Herein we extract all the frequency-dependent coupling-of-modes (COM) parameters, which will be used to the rapid simulation and optimal design of surface acoustic wave (SAW) devices. FEM/BEM is used to calculate the exact field distributions of forward and backward surface acoustic waves within a finite-length periodic grating at every frequency. The middle component of the grating, regarded as a periodic structure, is selected to be investigated which can satisfy the presupposition of the COM model. From these field distributions, the values of P-matrix elements of one cell are calculated. The COM parameters taken as functions of frequency are accurately obtained. Specifically, the frequency-dependent relationships of reflection coefficient and propagation velocity are obtained independently. Using the resultant COM parameters, a one-port resonator on the substrate of 128oYX-LiNbO 3 is simulated and the admittance curve shows good agreement with the simulating results using FEM/BEM. These results verify the validity and accuracy of this method.
