Surface acoustic wave filter, high frequency module, and multiplexer

A longitudinally coupled surface acoustic wave filter comprising:

• a plurality of resonators continuously disposed in a propagation direction of a surface acoustic wave, each of the plurality of resonators including a pair of comb-shaped electrodes each including a busbar electrode, and a plurality of electrode fingers connected to the busbar electrode and disposed parallel or substantially parallel to each other;
• wherein
• the pair of comb-shaped electrodes are disposed such that the plurality of electrode fingers in each of the pair of comb-shaped electrodes are alternately provided in the propagation direction of the surface acoustic wave;
• of the plurality of resonators, a first resonator connected to an output terminal of the surface acoustic wave filter includes four or more regions with different pitches of the electrode fingers, and in each of the four or more regions, the pitch of the electrode fingers is constant;
• of the four or more regions, a pair of first regions disposed at both ends of the resonator in the propagation direction of the surface acoustic wave have a smaller pitch of the electrode fingers than the pitch of the electrode fingers in the regions other than the pair of first regions;
• and
• the pitch of the electrode fingers in a second region adjacent to one of the pair of first regions is different from the pitch of the electrode fingers in a third region adjacent to another one of the pair of first regions.