Two dimensional periodic array of reflection centers on electrodes in SAW resonators

Periodic arrays of metallic patches on the electrodes of a “Rayleigh-type SAW resonator” are investigated to suppress undesired modes above resonance frequency. Both, the metallization ratio(η_t) and the period (P_L) of the patches in transversal direction, were varied. Simulations were performed employing the well established 2D P-matrix model. A well-designed periodic array is capable to suppress all transversal modes within the frequency band for ky = [0, π/p_T]. By evaluation of the overlap integral of the excitation and mode profile, and consequently, the analysis of the single mode contribution to the excitation strength, it is demonstrated that higher modes are responsible for remaining spurious peaks in the resonator´s frequency response. The analysis of the contribution of the transversal modes to the admittance provides insight how the Δν/ν waveguide, formed by the areas with and without patches, can be engineered to suppress bound and leaky continuum modes.