Which transducer has the same distance between the scan lines in both the near and far fields?

Which transducer has the same distance between the scan lines in both the near and far fields?

• A. Convex array
• B. Curvilinear array
• C. Linear array
• D. Phased array

Answer: (C)

The spacing between scan lines is determined by the geometry of the transducer and how its beams are arranged. A linear array uses a flat, straight row of evenly spaced elements, so the beams it produces are parallel and maintain a fixed angular spacing. That uniform beam geometry means the distance between adjacent scan lines stays the same as you move from the near field into the far field—the line spacing does not change with depth. Curved or curvilinear/convex arrays have footprints that bend, causing beams to fan out as depth increases. This fan effect makes adjacent scan lines spread further apart in the far field, so their spacing is not constant with depth. Phased arrays can steer beams electronically, which also introduces variations in line spacing with depth depending on steering, rather than keeping it perfectly uniform. So, the transducer whose scan-line spacing remains constant from near to far field is the linear array.

The spacing between scan lines is determined by the geometry of the transducer and how its beams are arranged. A linear array uses a flat, straight row of evenly spaced elements, so the beams it produces are parallel and maintain a fixed angular spacing. That uniform beam geometry means the distance between adjacent scan lines stays the same as you move from the near field into the far field—the line spacing does not change with depth.

Curved or curvilinear/convex arrays have footprints that bend, causing beams to fan out as depth increases. This fan effect makes adjacent scan lines spread further apart in the far field, so their spacing is not constant with depth. Phased arrays can steer beams electronically, which also introduces variations in line spacing with depth depending on steering, rather than keeping it perfectly uniform.

So, the transducer whose scan-line spacing remains constant from near to far field is the linear array.