Measurement and FEM/BEM simulation of transverse effects in SAW resonators in lithium tantalate

It is well known than transverse effects like radiation in busbars are an important contribution in the loss of Leaky SAW resonators. Due to the complex nature of the wave and to the presence of several modes, scalar models are not sufficient to predict these effects. It is also known that the electrode gap has a strong impact on these effects. A periodic FEM/BEM model is presented and used to simulate the effect of the gap. Test devices are measured and compared with the simulation with a good agreement. The results show that smaller gaps are favorable.