| 摘要 |
PURPOSE:To improve the asymmetricity of a frequency characteristic by changing an electrode pitch of an interdigital transducer IDT depending on the acoustic reflection weight. CONSTITUTION:The propagation speed of a surface wave of an electrode finger 3 subjected to acoustic reflection weighting depends only on the rate of the electrode to the width of the air gap. Thus, the electrode pitch of the transducer is decided depending on the acoustic reflection weight at the location. In a transducer, for example, whose acoustic weighting is distributed as a triangle, the electrode pitch having much acoustic reflection weighting is decreased more than the electrode pitch having the less electrode pitch.
|
