Simulation of short LSAW transducers including electrode massloading and finite finger resistance

The theory for a 2-D numerical analysis of acoustic wave generation from finite length LSAW transducer structures is presented. The massloading of the electrodes is incorporated through the use of the Finite Element Method (FEM). The substrate is modeled using both analytical and numerical means. The simulation is capable of extracting the individual bulk wave conductances from the overall conductance of a given device. Once the bulk wave conductances are calculated, the angular distribution of power radiated relative to the substrate surface can then be found. The simulation also includes the effect of finite electrode resistance through the use of a series equivalent resistance for each electrode in the structure. The paper will conclude by presenting simulation results for two separate freestanding transducers and a short transducer combined with a grating. The substrate materials used are 42⁰ LiTaO₃ and 64⁰ LiNbO₃ . The agreement between theory and experiment is shown