| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave filter which does not have a loss by mismatched impedance by finding an optimum electrode width of a reflector electrode for realizing wide band and small insertion loss an interdigital transducer. SOLUTION: This surface acoustic wave filter where a comb-shaped electrode is formed on a surface acoustic wave base has the interdigital transducer and reflectors arranged at both sides of the interdigital transducer. In the surface acoustic wave base, the radio h/λof the wavelengthλof a surface acoustic wave to an electrode film thickness (h) is within the range of 0.05<=h/λ<=0.15, the electrode width radio wr/pr of the electrode width wr of the reflectors to an electrode pitch pr is within the range of 0.5<=wr/pr<=0.6, and the electrode width ratio wi/pi of the electrode width wi of the comb-shaped electrode of the interdigital transducer to its pitch pi is also within the range of 0.6<=wi/pi<=0.9.
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