Tunable Interdigital Transducer for Lamb Waves

Abstract : In this paper a novel concept of a tunable transducer for exciting and sensing Lamb waves is presented. The proposed transducer is an extension of the Interdigital Transducer (IDT), which main advantage is mode selectivity. In the proposed transducer, further referred to as the Tunable IDT (T-IDT), comb electrodes with fixed pitch are replaced by a series of densely distributed discrete electrodes. They can be easily interconnected in different configurations to match required wavelength, which makes possible matching to different wavelengths without a need of physical changes of the electrodesÕ layout. In order to verify the properties of the T-IDT, numerical simulations and experimental tests were performed and their results compared to the ones obtained with a traditional IDT. Both the numerical and experimental results show that the T-IDT generates beampatterns similar to those generated by the conventional IDT. The preliminary results presented in the paper prove that the proposed T-IDT can be easily tuned to various wave modes and show the performance similar to the one observed for the conventional IDT.