| 摘要 |
PURPOSE:To enable channel selection differing in frequency interval by proviing a reflector, which stops the propagation of a elastic surface wave within a specific frequency range, on a elastic surface wave propagation line between two interdigital transducers on a substrate. CONSTITUTION:Inter digital transducers IDT3 and IDT4 that output a elastic surface wave as an electric signal of maximum amplitude at intervals of a constant frequency, e.g. 2MHz, are provided and between the two, grating reflector 7 that reflects a signal in a specific frequency range is provided. The center frequency of reflection characteristics of this reflector 7 is set between 4 channel and 5 channel and its reflection band width to about 4MHz. Therefore, a surface elastic wave propagating from IDT2 reaches output IDT3, but never reaches output IDT4. Thus, the channel selection differing in frequency interval can be made. |
