Investigation of platinum based periodic gratings on langasite

While the understanding of the properties of gratings is essential for any SAW design, high temperature stable electrodes, which are generally made of heavy materials, are not easily accessible by simulation. We have therefore studied this type of electrodes both experimentally and by simulation. Motivated by the demands made by SAW gas sensors operating at high temperatures we opted for a combination of langasite as substrate material and platinum as metallization of the electrodes. Delay line designs with free propagation paths as well as open and shorted gratings were used to assess the velocity inside the grating and the reflection coefficient. The operation frequency and the height of the electrodes were varied in several production runs to vary the ratio of metallization/wavelength. The experimental results are compared with calculated values using different simulation methods.