| 摘要 |
PURPOSE:To improve band-stopping characteristics and also to minimize the variation of the band-stopping characteristics due to variance of manufacture, by setting the ratio of the electrode width to the electrode pitch of a metal strip reflector formed on a piezoelectric substrate to 20-40%. CONSTITUTION:On piezoelectric substrate 1, the metal strip reflector of grating structure consisting of electrode fingers 5 is formed. Then, duty factor alpha=l/w, the ratio of width (l) of electrode fingers 2 of the metal strip reflector to pitch (w) of the electrode fingers is set to 20-40%. Thus, selecting the duty factor increases damping factor (beta) and specific band width DELTAf/f0, so that stopping characteristics will greatly improve. |
