| 摘 要： | A variational expression of angular frequency,ω~2,is introduced for surface acoustic waves propagatingon both free and metallized surfaces of piezoelectric crystals.By this expression an analytical solution for SAWelectromechanical coupling coefficient.K~2,can be established as a function of material constants.Comparisonof variational evaluations of K~2 with the exact data obtained by computer shows the applicability of thissolution as a guidance for estimation of K~2.Furthermore this expression is applied to analyse the reflection ofSAW through a short-circuited metal strip grating.The treatment is greatiy simplifed with the aid ofcoupling-of-mode theory and the reflectivity of a single strip within the grating is found as a function ofmaterial constants and strip geometric paramters in closed form.An extraordinary reflection,the increase ofreflectivity with the decrease of metal strip thickness,is predicted for some special configuration of substrateand metal film.
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