A Pulsed Near-Field Technique for Measuring the Directional Characteristics of Acoustic Receivers

near-field plane-wave pulses can he used to produce a complementary uncertainty also can introduce in measurement of response pattern; i.e., response vs. frequency at a constant angle, as opposed to response vs. angle at a constant frequency. Directional am- the phase response, particularly in the megahertz freplitude and phase responses in the 1-10 MHz range have been obtained quency range [31, [51. Another possible inaccuracy is reusing this method for miniature ultrasonic hydrophones (sl mm di- lated to the effect of the temperature variations on the ameter). The pulsed waveforms measured by the hydrophone were dig- measurement of the directional phase response. More will itized and Fourier-transformed. Normalization with respect to the hydrophone’s on-axis response was accomplished by a simple spectral subtraction procedure. The angular and frequency resolutions of the technique are typically 0.25” and 100 kHz, respectively. From these data of measuring the plane-wave directivity pattern has been be said on these potential phase errors later. To eliminate these potential errors, an alternate method an effective hydrophone radius as a function of frequency can be computed more quickly and efficiently than would be possible using present practices.