ABSTRACT
As known, perturbing transverse modes arising from the
waveguide properties of the interdigital transducers and reflectors can
appear in SAW resonator filters. Usually, these undesired modes are
suppressed by transducer apodization. This method has the disadvantage
of increasing the transducer impedance. We propose a longitudinally
coupled resonator filter, the basic elements of which are able to guide
the two slowest waveguide modes alone, but to excite and receive the
first mode only. The basic elements are arranged side by side forming
the co