Diffraction simulation of SAW filters using SAW source distribution

A new approach for the simulation of the diffraction effect in Surface Acoustic Wave (SAW) filters based on the two dimensional Angular Spectrum of Wave method is proposed. In this simulation, the line source is considered as the particle displacement distribution inbetween the electrode finger's overlap region on the surface of the material which was conventionally treated as the uniform intensity line wave source. In this paper, we describe the derivation of the SAW source distribution from the particle displacement which is derived from the three dimensional Finite Element Method (FEM) applied to an IDT finger overlap in the grating structure. Then we apply the above SAW source distribution to the simulation of the frequency response of the SAW filter including the diffraction effect. The frequency dependency of the SAW source distribution will be also discussed. The diffraction simulation including the newly presented method along with the conventional method are compared with the experimental results.