With linear phased array the width of each element is _______ of the sounds wavelength.

• A. 1/2 to 1
• B. 1/8 to 1/4
• C. 1 to 2
• D. 1/4 to 1/2

Answer: (D)

In a linear phased array, the width of each element is chosen as a fraction of the sound wavelength to shape the beam and enable steering. A width around one-quarter to one-half of the wavelength provides a practical balance: it keeps the aperture large enough to produce a fairly narrow main beam (good lateral resolution) and maintains control over unwanted artifacts when steering the beam. If the element were much smaller than this range, the aperture would be too small, broadening the beam and reducing resolution. If the element were much larger, steering can introduce grating lobes and image degradation. So the typical, effective range is one-quarter to one-half of the wavelength.