Waveguide coupling of SAW resonators with different properties

In contrast to conventional transversely coupled resonator filters, waveguide coupling of two one-port resonators with different resonance frequencies is described. The different resonance frequencies are adjusted by different central finger gaps. Consequently, the equivalent fingers and reflecting strips of different resonators are shifted to each other and the waveguide modes are therefore no longer independent from each other. This effect is called mutual coupling of waveguide modes and requires a new type of modeling. The main characteristics of the new modeling method are described. The advantage of the design principle consists of a wider bandwidth without changing the waveguide parameters