Wideband antenna array beam steering with free-space optical true-time delay engine

A 6-12 GHz Vivaldi wideband antenna array made of four sub-arrays (two elements per sub-array) was built to steer the beam with a White cell optical true-time delay (OTTD) engine. The OTTD engine was simulated to produce delays with a time delay increment of 25 ps. The beam is then steered combining the simulated OTTD delays and the measured mutual coupling of a Vivaldi array to a maximum scan angle of ±50°. The results demonstrate that the effect of optical losses and mutual coupling effects of the combined beam steering system is not negligible and must be carefully accounted for when implementing frequency-independent TTD beam steering systems.