Analysis of excitation and propagation characteristics of leaky modes in SAW waveguides

In this paper, we propose a method of analyzing the excitation and detection of leaky modes in a surface acoustic wave (SAW) waveguide structure. These properties could not be directly evaluated by the conventional scalar potential theory and mode expansion. In the present theory, the SAW excitation and detection are taken into account in the scalar potential theory, and then the SAW signal transfer between input and output ports is estimated in a form of the Fourier transform in the wavenumber domain. Finally, the contribution of each mode is estimated by the residue theorem. This method is effective in estimating the contribution of complete spectra, including leaky modes as well as non-leaky guided modes.