| 摘要 |
PROBLEM TO BE SOLVED: To improve phase characteristics with wide band, low loss and ultra angular shape by reducing a propagation loss caused by propagation on an electrode by dividing distributed interdigital electrodes, using downward and upward distributed interdigital electrodes using grating thin films, into such a length as to obtain unidirectrionality and disposing these electrodes in parallel, in a surface acoustic wave function element including interdigital electrodes for exciting or receiving surface acoustic waves on the surface of a piezoelectric substrate or piezoelectric thin film substrate. SOLUTION: Disclosed are a filter wherein, as illustrated in Fig.2, a distributed interdigital electrode surface acoustic wave having unidirectrionality in the down direction on the surface of a piezoelectric substrate 1 and a distributed interdigital electrode having unidirectrionality in the up direction are divided into such a length as to obtain unidirectionality and made to oppose to each other; and a surface acoustic wave filter having sharp cutoff property by applying distance weighting. COPYRIGHT: (C)2008,JPO&INPIT
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