Non-Ideal Radiators in Phased Array Transducers

Abstract

One dimensional arrays for medical acoustic imaging are a group of point radiators. The individual r adiators (transducer elements) are modeled as single mode, piston v ibrators w ith negligible cross-coupling. It is straightforward to calculate the acoustic beam response -- steering, focusing, and resolution -- from such a model. In real world arrays with high element density the situation becomes more complex. Cross-coupling between elements and multi-moding of the individual elements become the dominant problems. The beam response then departs from the ideal. This paper will discuss the sources of cross-coupling and explore suppression techniques. The mass-spring mode will be reviewed, and novel suppression techniques will be presented. Vibration modes in a single element will be explored, in particular, the relation between the non-ideal behavior of the array elements and the resulting beam response deficiencies.