What type of transducer could you choose to produce a beam that is symmetrical about the beam axis?

• A. A Annular array
• B. B Linear sequenced array
• C. C Phased array
• D. D Curved array

Answer: (A)

A circularly symmetric aperture is needed to produce a beam that is symmetrical around the beam axis. An annular array uses concentric rings around a common center, so energy is arranged in a rotationally symmetric way. With proper timing delays, these rings focus energy along the central axis and maintain that symmetry in all radial directions.

Other designs don’t start from a circular aperture: a linear sequenced array sits along a straight line, giving a beam that is elongated and fan-shaped rather than circularly symmetric. A phased array can steer and focus using many elements, but the typical rectangular or non-circular aperture means the resulting beam isn’t inherently symmetric about the axis. A curved array follows a curved line, producing a beam shape tied to that geometry and not the full rotational symmetry of a circular aperture.