Which artifact can be reduced by subdicing and apodization?

Which artifact can be reduced by subdicing and apodization?

• A. Grating lobes
• B. Mirror image
• C. Multipath
• D. Noise

Answer: (A)

Grating lobes arise from the regular spacing of elements in an array and show up as unwanted secondary beams at certain angles, which can create ghost structures in an image. Subdicing breaks each large element into smaller subelements, disrupting the uniform periodicity that gives rise to those secondary beams and reducing their strength. Apodization, by applying a taper to the excitation across the aperture, lowers the energy from the outer portions of the array, further suppressing far-field side lobes including grating lobes. The combined effect is a cleaner beam with fewer ghost artifacts, which is precisely what subdicing and apodization aim to achieve. Other artifacts like mirror images, multipath, or noise have different causes and are not primarily addressed by these techniques.

Grating lobes arise from the regular spacing of elements in an array and show up as unwanted secondary beams at certain angles, which can create ghost structures in an image. Subdicing breaks each large element into smaller subelements, disrupting the uniform periodicity that gives rise to those secondary beams and reducing their strength. Apodization, by applying a taper to the excitation across the aperture, lowers the energy from the outer portions of the array, further suppressing far-field side lobes including grating lobes. The combined effect is a cleaner beam with fewer ghost artifacts, which is precisely what subdicing and apodization aim to achieve. Other artifacts like mirror images, multipath, or noise have different causes and are not primarily addressed by these techniques.