7. Conclusion

This article has shown the degrees of refinement available today in the modelling of guided elastic waves and the implementation of advanced numerical methods for the design and analysis of surface wave filters. We have not been able to go into exhaustive detail on all the models developed for this purpose, which suggests the abundant activity on the subject. Moreover, while the propagation models presented here are clearly very well developed and intensively used by researchers and engineers in the field, research activity continues unabated, with the aim now being to develop three-dimensional models capable of accurately accounting for transverse effects in transducers, but also for the guiding effects of connection buses, particularly used for laterally coupled surface wave filters, and the possibility of improving the confinement of volume waves on thin films by adding suitable structures...