| 摘要 |
PURPOSE:To obtain desired filter characteristics by specifying the structure of interdigital electrodes, and eliminating a discontinuation point. CONSTITUTION:On a piezoelectric medium 1, transmission-side weighted reed screen type electrode fingers 10 and 11 and reception-side reed screen type electrode fingers 15 and 16 are formed respectively. Floating intermediate electrode fingers (floating electrode finger) 14 are provided between the transmission-side electrode fingers 10 and 11. Those electrode fingers are disconnected from electric signal input parts 17 and 18 and the length is set equal to intersection width. Those floating electrode fingers 14 are provided to eliminate the generation of a discontinuation point, thereby obtaining filter characteristics with fidelity. Thus, the desired filter characteristics are obtained. |
