Tunable resonant admittance on the basis of waveguide coupled SAW transducers

Waveguide interdigital transducers coupled transversely with a similar transducer, which is placed in a neighbouring acoustic channel and loaded by reactive circuit, is proposed for electrically tunable admittance. It´s shown that the system input conductance may have resonant shape with bandwidth far narrower than the transducer passband. By changing the external reactive load it is possible to retune the frequency of the resonant peak over an interval considerably lager than its bandwidth. The influence of internal reflections on admittance performances are analyzed taking into account possible radiation directivity. The proposed system may be used, for example, in tunable high-stable oscillators