| 摘要 |
PURPOSE:To enable to achieve sufficiently wide pass band, by devising the arrangement and opposing length of each electrode element constituting the transducer. CONSTITUTION:On the piezoelectric substrate 1, the transducer A having the electrodes EA1, EA2 respectively consisting of the electrode elements eA11, eA21 and the transducer B having the electrode EB1 consisting of the electrode elements eB11, 12, 11', and the electrode EB2 consisting of the elements eB21, 21' and 22' are located. Said electrode elements adjacent each other are located with the distance of lambda/2 (where lambda is the wave length of elastic surface wave). Further, the opposing length of the electrode elements is taken as shown in figure, so that the relations of 0.04R1<=R2<=0.2R1, where R1 and R2 are the opposing length. Thus, the band pass filter characteristics showing the double peak main lobe between the terminals TA1 and TA2 and the terminals TB1 and TB2, as shown in figure, can be obtained. |
