| 摘要 |
A matched filter has an input IDT and an output IDT, and also has a device for preventing propagating surface acoustic waves from diverging. By preventing the divergence of surface acoustic waves, signals obtained in units of electrode finger pairs of the output IDT are uniformed. Furthermore, this application also discloses the following arrangement. That is, an arrangement for converging surface acoustic waves is adopted, and the width of surface acoustic waves input to the output IDT is set to be larger than at least the crossing width of electrode fingers, nearest to the input IDT, of those of the output IDT, so that some surface acoustic waves propagate along non-crossing portions of the electrode fingers, on the input IDT side, of those of the output IDT. With this arrangement, the influence of the crossing portions of the electrode fingers, closer to the input IDT, on the surface acoustic waves input to the crossing portions of the electrode fingers, farther from the input IDT, can be relaxed. <IMAGE> |
