Which approach activates groups of elements in a sequence to scan the image?

• A. Sequenced array
• B. Phased array
• C. Synthetic aperture
• D. Dual-antenna

Answer: (A)

Activating groups of elements in sequence across the transducer is the idea behind a sequenced array. Here, a small subset of adjacent elements is fired to form one beam (a sub-aperture), and then the active group steps to the next position to produce the next beam. By sweeping the sub-aperture along the array, you scan across the image line by line to create the full frame. This approach keeps the channel count lower and can balance frame rate with resolution.

This differs from a phased array, which uses timing delays across a large number of elements to steer and focus the beam without changing which elements are active. It also differs from synthetic aperture, which builds a larger effective aperture by combining information from many transmit events to improve resolution, and from dual-antenna setups that use two separate transducers rather than sequentially activating groups within one array.