SURFACE WAVE FILTER ELEMENT

摘要

PURPOSE:To reduce the effect of reflected wave generated at an electrode and enhance the frequency characteristics, by forming a minute unevenness at the side edge part of at least the cross part of the electrodes. CONSTITUTION:The frequency characteristics of a surface wave filter is decided by the weighted part of electrodes 11 and 12 crossing each other in a comb-teeth shape, i.e. at the cross part of comb-teeth electrodes 11 and 12. Then an unevenness of about several mu is formed at the side edge parts 13 and 14 of electrodes 11 and 12 at the above-mentioned cross part. For a surface filter having such electrodes 11 and 12, an unevenness is formed at the parts 13 and 14 of electrodes 11 and 12 at the weighted part for the surface wave propagating on the surface of substrate in a working mode. Thus the surface wave has an irregular reflection at the uneven area to be attenuated. As a result, the level of reflection is reduced at electrodes 11 and 12 to enhance the frequency characteristics.