SURFACE ACOUSTIC WAVE FILTER AND CONVERTER USED FOR IT

摘要

PROBLEM TO BE SOLVED: To allow the surface acoustic wave filter to satisfy a desired insertion loss while keeping a desired required band width. SOLUTION: A reflection section 3 is made up of a plurality of electrode fingers 10 connecting electrically to a negative electrode 5 and up of floating electrodes 11 placed among a plurality of the electrode fingers 10. The electrode fingers 10 are formed periodically at a pitch ofλ/2, and the electrode finger 12 of each floating electrode 11 is offset byλ/12 from a center position between the electrode fingers 12 adjacent to the electrode 11 in a propagation direction of a surface acoustic wave or in the opposite direction so as to enhance more the unidirectionallity based on the asymmetrical structure and to reduce remarkably an insertion loss.