| 摘要 |
PURPOSE:To make a response only in a single frequency band by providing plural composite resonance elements on a substrate, and connecting mutually those resonance frequency which are so set as to the same resonance frequency with a different-degree overtone. CONSTITUTION:Electrodes 17 and 18 for excitation are formed on the substrate 11 and further a voltage thin film 13 and an electrode 19 for excitation are provided. An additive material is formed at one of facing parts 21 and 22 of the electrodes. When a high frequency voltage is impressed between terminals 15 and 16, areas 21 and 22 operate as a thickness-mode composite resonator to obtain a serial connection of two resonators viewed from between the terminals 15 and 16. The resonance frequency of an N-order overtone is set equal to necessary to in the area 21, and the thickness of the additive material 23 is nearly equlized to the half wave of an elastic wave of frequency (fo) to make the resonance frequency of an (N+1)-order overtone to (fo). Spurious frequencies are mutually different in both areas 21, so a response is obtained almost at only common frequency, i.e. resonance frequency (fo). |
