Diffraction analysis in surface acoustic wave devices using Green's function

There are many second order effects to be considered in a high performance surface acoustic wave filter design. Most of them have been solved,except t he diffraction effect. There are many studies on the diffraction by parabol a approximation or the angular spectrum method. However, these are not accu rate enough and, moreover, they did not include the distorted distribution of the electric charge at the linger ends. We use Green's function to analy ze the effect of the filter. The method we use is a two-dimensional analysi s,different from Milsom's work, which is limited to one dimension. We first calculate the charge distribution of the transducer based on the quasi-sta tic approximation by two-dimensional Green's function analysis,then calcula te the acoustic and electronic field by the charge distribution. Based on o ur work, can derive the frequency response of a narrow band filter. The fin ger end effect and diffraction are significant in the case of interdigital transducer with many small apertures weighting.