Ultrasonic waveguide with square wave surface grating.

The effect of spatial harmonics of a square-wave surface grating on the multiband frequency response of ultrasonic SH waves in an elastic plate is investigated. Stopbands are found to occur under simultaneous occurrence of first-order and higher-order Bragg resonances together with co-directional and/or contra-directional mode coupling conditions. The odd harmonic nature of the structure causes stopbands to appear above the cutoff frequencies of the odd-numbered modes.