OPTICALLY GENERATED TRUE-TIME DELAY IN PHASED-ARRAY ANTENNAS

This tutorial review paper deals with various methods for solving a ba sic problem of wideband phased arrays, i.e. beam squinting, using opti cal technologies. The problem of beam squinting in phased arrays is an alyzed and the concept of true-time delay is introduced. The advantage s of realizing variable delay hues by optical rather than by microwave means are reviewed, together with principles of operation. Among the techniques described are switched-path length delay lines, fiber stret chers, tunable lasers with highly dispersive fiber, and coherent techn iques incorporating dispersive delay. Recent experimental results are discussed in the light of practical system requirements.