| 摘要 |
PURPOSE:To prevent the effect of bulk waves, by locating an output transducer in series with propagating direction of waves at a location other than the opposing region with an input transducer at one side of a multistrip coupler, in a multichannel filter. CONSTITUTION:A signal from a tuner is inputted to terminals 21, 22, generated 2 surface acoustic waves are converted for transmission line at a coupler 3 and converted into electric energy. The energy passes sequentially through transducers 4, 5. First, a signal including carrier chrominance signal CC, video carrier wave PC only passes through from the filter 4, the signals around audio carrier wave is attenuated, and a signal including SC and the PC only pass at the filter 5 to attenuate signals other than the PC. The filter characteristics can be determined by selecting the crossing width of reed screen electrode of each transducer and the pitch. With the location like this, since the bulk waves passing through the coupler 3 do not give any effect on the output transducer, a surface acoustic wave filter excellent for the frequency and spurious characteristics can be achieved. |
