title: Analysis of acoustic impedance matching in dual-band ultrasound transducers.
abstract: Dual-frequency band probes are needed for ultrasound (US) reverberation suppression and are useful for image-guided US therapy. A challenge is to design transducer stacks that achieve high bandwidth and efficiency at both operating frequencies when the frequencies are widely separated with a frequency ratio ∼6:1-20:1. This paper studies the loading and backing conditions of transducers in such stacks. Three stack configurations are presented and analyzed using one-dimensional models. It is shown that a configuration with three layers of material separating the transducers is favorable, as it reduces high frequency ringing by ∼20 dB compared to other designs, and matches the low frequency (LF) transducer to the load at a lower frequency. In some cases, the LF load matching is governed by a simple mass-spring interaction in spite of having a complicated matching structure. The proposed design should yield improved performance of reverberation suppression algorithms. Its suitability for reduction of probe heating, also in single-band probes, should be investigated.
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, P.O. Box 8905, N-7489 Trondheim, Norway.
authors.forename: Ola Finneng
authors.initials: OF
authors.lastname: Myhre
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, P.O. Box 8905, N-7489 Trondheim, Norway.
authors.forename: Tonni Franke
authors.initials: TF
authors.lastname: Johansen
authors.affiliation: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, P.O. Box 8905, N-7489 Trondheim, Norway.
authors.forename: Bjørn Atle
authors.initials: BA
authors.lastname: Johan Angelsen