| 摘要 |
PURPOSE:To enable to obtain sufficiently broad passage band width, by taking care of the location and opposing length of each electrode element constituting the transducer. CONSTITUTION:On the piezoelectric substrate 1, the transducer A having the electrode EA1 consisting of the electrode EA1, and the electrode EA2 consisting of the electrode elements eA21, eA22, and the transducer B having the electrode EB1 consisting of the electrode elements eB10, 11, 11', 12, 12' and the electrode EB2 consisting of the electrode elements eB21, 21', 22, 22', are located. The electrode element adjacent is 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 R1, R2, R3 as shown in figure so that the relation of 0<R2<=R, and 0.03<=R3<= 0.375R1 can be obtained. Thus, as shown in figure, the band pass filter characteristics having the double peak type main lobe between the terminals TA1 and TA2 and between TB1 and TB2, can be obtained. |
