Surface acoustic wave filter

摘要

A surface acoustic wave filter is freed from any loss arising from impedance mismatching by adopting optimum values achieving a widened band and lowered loss for the electrode widths of interdigital transducers (1, 2, 3) and reflector electrodes (4, 5). The surface acoustic wave filter includes interdigital transducers (1, 2, 3) and reflectors (4, 5) arranged on both sides of the transducer. The piezoelectric substrate has a ratio h/ lambda of an electrode thickness h to a surface acoustic wave wavelength lambda lying within the range of 0.05 </= h/ lambda </= 0.15 and has an electrode width ratio wr/pr of a reflector electrode width wr to an electrode pitch pr lying within the range of 0.5 </= wr/pr </= 0.6 and has an electrode width ratio wi/pi of an interdigital transducer interdigital electrode width wi to a pitch pi lying within the range of 0.6 </= wi/pi </= 0.9. <IMAGE>