| 摘要 |
PURPOSE:To suppress a bulk wave and to keep the amplitude and group delay characteristics in excellent ways, by specifying the coating part of a sound absorbing agent. CONSTITUTION:Both ends of excitation effective parts of a comb-tooth electrode of an excitation electrode 2 at the remotest position from a reception electrode 3 are taken respectively as points (a) and (b). Further, both ends of reception effective parts of the comb-tooth electrode at the nearest position to the electrode 2 of the reception electrode 3 are taken as points (c) and (d). The sound absorbing agent 12 is applied on a piezoelectric base 1 and the electrode 2 along the sides of a trapezoid region 13, not on the region 13 formed by tying the points (a-d). In the surface acoustic wave element, a surface acoustic wave is excited, irradiated and propagated on the piezoelectric base 1 from the electrode 2 by an input signal and converted into an output signal at the reception electrode 3, and the output signal having the desired band characteristics in accordance with the weighting of the electrode 2, for example, is obtained. |
