Contribution to the design of the wave filters composed from the elastically coupled two resonators structure

The large electromechanical coupling coefficient of langasite makes possible the production of monolithic filters with much wider bandwidth than are achievable on quartz. In this paper we present a new design method for eight-pole band-pass filter using an Y-cut langasite substrate. The computation of exact values of the inter-resonator coupling coefficient is performed by using the Tiersten's description of the monolithic structure. The results are compared with those deduced from the relation between coupling coefficient and dimensions of two-pole monolithic structure.