Electronically variable surface-acoustic-wave velocity and tunable SAW resonators

From measurements of shifts in the resonant frequency of SAW resonators, it has been observed that the SAW propagation velocity under an interdigital transducer varies continuously as a function of external resistive or capacitive loads. For Al on YZ LiNbO3 at 34 MHz, the velocity under a transducer can be varied over a 1.4% range. Resonators, using a transducer to control the cavity transit time, have been fabricated which are continuously tunable up to 60 kHz. Capacitances are found to be superior as tuning elements, owing to the severe degradation of the resonance caused by resistances.