Which term describes the deliberate reduction of sidelobes by varying element amplitudes across the array?

Which term describes the deliberate reduction of sidelobes by varying element amplitudes across the array?

• A. Dynamic aperture
• B. Apodization
• C. Interelement isolation
• D. Subdicing

Answer: (B)

Apodization is the deliberate shaping of the array’s amplitude excitation to suppress sidelobes. By tapering how strongly each element is fed—from the center toward the edges—the interference pattern changes so the energy that would form high sidelobes is reduced. This is like windowing a signal: using a tapered window (such as Hamming, Hann, or Blackman) lowers the sidelobe levels in the radiation pattern, though it often broadens the main lobe slightly and may reduce peak gain. Other terms don’t describe this weighting of element amplitudes to control sidelobes. Dynamic aperture involves time-varying or synthesized aperture size, not a static amplitude taper. Interelement isolation deals with reducing mutual coupling between elements, not shaping the pattern via amplitude tapering. Subdicing refers to subdividing elements, typically to affect bandwidth or impedance, rather than applying a deliberate amplitude taper across the array.

Apodization is the deliberate shaping of the array’s amplitude excitation to suppress sidelobes. By tapering how strongly each element is fed—from the center toward the edges—the interference pattern changes so the energy that would form high sidelobes is reduced. This is like windowing a signal: using a tapered window (such as Hamming, Hann, or Blackman) lowers the sidelobe levels in the radiation pattern, though it often broadens the main lobe slightly and may reduce peak gain.

Other terms don’t describe this weighting of element amplitudes to control sidelobes. Dynamic aperture involves time-varying or synthesized aperture size, not a static amplitude taper. Interelement isolation deals with reducing mutual coupling between elements, not shaping the pattern via amplitude tapering. Subdicing refers to subdividing elements, typically to affect bandwidth or impedance, rather than applying a deliberate amplitude taper across the array.