ANGULAR RESPONSE OF PIEZOELECTRIC ELEMENTS IN PHASED ARRAY ULTRASOUND SCANNERS.
In the design of phased linear array sector scanners for medical applications, it is important to preserve uniform response at each angle throughout the sector scan of plus or minus 45 degree . Examination of linear array transducers showed reduced transmit pressure and receive sensitivity at angles beyond plus or minus 20 degree by individual array elements. The angular response of piezoelectric elements, many wavelengths long and approximately one wavelength or less in width, do not agree with the predictions of simple diffraction theory for plane apertures. Continuous wave (CW) angular response measurements using the RCA Ultrasonovision of individual piezoelectric elements 0. 6 lambda to 2 lambda wide indicated this behavior was independent of inter-element coupling and pulse excitation effects within a linear array transducer.
