A method of tuning ultrasonic transducers by using the admittance of the transducer as the tuning parameter rather than the phase angle. The admittance magnitude of a transducer is not related to the phase angle and thus, using the admittance of the transducer as the tuning parameter allows tuning over...http://www.google.se/patents/US5431664?utm_source=gb-gplus-sharePatent US5431664 - Method of tuning ultrasonic devices
