| 摘要 |
1,150,878. Electromechanical filters. CLEVITE CORP. 5 April, 1966 [19 April, 1965], No. 15185/66. Heading H3U. [Also in Division H1] A piezoelectric plate resonator of the type having a restricted electroded region (as described in Specification 1,147,881) is adjusted in frequency by applying to both the electroded and non-electroded regions a coating of high-Q insulative material. The invention may be applied to piezoelectric plates having two or more regions resonant at the same or at different frequencies and interconnected to form e.g. a T-section filter, as described in the abovementioned Specification. The coating may consist of silicon monoxide or an anodized metal such as aluminium or tantalum and the frequency is measured as the coating is applied e.g. by sputtering. The resonant frequency fa of the electroded region is lower than the resonant frequency fb of the surrounding region and the ratio fa/fb lies in the range 0À80000 to 0À99999 whereby wave propagation beyond the electroded region is minimized. |
