To reduce beam divergence, increasing transducer diameter will have which effect?

To reduce beam divergence, increasing transducer diameter will have which effect?

• A. Increase divergence
• B. Decrease divergence
• C. No change
• D. Depends on frequency

Answer: (B)

Beam divergence is mainly determined by diffraction from the transducer’s aperture. A larger aperture acts like a more directional antenna, narrowing the diffraction pattern. Since the beam’s angular spread is roughly set by wavelength divided by diameter, increasing the diameter lowers this ratio, making the beam less spread out. So the beam becomes more collimated and divergence decreases, improving lateral directivity and resolution.

Beam divergence is mainly determined by diffraction from the transducer’s aperture. A larger aperture acts like a more directional antenna, narrowing the diffraction pattern. Since the beam’s angular spread is roughly set by wavelength divided by diameter, increasing the diameter lowers this ratio, making the beam less spread out. So the beam becomes more collimated and divergence decreases, improving lateral directivity and resolution.