In‐plane acoustic scattering measurements at NRL

The Naval Research Laboratory's pool facilities provide a unique capability for the investigation of underwater acoustic scattering and radiation phenomena. Scattering measurements are often preceded by calibration or test series, and the results presented here were obtained in a calibration performed with a solid aluminum sphere as a reference target. The source, receiver, and target center are coplanar in the measurements, and the data were acquired as the receiver was rotated a full 180° about the sphere; the data set thus includes scattering in the forward direction. The ka range of the results presented extends between 0.9 and 7.0 ka; here, ka is 2Πa/λ, where a is the sphere radius and λ is the sound wavelength in water. Specular reflection, the creeping wave, and the leaky‐Rayleigh surface wave are the mechanisms that produce the scattered field in this ka region. The data and theoretical predictions are displayed in a variety of ways to expose their functional dependence on angle and ka.