Surface Wave Reflection from Metal-Strips and Transducers

Abstract

Various contributions to the surface wave reflection, viz., piezo-shorting, mass and stress loading and electrical regeneration, are treated appropriately for the estimation of overall reflection from metallic strips and transducers. The effect of mass loading is studied for metal strips deposited on YZ LiNbO₃ and ST-X quartz substrates. A simple theory is developed which predicts zero reflection for an open aluminium strip and short gold strip on YZ LiNbO₃ for specific values of metallisation ratio. The theory also describes the reflection process in ordinary bi-directional and group type unidirectional transducers. Experimental results obtained on YZ LiNbO₃ substrate are in close agreement with the theoretical predictions. The theory may prove to be useful in the design of SAW transversal and resonator filters.

Indexing terms:

• Surface wave reflection
• SAW devices
• Metal strips
• Transducers
• GUDT