Finite element simulation of saw delay line operating with the use of third harmonic frequency

A numerical practical approach for a simulation of surface acoustic wave delay line is proposed. The principle of operation of transducers with split electrodes at frequency harmonics is shown. Practical recommendations and calculation algorithm in COMSOL Multiphysics are considered. Admittance parameters were calculated from simulations of delay line employing COMSOL software. Finally, obtained Y-parameters were converted into a full set of S-parameters. The numerical approach makes it possible to accurately model the SAW device using the universal finite element method with automatic inclusion of second-order effects in the device. To demonstrate the finite element method, the frequency response for 1.5 GHz SAW delay line with a relative bandwidth of 7.46 % on 128$^{\circ}$ YX-cut LiNbO$_3$ are calculated. Input interdigital transducer operates at main frequency, output transducer operates at the third harmonic frequency. The simulation results are in good agreement with the experimental data.