Surface wave filter with a specified transducer impulse train that reduces diffraction

摘要

A transversal SAW filter capable of reducing the effect of diffraction to achieve desired transmission characteristics without increasing the size of the surface wave substrate includes first and second IDTs arranged on a surface wave substrate so as to be spaced from each other by a predetermined distance. The first IDT has a plurality of impulses and the impulse in the 2n-th (n is a natural number) position counted from an impulse located at a maximum cross length in the 0-th position toward the second IDT has a magnitude which is equal to a magnitude of the (2n-1)-th impulse multiplied by -1.0.