Subdicing reduces grating lobes by subdividing the element.

• A. Reduces grating lobes
• B. Increases grating lobes
• C. Has no effect on grating lobes
• D. Causes random lobes

Answer: (A)

Grating lobes come from the periodic spacing of radiating elements: when the center-to-center spacing is larger than about half a wavelength in the medium, additional maxima appear at angles away from the main beam. Subdividing a single element into many smaller subelements and driving them together effectively makes the aperture denser, lowering the spacing between emitting sources. With this reduced spacing (below half a wavelength), those off-axis maxima are suppressed, so the energy stays concentrated in the main beam. Subdicing also smooths the aperture distribution, reducing the tendency to form periodic sidelobes. So, this technique reduces grating lobes rather than increasing them or having no effect.