Adaptive nulling in time-modulated antenna arrays

A flexible approach based on a hybrid differential evolution strategy (HDES) is developed for adaptive pattern nulling with time modulated linear antenna arrays. The HDES adjusts the least significant bits of the digital phase shifters and the on-off time sequence to minimize the total output power, deep nulls can then be placed in the direction of the interferences. Thanks to the new design freedom introduced in time modulated antenna arrays, this adaptive nulling approach exhibits better performance over the traditional phase-only, amplitude-only, and phase-amplitude adaptive nulling methods, in terms of the practical implementation, nulling depth, and pattern deterioration. Several representative examples are presented to show the effectiveness of the proposed adaptive nulling approach.