SURFACE ACOUSTIC WAVE FILTER ELEMENT

PURPOSE:To obtain an input electrode while prevents an unnecessary wave of a thickness sliding wave and controls electrostatic capacity, by providing a couple of bus electrodes which connect comb tooth parts successively along envelopes, and also providing electrode capacity control parts outside the bus electrodes. CONSTITUTION:On one main surface of a piezoelectric substrate 21, input electrodes 22 and 23 whose comb tooth parts 221 and 231 are weighted to partially have an intersection part along a couple a envelopes 241 and 242, and output electrodes 26 and 27 are provided. From the side of the shield electrode 25 of the envelopes 241 and 242 to the maximum intersection width position of main loops 241a and 242a, bus electrodes 30 and 31 connecting comb tooth parts 222 and 232 successively along the envelopes are provided, comb tooth parts 222 and 232 other than the bus electrodes 30 and 31 are disconnected, and dummy electrodes are formed in conductive contact with an earth electrode 32. Then, comb tooth parts 223 and 233 at the outside of the envelope extending from the circumference of said maximum intersection width part in a sound absorbing layer direction are used as electrode capacity control parts.