| Popis: |
A new model describing the reflectivity of the transducer surface was developed. It decomposed the transducer reflection factor into an acoustic and electric component. The latter was dependent on the receive impedance whereas the former was not. This allowed us to determine a frequency dependent receive impedance function such that the reflectivity vanished. By this the problem of transducer reverberation noise would be eliminated. However, in order to be able to realize the impedance function with passive components, the real part had to be greater than zero. This turned out to be the case over a large interval in the interesting frequency band of the transducer. But though zero reflectivity is possible in theory, one has to seek for a compromise in a real situation since the frequency dependency of the optimum receive impedance was rather complicated. |
