Measured radiation patterns of the scale model dipole tool

The sound field of finite dipole acoustic transducers in a steel tool was investigated and their horizontal by measuring their vertical radiation patterns in water at two different frequencies. Measurements were also made with the tool in scale models representative of sonic logging conditions in the field. A Lucite borehole model was used to represent a soft formation and an Austin Chalk borehole model was used to represent a hard formation. The presence of the tool as a finite baffle for the transducer, introduces differences between the vertical and horizontal radiation patterns. In contrast to the vertical pattern, the horizontal radiation pattern has a narrower main lobe with relatively larger side lobes. The angular location of the side lobes as seen in the water measurements, do not change much in the borehole.