| 摘要 |
PURPOSE:To reduce manufacture variations of the resonance frequency and center frequency of a filter, etc., by constituting a reflector for a surface elastic wave by selectively bonding an aluminum film on a substrate and by causing acoustic reflection of the surface elastic wave. CONSTITUTION:On lithium tantalate substrate 7, input-output transducers 8 are formed at a proper interval to permit a surface elastic wave to propagate and between input-output transducers 8, concave reflecting stripes 9 are provided by photoetching an aluminum film. Those stripes 9 are arranged at intervals one fourth surface elastic wavelength lambdaR while the repetitive intervals are a half lambdaR and three fourths only at the center part. While reflection at the end part of each stripe 9 is made possible by fixing the number of stripes 9, the reflector for surface waves is constituted to reduce manufacture variations of the resonance frequency and center frequency of the filter. |
