At a given frequency, a smaller diameter transducer produces which type of beam?

• A. Less Divergent Beam
• B. More Divergent Beam
• C. Same Divergence
• D. Narrower Bandwidth

Answer: (B)

Beam divergence is governed by diffraction from the transducer’s aperture. At a fixed frequency, the wavelength is fixed, so the way the beam spreads depends on the size of the active element. A smaller diameter transducer acts like a smaller aperture, causing the ultrasound to diffract more and spread out into a wider angle. That means the beam is more divergent. A larger diameter would Direct more of the energy into a narrower, more collimated beam. The bandwidth isn’t determined by the diameter in this straightforward view, so the key effect here is the diffraction-driven increase in divergence when the diameter decreases.