How does a phased array transducer achieve electronic steering without mechanical movement?

• A. Uses a mechanical paddle to steer the beam.
• B. Applies time-delayed excitation to each element to steer electronically.
• C. Changes the frequency of all elements to steer.
• D. Requires moving transducer to steer.

Answer: (B)

Electronic steering relies on timing. A phased array has many small elements. By applying deliberate delays to when each element is excited, the emitted waves from all elements interfere constructively in a tilted direction. Those delays effectively tilt the wavefront so the main beam points off-axis without moving the transducer itself. This fast, electronic control lets the system steer the beam across a sector and even dynamically focus as it scans.

Changing the frequency of all elements would alter wavelength and imaging depth/resolution, not the beam’s direction. Moving parts like a mechanical paddle would physically reposition the transducer, which is not how electronic steering is achieved.