The IDT with high internal reflection suppression

Based on Chen-Haus' theory 1, a detailed experimental research on the reflection characteristic of SAW from a short-circuited Au-strip grating on YZ-LiNbO₃ and a short-circuited Al-recessed groove on ST-X quartz is first presented in this paper where an anomalous reflection phenomena existing in the two grating are confirmed. In addition, a residual reflection which couldn't be completely cancelled by means of changing strip-thickness is pointed out for a short-circuited Au-strip grating both experimentally and theoretically through extending Chen-Haus' theory to anisotropic crystals.
Finally, two kinds of IDT composed of single electrodes (Au-single-electrode on YZ LiNbO₃ and Al-recessed-groove-single-electrode on ST-X quartz) are proposed for high internal reflection suppression. The experimental results of bandpass filters constructed with the IDTs mentioned above show a great improvement in passband distortion and a potential usefulness of new structure in high frequency range.