  This study presents a tunable phase-modulated metasurface composed of
periodically distributed piezoelectric patches with resonant-type shunt
circuits. The fully coupled electromechanical model is established to study the
transmission characteristics of the metasurface unit and validated through
numerical and experimental studies. Based on the analysis of the metasurface
unit, we first explore the performance of electroelastic metasurface with
single-resonant shunts and then extend its capability with multi-resonant
shunts. By only tuning the electric loads in the shunt circuits, we utilize the
proposed metasurface to accomplish wave deflection and wave focusing of A0 mode
Lamb waves at different angles and focal points, respectively.
