Annular phased arrays are also known as _______.

Annular phased arrays are also known as _______.

• A. Multi-focus
• B. Single-focus
• C. Wide-beam
• D. Dual-focus

Answer: (A)

Annular phased arrays are designed to create several focus points along the imaging axis by using multiple concentric rings, each with its own phase delay. This arrangement lets the beam be focused at different depths without moving the transducer, producing multiple focal regions in one shot. That multi-focal capability is why the term multi-focus fits best. A single-focus system would be limited to one depth of focus, while a dual-focus implies only two foci, and a wide-beam describes a broad, unfocused pattern—neither of which captures the flexible, multiple-foci behavior of annular phased arrays.

Annular phased arrays are designed to create several focus points along the imaging axis by using multiple concentric rings, each with its own phase delay. This arrangement lets the beam be focused at different depths without moving the transducer, producing multiple focal regions in one shot. That multi-focal capability is why the term multi-focus fits best. A single-focus system would be limited to one depth of focus, while a dual-focus implies only two foci, and a wide-beam describes a broad, unfocused pattern—neither of which captures the flexible, multiple-foci behavior of annular phased arrays.