What is the purpose of null steering in array antennas?

• A. Randomizes the beam pattern to confuse attackers.
• B. Creates deep nulls in the radiation pattern toward jammer directions to minimize interference to the receiver.
• C. Avoids use of antennas in EW.
• D. Increases antenna gain uniformly in all directions.

Answer: (B)

Null steering uses an array antenna to shape its radiation pattern by adjusting the relative phase and amplitude of signals from each element. By choosing those weights, the pattern is made to have deep nulls in specific directions where interference or jammers are located. This suppression reduces the energy from the jammer reaching the receiver, improving the signal quality from the desired direction. It leverages destructive interference in the jammer directions while preserving or steering gain toward the intended target. This is fundamentally about interference rejection, not about randomly changing patterns, avoiding antennas, or boosting gain everywhere—actions that would either fail to suppress the jammer or simply amplify interference.