Which transducer type forms the beam by firing most or all elements at once with small time differences to focus and steer the beam?

• A. Linear segmental array
• B. Convex array
• C. Annular array
• D. Phased array

Answer: (D)

Electronic beamforming relies on applying precise time delays across the array elements so their emitted waves interfere constructively in a chosen direction and at a chosen depth. In a phased array, nearly all elements are fired with small, carefully controlled delays. Those delays create a tilted wavefront for steering in the imaging plane and a curved delay pattern to focus at a specific depth. The beam can be steered and focused electronically without moving the transducer, which is the defining capability of this transducer type. Other designs rely more on fixed geometry or mechanical motion, whereas the described method—exciting many elements at once with inter-element delays to shape and direct the beam—is the hallmark of a phased array.