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在设计相对通带△f/f_0<5·10~(-2)的窄带表声波滤波器时,应特别注意选择:滤波器的结构、抑制三次行程回波和体波假信号的方法、实现滤波器中心频率所必需的精度,以及考虑负载和各种不稳定因素对滤波器参数的影响。下面将根据这种窄带滤波器的设计特点来探讨上述每一个问题。滤波器的结构选择温度稳定性良好的ST切割的石英片(xyl/42°45′)是制造窄带滤波器导声体的主要材料。在给定中心频率时,滤波器通带的下限受下述各个因素的制约:大面积照相印刷
When designing the narrow passband acoustic filter with relative passband △ f / f_0 <5 · 10 ~ (-2), special attention should be paid to the choice of the structure of the filter, the method of suppressing the triple-pass echo and the body-wave spurious signal, The necessary accuracy of the filter center frequency, as well as the influence of the load and various instability factors on the filter parameters. The following will be based on the design characteristics of this narrow-band filter to explore each of the above problems. Filter Structure Selection ST-cut quartz plates (xyl / 42 ° 45 ’) with good temperature stability are the main materials used to make the narrow band filter. At a given center frequency, the lower limit of the filter passband is governed by various factors as follows: Large area photographic printing