Time‐modulated multibeam steered antenna array synthesis with optimally designed switching sequence

Abstract

SummarySteering the radiation pattern of an antenna array towards the desired spatial angle is beneficial for modern‐age communication systems. The generation of multiple steered patterns by enhancing the first‐order harmonics of a time‐modulated antenna array (TMAA) with controlled radiation features is proposed in this paper. Suitable switching sequences are designed to realize an efficient electronic beam steering with these simultaneously generated narrow directional beam patterns. TMAAs are considered the time‐domain counterparts of phased arrays where high‐speed switches are used to achieve a weighted response by periodically modulating the array elements instead of attenuators or phase shifters. This periodic modulation inherently produces spurious harmonic patterns generally considered as power loss in unintended directions. The beam steering aimed in this paper is accomplished by exploiting the first‐order harmonic patterns in some specific directions keeping the fundamental pattern unaltered. The intended first positive and first negative harmonic components of the TMAA are utilized as steered multibeam patterns, whereas all the remaining harmonic components are suppressed to improve the efficiency of the array. To achieve this, suitable switching sequences are designed by optimizing the ON‐time duration and switching intervals of the elements with a wavelet mutation‐based particle swarm optimization (PSOWM). 16‐element linear TMAA is used to generate the desired patterns with low sidelobe levels (SLLs) for enhanced performance. Numerical results obtained for spatially independent steered patterns are presented and compared with the state‐of‐the‐art literature results.