Abstract: A surface acoustic wave filter includes a longitudinal mode resonator type first filter portion, a longitudinal mode resonator type second filter portion, an input terminal, and an output terminal. Assuming a wavelength of a frequency propagating through the first filter portion is defined as ?, a distance between a center of a width of an electrode finger closest to the output side IDT electrode and a center of a width of an electrode finger closest to the input side IDT electrode is equal to or more than 0.57?. The electrode finger closest to the output side IDT electrode is closest among electrode fingers that constitute the input side IDT electrode and are arranged in the propagation direction, and the electrode finger closest to the input side IDT electrode is closest among electrode fingers that constitute the output side IDT electrode and are arranged in the propagation direction.

Abstract: An elastic wave filter includes a piezoelectric substrate, an input side IDT electrode, an output side IDT electrode, and a reflector. At least one IDT electrode among the input side IDT electrode and the output side IDT electrode is weighted only with a main lobe among an apodized weighting method such that the intersection length becomes short from a part at which one electrode finger is opposed to another electrode finger adjacent to the one electrode finger toward an end portion of the at least one IDT electrode in a propagation direction of an elastic wave. A part with the largest intersection length in the at least one IDT electrode is shifted to any one of one side and another side in the propagation direction of the elastic wave from a center position at the at least one IDT electrode in the propagation direction of the elastic wave.

Abstract: An elastic wave filter includes a piezoelectric substrate, an input side IDT electrode, an output side IDT electrode, and a reflector. At least one IDT electrode among the input side IDT electrode and the output side IDT electrode is weighted only with a main lobe among an apodized weighting method such that the intersection length becomes short from a part at which one electrode finger is opposed to another electrode finger adjacent to the one electrode finger toward an end portion of the at least one IDT electrode in a propagation direction of an elastic wave. A part with the largest intersection length in the at least one IDT electrode is shifted to any one of one side and another side in the propagation direction of the elastic wave from a center position at the at least one IDT electrode in the propagation direction of the elastic wave.

Abstract: In an elastic wave device including an input side electrode and an output side electrode being a resonant single-phase unidirectional transducers (RSPUDT) provided with respective pairs of bus bars opposing to each other on a piezoelectric substrate and a number of excitation electrode fingers extending in a comb-teeth shape so as to respectively cross each other from the respective bus bars, the elastic waves are repeatedly reflected and amplified between the central part of the input side electrode and the central part of the output side electrode along the direction of extension of the respective bus bars by the excitation electrode fingers of the input side electrode and the output side excitation electrode, the elastic wave device includes a damper at least on either one of the input side bus bar or the output side bus bar in an area between the central part of the input side electrode in the direction of movement of the elastic waves and the central part of the output side electrode in the direction of

Abstract: In an elastic wave device including an input side electrode and an output side electrode being a resonant single-phase unidirectional transducers (RSPUDT) provided with respective pairs of bus bars opposing to each other on a piezoelectric substrate and a number of excitation electrode fingers extending in a comb-teeth shape so as to respectively cross each other from the respective bus bars, the elastic waves are repeatedly reflected and amplified between the central part of the input side electrode and the central part of the output side electrode along the direction of extension of the respective bus bars by the excitation electrode fingers of the input side electrode and the output side excitation electrode, the elastic wave device includes a damper at least on either one of the input side bus bar or the output side bus bar in an area between the central part of the input side electrode in the direction of movement of the elastic waves and the central part of the output side electrode in the direction of

Abstract: The inside-band characteristic of an internal reflection type unidirectional surface acoustic wave filter is improved by using an internal reflection type unidirectional surface acoustic wave filter having positive and negative finger electrodes (10, 11) of the interdigital transducer and having open or short-circuit type floating electrodes (12) therebetween. The finger electrodes are subjected to weighting by a withdrawal technique and the filter is structured such that at portions wherein no electrical cross is made between the positive and negative finger electrodes, i.e., in case where adjacent finger electrodes each have the same sign as that of the positive finger electrode or negative finger electrode, the floating electrodes (13) located therebetween are not displaced from the center positions therebetween.