Sensitivity of the Adaptive Nulling to Random Errors in Amplitude and Phase Excitations in Array Elements

Abstract

Adaptive antenna arrays have shown their effectiveness and powerful capabilities in modern communication and radar systems. However, maintaining this effectiveness under conditions of random errors in their element excitations is the most challenging problem. In this paper, the degradation in performance, exhibited as the elevation in the sidelobe level and changing the angular locations of the desired nulls, due to random errors in the phase and amplitude of the element excitations is investigated. First, an efficient constrained optimization approach was used to synthesize an adaptive linear array. The approach maximizes the gain in the desired direction and rejects undesired interfering signals by placing nulls towards their angles of arrivals. Then, the effects of random amplitude and phase errors in the element excitations were investigated. Simulation results showed that the nulls and the sidelobe level in the adaptive arrays are more sensitive to random errors in element phase excitations as compared to amplitude excitations.