance approach that performs phase-to-amplitude transduction in the analog front-end before heavy digital post-processing. The mechanism is based on interference between symmetric and antisymmetric modes in conservatively coupled electronic resonators, enabling robust amplitude asymmetry from small phase gradients while preserving a scattering-free sensing field. Experimentally, a compact acoustic imaging system achieves high-fidelity direction-of-arrival estimation with a mean error of ∼2.5° at subwavelength spacing below λ/8.