A permanently attached guided wave array for the constant monitoring of defects in plate‐like structures is designed and a prototype built. Employing the first antisymmetric Lamb wave mode A0, the condition of large areas can be monitored from a single position of the device with minimum power consumption, necessary for long term operation independent of external power sources. The performance of the piezoelectric transducer elements used for the excitation and measurement of the A0mode is studied. Preliminary measurement results on an aluminum plate containing a model defect are presented. © 2003 American Institute of Physics